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Changes in body composition in triathletes during an Ironman race
Abstract
Purpose:
Triathletes lose body mass during an Ironman triathlon. However, the associated body composition changes remain enigmatic. Thus, the purpose of this study was to investigate Ironman-induced changes in segmental body composition, using for the first time dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT).
Methods:
Before and after an Ironman triathlon, segmental body composition and lower leg tissue mass, areas and densities were assessed using DXA and pQCT, respectively, in eight non-professional male triathletes. In addition, blood and urine samples were collected for the determination of hydration status.
Results:
Body mass decreased by 1.9 ± 0.8 kg. This loss was due to 0.4 ± 0.3 and 1.4 ± 0.8 kg decrease in fat and lean mass, respectively (P < 0.01). Calf muscle density was reduced by 1.93 ± 1.04 % (P < 0.01). Hemoglobin, hematocrit, and plasma [K(+)] remained unchanged, while plasma [Na(+)] (P < 0.05), urine specific gravity and plasma and urine osmolality increased (P < 0.01).
Conclusions:
The loss in lean mass was explained by a decrease in muscle density, as an indicator of glycogen loss, and increases in several indicators for dehydration. The measurement of body composition with DXA and pQCT before and after an Ironman triathlon provided exact values for the loss in fat and lean mass. Consequently, these results yielded more detailed insights into tissue catabolism during ultra-endurance exercise.
... Indeed, it has been recently argued that BW losses between 1.9-5% seem advisable to sustain body water balance and maintain euhydration during ultramarathons lasting for approximately 25-30 h (Hoffman et al., 2018). In that line, Mueller et al. (2013) demonstrated that BW loss following an Ironman was due to a 28% loss in fat mass and a 72% loss in lean body mass, the latter being attributable to a loss of glycogen, as fuel for energy production, and the corresponding loss of body water. Therefore, considering the results from Mueller et al. (2013) and the positive correlations found between SPEEDABS and SPEEDVT2 with relative BW at those race segments where BW loss was greater (i.e., the first and the last section of the race, Figure 4), it seems that intracompetition BW loss during MUMs mainly reflect energy expenditure and it is indicative of superior performance (Landman et al., 2012;Martinez-Navarro et al., 2018;Mueller et al., 2013). ...
... In that line, Mueller et al. (2013) demonstrated that BW loss following an Ironman was due to a 28% loss in fat mass and a 72% loss in lean body mass, the latter being attributable to a loss of glycogen, as fuel for energy production, and the corresponding loss of body water. Therefore, considering the results from Mueller et al. (2013) and the positive correlations found between SPEEDABS and SPEEDVT2 with relative BW at those race segments where BW loss was greater (i.e., the first and the last section of the race, Figure 4), it seems that intracompetition BW loss during MUMs mainly reflect energy expenditure and it is indicative of superior performance (Landman et al., 2012;Martinez-Navarro et al., 2018;Mueller et al., 2013). ...
... In that line, Mueller et al. (2013) demonstrated that BW loss following an Ironman was due to a 28% loss in fat mass and a 72% loss in lean body mass, the latter being attributable to a loss of glycogen, as fuel for energy production, and the corresponding loss of body water. Therefore, considering the results from Mueller et al. (2013) and the positive correlations found between SPEEDABS and SPEEDVT2 with relative BW at those race segments where BW loss was greater (i.e., the first and the last section of the race, Figure 4), it seems that intracompetition BW loss during MUMs mainly reflect energy expenditure and it is indicative of superior performance (Landman et al., 2012;Martinez-Navarro et al., 2018;Mueller et al., 2013). ...
The study was aimed at comparing pacing adopted by males and females in a 107-km mountain ultramarathon and assessing whether pacing-related variables were associated with intracompetition body weight changes and performance. Forty-seven athletes (29 males; 18 females) were submitted to a cardiopulmonary exercise test before the race. Athletes were also weighted before the start of the race, at three midpoints (33 km, 66 km and 84 km) and after the race. Pacing was analyzed using absolute and relative speeds and accelerometry-derived sedentary time spent during the race. Results showed that females spent less sedentary time (4.72 ± 2.91 vs. 2.62 ± 2.14%; p = 0.035; d = 0.83) and displayed a smaller body weight loss (3.01 ± 1.96 vs. 4.37 ± 1.77%; p = 0.048; d = 0.77) than males. No significant sex differences were revealed for speed variability, absolute and relative speed. In addition, finishing time was correlated with: speed variability (r = 0.45; p = 0.010), index of pacing (r = -0.63; p < 0.001) and sedentary time (r = 0.64; p < 0.001). Meanwhile, intracompetition body weight changes were related with both the absolute and relative speed in the first and the last race section. These results suggest that females, as compared with males, take advantage of shorter time breaks at aid stations. Moreover, performing a more even pacing pattern may be positively associated with performance in mountain ultramarathons. Finally, intracompetition body weight changes in those races should be considered in conjunction with running speed fluctuations.
... A loss in body mass in a single Ironman triathlon [50,51] and an ultra-triathlon [52][53][54][55] is a common finding where the loss in body mass in an Ironman triathlon is related to a loss in skeletal muscle mass [50]. This loss in muscle mass is due to depletion in muscle glycogen stores [50]. ...
... A loss in body mass in a single Ironman triathlon [50,51] and an ultra-triathlon [52][53][54][55] is a common finding where the loss in body mass in an Ironman triathlon is related to a loss in skeletal muscle mass [50]. This loss in muscle mass is due to depletion in muscle glycogen stores [50]. ...
... A loss in body mass in a single Ironman triathlon [50,51] and an ultra-triathlon [52][53][54][55] is a common finding where the loss in body mass in an Ironman triathlon is related to a loss in skeletal muscle mass [50]. This loss in muscle mass is due to depletion in muscle glycogen stores [50]. In ultra-endurance triathletes competing in longer races than an Ironman triathlon, mainly body fat is lost. ...
This case study analyzed performance, pacing and potential predictors in a self-paced world record attempt of a professional triathlete to finish 40 Ironman triathlons within 40 days. Split times (swimming, cycling, running) and overall times, body weight, daily highest temperature, wind speed, energy expenditure, mean heart rate, and sleeping time were recorded. Non-linear regressions were applied to investigate changes in split and overall times. Multivariate regression analyses were performed to test which variables showed the greatest influence on the dependent variables cycling, running and overall time. The athlete completed the 40xIronman distances in a total time of 444:22 h:min. He invested 50:26 h:min in swimming, 245:37 h:min in cycling, 137:17 h:min in running and 11:02 h:min in transition times. Performance in swimming and cycling became reduced over the days, whereas running performance improved until the 20th day and became reduced to the 40th day. Overall time decreased until the 15th day, improved up to 31st, and started then to decrease until the end. Wind speed, overall time on the previous day and average heart race during cycling were significant independent variables to influence cycling performance. Body weight and average heart rate during running were the significant independent variables to influence running performance. Cycling performance, running performance and body weight were the significant independent variables to influence overall time. In summary, running performance was influenced by body weight, cycling was influenced by wind speed and overall time was influenced by both running and cycling performances.
Keywords: swimming; cycling; running; ultra-endurance; recovery
... Most studies used fan beam systems (Lunar iDXA, Prodigy or Hologic Discovery, Hologic Explorer) and four studies used pencil beam technology (Lunar DPX-L, and Norland XR800) [10,12,15,34]. Fourteen studies were published between 1980 and 2013 [10][11][12][34][35][36][37][38][39][40][41][42][43][44] and eleven studies between 2014 and 2016 [13][14][15][16][17][45][46][47][48][49][50]. The duration of follow-up ranged from pre and post a sports event months [12,39]. ...
... The duration of follow-up ranged from pre and post a sports event months [12,39]. There were fourteen studies with two testing points [10,13,[34][35][37][38][40][41][42][43][44][45][46][48][49] and nine with three or more testing points [11][12][14][15][16][17]37,39,[47][48]. ...
... Three of the studies were conducted in female athletes, [35,41,46] twelve in male athletes [11][12][14][15][16][17]34,36,44,[48][49][50] and ten studied male and female athletes [10,13,37,[39][40][41]43,45,47]. Sample sizes varied from n=1 [51] to n=212 [47] and mean age ranged from 15.5 [37] to 43.8 years [44]. ...
Dual energy X-ray absorptiometry (DXA) is a medical imaging device which has become the method of choice for the measurement of body composition in athletes. The objectives of this review were to evaluate published longitudinal DXA body composition studies in athletic populations for interpretation of 'meaningful' change, and to propose a best practice measurement protocol. An online search of PubMed and CINAHL via EBSCO Host and Web of Science enabled the identification of studies published until November 2016. Those which met the inclusion criteria were reviewed independently by two authors according to their methodological quality and interpretation of body composition change. Twenty-five studies published between 1996 and November 2016 were reviewed (male athletes: 13, female athletes: 3, mixed: 9) and sample sizes ranged from n = 1 to 212. The same number of eligible studies were published between 2013 - 2016, as over the 16 years prior (1996 - 2012). Seven did not include precision error, and fewer than half provided athlete-specific precision error. There were shortfalls in the sample sizes on which precision estimates were based and inconsistencies in the level of pre-scan standardisation, with some reporting full standardisation protocols and others reporting only single (e.g. overnight fast) or no control measures. There is a need for standardised practice and reporting in athletic populations for the longitudinal measurement of body composition using DXA. Based on this review and that of others, plus the official position of the International Society for Clinical Densitometry, our recommendations and protocol are proposed as a guide to support best practice.
... Of interest, the nature of the event (continuous or multistage) seems to dictate these effects. In general, continuous triathlons reduce body mass, fat mass, and lean mass (Knechtle et al. 2008a(Knechtle et al. , 2010a with losses in lean mass being primarily explained by reductions in muscle glycogen (Mueller et al. 2013). Conversely, during multistage events where athletes likely replenish glycogen stores overnight, lean mass is seemingly spared while body mass is commonly found to be unchanged (Knechtle et al. 2008b(Knechtle et al. , 2009a or even increased (Raschka and Plath 1992). ...
... In continuous events without overnight breaks, FFM is often reported to be reduced (Helge et al. 2003;Knechtle and Kohler 2007;Knechtle et al. 2008a). Indeed, a recent study by Mueller et al. (2013) reported that these reductions are likely the result of muscle glycogen depletion (Mueller et al. 2013). In races with defined rest periods, athletes likely replenish glycogen stores overnight thus maintaining FFM (Burke et al. 1996). ...
... In continuous events without overnight breaks, FFM is often reported to be reduced (Helge et al. 2003;Knechtle and Kohler 2007;Knechtle et al. 2008a). Indeed, a recent study by Mueller et al. (2013) reported that these reductions are likely the result of muscle glycogen depletion (Mueller et al. 2013). In races with defined rest periods, athletes likely replenish glycogen stores overnight thus maintaining FFM (Burke et al. 1996). ...
Purpose:
The primary purpose of this investigation was to determine the effects of participation in a 3-day multistage ultraendurance triathlon (stage 1 = 10 km swim, 144.8 km bike; stage 2 = 275.4 km bike; stage 3 = 84.4 km run) on body mass and composition, hydration status, hormones, muscle damage, and blood glucose.
Methods:
Eighteen triathletes (mean ± SD; age 41 ± 7.5 years; height 175 ± 9 cm; weight 73.5 ± 9.8 kg; male n = 14, female n = 4) were assessed before and after each stage of the race. Body mass and composition were measured via bioelectrical impedance, hydration status via urine specific gravity, hormones and muscle damage via venous blood draw, and blood glucose via fingerstick.
Results:
Following the race, significant changes included reductions in body mass (qualified effect size: trivial), fat mass (moderate), and percent body fat (small); increases in percent total body water (moderate) and urine specific gravity (large); and unchanged absolute total body water and fat-free mass. There were also extremely large increases in creatine kinase, C-reactive protein, aldosterone and cortisol combined with reductions in testosterone (small) and the testosterone:cortisol ratio (moderate). There were associations between post-race aldosterone and total body water (r = -0.504) and changes in cortisol and fat-free mass (r = -0.536). Finally, blood glucose increased in a stepwise manner prior to each stage.
Conclusions:
Participation in Ultraman Florida leads to fluid retention and dramatic alterations in body composition, muscle health, hormones, and metabolism.
... 34 Similarly, becoming an Ironman triathlon leads to a decrease in body mass, [35][36][37][38][39][40] where both fat mass and lean body mass decrease during the race. 41 However, differences seem to exist between women and men. While body mass decreased in male Ironman triathletes, 39,41 it remained unchanged in female athletes. ...
... 41 However, differences seem to exist between women and men. While body mass decreased in male Ironman triathletes, 39,41 it remained unchanged in female athletes. 42 Most probably, the body's own stores are needed as fuel during the race. ...
... Participating in an Ironman triathlon leads to a considerable energy deficit, 36,43,44 which seems to be covered by a decrease in muscle glycogen. 36,41 In ultra-triathlon competition, the energy deficit is most probably covered by a reduction in adipose subcutaneous tissue. [30][31][32] For Triple Iron ultra-triathletes, the decrease in percent body fat was inversely associated with race time. ...
Objective
This narrative review summarizes recent intentions to find potential predictor variables for ultra-triathlon race performance (ie, triathlon races longer than the Ironman distance covering 3.8 km swimming, 180 km cycling, and 42.195 km running). Results from studies on ultra-triathletes were compared to results on studies on Ironman triathletes.
Methods
A literature search was performed in PubMed using the terms “ultra”, “triathlon”, and “performance” for the aspects of “ultra-triathlon”, and “Ironman”, “triathlon”, and “performance” for the aspects of “Ironman triathlon”. All resulting papers were searched for related citations. Results for ultra-triathlons were compared to results for Ironman-distance triathlons to find potential differences.
Results
Athletes competing in Ironman and ultra-triathlon differed in anthropometric and training characteristics, where both Ironmen and ultra-triathletes profited from low body fat, but ultra-triathletes relied more on training volume, whereas speed during training was related to Ironman race time. The most important predictive variables for a fast race time in an ultra-triathlon from Double Iron (ie, 7.6 km swimming, 360 km cycling, and 84.4 km running) and longer were male sex, low body fat, age of 35–40 years, extensive previous experience, a fast time in cycling and running but not in swimming, and origins in Central Europe.
Conclusion
Any athlete intending to compete in an ultra-triathlon should be aware that low body fat and high training volumes are highly predictive for overall race time. Little is known about the physiological characteristics of these athletes and about female ultra-triathletes. Future studies need to investigate anthropometric and training characteristics of female ultra-triathletes and what motivates women to compete in these races. Future studies need to correlate physiological characteristics such as maximum oxygen uptake (VO2max) with ultra-triathlon race performance in order to investigate whether these characteristics are also predictive for ultra-triathlon race performance.
... Body composition changes during an Ironman are well investigated. These changes comprise fluid loss (Hiller et al. 1987), glycogen depletion (Gillum et al. 2006;Knechtle et al. 2010) and decreases in fat mass (Mueller et al. 2013). Contrary to these investigations, comprehensive data on the changes in neuromuscular performance are scarce. ...
... All experiments were approved by the ethics committee of the canton of Zurich (Switzerland), and the study was performed in accordance with the ethical standards laid down in the Declaration of Helsinki for human experimentation. Eight of these athletes also participated in our study, in which we investigated the changes in body composition after an Ironman race (Mueller et al. 2013). ...
... These results are supported by the impaired rate of Fig. 2 Pre and post Ironman results for countermovement jump a jump height, b peak force, c peak velocity, and d peak power for each participant force development after the Ironman. The reduced rate of force development might be attributed to glycogen depletion after the Ironman competition (Mueller et al. 2013), whereby glycogen content below a critical level is associated with reductions in sarcoplasmatic reticulum vesicle Ca 2+ release rate in endurance athletes (Gejl et al. 2014). ...
An Ironman triathlon is associated with changes in body composition as well as decreases in neuromuscular function. While the changes in body composition occurring during an Ironman are well investigated, comprehensive data on the changes in neuromuscular performance are scarce. In the present study, we investigated the mechanical alterations underlying reported reductions in maximal muscular force and power after an Ironman race in men.
Before and directly after an Ironman, countermovement jump (CMJ), squat jump (SJ), and multiple one-legged hopping (m1LH) maneuvers were performed to assess fatigue-related alterations in mechanical variables in thirteen male non-professional triathletes.
During CMJ, peak power (P = 0.003), peak velocity (P < 0.001), jump height (P = 0.007), and rate of force development (P = 0.042) decreased during the Ironman. Total (P < 0.001) and positive (P = 0.003) impulses during a CMJ were reduced after the triathlon, while both negative impulses did not differ pre to post Ironman. Absolute peak force remained constant during CMJ (P = 0.200) and SJ (P = 0.764). Maximal voluntary ground reaction force (F m1LH, P < 0.001) and peak stiffness (P = 0.003) during m1LH were decreased after the Ironman.
The reduced CMJ height was a result of the lower positive impulse. Therefore, the neuromuscular deficit after the Ironman race was due to impairments in force transmission, resulting in a lower average positive force during CMJ, because of a slower rate of force development. The decreased F m1LH could be partly explained by reduced leg stiffness.
... In both events, body mass initially decreased until day 20 in Event 2 and day 30 in Event 3. Body mass remained low in Event 2 but increased in Event 3 after day 30 to reach the initial value of ∼77 kg by the end. A decrease in body mass generally occurs during a single IRONMAN ® triathlon (56)(57)(58) and also during multi-stage Ironman-distance triathlon events (23, 32,59). The decrease in body mass during a single IRONMAN ® triathlon is most likely due to dehydration (60) and body water loss (56, 57) but can also be due to a loss in solid mass (58,61). ...
... This loss in solid mass Mean daily results of sleep duration, body mass, cycling, and running heart rate for event 3 (60 ironman triathlons in 60 days) with the corresponding linear regressions and correlation coefficients. Frontiers in Sports and Active Living occurs especially of the lower limbs (57, 61) due to glycogen depletion in the leg muscles (57,58). The decrease or increase in body mass during a multi-stage event such as a multi-stage Ironman-distance triathlon is most likely due to a change in both solid mass and total body water. ...
Background
Triathletes are pushing their limits in multi-stage Ironman-distance triathlons. In the present case study, we investigated the pacing during 20, 40, and 60 Ironman-distance triathlons in 20, 40, and 60 days, respectively, of one professional IRONMAN® triathlete.
Case study
Event 1 (20 Ironman-distance triathlons in 20 days), Event 2 (40 Ironman-distance triathlons in 40 days), and Event 3 (60 Ironman-distance triathlons in 60 days) were analyzed by discipline (swimming, cycling, running, and overall event time), by Deca intervals (10 days of consecutive Ironman-distance triathlons) and additional data (sleep duration, body mass, heart rate in cycling and running). To test differences between Events and Deca intervals within the same discipline, T-tests (2 groups) or one-way ANOVAs (3 or more groups) were used.
Results
Swimming splits were fastest in Event 1, (ii) cycling and running splits were fastest in both Event 2 and 3, (iii) overall speed was fastest in Event 3, (iv) sleep duration increased during Event 2 but decreased in Event 3, (v) body mass decreased in Event 2, but increased in Event 3 and (vi) heart rate during cycling was similar in both Event 2 and 3. In contrast, heart rate during running was greater in Event 3.
Conclusion
In a professional IRONMAN® triathlete finishing 20, 40, and 60 Ironman-distance triathlons in 20, 40, and 60 days, respectively, split performances and both anthropometrical and physiological changes such as body mass and heart rate differed depending upon the duration of the events.
... A body mass loss of up to 3% is tolerated by well-trained triathletes during an Ironman competition in warm conditions without any evidence of thermoregulatory failure [45]. However, a loss in solid mass is due to a decrease in both fat and lean mass [48]. The loss in lean mass was explained by a decrease in muscle density, as an indicator of glycogen loss, and increases in several indicators for dehydration (i.e., hematocrit, hemoglobin, electrolytes, urine-specific gravity, and urine osmolality) [48]. ...
... However, a loss in solid mass is due to a decrease in both fat and lean mass [48]. The loss in lean mass was explained by a decrease in muscle density, as an indicator of glycogen loss, and increases in several indicators for dehydration (i.e., hematocrit, hemoglobin, electrolytes, urine-specific gravity, and urine osmolality) [48]. ...
The Ironman triathlon is a multi-sport event consisting of 3.8 km swimming, 180 km cycling, and 42.195 km running performed in this sequence. The order of the disciplines has an impact on the performance in the running split (i.e., the marathon). The cycling split seems to be the Ironman triathlon discipline that most improved overall race times during the last years and is also the discipline with the greatest influence on the overall race time of elite men and women in the Ironman World Championship, the “Ironman Hawaii.” Regarding race tactics in an Ironman triathlon, athletes should focus on saving energy during swimming and cycling for the running split (i.e., the marathon). In order to achieve the optimum performance in an Ironman triathlon, the athlete should specifically prepare for the race regarding training, mental preparation, and nutrition. Also, previous experience is of importance. Anthropometric characteristics (e.g., low body fat) are important for overall race time and the marathon split, especially in male Ironman triathletes. Individual marathon time is important for a fast Ironman race time and a faster running split.
... In contrast, % body fat did not significantly change; this apparent discrepancy was attributed to the decline in lean mass post exercise. (Mueller, Anliker, Knechtle, Knechtle, & Toigo, 2013) To date, the literature on DXA measured change in fat mass from an acute exercise bout appears modest. However, these studies enrolled normal weight active participants and did not report changes in visceral fat, which has high metabolic relevance. ...
... (Mittendorfer, Fields, & Klein, 2004) As previously reported, the effect of acute exercise in altering fat mass, as measured by DXA, is modest. (Hew-Butler et al., 2015;Mueller et al., 2013;Nana et al., 2013) Similarly, we observed that body fat, as measured by percent change or absolute change, was not altered by a 90 minute run at 60% HRR. We note that DXA may not be sufficiently sensitive to measure fat mass change from the exercise exposure. ...
Objectives:
Although physical activity ameliorates the metabolic impact of high body mass index (BMI), runners with BMI≥25 kg/m2 are relatively understudied.This study had two goals: 1) Identify differences in body composition, as measured by dual X-ray absorptiometry (DXA), between overweight (BMI≥25 kg/m2) runners (OWR) and normal weight (BMI<25 kg/m2) runners (NWR) and 2) Examine whether an 90 minute run alters total or regional fat mass, as measured by DXA, in OWR and NWR. We hypothesized that OWR would have higher total body fat than NWR and OWR with greater changes in visceral fat after a prolonged run.
Design:
Body composition analysis before and after a supervised run.
Methods:
We recruited NWR (n=16,F:n=7,28.1±1.4 years, BMI 22.0±0.4 kg/m2, results as mean±SE) and OWR (n=11,F:n=7,32.0±1.6 years, BMI 30.5±1.4kg/m2) participants. DXA based body composition was measured before and after a supervised, 90 minute run at 60% heart rate reserve.
Results:
OWR had higher body fat than NWR in all measured regions.. Both groups did not significantly reduce fat mass at any measured fat depots after the running exposure.
Conclusions:
OWR had higher body fat in all measured regions than NWR. DXA could not demonstrate any acute fat mass changes after a prolonged run.
... The high prevalence of dehydration after exercise detected by USG has been previously described in adolescent swimmers (9) , sports club members (8) , rugby players (21) , triathletes (12,19) and junior soccer players (7) . On the other hand, Hahn and Waldréus reported a state of euhydration in tennis players, cross-country runners and Muay Thai boxers before exercise (8) . ...
... In our study, despite the ad libitum fluid intake by participants during exercise, there was a high prevalence of post-exercise dehydration according to this parameter. Similar results have been found in studies with triathletes (2,12,19) . In addition, studies where the amount of fluid intake was restricted, it was also observed a loss of body mass by dehydration higher than 2% in amateur sports athletes (22) and indoor tennis players (13) . ...
Rowing is characterized by high physiological demands and environmental challenges.
The aim of this study was to assess hydration status of rowers before and after indoor and outdoor training conditions. Ten male competitive rowers (20 ± 4 years; 11 ± 2% of body fat; training 4h/day, 7 days/week, underwent two 16-km training sessions, one indoor (60 min) and one outdoor (80 min). Urine color (color chart), urine specific gravity (refractometer), body mass alterations, fluid intake and sweating rate were assessed before and after training sessions. Dehydration was present in at least 70% of athletes, before both training sessions, as measured by urine color and urine specific gravity. There was a body mass loss greater than 2% in 80% (indoor) and 70% (outdoor) of the rowers. Sweating rate was higher indoor (1.8 ± 0.7 L.h-1) as compared with outdoor (1.2 ± 0.4 L.h-1) (p = .016). The majority of the rowers start the morning training sessions hypohydrated and further dehydrated beyond 2% body mass due to sweating during both bouts. Sweating rate and body mass changes were higher after indoor training.
... The results of this present study show that an Olympic distance triathlon for non-professionals also produced metabolic stress and muscle damage, as well as lower performance levels in the vertical jump. The loss of body weight has been noted following a triathlon (Aragon-Vargas, Wilk, Timmons, & Bar-Or, 2013) and has been related to an indirect measurement of the degree of dehydration or to loss in lean mass by a decrease in muscle density, as an indicator of glycogen loss (Mueller, Anliker, Knechtle, Knechtle, & Toigo, 2013). ...
... In this study weight loss was also experienced following the triathlon, although without being as noteworthy as the effects following a half-ironman triathlon (Del Coso et al., 2014) or an Ironman (Mueller et al., 2013). Elevated temperature during the race might be one reason to increase dehydration in participants by losing fluid liquids, decreasing body weight and provoking blood concentration. ...
Given increasing popularity of triathlon, the objective of this study was to evaluate the acute effects upon the health of triathletes. To do so, with a sample of 23 male athletes (34.4 ± 7.9 years old), an assessment was carried out both before and after an Olympic distance triathlon, of the bodily composition, the jumping ability and the BORG and VAS scales, as well as a blood analysis of the following: Lactate (mmol/L), Hematrocrit (%), Glucose (mg/dL), Total proteins (mg/dL), Triglycerides (mg/dL), Bilirubin (mg/dL), GOT (IU/L), GPT (IU/L), LDH (IU/L), CPK (IU/L). The results showed an increase (p < 0.001) in the different markers of metabolic stress and muscular damage following the triathlon, but always within a normal range considered to be healthy, with the exception of CPK (IU/L) (PRE 149.33 ± 108.16 vs POST 290.10 ± 102.48). Therefore, it would seem that competing in an Olympic-distance triathlon does not pose health risks for trained subjects.
... Other reasons for the sex difference in performance could be different changes in body composition in women and men during an Ironman triathlon (38). Although male Ironman triathletes loose skeletal muscle mass during an Ironman triathlon (17) mainly due to a depletion of glycogen stores of the lower limbs (38), no change in body mass could be detected in female Ironman triathletes (24). ...
... Other reasons for the sex difference in performance could be different changes in body composition in women and men during an Ironman triathlon (38). Although male Ironman triathletes loose skeletal muscle mass during an Ironman triathlon (17) mainly due to a depletion of glycogen stores of the lower limbs (38), no change in body mass could be detected in female Ironman triathletes (24). ...
In Ironman triathlon, the number of overall male and female finishers increased in the last 30 years, while an improvement in performance has been reported. Studies concluding these numbers only analysed the top ten athletes per age group instead of all finishers, therefore a selection bias might have occurred. The aim of the present study was to investigate participation, performance and the age-related performance decline of all pro and age group triathletes ranked in all Ironman triathlons held worldwide between 2002 and 2015. Split and overall race times of 329,066 (80%) male and 81,815 (20%) female athletes competing in 253 different Ironman triathlon races were analysed. The number of finishers increased in all age groups with exception of women in age group 75-79 years. In pro athletes, performance improved in all disciplines. In age group athletes, performance improved in younger age groups for running (18-24 to 40-44 years) and older age groups for swimming (50-54 to 65-69 years) and cycling (35-39 to 55-59 years), while it impaired in younger age groups for swimming (18-24 to 45-49 years) and cycling (18-24 to 30-34), and older age groups in running (45-49 to 70-74 years). The age-related performance decline started in women in age group 25-29 years in swimming and in age group 30-34 years in cycling, running and overall race time, whereas it started in men in age group 25-29 years in swimming and in age group 35-39 years in cycling, running and overall race time. For athletes and coaches, performance improved in younger age groups for running and older age groups for swimming and cycling and the age-related decline in performance started earlier in swimming than in cycling and running.In summary, women should start competing in Ironman triathlon before the age of 30 years and men before the age of 35 years to achieve their personal best Ironman race time.
... Regarding postrace values, previous studies carried out in other ultraendurance events have shown divergent results. Our absence of a significant prerace to postrace difference has been formerly reported after a mountain marathon, a 24-h ultramarathon or a 1230-km cycling event (9, 13, 33), whereas a significant increase has been observed following a 80.5-km mountain race, a 100-km flat race, a 24-h mountain bike race or an Ironman triathlon (9,27,30,31,38). ...
... Therefore, considering the abovementioned results from Mueller and cols. (31) and the fact that none of our participants showed a severe dehydration according to USG results, it is arguable that greater weight losses among best performers during self-paced ultraendurance events could be mainly a reflection of their greater energy expenditure. ...
Purpose:
The present study aimed to explore whether Blood Pressure (BP) and Heart Rate Variability (HRV) responsiveness to orthostatism, jointly with Executive Function (EF) performance, were diminished following an ultraendurance mountain race. Besides, we wanted to assess whether hydration status was related to either performance or the abovementioned alterations.
Methods:
Fifty recreational ultraendurance athletes participating in the Penyagolosa Trails CSP115 race (118 km and a total positive elevation of 5439 m) were evaluated before and after the competition. HRV and BP were measured in response to an orthostatic challenge. EF was evaluated using the color-word interference task of the Stroop test. Body Mass (BM) and Urine Specific Gravity (USG) changes were employed to assess hydration status.
Results:
HRV and BP responsiveness to orthostatism were diminished following the race. Besides, a significant BM loss of 3.51 ± 2.03% was recorded. Conversely, EF and USG showed no significant changes from prerace to postrace. Eventually, BM loss was inversely related to finishing time (r=-0.34) and postrace orthostatic HR and EF were positively associated (r=0.60).
Conclusions:
USG and BM loss appears to provide different insights into hydration status and our results challenge the well-established criteria that BM losses >2% are detrimental to performance.
Practical applications:
Coaches are advised to consider athletes' performance level when interpreting their BM changes during an ultraendurance competition. Similarly, coaches should be aware that increased vulnerability to orthostatism is a common phenomenon following ultraendurance races and diminished HR responsiveness to orthostatism could constitute a practical indicator of EF worsening.
... Durante el entrenamiento de ciclismo se puede observar que la pérdida de peso en chicos es mucho mayor que en chicas, y esto puede ser debido a una mejor adaptación y mayor tiempo de entrenamiento; a su vez, la TS es mayor en chicos que en chicas. Durante un Ironman, Mueller et al. 19 mostraron una pérdida de peso media de -1,9±0,8kg en 8 triatletas varones. Sin embargo, en nuestro estudio mostramos una pérdida de peso inferior en todos los entrenamientos, siendo el resultado más alto en hombres para el entrenamiento de ciclismo (0,98±0,43kg). ...
... En eventos de triatlón de larga distancia se ha observado cambios de peso corporal que varían entre -10,7% y +3,7% 17 , debidos a la sudoración y utilización de sustrato energético. Mientras tanto, en nuestro estudio, se observó en cada tipo de entrenamiento una pérdida de peso pero sin que esta disminución superará las mostradas por otros autores 19,20 . ...
Introducción: El triatlón es un deporte de resistencia que comprende tres disciplinas: natación, ciclismo y carrera a pie. Es necesario establecer pautas de hidratación para prevenir deshidrataciones durante entrenamientos o competiciones y mantener un buen estado de hidratación antes, durante y después del ejercicio. El objetivo de este estudio es evaluar la ingesta de líquido, pérdida de peso y tasa de sudoración en jóvenes triatletas, durante diferentes entrenamientos.
Material y Métodos: Estudio descriptivo-observacional en 14 triatletas (7 chicos y 7 chicas) durante una sesión de natación, otra de ciclismo y otra de carrera a pie. Se valoró la ingesta de líquido, pérdida de peso, % agua corporal total, % deshidratación y tasa de sudoración. Los triatletas bebieron agua en sus respectivos bidones de 750 ml y se realizó una medición de orina en containers.
Resultados: Los resultados del estudio siguiendo el orden de natación, ciclismo y carrera a pie fueron: ingesta agua 2,66±1,94ml/min, 7,91±7,69ml/min y 7,08±4,13ml/min en chicos y 3,43±1,53ml/min, 6,39±5,36ml/min y 8,33±2,74ml/min en chicas; pérdida de peso 0,83±0,5kg, 0,47±0,3kg y 0,98±0,4kg en chicos y 0,79±0,3kg, 0,47±0,58kg y 0,28±0,21kg en chicas; y tasa sudoración 4,44±4,9ml/min, 11,81±6,46ml/min y 5,29±3,13ml/min en chicos y 3,89±2,4ml/min, 4,69±4,20ml/min y 7,96±5,06ml/min en chicas.
Conclusiones: Se comparó el porcentaje de agua corporal y deshidratación, la pérdida de peso y la tasa de sudoración con otros estudios y se observa que nuestros resultados son inferiores a los estudios comparados, además están por debajo de la media de recomendaciones de líquido establecidas por el consenso de hidratación.
... The reduction of the body stores of energy can also explain changes in the BM of athletes after ultra-endurance events. For instance, there is evidence indicating a significant decrease in muscle density (glycogen loss) and fat mass of athletes after a UET [13][14][15][16]. In addition, Laursen et al. [17] reported that a body mass loss of up to 3% was not linked with thermoregulatory failure in 10 triathletes performing a UET suggesting that part of the BM reduction occurred due to losses of glycogen and fat. ...
... Decreases in BM up to as much as 11% of the total body weight have been shown previously [5,17,[28][29][30]. These BM losses can be explained by high energy deficits which induce a decrease in muscle density (glycogen loss) and fat mass of the body of athletes participating in ultra-endurance events [13][14][15][16]. In the current study, we found a fluid deficit of 1.3 L which was far from the mean loss of body weight. ...
The nutritional strategy during an ultra-endurance triathlon (UET) is one of the main concerns of athletes competing in such events. The purpose of this study is to provide a proper characterization of the energy and fluid intake during real competition in male triathletes during a complete UET and to estimate the energy expenditure (EE) and the fluid balance through the race.
Eleven triathletes performed a UET. All food and drinks ingested during the race were weighed and recorded in order to assess the energy intake (EI) during the race. The EE was estimated from heart rate (HR) recordings during the race, using the individual HR-oxygen uptake (Vo2) regressions developed from three incremental tests on the 50-m swimming pool, cycle ergometer, and running treadmill. Additionally, body mass (BM), total body water (TBW) and intracellular (ICW) and extracellular water (ECW) were assessed before and after the race using a multifrequency bioimpedance device (BIA).
Mean competition time and HR was 755 ± 69 min and 137 ± 6 beats/min, respectively. Mean EI was 3643 ± 1219 kcal and the estimated EE was 11,009 ± 664 kcal. Consequently, athletes showed an energy deficit of 7365 ± 1286 kcal (66.9% ± 11.7%). BM decreased significantly after the race and significant losses of TBW were found. Such losses were more related to a reduction of extracellular fluids than intracellular fluids.
Our results confirm the high energy demands of UET races, which are not compensated by nutrient and fluid intake, resulting in a large energy deficit.
... B. durch Schwitzen oder vermehrte Flüssigkeitsaufnahme, die Nachlast (Widerstand des Gefäßsystems) z. B. durch Wärmeentwicklung und Vasodilatation [14,51]. Weitere Veränderungen erfolgen auf zellulärer Ebene durch Azidose, Glykogenentzug und Elektrolytverschiebung [29,40,67]. ...
... Die Effekte der Vorlast-/Nachlaständerung und die Änderung des Adrenalinstatus haben während der Ausdauerbelastung ein erhebliches Ausmaß [14,51]. Diese Veränderungen (z. ...
Background. The potential for left- or rightventricular
injury induced by intensive sporting
activities has been continually reported
for years. The spectacular sudden deaths that
occur during marathons, football, soccer, and,
more recently, in the trend discipline triathlons
seem to support that view. In addition,
reports about the “athlete’s heart” and complications
in the elderly causes uncertainty
among endurance athletes and their coaches
as well as those, hoping that sporting activity
will lead to weight reduction or will improve
diabetes or general fitness.
Methods. This article provides an overview
of the physiology of the athlete’s heart. Sudden
cardiac death (SCD) caused by sporting
activity and studies on the topic of left- and
right-ventricular injury are discussed. This
is followed by an analysis of sports-related
heart diseases in the elderly and of the prognosis
of the older athletes.
Results. Young athletes die during sporting
activity five times more often compared with
non-athletes. Cardiac injuries in the elderly
(primarily cardiac arrhythmias) may occur
in athletes, even if (only) endurance athletes
seem to live longer on average.
Conclusion. The life prolonging and positive
effect of moderate sporting activity is
not up for discussion, but competitive sports
may have negative effects. The extent of the
“negative dosage of sport” is unknown; however,
a daily expenditure of 490 kcal by physical
activity in the aerobic zone and adequate
screening of the personal disposition/
risks are clear recommendations for avoiding
SCD and other negative effects of sporting
activity.
Keywords
Marathon · Triathlon · Cardiac sudden death ·
Competative sports · Cardiac arrhythmias
... The decreases in both running speed and relative VO 2 point to emptying of intrinsic energy stores. This is seen in the pronounced reduction in fat mass in the legs after the marathon despite an increase in total body fat mass and in the concomitant decreases in lean mass and muscle density that might point to a loss of glycogen, as we previously described in Ironman triathletes (Mueller et al. 2013). ...
... In consideration of the distinct movement pattern of the participant, i.e. asymmetric running with a pronounced loading of the left leg and sparing of the right, we assume that fluid outand inflow were different, with respect to body side and bone site. To our knowledge, only one study did measure vBMC in the lower leg directly before and after an extreme endurance event, showing no alteration at any site after an Ironman triathlon in recreationally active males (Mueller et al. 2013). ...
Introduction:
Endurance performance decreases during ageing due to alterations in physiological characteristics, energy stores, and psychological factors. To investigate alterations in physiological characteristics and body composition of elderly master athletes in response to an extreme endurance event, we present the case of the first ninety-year-old official male marathon finisher.
Case description:
Before and directly after the marathon, a treadmill incremental test, dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, mechanography, and dynamometry measurements were conducted. The athlete finished the marathon in 6 h 48 min 55 s, which corresponds to an average competition speed of 6.19 km h(-1).
Discussion and evaluation:
Before the marathon, [Formula: see text] was 31.5 ml min(-1) kg(-1) body mass and peak heart rate was 140 beats min(-1). Total fat mass increased in the final preparation phase (+3.4%), while leg fat mass and leg lean mass were slightly reduced after the marathon (-3.7 and -1.6%, respectively). Countermovement jump (CMJ) peak power and peak velocity decreased after the marathon (-16.5 and -14.7%, respectively). Total impulse during CMJ and energy cost of running were not altered by the marathon. In the left leg, maximal voluntary ground reaction force (F m1LH) and maximal isometric voluntary torque (MIVT) were impaired after the marathon (-12.2 and -14.5%, respectively).
Conclusions:
Side differences in F m1LH and MIVT could be attributed to the distinct non-symmetrical running pattern of the athlete. Similarities in alterations in leg composition and CMJ performance existed between the nonagenarian athlete and young marathon runners. In contrast, alterations in total body composition and m1LH performance were markedly different in the nonagenarian athlete when compared to his younger counterparts.
... Belli et al. [10] verified possible relationships between the decrease in lean mass and the performance of athletes in the 217 km ultramarathon, with a 3.04% loss being reported. Mueller et al. [33] reported that the loss of body weight after an Ironman Triathlon was due to a 4.5% loss in fat mass and a 2.4% loss in lean body mass, the latter being attributable to the loss of glycogen as fuel for the production of energy and the corresponding loss of body water. ...
Although the studied polymorphisms affect muscular proteins, aerobic adaptations, and recovery, their influence on the anthropometric variables and performance in ultramarathon runners is still poorly understood. This study aimed to determine the influence of ACTN3 R577X, ACE I/D, and CK MM A/G NcoI polymorphisms on the changes in the anthropometric variables and running time of 105 km mountain runners, in which 22 male Brazilian elite athletes (35.9 ± 6.5 years) were evaluated. Genotyping of the R577X (RR, RX, and XX), ACE I/D (DD, ID, and II), and CK MM A/G Ncol (AA, AG, and GG) polymorphisms was performed using the Polymerase Chain Reaction–Restriction Fragment Length Polymorphism (PCR-RFLP) technique with DNA extracted from saliva. Body composition was determined via bioimpedance. Pre- and post-race weight differences were observed on athletes with the AA genotype (77.1 ± 5.9 kg; 74.6 ± 5.6 kg) compared with those with the AG genotype (74.5 ± 8.0 kg; 68 ± 5.1 kg) (p = 0.02; p = 0.02). The RR genotype showed a correlation between BMI and running time (R = 0.97; p = 0.004). The genotype II showed a correlation with % fat and fat mass concerning running time (R = 0.91; p = 0.003; R = 0.99; p < 0.0001). The AA genotype was associated with post-race weight and lean mass loss, while the RR genotype correlated with BMI, and the genotype II correlated with % body fat and fat mass in relation to times in the 105 km mountain ultramarathon.
... Belli et al. [10] verified possible relationships between the decrease in lean mass and the performance of athletes in the 217 km ultramarathon, with a 3.04% loss being reported. Mueller et al. [33] reported that the loss of body weight after an Ironman Triathlon was due to a 4.5% loss in fat mass and a 2.4% loss in lean body mass, the latter being attributable to the loss of glycogen as fuel for the production of energy and the corresponding loss of body water. ...
Although the studied polymorphisms affect muscular proteins, aerobic adaptations, and recovery, their influence on the anthropometric variables and performance in ultramarathon runners is still poorly understood. This study aimed to determine the influence of ACTN3 R577X, ACE I/D, and CK MM A/G NcoI polymorphisms on the changes in the anthropometric variables and running time of 105 km mountain runners, in which 22 male Brazilian elite athletes (35.9 ± 6.5 years) were evaluated. Genotyping of the R577X (RR, RX, and XX), ACE I/D (DD, ID, and II), and CK MM A/G Ncol (AA, AG, and GG) polymorphisms was performed using the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique with DNA extracted from saliva. Body composition was determined via bioimpedance. Pre-and post-race weight differences were observed on athletes with the AA genotype (77.1 ± 5.9 kg; 74.6 ± 5.6 kg) compared with those with the AG genotype (74.5 ± 8.0 kg; 68 ± 5.1 kg) (p = 0.02; p = 0.02). The RR genotype showed a correlation between BMI and running time (R = 0.97; p = 0.004). The genotype II showed a correlation with % fat and fat mass concerning running time (R = 0.91; p = 0.003; R = 0.99; p < 0.0001). The AA genotype was associated with post-race weight and lean mass loss, while the RR genotype correlated with BMI, and the genotype II correlated with % body fat and fat mass in relation to times in the 105 km mountain ultramarathon.
... Several studies have shown that a marked state of mild to moderate hypohydration occurs during ultramarathon running competitions [17][18][19][20]. This might be because not enough fluid was ingested to compensate for sweat losses during exercise [21]. ...
In different endurance events, athletes have limited access to fluid intake, such as ultra-endurance running. For this reason, it is necessary to establish an adequate hydration strategy for this type of long-duration sporting event. Indeed, it seems that the intake of seawater is a suitable hydration alternative to improve post-exercise recovery in this type of endurance event. This seawater is characterized by being a deep natural mineral water of moderate mineralization, which is usually extracted from a depth of about 700 m. Therefore, the aim of this systematic review is to evaluate the efficacy of seawater consumption in both performance and post-exercise recovery in long-duration sport events. A systematic and comprehensive literature search was performed in PubMed, Scopus, and Web of Science in September 2022. Initially, 8 out of 558 articles met the inclusion criteria. Among these eight studies, six were randomized clinical trials, and two were observational studies (one cross-sectional and one prospective study in well-conditioned student athletes). The results showed that deep sea water consumption accelerated the recovery of aerobic capacity and leg muscle capacity on running performance. In addition, the lactate production after the running exercise in seawater was significantly lower than in pure water. In conclusion, the present review demonstrates that seawater consumption could significantly improve the capacity of recovery after exercise.
... Several studies suggest that post-competition triathletes exhibit a marked state of mild to moderate hypohydration [11,12]. This might be because not enough fluid has been ingested to compensate for sweat losses during exercise [13] which, combined with hyperthermia, could induce cardiovascular instability, such as reduction in plasma volume, cardiac filling, and stroke volume [3,14]. ...
A triathlon is an endurance event in which athletes need an efficient hydration strategy since hydration is restricted at different stages. However, it seems that seawater intake can be a suitable hydration alternative for this type of endurance event. Therefore, the aim of this study was to evaluate the efficacy of seawater hydration during a triathlon on cytokine production. Fifteen trained male triathletes (age = 38.8 ± 5.62 years old; BMI = 22.58 ± 2.51 kg/m2) randomly performed three triathlons, one of them consuming seawater (Totum SPORT, Laboratories Quinton International, S.L., Valencia, Spain), the other one consuming tap water ad libitum, and the last a physiologic saline solution as placebo. The triathlon consisted of an 800 m swim, a 90 km bike ride, and a 10 km run. Blood samples were taken at rest and after training, where markers of inflammation, hemoglobin, and hematocrit concentration were assessed. While the seawater was not ergogenic, it significantly increased the release of IL-6 and apelin post-exercise. However, no differences were found between the fractalkine, IL-15, EPO, osteonectin, myostatin, oncostatin, irisin, FSTL1, osteocrin, BDNF, and FGF-21 values over those of the placebo group. The present study demonstrates that hydration with seawater stimulates myokine production, which could lead to improved performance recovery after exercise.
... The significant LBM reduction after the race could be attributed to reduced muscle density, glycogen depletion, and dehydration [32]. However, considering the results of this study, it seems that the inappropriate carbohydrate and protein intakes in combination with the age-related changes of metabolic function [9,22À24] and the strenuous nature of marathons [1,4,7,8,33] may facilitate LBM race-induced losses via a biochemical mechanism to compensate for energy availability during the race. ...
Objective
The aim of the present study was to investigate the relationships between protein intake (during the tapering period and the race), marathon performance, body composition, acute race induced changes and selected metabolic and muscle damage-related blood biomarkers, in recreational master runners.
Methods
In 58 experienced master runners (58.28 ± 1.07yr, 174.06 ± 0.72cm, 78.51 ± 0.76kg body mass, 21.38 ± 0.52% body fat, mean ± SEM), nutritional intake was evaluated one week before the race and during the marathon. Body composition was evaluated before and 2 hours after the race. Blood samples were collected at the same time points.
Results
Body fat and lean body mass were significantly reduced after the marathon race (p<0.01; η²: 0.311-0.888). Significant negative correlations were observed between energy intake from carbohydrates and proteins [expressed per lean body mass (LBM)], marathon performance and race induced changes of blood metabolic-muscle damage indices (p<0.05; r: -0.522 - -0.789). Positive correlations were observed between energy from carbohydrates and proteins per LBM, and body mass and LBM changes (p<0.05; r: 0.485 - 0.814). The specific contribution of protein intakes per LBM (B coefficient: -0.789–0.615) on race induced changes of body composition and blood markers was the same as that of carbohydrate intakes per LBM (B coefficient: -0.777–0.559).
Conclusions
Marathon race induced changes in body composition and metabolic blood indices are highly related to protein intake, either during the tapering period or during the race, with runners experiencing the lowest changes when consuming higher protein intakes.
... For example, in their case study of a PTWC H1 paratriathlete with an SCI, Graham-Paulson et al. (2017) reported a body fat of 25.4%, as assessed via dual-energy X-ray absorptiometry. This is considerably higher than 15.1 ± 5.6% shown by Mueller et al. (2013) in their descriptors of male AB triathletes, employing similar methods. ...
Paratriathlon is a multi-impairment, endurance sport which made its Paralympic Games debut in 2016. Athletes’ impairments typically include but, are not limited to, spinal cord injury; cerebral palsy, or other neurological disorders; amputations or visual impairments. However, despite athletes displaying impairments that present several considerations for coaches and practitioners, there has been very little research in the sport. Specifically, there is little understanding of how athletes’ impairments may impact their physiological response to acute or chronic changes in training load. Similarly, it is not known how consequences of athletes’ impairments affect thermoregulation and the ability to adapt to the heat. Thus, this thesis aimed to elucidate these unknown areas whilst bridging the knowledge gap to research in able-bodied triathlon.
The first two studies of this thesis investigated paratriathletes’ response to changes in training load, longitudinally (Chapter four) and more acutely (Chapter five). Specifically, Chapter four noted paratriathletes’ mucosal immune function, represented by salivary secretory immunoglobulin A, displayed an inverse relationship with weekly training duration, but not measures of training load. Furthermore, upper respiratory illness incidence was not related to mucosal immunity. In Chapter five, it was shown that paratriathletes are resilient to large changes in training load in the form of a two-week intensified training period. A 14-d overseas training camp did not negatively affect hormonal, immunological or wellness measures whilst self-perceived sleep, stress and recovery parameters were improved. One explanation is that the camp environment minimised external life stresses and coaches’ careful management of training load reduced the likelihood of overreaching.
In Chapter six, the thermoregulatory strain of paratriathlon competition in the heat was characterised. It was shown, via the use of ingestible sensors, that paratriathletes’ core temperature reached levels significantly higher than previous research in able-bodied triathletes. Furthermore, trends for category-specific responses are presented, namely between those in PTWC and PTVI, highlighting the differences between impairment groups. Selfreported heat illness symptomatology was also greater than previous research in able-bodied athletes. Acknowledging the thermal strain paratriathletes face during competition in hot environments, Chapter seven sought to present the effectiveness of an ecologically valid preparatory heat acclimation strategy. Utilising a mixed active and passive intervention, controlling the relative intensity of exercise by heart rate, it was shown that paratriathletes are capable of partial heat acclimation through thermoregulatory adaptations. However, the breadth of adaptations was less than able-bodied triathletes.
These were the first studies of paratriathletes’ physiological and thermoregulatory response to training load and competition in the heat. It was shown that paratriathletes of a high training level are robust to acute changes in training load whilst training load had no relationship with mucosal immunity, despite a high illness incidence. However, paratriathletes are at heightened risk of thermoregulatory strain when competing in the heat, as shown by high core temperatures and self-reported heat illness symptomatology. Nonetheless, strategies can be utilised to induce thermoregulatory adaptations in this cohort. This provides valuable information for coaches and practitioners working with paratriathletes as they seek to minimise training time-loss and ameliorate the strain of competition in the heat.
... During these long endurance events, body mass changes are substantial. Mueller showed that participation in an Ironman event can lead to important changes in body composition such as a substantial loss of fat mass, which can affect energy availability since fat provides up to 50% of whole energy expenditure (Mueller et al., 2013). Knechtle and colleagues showed that male triathletes in an Ironman lose an average of 1.8 kg of body mass and 1 kg of skeletal muscle mass, presumably due to a depletion of stored glycogen and lipids within myocytes (Knechtle et al., 2010). ...
The Ironman triathlon consists of a 3.8 km swim, 180 km bike, and 42.195 km run. Thermoregulation responses play an important role in performance optimization and injury prevention. Factors such as environmental conditions including heat and humidity, athlete training level, and race duration can affect thermoregulation. Hyperthermia occurs when the core temperature rises above 38.5°C. The present study aims to describe core temperature (Tcore) in top-level and well-trained age group triathletes during the marathon of Ironman World Championship 2014 in Kona-Hawaii under thermal stress conditions. Tcore of 15 triathletes (age: 36.11 ± 7.36 years, body mass: 71.14 ± 7.12 kg, height: 179 ± 0.04 cm, and fat %: 8.48 ± 0.85) who classified for the Ironman World Championship was measured by an ingestible pill telemetry system prior to competition, during the marathon and 60 min after finishing the race. Mean wet bulb globe temperature (WBGT) during the marathon was 24.66°C (range 22.44–28.50°C). Body mass index (BMI) and perceived exertion (Borg Scale and Visual Analog Scale-Pain) were collected before the race and 60 min after the event. Time variables were extracted from their official race time and split times. Finish time was 10: 06:56 ± 0:48:30. Tcore was initially 36.62 ± 0.17°C, increased at the end of the event (38.55 ± 0.64; p < 0.01) and remained elevated 60 min after the event (38.65 ± 0.41°C; p < 0.002). BMI significantly decreased after the event (22.85 ± 1.11 vs. 21.73 ± 1.36; p < 0.05), whereas both exercise perceived exertion [Borg Scale (10.2 ± 1.64 vs. 18.60 ± 1.67; p < 0.003)] and perceived muscle pain [VAS Pain (2.75 ± 1.59 vs. 9.08 ± 1.13; p < 0.001)] increased significantly after the event. Tcore during competition correlated negatively with position in age group (r − 0.949, p = 0.051), but not with race time (r = −0.817; p = 0.183). High-level age group triathletes competing under thermal stress conditions in the Kona Ironman reached a state of hyperthermia during the marathon. After 60 min of recovery the hyperthermia persisted. Strategies to aid post-event cooling and recovery should be considered to avoid the potentially dangerous adverse health effects of hyperthermia.
... Visceral and other ectopic fat volumes are usually quantified by segmentation of multiplanar images derived from computed tomography or magnetic resonance imaging. Quantitative measures of body composition can be essential for the monitoring of therapeutic approaches of patients with obesity such as sport interventions [6], pharmacological trials [7] or bariatric surgery [8][9][10][11]. ...
Background:
The purpose of this study was to determine to what extent the whole volumes of abdominal subcutaneous (ASAT) and visceral adipose tissue (VAT) of patients with obesity can be predicted by using data of one body half only. Such a workaround has already been reported for dual-energy x-ray absorption (DEXA) scans and becomes feasible whenever the field of view of an imaging technique is not large enough.
Methods:
Full-body abdominal MRI data of 26 patients from an obesity treatment center (13 females and 13 males, BMI range 30.8-41.2 kg/m2, 32.6-61.5 years old) were used as reference (REF). MRI was performed with IRB approval on a clinical 1.5 T MRI (Achieva dStream, Philips Healthcare, Best, Netherlands). Segmentation of adipose tissue was performed with a custom-made Matlab software tool. Statistical measures of agreement were the coefficient of determination R2 of a linear fit.
Results:
Mean ASATREF was 12,976 (7812-24,161) cm3 and mean VATREF was 4068 (1137-7518) cm3. Mean half-body volumes relative to the whole-body values were 50.8% (48.2-53.7%) for ASATL and 49.2% (46.3-51.8%) for ASATR. Corresponding volume fractions were 56.4% (51.4-65.9%) for VATL and 43.6% (34.1-48.6%) for VATR. Correlations of ASATREF with ASATL as well as with ASATR were both excellent (R2 > 0.99, p < 0.01). Corresponding correlations of VATREF were marginally lower (R2 = 0.98 for VATL, p < 0.01, and R2 = 0.97 for VATR, p < 0.01).
Conclusions:
In conclusion, abdominal fat volumes can be reliably assessed by half-body MRI data, in particular the subcutaneous fat compartment.
... Eccentric running led to a damage of SM and consequently to its loss due to the depletion of intramyocellular lipid and/or muscle triglyceride stores caused by a substantial energy deficit (Knechtle and Bircher, 2005). The loss in lean BM including water, proteins, glycogen and non-bone minerals was explained by a decrease in muscle density caused by glycogen loss in Ironman triathletes (Mueller et al., 2013). The reduction in glycogen stores together with water bound to glycogen could result in the loss of SM as well as in BM loss in the present runners. ...
Background: To date, no study has focused on body composition characteristics and on parameters associated with skeletal muscle damage and renal function in runners participating in a 24-h winter race held under extremely cold environmental conditions (average temperature of -14.3°C). Methods: Anthropometric characteristics, plasma urea (PU), plasma creatinine (Pcr), creatine kinase (CK), plasma volume (PV) and total body water (TBW) were assessed pre- and post-race in 20 finishers (14 men and 6 women). Results: In male runners, body mass (BM) (p = 0.003) and body fat (BF) (p = 0.001) decreased [-1.1 kg (-1.4%) and -1.1 kg (-13.4%), respectively]; skeletal muscle mass (SM) and TBW remained stable (p > 0.05). In female runners, BF decreased (p = 0.036) [-1.3 kg (-7.8%)] while BM, SM and TBW remained stable (p > 0.05). The change (Δ) in BM was not related to Δ BF; however, Δ BM was related to Δ SM [r = 0.58, p = 0.007] and Δ TBW (r = 0.59, p = 0.007). Δ SM correlated with Δ TBW (r = 0.51, p = 0.021). Moreover, Δ BF was negatively associated with Δ SM (r = -0.65, p = 0.002). PV (p < 0.001), CK (p < 0.001), Pcr (p = 0.004) and PU (p < 0.001) increased and creatinine clearance (CrCl) decreased (p = 0.002). The decrease in BM was negatively related to the increase in CK (r = -0.71, p < 0.001). Δ Pcr was positively related to Δ PU (r = 0.64, p = 0.002). The decrease in CrCl was negatively associated with the increase in both PU (r = -0.72, p < 0.001) and CK (r = -0.48, p = 0.032). Conclusion: The 24-h running race under extremely cold conditions led to a significant BF decrease, whereas SM and TBW remained stable in both males and females. Nevertheless, the increase in CK, Pcr and PU was related to the damage of SM with transient impaired renal function.
... One of the most cost-effective field methods include the assessment of changes in body weight, which are considered to be reflective of changes in hydration status over activities of short duration [86][87][88]. However, for prolonged exercise lasting longer than approximately 4 h, it has been argued that changes in body weight may also be due to the depletion of body fuel stores such as muscle glycogen and body fat [91]. As such, data obtained with this method should be considered carefully, and the method should ideally be implemented in combination with other indicators of hydration status. ...
... The runner started with a relatively high running speed, and then the pace dropped relatively fast within a few hours. This first phase, with a fast drop in running speed, may have been due to the breakdown of intramuscular glycogen as a rapidly available source of energy [29]. In the further course of the race, the intra-myocellular lipids of the legs may have been used as another high-energy substrate [30], since these lipids are an important high-energy substrate for prolonged endurance exercise [31]. ...
Pacing has been investigated in elite and master runners competing in marathon and ultra-marathon races up to 100 km and 100 miles, but not in longer ultra-marathons. In this case study, a 54-year-old master ultra-marathoner—intending to achieve as many kilometers as possible in a 48 h run—was examined. The changes in running speed during the race and selected anthropometric characteristics using bioelectrical impedance analysis (i.e., body mass and body water), during and after the race, were analyzed. The runner achieved a total distance of 230 km and running speed decreased non-linearly during the race. Body mass decreased, while percent body water increased, non-linearly, across the race. There was no statistically significant relationship between the decrease in body mass and the increase in percent body water. Considering the popularity of ultra-endurance running races, the findings of the present study offered valuable insight in the pacing and changes of body mass and body water during a 48 h run, and this information can be used by ultra-endurance runners and practitioners working with them.
... The similar weather conditions on race days (no heat stress) support our conclusion of similar and sufficient hydration of all athletes. Commented [SCP<1]: Deleted: Hydration status was assessed by measurement of change in plasma hematocrit, which has been shown to accurately reflect changes in plasma volume ( Dill and Costill, 1974;Malisova et al., 2016), although it does not reflect tissue dehydration resulting from muscle glycogen loss during triathlon ( Mueller et al., 2013). However, for the purpose of validating the exercise-and/or caffeine-induced changes in blood parameters assessed, we are confident that this parameter was a suitable choice. ...
The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidate realistically the effect of caffeine on triathlon event performance using a field study design, while allowing investigation into potential mechanisms at play. A double-blind, randomized, crossover, field trial was conducted. Twenty-six triathletes (14 males, 12 females) participated (age: 37.8±10.6 years, habitual caffeine intake: 413±505 mg/day, percentage body fat: 14.5±7.2%, training/week: 12.8±4.5 hours). Microencapsulated caffeine (6 mg/kg body weight) was supplemented 60 minutes pre-trial. Performance data included time to completion (TTC), rating of perceived exertion (RPE) and profile of mood states (POMS). Blood samples taken before, during and post-race were analyzed for cortisol, testosterone and full blood count. Capillary blood lactate concentrations were assessed pre-race, during transitions and 3, 6, 9, 12, 15 minutes after triathlons. Caffeine supplementation resulted in a 3.7% reduction in swim time (33.5±7.0 vs. 34.8±8.1 minutes, p<0.05) and a 1.3% reduction in TTC (149.6±19.8 vs. 151.5±18.6 minutes, p<0.05) for the whole group. Gender differences and individual responses are also presented. Caffeine did not alter RPE significantly, but better performance after caffeine supplementation suggests a central effect resulting in greater overall exercise intensity at the same RPE. Caffeine supplementation was associated with higher post-exercise cortisol levels (665±200 vs. 543±169 nmol/l, p<0.0001) and facilitated greater peak blood lactate accumulation (ANOVA main effect, p<0.05). We recommend that triathlon athletes with relatively low habitual caffeine intake may ingest 6 mg/kg body weight caffeine, 45-60 minutes before the start of Olympic-distance triathlon in order to improve performance.
... The decrease in fat-free mass was most probably due to the depletion of intramyocellular glycogen stores as it has been described for long-distance triathletes. 23 Creatine kinase generally increases after a longer run as a measure of skeletal muscle damage 24 where the increase depends on the age of the athlete and the length of the race. 25,26 An explanation for the relatively low increase in creatine kinase might be the low fat-free mass of the athlete due to his older age. ...
It is well known that elderly people up to 90 years of age are able to finish a marathon. We have no knowledge, however, how runners at the age of 90 years or older pace during a long run. In this case report, we describe the pacing of a 94-year-old man competing in a 6-hour run in order to prepare for a marathon at the age of 95 years in category M95. In the “6-Stunden-Lauf ” held in Brugg, Switzerland, participants have to run as many laps of 0.934 km as possible on a completely flat circuit within 6 hours to achieve as many kilometers as possible. Before and after the competition we measured body weight, percentage of body fat, fat-free mass and percentage of body water using a bioelectrical impedance scale. On the day before the start, 24 hours after the finish and then every 24 hours for the following 4 days, capillary blood samples at a fingertip were drawn to determine hemoglobin, hematocrit, leukocytes, platelets, C-reactive protein, creatine kinase, creatinine and potassium and sodium. The runner achieved 26 laps during the 6 hours, equal to 24.304 km. Lap times increased continuously and running speed decreased nearly linearly. A large main effect of time point (hours) of the race on running speed was observed (p=0.015, η²=0.48) with running speed being slower in the last hour than that in the first hour (3.5±1.4 km/h versus 5.3±0.4 km/h). Body mass decreased by 0.6%, percent body fat by 1.4% and fat-free mass by 0.7%. During recovery, hemoglobin, hematocrit and the number of thrombocytes increased, whereas the number of leukocytes remained unchanged. C-reactive protein was highest on day 1 after the race and decreased by day 4 nearly to zero. Creatine kinase was slightly elevated pre-race, highest the day after the race and remained slightly elevated until day 4. Creatinine and potassium were increased pre-race but returned to normal values during recovery. Sodium remained within normal values on all days. Based on the linear decrease in running speed, we extrapolated for the marathon distance to run a marathon in age group M95 (i.e., male marathoners aged 95–99 years). In the worst-case scenario (i.e., the athlete develops maximal fatigue), he would stop the race before 40 km, in the best scenario (i.e., the athlete develops minimal fatigue), he would achieve an overall race time of ~8.3 hours and in the most probable scenario (i.e., the athlete can continue in the same manner), the final race time will be longer than 11 hours.
... Manz and Wentz (9) feel that urinary osmolality (Uosm) is the most integrative manner to assess human hydration, and they defi ne normative "euhydration" as a Uosm in the range of 90-900 mOsm/kg. Plasma osmolality, by contrast, is tightly regulated in a narrow range around 300 mOsm/kg (9) and is generally only responsive to acute and profound hydration stress (7,10). Osmolality in human milk is also tightly regulated, and close to the range for plasma. ...
Background:
It has been demonstrated that human milk osmolality (Mosm) is regulated within an established range, typically 290 to 300 mOsm/kg, and appears to be resistant to effects of maternal dehydration, as refl ected by high urinary osmolality (Uosm).
Objective:
To determine the degree of association between Mosm and Uosm at a common point in time, as well as the reproducibility of both measures over a one-week interval of sampling.
Methods:
Mosm and Uosm were measured with a Vogel Löser 450 osmometer on samples of the respective biological fluids collected concurrently in 31 lactating women, with infants aged between 30 and 340 days. In the first 15 women recruited, collections were repeated 7 days after the initial ones.
Results:
The median Mosm for the 46 samples collected was 308 mOsm/kg with a range from 288 to 448 mOsm/kg. The corresponding values for Uosm were 598 mOsm/kg with a range from 93 to 1,678 mOsm/kg. The Spearman rank-order correlation coeffi cient for within-individual association of Mosm and Uosm was r = 0.214 (p = 0.153). The median Mosm for the 15 repeat-subjects was 309 mOsm/kg on both occasions, with a within-individual Spearman coeffi cient of r = 0.326 (p = 0.118). By contrast, for the Uosm, the within-subject association was much stronger, with r = 0.699 (p = 0.002).
Conclusions:
The osmometry technique proved to be a highly stable and reproducible measurement technique. Mosm and Uosm are not significantly associated at a point in time. Intra-subject Mosm varies more across time than intra-subject Uosm.
... However, limited information exists as to the extent by which habitual cycling of hydration status, tissue substrate, and metabolic water that occurs during exercise and recovery can alter the measurement of lean tissue mass (LTM) measurement in athletes. Knowledge of potential errors in compositional measurement in athletes is an imperative given the extreme challenge to body and tissue specific hydration that can potentially occur, e.g., ultraendurance events (Hew-Butler et al. 2015;Mueller et al. 2013) and weight division sports (Clark et al. 2007;Santos et al. 2010). ...
PurposeAthletes cycle between exercise and recovery. Exercise invokes changes in total body water from thermal sweating, muscle and hepatic glycogen depletion and metabolic water loss. Recovery from exercise results in rehydration, substrate repletion, and possible glycogen supercompensation. Such changes may corrupt the measurement of hydrated tissues, such as lean tissue mass (LTM), by dual-energy X-ray absorptiometry (DXA). The purpose of this study was to determine the effect of exercise and thermal dehydration and subsequent glycogen supercompensation on DXA-based measurement of body composition. Methods
Twelve active adult (18–29 years) males exercised at 70% VO2max on a cycle ergometer in a thermal environment (30 °C) to induce a 2.5% reduction in body mass. Participants subsequently underwent a glycogen supercompensation phase, whereby a high carbohydrate diet (8–12 g/kg body mass/day) was consumed for a 48-h period. Whole-body DXA measurement was performed at baseline, following exercise and supercompensation. ResultsFollowing exercise, mean body mass decreased by −1.93 kg (95% CI −2.3, −1.5), while total LTM decreased by −1.69 kg (−2.4, −1.0). Supercompensation induced a mean body mass increase of 2.53 kg (2.0, 3.1) and a total LTM increase of 2.36 kg (1.8, 2.9). No change in total fat mass or bone mineral content was observed at any timepoint. Conclusions
Training regimens that typically induce dehydration and nutrition regimens that involve carbohydrate loading can result in apparent changes to LTM measurement by DXA. Accurate measurement of LTM in athletes requires strict observation of hydration and glycogen status to prevent manipulation of results.
... Manz and Wentz (9) feel that urinary osmolality (Uosm) is the most integrative manner to assess human hydration, and they define normative "euhydration" as a Uosm in the range of 90-900 mOsm/kg. Plasma osmolality, by contrast, is tightly regulated in a narrow range around 300 mOsm/kg (9) and is generally only responsive to acute and profound hydration stress (7,10). Osmolality in human milk is also tightly regulated, and close to the range for plasma. ...
Background:
It has been demonstrated that human milk osmolality (Mosm) is regulated within an established range, typically 290 to 300 mOsm/kg, and appears to be resistant to effects of maternal dehydration, as refl ected by high urinary osmolality (Uosm).
Objective:
To determine the degree of association between Mosm and Uosm at a common point in time, as well as the reproducibility of both measures over a one-week interval of sampling.
Methods:
Mosm and Uosm were measured with a Vogel Löser 450 osmometer on samples of the respective biological fluids collected concurrently in 31 lactating women, with infants aged between 30 and 340 days. In the first 15 women recruited, collections were repeated 7 days after the initial ones.
Results:
The median Mosm for the 46 samples collected was 308 mOsm/kg with a range from 288 to 448 mOsm/kg. The corresponding values for Uosm were 598 mOsm/kg with a range from 93 to 1,678 mOsm/kg. The Spearman rank-order correlation coeffi cient for within-individual association of Mosm and Uosm was r = 0.214 (p = 0.153). The median Mosm for the 15 repeat-subjects was 309 mOsm/kg on both occasions, with a within-individual Spearman coeffi cient of r = 0.326 (p = 0.118). By contrast, for the Uosm, the within-subject association was much stronger, with r = 0.699 (p = 0.002).
Conclusions:
The osmometry technique proved to be a highly stable and reproducible measurement technique. Mosm and Uosm are not significantly associated at a point in time. Intra-subject Mosm varies more across time than intra-subject Uosm.
... A recent study using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography in the investigation of male Ironman triathletes showed that calf muscle density was reduced by ∼1.9% and the decrease was interpreted as a loss in lean mass due to glycogen loss. 18 We assume that the athlete lost substantial mass of the lower limb and developed, at the same time, subcutaneous edema. The poststage volume of the foot was related to poststage total body water, poststage creatinine, and poststage urea. ...
Recent studies investigating ultraendurance athletes showed an association between excessive fluid intake and swelling of the lower limbs such as the feet. To date, this association has been investigated in single-stage ultraendurance races, but not in multistage ultraendurance races. In this case study, we investigated a potential association between fluid intake and feet swelling in a multistage ultraendurance race such as a Deca Iron ultratriathlon with ten Ironman triathlons within 10 consecutive days. A 49-year-old well-experienced ultratriathlete competed in autumn 2013 in the Deca Iron ultratriathlon held in Lonata del Garda, Italy, and finished the race as winner within 129:33 hours:minutes. Changes in body mass (including body fat and lean body mass), foot volume, total body water, and laboratory measurements were assessed. Food and fluid intake during rest and competing were recorded, and energy and fluid turnovers were estimated. During the ten stages, the volume of the feet increased, percentage body fat decreased, creatinine and urea levels increased, hematocrit and hemoglobin values decreased, and plasma [Na⁺] remained unchanged. The increase in foot volume was significantly and positively related to fluid intake during the stages. The poststage volume of the foot was related to poststage total body water, poststage creatinine, and poststage urea. This case report shows that the volume of the foot increased during the ten stages, and the increase in volume was significantly and positively related to fluid intake during the stages. Furthermore, the poststage volume of the foot was related to poststage total body water, poststage creatinine, and poststage urea. The continuous feet swelling during the race was most probably due to a combination of a high fluid intake and a progressive decline in renal function (ie, continuous increase in creatinine and urea), leading to body fluid retention (ie, increase in total body water).
... As expected here, we reported an increase in total body water (+10 %) in runners Post-MUM. This result could be explained by muscle tissue catabolism and increased plasma osmolality as recently reported in triathletes [31]. Moreover, an increase in plasma volume due to sodium retention [16,17,32] or to an increase in the total exchangeable potassium [12] has previously been reported after endurance events [16,33,34]. ...
Background. Studies have recently focused on the effect of running a mountain ultra-marathon (MUM) and their results shows muscular inflammation, damage and force loss. However, the link between peripheral oedema and muscle force loss is not really established. We tested the hypothesis that, after a MUM, lower leg muscles swelling could be associated with muscle force loss. The knee extensor (KE) and the plantar flexor (PF) muscles contractile function was measured by supramaximal electrical stimulations, potentiated low- and high- frequency doublets (PS10 and PS100) of the KE and the PF were measured by transcutaneous electrical nerve stimulation and bioimpedance was used to assess body composition in the runners (n=11) before (Pre) and after (Post) the MUM and compared with the controls (n=8).
Results. The maximal voluntary contraction of the KE and the PF significantly decreased by 20% Post-MUM in the runners. Hydration of the non-fat mass (NF-Hyd) and extracellular water volume (Ve) were increased by 12% Post-MUM (p<0.001) in the runners. Calf circumference (+2%, p<0.05) was also increased. Significant relationships were found for percentage increases in Ve and NF-Hyd with percentage decrease in PS10 of the PF (r= -0.68 and r= -0.70, p<0.05) and with percentage increase of calf circumference (r=0.72 and r=0.73, p<0.05) in the runners.
Conclusions. The present study suggests that increases in circumference and in hydric volume are associated to contractile impairment in the calf in ultra-marathon runners.
... The main performance outcome derived from muscle fiber damage is the reduction of active muscle function as found during jump tests [6,37] and muscular strength tests [4,37,39]. The breakdown of body protein during endurance exercise has been found to produce the mobilization and oxidation of amino acids in muscle fiber [40] as has been indirectly confirmed by the reduction in skeletal muscle mass found in ultra-endurance triathletes [41]. Supplementation with BCAA to increase the serum concentration of this type of amino acids has been suggested as a strategy to prevent muscle damage because of its effectiveness to promote protein synthesis [11] and to preclude proteolysis [12]. ...
The aim of this study was to investigate the relationship between changes in serum free amino acids, muscle fatigue and exercise-induced muscle damage during a half-ironman triathlon. Twenty-six experienced triathletes (age = 37.0 ± 6.8 yr; experience = 7.4 ± 3.0 yr) competed in a real half-ironman triathlon in which sector times and total race time were measured by means of chip timing. Before and after the race, a countermovement jump and a maximal isometric force test were performed, and blood samples were withdrawn to measure serum free amino acids concentrations, and serum creatine kinase levels as a blood marker of muscle damage. Total race time was 320 ± 37 min and jump height (-16.3 ± 15.2%, P < 0.001) and isometric force (-14.9 ± 9.8%; P = 0.007) were significantly reduced after the race in all participants. After the race, the serum concentration of creatine kinase increased by 368 ± 187% (P < 0.001). In contrast, the serum concentrations of essential (-27.1 ± 13.0%; P < 0.001) and non-essential amino acids (-24.4 ± 13.1%; P < 0.001) were significantly reduced after the race. The tryptophan/BCAA ratio increased by 42.7 ± 12.7% after the race. Pre-to-post changes in serum free amino acids did not correlate with muscle performance variables or post-race creatine kinase concentration. In summary, during a half-ironman triathlon, serum amino acids concentrations were reduced by > 20%. However, neither the changes in serum free amino acids nor the tryptophan/BCAA ratio were related muscle fatigue or muscle damage during the race.
... 39 The loss in body mass in male Ironman triathletes was mainly due to a loss in skeletal muscle mass due to glycogen depletion. 41,42 Origin of the athletes The "Ironman Hawaii" was invented in Hawaii, USA. 43 Since its first edition, women and men from the USA dominated both participation and performance in "Ironman Hawaii". ...
Objective
This narrative review summarizes findings for Ironman triathlon performance and intends to determine potential predictor variables for Ironman race performance in female and male triathletes.
Methods
A literature search was performed in PubMed using the terms “Ironman”, “triathlon”, and “performance”. All resulting articles were searched for related citations.
Results
Age, previous experience, sex, training, origin, anthropometric and physiological characteristics, pacing, and performance in split disciplines were predictive. Differences exist between the sexes for anthropometric characteristics. The most important predictive variables for a fast Ironman race time were age of 30–35 years (women and men), a fast personal best time in Olympic distance triathlon (women and men), a fast personal best time in marathon (women and men), high volume and high speed in training where high volume was more important than high speed (women and men), low body fat, low skin-fold thicknesses and low circumference of upper arm (only men), and origin from the United States of America (women and men).
Conclusion
These findings may help athletes and coaches to plan an Ironman triathlon career. Age and previous experience are important to find the right point in the life of a triathlete to switch from the shorter triathlon distances to the Ironman distance. Future studies need to correlate physiological characteristics such as maximum oxygen uptake with Ironman race time to investigate their potential predictive value and to investigate socio-economic aspects in Ironman triathlon.
... For example, an increase in muscle load causes the muscle to become hypertrophic, unloading results in muscle atrophy. Similarly, high energy demand can cause some loss of lean body mass during ultra-endurance races, such as an Ironman triathlon (314). Thus muscle contains molecular sensors that allow the adjustment of the balance between protein synthesis and protein breakdown (157,368,377). ...
The neuromuscular junction is the chemical synapse between motor neurons and skeletal muscle fibers. It is designed to reliably convert the action potential from the presynaptic motor neuron into the contraction of the postsynaptic muscle fiber. Diseases that affect the neuromuscular junction may cause failure of this conversion and result in loss of ambulation and respiration. The loss of motor input also causes muscle wasting as muscle mass is constantly adapted to contractile needs by the balancing of protein synthesis and protein degradation. Finally, neuromuscular activity and muscle mass have a major impact on metabolic properties of the organisms. This review discusses the mechanisms involved in the development and maintenance of the neuromuscular junction, the consequences of and the mechanisms involved in its dysfunction, and its role in maintaining muscle mass during aging. As life expectancy is increasing, loss of muscle mass during aging, called sarcopenia, has emerged as a field of high medical need. Interestingly, aging is also accompanied by structural changes at the neuromuscular junction, suggesting that the mechanisms involved in neuromuscular junction maintenance might be disturbed during aging. In addition, there is now evidence that behavioral paradigms and signaling pathways that are involved in longevity also affect neuromuscular junction stability and sarcopenia.
Copyright © 2015 the American Physiological Society.
... Specifically, the reliable quantification of upper and lower extremity segmental masses is highly important for use in sensitive biomechanical models and human movement research when examining normal and abnormal gait (Lee et al. 2009b; Holmes et al., 2005; Pearsall and Costigan, 1999; Rossi et al., 2013), or to objectively examine more specific and localised changes in composition during longitudinal exercise interventions as a mechanism to assess program effectiveness (Mueller et al., 2013; Sillanpää et al., 2013; Wood et al., 2010). Unfortunately, no definitive boundaries have been reliably described to manually and uniformly distinguish between individual segments of the upper and lower extremities using scan technology. ...
Musculoskeletal examinations provide informative and valuable quantitative insight into muscle and bone health. DXA is one mainstream tool used to accurately and reliably determine body composition components and bone mass characteristics in-vivo. Presently, whole body scan models separate the body into axial and appendicular regions, however there is a need for localised appendicular segmentation models to further examine regions of interest within the upper and lower extremities. Similarly, inconsistencies pertaining to patient positioning exist in the literature which influence measurement precision and analysis outcomes highlighting a need for standardised procedure. This paper provides standardised and reproducible: 1) positioning and analysis procedures using DXA and 2) reliable segmental examinations through descriptive appendicular boundaries. Whole-body scans were performed on forty-six (n = 46) football athletes (age: 22.9 ± 4.3 yrs; height: 185.2 ± 7.2 cm; weight: 87.4 ± 10.3 kg; body fat: 11.4 ± 4.5 %) using DXA. All segments across all scans were analysed three times by the main investigator on three separate days, and by three independent investigators a week following the original analysis. To examine intra-rater and inter-rater, between day and researcher reliability, coefficients of variation (CV) and intraclass correlation coefficients (ICC) were determined. Positioning and segmental analysis procedures presented in this study produced very high, nearly perfect intra-tester (CV ≤ 2.0%; ICC ≥ 0.988) and inter-tester (CV ≤ 2.4%; ICC ≥ 0.980) reliability, demonstrating excellent reproducibility within and between practitioners. Standardised examinations of axial and appendicular segments are necessary. Future studies aiming to quantify and report segmental analyses of upper- and lower-body musculoskeletal properties using whole-body DXA scans are encouraged to use the patient positioning and image analysis procedures outlined in this paper.
... The metabolic pattern of such athletes is characterised by relevant variations of the body composition, and the measurement of body impedance provides reliable information about the FM and FFM loss, allowing an estimation of tissue catabolism during an ultraendurance exercise. Variations of fat-free mass and bodyweight are fully expected after such level of physical stress; our results are comparable, even quantitatively, with those registered with more sophisticated techniques like dual-energy X-ray absorptiometry and quantitative computed tomography; 16 the difference between IR and HIR is likely due to the greater intensity of the effort and the concomitant lesser degree of integration of liquids and food during stress. Despite the significant reduction in TBW shown by all the athletes, we confirm no variation in haemoglobin and haematocrit; as expected, plasma osmolarity slightly increased after the race. ...
Background
Intense physical stress might promote inflammatory responses, whereas a regular physical exercise has positive influence. Little is known on the acute metabolic and inflammatory responses to different levels of strenuous exercise in trained athletes.AimTo compare the short-term effect of two different ultra-endurance competitions on the inflammatory profile in male triathletes.Methods
We studied 14 Ironman (IR) and 13 Half Ironman (HIR) before and after their own specific race. We assessed body composition and measured blood cells, lipids, iron metabolism and plasma levels of some acute-phase cytokines and inflammatory markers.ResultsAfter the race, IR showed reduced total body water and fat-free mass, not related with the duration of exercise, and increased white cells and platelets; high-density lipoprotein levels also increased. IR, but not HIR, showed reduced iron levels, increased ferritin and transferrin, reduced % saturated transferrin. HIR showed higher basal interleukin (IL)-6, tumour necrosis factor (TNF)-α, IL-10, IL-1β than IR; however, the post-performance rise was greater in IR. Irisin increased only in HIR and osteocalcin decreased in IR. In the whole study group, delta of white blood cells was directly related with delta of monocyte chemoattractant protein 1, and Δ ferritin was inversely related with Δosteocalcin.ConclusionsA single ultra-endurance competition induces an inflammatory response depending on the duration of physical effort, with increased acute-phase cytokines, and an altered iron metabolism. Irisin, whose biological meaning is still uncertain, seems to be associated with acute variations of some metabolic parameters.
... Best Practice protocols require that "free-living" subjects be scanned in a fasted and rested state, preferably at the same time of the day to remove diurnal variation [28,30]. As such, the use of DXA scans to quantify acute changes in body composition variables before and after exercise has been investigated after cycling and strength training sessions in 55 subjects after an unspecified amount of time [29] and after an Ironman Triathlon in 8 males after ~11 h of competition [27]. However, before and after exercise comparisons of body composition measurement techniques have yet to be evaluated following prolonged endurance exercise ( > 20 h), such as a 161 km mountain footrace. ...
The low cost, ease of application and portability of bioelectrical impedance analysis (BIA) and spectroscopy (BIS) devices make them attractive tools for measuring acute changes in body composition before and after exercise, despite potential limitations from active compartmental fluid shifts. The primary study aim was to evaluate use of dual energy x-ray absorptiometry (DXA) against BIA and BIS in measurements of percent body fat (%BF) and percent total body water (%TBW) before and after prolonged endurance exercise. 10 runners were measured pre-race and at race finish. Significant linear relationships were noted pre-race between DXA vs. BIS for %BF (r(2)=0.76; p<0.01) and %TBW (r(2)=0.74; p<0.01). Significant correlations were noted at race finish between DXA vs. BIS for %BF (r(2)=0.64; p<0.01) and %TBW (r(2)=0.66; p<0.05), but only when one outlier was removed. Limits of agreement (LOA) between DXA vs. BIS were wide for both %BF (mean difference of -3.6, LOA between 5.4 and -12.6) and %TBW (mean difference 2.4, LOA between 0.4 and -4.6). LOA was closer between the DXA vs. BIA with DXA measuring slightly higher than BIA for %BF (mean difference of 0.5, LOA between 2.1 and -3.1) and slightly lower than BIA for %TBW (mean difference 0.3, LOA between 3.3 and -2.7). Linear correlations between DXA vs. BIA were not statistically significant for %BF or %TBW before or after the race. DXA measurement of acute changes in %BF and %TBW are not congruent with BIA or BIS measurements. These 3 techniques should not be utilized interchangeably after prolonged endurance running.
Background:
Ironman-distance events are ultra-endurance competitions involving three sports, leading to various adverse medical incidents. While some athletes compete in the same event over multiple years, medical trends among repeat competitors have not been studied. This study aimed to determine the recurrence of common medical incidents in repeat competitors over time in a longstanding Ironman-distance championship event.
Methods:
Data were collected using standardized sheets completed by nurses and physicians during athlete medical evaluations from 1989-2019. Competitors (N.=427) were included in the analysis if they received medical evaluation in at least three competitions within a fifteen-year period. Bivariate correlations were calculated to determine associations among medical incidents during competitors' first year of medical evaluation. Logistic regression analyses were performed to investigate the likelihood of medical incidents reoccurring in subsequent years following the initial occurrence.
Results:
Significant associations were found between several adverse medical incidents during competitors' first medical evaluations and for those evaluated in 3+ years. Competitors diagnosed with hyponatremia (aOR=2.42, 95% CI: 1.07-5.46), nausea (aOR=1.83, 95% CI: 1.14-2.94), dizziness (aOR=1.71, 95% CI: 1.09-2.68), and muscle cramps (aOR=1.62, 95% CI: 1.05-2.50) during their first year were significantly more likely to return with the same issue in subsequent years. In contrast, those who experienced vomiting during their first year were less likely to return for the same problem (aOR=0.45, 95% CI: 0.27-0.77).
Conclusions:
There are significant correlations and clear patterns of recurrence for specific medical incidents among elite ultra-endurance triathletes. Further analyses of other triathlon repeat populations and more specific examinations by age and sex are needed.
Resumo O objetivo deste estudo foi caracterizar a evolução do triatlo ao longo dos anos a nível dos resultados, idade e género. Este estudo baseou-se na recolha de dados on-line, na internet. Foram analisados como amostra os 20 primeiros classificados em cada Campeonato do Mundo entre 2005 e 2015. Os resultados têm vindo a melhorar no seu global, com especial ênfase no segmento de corrida, o último a ser percorrido, o que revela uma melhoria em aspetos relacionados com a metodologia específica do treino e fatores como a recuperação. Devem ser consideradas no processo de treino as idades em que decorrem os melhores resultados nesta modalidade despor-tiva, nomeadamente entre homens e mulheres. O género condiciona o desempenho no triatlo, devendo ser um fator a ser considerado no processo de treino diário, ob-servando-se atualmente uma tendência de aproximação de rendimento desportivo nesta modalidade desportiva entre géneros. Uma correta avaliação e controlo do treino no triatlo é fundamental por ser uma modalidade desportiva muito complexa. Abstract The aim of this study was to characterize the evolution of triathlon over the years in terms of results, age and gender. This study was based on online data collection, on the internet. The top 20 qualified in each World Championship between 2005 and 2015 were analyzed. The results have been improving overall, with special emphasis on the running segment, the last to be covered, which reveals an improvement in aspects related to specific training methodology and factors such as recovery. The ages in which the best results in this sport are occurring, namely between men and women, should be considered in the training process. Gender limits the performance in the triathlon and should be a factor to be considered in the daily training process, currently observing a trend of approximation of sports performance in this sports modality between genders. A correct evaluation and control of training in triathlon is essential because it is a very complex sport.
Paratriathlon is a multi-impairment, Paralympic, endurance sport with athletes’ impairments typically consisting of spinal cord injury, cerebral palsy or other neurological disorders, amputations, or visual impairments. As the sport made its Paralympic Games debut only in 2016, there is a dearth of literature concerning the sport. This opposes able-bodied triathlon whereby a significant mass of information is available concerning the physiology, training habits and competitive performance of athletes. However, due to primary or secondary consequences of paratriathletes’ impairments, there are many considerations that must be made when attempting to transfer information on training or competition from able-bodied triathletes. Paratriathletes may be at risk of intolerably high internal training load as movement inefficiencies augment the metabolic cost of daily ambulation and sporting performance. This can then result in a susceptibility for mucosal immunity suppression, and subsequent illness, or overreaching genesis. Likewise, paratriathletes’ impairments may diminish their thermoregulatory capacity, resulting in amplified strain when competing in the heat. This has implications for all impairment types due to myriad factors that interact with heat loss or gain during races. Nonetheless, strategies, such as heat acclimation, may be utilised to ameliorate the thermal strain of competition in the heat.
The Ironman is one of the most popular triathlon events in the world. Such a race involves a great number of tactical decisions for a healthy finish and best performance. Dehydration is widely postulated to decrease performance and is known as a cause of dropouts in Ironman. Despite the importance of hydration status after an Ironman triathlon, there is a clear lack of review and specially meta-analysis studies on this topic. Therefore, the objective was to systematically review the literature and carry out a meta-analysis investigating the hydration status after an Ironman triathlon. We conducted a systematic review of the literature up to June 2016 that included the following databases: PubMed, SCOPUS, Science Direct and Web of Science. From the initial 995 references, we included 6 studies in the qualitative analysis and in the meta-analysis. All trials had two measures of hydration status after a full Ironman race. Total body water, blood and urine osmolality, urine specific gravity and sodium plasma concentration were considered as hydration markers. Three investigators independently abstracted data on the study design, sample size, participants’ and race characteristics, outcomes, and quantitative data for the meta-analysis. In the pooled analysis, it seems that the Ironman event led to a moderate state of dehydration in comparison to baseline values (SMD 0.494; 95% CI 0.220 to 0.767; p = 0.001). Some evidence of heterogeneity and consistency was also observed: Q = 19.6; I2 = 28.5%; τ2 = 2.39. The results suggest that after the race athletes seem to be hypo-hydrated in comparison to baseline values.
Keywords: endurance, dehydration, swimming, cycling, running.
Introduction
The anthropometric characteristics of moderate and below-average body fat tissue (Miletić, et al. 2004), below average weight and height (Branda 2004) are desired for one to achieve success in aesthetic sports. The research problem is to determine differences among the morphological characteristics of girls engaged in aesthetic activities, such as ballet, rhythmic gymnastics and Latin dances. The hypothesis assumes the statistically significant morphological characteristics differences among girls involved in various aesthetic sports.
Methods of research
The sample of the research participants consisted of 80 girls, 11 to 15 years of age, grouped according to the movement activity they practice: three groups consisting of girls engaged in aesthetic movement activities from their childhood (rhythmic gymnastics, ballet and Latino dances) and a control group. There were 14 variables for morphological characteristics evaluation applied: longitudinal, transverse skeleton dimensionality, body mass and body volume factor, subcutaneous body fat measurements and BMI value, In data processing, Multivariate Analysis Of Variance (MANOVA) and LSD test were used to establish group and individual morphological characteristics differences and to help determine the level of the statistical significance of the differences by variables, respectively.
Results and Discussion
The results of differences significance evaluation tests show statistically significant differences in the morphological characteristics in all the four groups. The girls involved in rhythmic gymnastics were proven to have the smallest body measurements. The largest differences were found in the following variables: pelvis diameter, upper arm skin fold thickness, BMI.
Conclusion
Aesthetic sport activities greatly affect the morphological characteristics in girls. In all the morphological characteristics variables, all the girls engaged in aesthetic sports achieved significantly better results than their peers not engaged in any kind of sport activities. Fit physique and low body fat percentage are often an important prerequisite in achieving the highest results. Each of the aesthetic sports promotes the ideal and specific aesthetic body type most suitable for the nature of that sport activity.
Background.The aim of the present study was to examine the effect of age, sex and calendar year on triathlon performance and variation of performance by events (i.e. swimming, cycling 1, cycling2 and running) in ‘Ultraman Hawaii’ held between 1983 and 2015.
Methods.Within each sex, participants were grouped in quartiles (i.e. Q1, Q2, Q3 and Q4) with Q1 being the fastest (i.e. lowest overall time) and Q4 the slowest (i.e. highest overall time).Different trends among events (i.e. swimming, cycling 1, cycling2 and running)were observed byperformance group and by sex.
Results.A between-within subjects ANOVA showed a large sex×event (p=0.015, η2=0.014) and a medium performance group×event interaction (p=0.001, η2=0.012). No main effect of event on performance was observed (p=0.174, η2=0.007). With regards to the sex×event interaction, three female performance groups (i.e. Q2, Q3 and Q4) increased race time from swimming to cycling 1, whereas only one male performance group (Q4) revealed a similar trend. From cycling 1 to cycling 2, the two slower female groups (Q3 and Q4) and the slowest male group (Q4) increased raced time. In women, the fastest group decreased (i.e. improved) race time from swimming to cycling 1 and thereafter, maintained performance, whereas in men, the fastest group decreased race time till cycling 2 and increased it in the running.
Conclusion.In summary, women pace differently than men during ‘Ultraman Hawaii’ where the fastest women decreased performance on day 1 and could then maintain on day 2 and 3, whereas the fastest men worsened performance on day 1 and 2 but improved on day 3.
Introduction:
Malnutrition is a serious and relatively common problem among hospitalized patients; moreover, it is known that a good hydration state contributes to health and wellbeing.
Objective:
The aim of this study was to determine the relationship between nutritional status, functional dependency, quality of life and liquid-intake habits in malnourished patients after hospital discharge.
Methods:
Cross-sectional descriptive study in 91 patients (45 males) who presented malnutrition at hospital discharge. The patients were grouped according to their liquid intake estimated through the Mini Nutritional Assessment questionnaire: 3-5 glasses (n = 42), and > 5 glasses (n = 46); removing from analysis < 3 glasses of liquid intake (n = 3). The body mass index, weight, Malnutrition Universal Screening Tool (MUST), functional dependency (Barthel questionnaire), and quality of life (Short Form 12 Health Survey [SF-12]) were assessed 2-months after discharge. Results: The > 5 glasses liquid intake group showed better nutritional status than the 3-5 glasses intake group, for weight (p < 0.001), body mass index (p = 0.001), and MUST scale (p = 0.020). Additionally, the > 5 glasses liquid intake group signifi cantly scored higher values in the total SF-12 questionnaire (p = 0.013), presenting better self-reported quality of life, and higher functional independency in the Barthel index (p = 0.037) than the 3-5 glasses liquid intake group (p = 0.013).
Conclusions:
Although further research is needed to elucidate the characteristics of this relationship, descriptive comparisons between groups showed favorable nutritional status, functional independency and quality of life for the > 5 glasses of liquid intake compared with the 3-5 glasses of liquid intake group during a 2-months follow-up.
The aim of the study was to verify the hydration status and the kidney function in marathoners during the training season and after a marathon race. Nine male runners were investigated during 12 weeks of training. Urine was collected in four moments; in the beginning (C1) and during (C2) the training program, before (C3) and after (C4) the competition. Urine pH was measured using reagent tapes, urine density with a refractometer, protein excretion by Bradford assay and erythrocytes and leucocytes by microscopy. Changes were observed when C-4 was compared to the other collection times for all variables investigated. It is possible to conclude that physical exertion induced important changes in the hydration status and glomerular membrane selectivity to macromolecules, modifying the kidney function of the marathoners in C4.
Objective: To record weight changes, fluid intake and changes in serum sodium concentration in ultradistance triathletes.
Design: Descriptive research.
Setting: Ironman triathlon (3.8 km swim, 180 km cycle, 42.2 km run). Air temperature at 1200 h was 21°C, (relative humidity 91%). Water temperature was 20.7°C.
Participants: 18 triathletes.
Interventions: None.
Main Outcome Measures: Subjects were weighed and had blood drawn for serum sodium concentration [Na], hemoglobin, and hematocrit, pre-race, post-race, and at 0800 h on the morning following the race (recovery); subjects were also weighed at transitions. Fluid intake during the race was estimated by athlete recall.
Results: Median weight change during the race = -2.5 kg (p < 0.0006). Subjects lost weight during recovery (median = -1.0 kg) (p < 0.03). Median hourly fluid intake = 716 ml/h (range 421-970). Fluid intakes were higher on the bike than on the run (median 889 versus 632 ml/h, p = 0.03). Median calculated fluid losses cycling were 808 ml/h and running were 1,021 ml/h. No significant difference existed between pre-race and post-race [Na] (median 140 versus 138 mmol/L) or between post-race and recovery [Na] (median 138 versus 137 mmol/L). Plasma volume increased during the race, median + 10.8% (p = 0.0005). There was an inverse relationship between change in [Na] pre-race to post-race and relative weight change (r = -0.68, p = 0.0029). Five subjects developed hyponatremia ([Na] 128-133 mmol/L).
Conclusions: Athletes lose 2.5 kg of weight during an ultra-distance triathlon, most likely from sources other than fluid loss. Fluid intakes during this event are more modest than that recommended for shorter duration exercise. Plasma volume increases during the ultradistance triathlon. Subjects who developed hyponatremia had evidence of fluid overload despite modest fluid intakes.
Purpose:
Dual-energy x-ray absorptiometry (DXA) is rapidly becoming more accessible and popular as a technique to monitor body composition, especially in athletic populations. This study investigates the reliability of DXA in measuring body composition of active individuals, specifically to ascertain biological variability associated with two different types of exercise under free-living conditions in active individuals.
Methods:
Well-trained individuals (27 strength-trained male subjects, 14 female cyclists, and 14 male cyclists) underwent three whole-body DXA scans over a 1-d period: in the morning after an overnight fast, approximately 5 min later after repositioning on the scanning bed, and shortly after a self-chosen exercise session (resistance training or cycling). Subjects were allowed to consume food and fluid ad libitum before and during exercise as per their usual practices. Magnitude of typical (standard) errors of measurement and changes in the mean of DXA measures were assessed by standardization.
Results:
Exercise and its related practices of fluid and food intake are associated with changes in the mean estimates of total and regional body composition that range from trivial to small but substantial. An exercise session also increases the typical error of measurement of these characteristics by approximately 10%.
Conclusion:
The easiest and most practical way to minimize the biological "noise" associated with undertaking a DXA scan is to have subjects fasted and rested before measurement. Until sufficient data on the smallest important effect are available, both biological and technical "noises" should be minimized so that any small but potentially "real" changes can be confidently detected.
To assess adaptations of the lower leg muscle-bone unit in 8- to 12-year-old children following a randomized controlled jumping exercise intervention for 9 months.
Twelve boys and 10 girls (INT) performed a supervised jumping protocol during the first 10 min of their regularly scheduled physical education class twice a week, while 11 boys and 12 girls (CON) completed the regular curriculum. We assessed maximum voluntary ground reaction force during multiple one-legged hopping (F(m1LH)), and tibial bone strength/geometry by peripheral quantitative computed tomography (pQCT) at the 4-, 14-, 38- and 66%-site pre, intermediate, and post intervention.
Whether increases in F(m1LH) (+2.1% points, P= 0.752), nor changes in bone strength/geometry (+1 to +3% points, 0.169<P<0.861), were significantly different for INT relative to CON. The relationship between F(m1LH) and volumetric bone mineral content at the 14%-site (vBMC(14%)) was very strong for both groups, pre and post intervention (0.51≤R(2)≤0.88). However, changes in F(m1LH) and vBMC(14%) were not correlated.
In children, growth and exercise did not increase maximum muscle force and bone strength in proportion to each other, meaning that the adaptive processes were not tightly coupled or follow different time courses.
Dual-energy x-ray absorptiometry (DXA) is becoming a popular tool to measure body composition in athletes, owing to its ease of operation and comprehensive analysis of body composition. This study represents the first systematic investigation of the reliability of DXA measurements of body composition in trained individuals and includes measurements of daily variability as well as the specific effect of the intake of a meal.
Physically active young adults (15 females, 16 males) underwent five whole-body DXA scans during a 2-d period: in the morning after an overnight fast, ~5 min later after repositioning on the scanning bed, ~8 h later after usual daily activities, and the next morning before and ~30 min after consumption of a simple breakfast. Magnitudes of typical (standard) errors of measurement and changes in the mean of DXA measures were assessed by standardization.
Repositioning produced trivial typical errors for whole-body composition, whereas regional body composition showed substantial errors. Daily activities and consumption of breakfast generally produced a substantial increase in the typical error and mean of DXA estimates of total and regional lean mass and associated body mass.
Having a standardized scanning protocol and fasted subjects is the most practical way to minimize measurement errors. Future studies involving DXA in measuring body composition should report their scanning and analysis protocol with their associated typical errors of measurement so that the level of reliability can be assessed.
Each year in the past three decades has seen hundreds of thousands of runners register to run a major marathon. Of those who attempt to race over the marathon distance of 26 miles and 385 yards (42.195 kilometers), more than two-fifths experience severe and performance-limiting depletion of physiologic carbohydrate reserves (a phenomenon known as 'hitting the wall'), and thousands drop out before reaching the finish lines (approximately 1-2% of those who start). Analyses of endurance physiology have often either used coarse approximations to suggest that human glycogen reserves are insufficient to fuel a marathon (making 'hitting the wall' seem inevitable), or implied that maximal glycogen loading is required in order to complete a marathon without 'hitting the wall.' The present computational study demonstrates that the energetic constraints on endurance runners are more subtle, and depend on several physiologic variables including the muscle mass distribution, liver and muscle glycogen densities, and running speed (exercise intensity as a fraction of aerobic capacity) of individual runners, in personalized but nevertheless quantifiable and predictable ways. The analytic approach presented here is used to estimate the distance at which runners will exhaust their glycogen stores as a function of running intensity. In so doing it also provides a basis for guidelines ensuring the safety and optimizing the performance of endurance runners, both by setting personally appropriate paces and by prescribing midrace fueling requirements for avoiding 'the wall.' The present analysis also sheds physiologically principled light on important standards in marathon running that until now have remained empirically defined: The qualifying times for the Boston Marathon.
G*Power is a free power analysis program for a variety of statistical tests. We present extensions and improvements of the version introduced by Faul, Erdfelder, Lang, and Buchner (2007) in the domain of correlation and regression analyses. In the new version, we have added procedures to analyze the power of tests based on (1) single-sample tetrachoric correlations, (2) comparisons of dependent correlations, (3) bivariate linear regression, (4) multiple linear regression based on the random predictor model, (5) logistic regression, and (6) Poisson regression. We describe these new features and provide a brief introduction to their scope and handling.
Previous studies using indirect means to assess the response of protein metabolism to exercise have led to conflicting conclusions. Therefore, in this study we have measured the rate of muscle protein synthesis in normal volunteers at rest, at the end of 4 h of aerobic exercise (40% maximal O2 consumption), and after 4 h of recovery by determining directly the rate of incorporation of 1,2-[13C]leucine into muscle. The rate of muscle protein breakdown was assessed by 3-methylhistidine (3-MH) excretion, and total urinary nitrogen excretion was also measured. There was an insignificant increase in 3-MH excretion in exercise of 37% and a significant increase (P less than 0.05) of 85% during 4 h of recovery from exercise (0.079 +/- 0.008 vs. 0.147 +/- 0.0338 mumol.kg-1.min-1 for rest and recovery from exercise, respectively). Nonetheless, there was no effect of exercise on total nitrogen excretion. Muscle fractional synthetic rate was not different in the exercise vs. the control group at the end of exercise (0.0417 +/- 0.004 vs. 0.0477 +/- 0.010%/h for exercise vs. control), but there was a significant increase in fractional synthetic rate in the exercise group during the recovery period (0.0821 +/- 0.006 vs. 0.0654 +/- 0.012%/h for exercise vs. control, P less than 0.05). Thus we conclude that although aerobic exercise may stimulate muscle protein breakdown, this does not result in a significant depletion of muscle mass because muscle protein synthesis is stimulated in recovery.
Stable isotope tracers and indirect calorimetry were used to evaluate the regulation of endogenous fat and glucose metabolism in relation to exercise intensity and duration. Five trained subjects were studied during exercise intensities of 25, 65, and 85% of maximal oxygen consumption (VO2max). Plasma glucose tissue uptake and muscle glycogen oxidation increased in relation to exercise intensity. In contrast, peripheral lipolysis was stimulated maximally at the lowest exercise intensity, and fatty acid release into plasma decreased with increasing exercise intensity. Muscle triglyceride lipolysis was stimulated only at higher intensities. During 2 h of exercise at 65% VO2max plasma-derived substrate oxidation progressively increased over time, whereas muscle glycogen and triglyceride oxidation decreased. In recovery from high-intensity exercise, although the rate of lipolysis immediately decreased, the rate of release of fatty acids into plasma increased, indicating release of fatty acids from previously hydrolyzed triglycerides. We conclude that, whereas carbohydrate availability is regulated directly in relation to exercise intensity, the regulation of lipid metabolism seems to be more complex.
Although dual-energy X-ray absorptiometry (DXA) is widely used in clinical research as a means of quantifying body composition, there remains at present little published information that reviews the method's underlying physical basis. Because a clear understanding of DXA physical concepts is integral to appropriate use and interpretation, we present here a three-section review that includes both relevant in vitro and in vivo experimental demonstrations. In the first section we describe the main physical principles on which DXA is based. The section that follows presents a step-by-step analysis of the DXA two-component soft tissue model. In the final section we demonstrate how knowledge of physical concepts can lead to resolution of important methodological concerns, such as the influence of hydration changes on DXA fat estimates. A thorough understanding of DXA physical concepts provides a basis for appropriate interpretation of measurement results and stimulates many new and important research questions.
In order to assess the accuracy of peripheral QCT (Stratec XCT 960) we analysed scans of the European Forearm Phantom and another phantom consisting of K2HPO4 encased in aluminium tubes to simulate cortical walls. Additionally 14 cadaveric forearm specimen scans were compared to CT scans acquired on a GE9800Q. The accuracy for density assessment of the European Forearm Phantom was better than 3%. A small increase in density was observed with increasing thickness of the aluminium wall (10% for each mm). Density measurements within the wall were confounded by limited spatial resolution. For a thickness of less than 4 mm, the density within the wall was underestimated by up to 40%. The measurement of mineral content was not influenced by this effect and showed an accuracy error of less than 6%. The agreement of density measurements on the different CT systems was very strong (R2 > 0.96; RMSE < 6.2%). Our findings suggest that the Stratec pQCT scanner very accurately measures volumetric trabecular and total bone mineral densities at the distal radius while the assessment of cortical density is associated with considerable inaccuracies due to limited spatial resolution.
In this study, we estimated the specific tensions of soleus (Sol) and tibialis anterior (TA) muscles in six men. Joint moments were measured during maximum voluntary contraction (MVC) and during electrical stimulation. Moment arm lengths and muscle volumes were measured using magnetic resonance imaging, and pennation angles and fascicular lengths were measured using ultrasonography. Tendon and muscle forces were modeled. Two approaches were followed to estimate specific tension. First, muscle moments during electrical stimulation and moment arm lengths, fascicular lengths, and pennation angles during MVC were used (data set A). Then, MVC moments, moment arm lengths at rest, and cadaveric fascicular lengths and pennation angles were used (data set B). The use of data set B yielded the unrealistic specific tension estimates of 104 kN/m(2) in Sol and 658 kN/m(2) in TA. The use of data set A, however, yielded values of 150 and 155 kN/m(2) in Sol and TA, respectively, which agree with in vitro results from fiber type I-predominant muscles. In fact, both Sol and TA are such muscles. Our study demonstrates the feasibility of accurate in vivo estimates of human muscle intrinsic strength.
Although skeletal muscle is capable of oxidizing selected amino acids, exercise in the fed and carbohydrate-replete condition results in only a small increase in amino acid utilization. Nevertheless, it may be important to increase the dietary protein requirements of active individuals. There is ongoing debate as to whether the amino acids for oxidation are derived from the free amino acid pool, from net protein breakdown, or a combination of both. There has been interest in the potential ergogenic benefits of amino acid ingestion; however, BCAA ingestion does not appear to affect fatigue during prolonged exercise, there is little support from controlled studies to recommend glutamine ingestion for enhanced immune function, and although glutamine stimulates muscle glycogen synthesis, its addition to carbohydrate supplements provides no additional benefit over ingestion of carbohydrate alone.
Energy balance of 10 male and 8 female triathletes participating in an Ironman event (3.8-km swim, 180-km cycle, 42.2-km run) was investigated. Energy intake (EI) was monitored at 7 designated points by dietary recall of food and fluid consumption. Energy expenditure (EE) during cycling and running was calculated using heart rate-VO, regression equations and during swimming by the multiple regression equation: Y = 3.65v+ 0.02W- 2.545 where Yis VO,in L x min(-1), v is the velocity in m s(-1), Wis the body weight in kilograms. Total EE (10,036 +/- 931 and 8,570 +/- 1,014 kcal) was significantly greater than total EI (3,940 +/- 868 and 3,115 +/- 914 kcal, p <.001) for males and females, respectively, although energy balance was not different between genders. Finishing time was inversely related to carbohydrate (CHO) intake (g x kg(-1) x h(-1)) during the marathon run for males (r = -.75,p <.05), and not females, suggesting that increasing CHO ingestion during the run may have been a useful strategy for improving Ironman performance in male triathletes.
The aims of this study were to compare different tracer methods to assess whole body protein turnover during 6 h of prolonged endurance exercise when carbohydrate was ingested throughout the exercise period and to investigate whether addition of protein can improve protein balance. Eight endurance-trained athletes were studied on two different occasions at rest (4 h), during 6 h of exercise at 50% of maximal O2 uptake (in sequential order: 2.5 h of cycling, 1 h of running, and 2.5 h of cycling), and during subsequent recovery (4 h). Subjects ingested carbohydrate (CHO trial; 0.7 g CHO·kg -1·h-1) or carbohydrate/protein beverages (CHO + PRO trial; 0.7 g CHO·kg-1·h-1 and 0.25 g PRO·kg-1·h-1) at 30-min intervals during the entire study. Whole body protein metabolism was determined by infusion of L-[1-13C]leucine, L-[2H5]phenylalanine, and [15N2]urea tracers with sampling of blood and expired breath. Leucine oxidation increased from rest to exercise [27 ± 2.5 vs. 74 ± 8.8 (CHO) and 85 ± 9.5 vs. 200 ± 16.3 mg protein·kg-1·h-1 (CHO + PRO), P < 0.05], whereas phenylalanine oxidation and urea production did not increase with exercise. Whole body protein balance during exercise with carbohydrate ingestion was negative (-74 ± 8.8, -17 ± 1.1, and -72 ± 5.7 mg protein·kg-1·h-1) when L-[1- 13C]leucine, L-[2H5]phenylalanine, and [ l5N2]urea, respectively, were used as tracers. Addition of protein to the carbohydrate drinks resulted in a positive or less-negative protein balance (-32 ± 16.3, 165 ± 4.6, and 151 ± 13.4 mg protein·kg-1·h-1) when L-[1- 13C]leucine, L-[2H5]phenylalanine, and [ 15N2]urea, respectively, were used as tracers. We conclude that, even during 6 h of exhaustive exercise in trained athletes using carbohydrate supplements, net protein oxidation does not increase compared with the resting state and/or postexercise recovery. Combined ingestion of protein and carbohydrate improves net protein balance at rest as well as during exercise and postexercise recovery.
The purpose of this study was to determine for the first time by repeated non-invasive 13C-NMR spectrometry whether blood lactate concentration affects glycogen reduction in non-exercising muscle during prolonged (6 h) physical exercise in healthy adult males. Such an effect would indirectly show that glycogenolysis independent of nervous activation occurs in non-exercising muscle. After an overnight fast, 12 subjects performed alternating one-leg cycle exercise and arm cranking exercise at an average work load of 106 (SD 26) W [63 (9)% maximum oxygen consumption for one-leg exercise] and 69 (13) W [61 (10)% maximum oxygen consumption for arm cranking exercise], respectively. During the 6-h exercise test, glycogen concentration of the non-exercising calf muscle decreased by 17 (7)% while the glycogen concentration in the exercising calf muscle decreased by 45 (8)%. In a resting control group (n=6), the glycogen concentration did not decrease significantly. The higher the exercise intensity and therefore blood lactate concentration, the smaller was the glycogen reduction in the non-exercising calf muscles. We conclude that during prolonged physical exercise glycogenolysis in non-exercising human muscles decreases as exercise intensity increase contrary to exercising muscles. This observation might be an indirect evidence for a non-exercise induced glycogenolysis in inactive muscles.
The development of symptomatic hyponatraemia consequent on participation in marathon and ultraendurance races has led to questions about its aetiology and prevention.
To evaluate: (a) the assertion that sweat sodium losses cannot contribute to the development of hyponatraemia during endurance exercise; (b) the adequacy of fluid replacement recommendations issued by the International Marathon Medical Directors Association (IMMDA) for races of 42 km or longer; (c) the effectiveness of commercial sports drinks, compared with water, for attenuating plasma sodium reductions.
A mathematical model was used to predict the effects of different drinking behaviours on hydration status and plasma sodium concentration when body mass, body composition, running speed, weather conditions, and sweat sodium concentration were systematically varied.
Fluid intake at rates that exceed sweating rate is predicted to be the primary cause of hyponatraemia. However, the model predicts that runners secreting relatively salty sweat can finish ultraendurance exercise both dehydrated and hyponatraemic. Electrolyte-containing beverages are predicted to delay the development of hyponatraemia. The predictions suggest that the IMMDA fluid intake recommendations adequately sustain hydration over the 42 km distance if qualifiers-for example, running pace, body size-are followed.
Actions to prevent hyponatraemia should focus on minimising overdrinking relative to sweating rate and attenuating salt depletion in those who excrete salty sweat. This simulation demonstrates the complexity of defining fluid and electrolyte consumption rates during athletic competition.
Numerous laboratory based studies have documented that aggressive hydration strategies (approximately 1-2 litres/h) are required to minimise a rise in core temperature and minimise the deleterious effects of hyperthermia on performance. However, field data on the relations between hydration level, core body temperature, and performance are rare.
To measure core temperature (Tcore) in triathletes during a 226 km Ironman triathlon, and to compare Tcore with markers of hydration status after the event. Method: Before and immediately after the 2004 Ironman Western Australia event (mean (SD) ambient temperature 23.3 (1.9) degrees C (range 19-26 degrees C) and 60 (14)% relative humidity (44-87%)) body mass, plasma concentrations of sodium ([Na+]), potassium ([K+]), and chloride ([Cl-]), and urine specific gravity were measured in 10 well trained triathletes. Tcore was measured intermittently during the event using an ingestible pill telemetry system, and heart rate was measured throughout.
Mean (SD) performance time in the Ironman triathlon was 611 (49) minutes; heart rate was 143 (9) beats/min (83 (6)% of maximum) and Tcore was 38.1 (0.3) degrees C. Body mass significantly declined during the race by 2.3 (1.2) kg (-3.0 (1.5)%; p < 0.05), whereas urine specific gravity significantly increased (1.011 (0.005) to 1.0170 (0.008) g/ml; p < 0.05) and plasma [Na+], [K+], and [Cl-] did not change. Changes in body mass were not related to finishing Tcore (r = -0.16), plasma [Na+] (r = 0.31), or urine specific gravity (r = -0.37).
In contrast with previous laboratory based studies examining the influence of hypohydration on performance, a body mass loss of up to 3% was found to be tolerated by well trained triathletes during an Ironman competition in warm conditions without any evidence of thermoregulatory failure.
To present recommendations to optimize the fluid-replacement practices of athletes.
Dehydration can compromise athletic performance and increase the risk of exertional heat injury. Athletes do not voluntarily drink sufficient water to prevent dehydration during physical activity. Drinking behavior can be modified by education, increasing accessibility, and optimizing palatability. However, excessive overdrinking should be avoided because it can also compromise physical performance and health. We provide practical recommendations regarding fluid replacement for athletes.
Educate athletes regarding the risks of dehydration and overhydration on health and physical performance. Work with individual athletes to develop fluid-replacement practices that optimize hydration status before, during, and after competition.
Several aspects of body composition, in particular the amount and distribution of body fat and the amount and composition of lean mass, are now understood to be important health outcomes in infants and children. Their measurement is increasingly considered in clinical practice; however, paediatricians are often unsure as to which techniques are appropriate and suitable for application in specific contexts. This article summarises the pros and cons of measurement technologies currently available for paediatric application. Simple techniques are adequate for many purposes, and simple regional data may often be of greater value than "whole body" values obtained by more sophisticated approaches.
Evidence in human studies of the association of long term habitual exercise with bone mineral content (BMC) and density (BMD) largely comes from studies in athletes. In young adults, the highest BMC and BMD values have been found in strength and power-trained athletes, while endurance activities such as long distance running and swimming seem less effective with regard to peak bone density. Intensive endurance training may even be associated with amenorrhoea and decreased trabecular bone density in young females. However, after menopause female athletes show greater bone mass indicating that they do not share the accelerated decline in BMC observed in a nonathletic population. Middle-aged and elderly male athletes from various sports have significantly higher BMC and BMD than controls, especially in trabecular bone sites, but higher cortical BMC has also been found in the dominant/nondominant arm comparisons with unilateral exercises such as tennis. The differences found between female athletes and controls have generally been less pronounced than those among men, but a number of studies suggest that in women long term physical training may counteract the low BMC and BMD associated with reduced bone mass. Although the interpretation of results of cross-sectional studies should be treated with caution, studies in athletes serve as an economical alternative approach to experimental trials with their long term follow-up and exercise compliance problems. The differences found in BMD between those who have devoted themselves to life-long training and those who have been much less active should not be underestimated.
G*Power (Erdfelder, Faul, & Buchner, 1996) was designed as a general stand-alone power analysis program for statistical tests commonly used in social and behavioral research. G*Power 3 is a major extension of, and improvement over, the previous versions. It runs on widely used computer platforms (i.e., Windows XP, Windows Vista, and Mac OS X 10.4) and covers many different statistical tests of the t, F, and chi2 test families. In addition, it includes power analyses for z tests and some exact tests. G*Power 3 provides improved effect size calculators and graphic options, supports both distribution-based and design-based input modes, and offers all types of power analyses in which users might be interested. Like its predecessors, G*Power 3 is free.
The German Food Composition Table, founded in the 1960s by S. W. Souci, W. Fachmann and H. Kraut has been published since 1968 as a regular printed version via a scientific publisher. Analogous to the development of this media, an electronic version of the database, corresponding to the fifth edition of the table, was available for the first time in 1995. However, contemporaneously with the publishing of the sixth edition an online-version of the database has been developed and transferred into the World Wide Web, providing detailed food composition data of about 800 food items and 260 food constituents (http://www.sfk-online.net). The documentation includes the average values and variations of the nutrient concentrations, as well as energy- and waste values of the specific food items. The concept of the database enables the user to search for specific food items, defined constituent concentrations and energy values, as well as to export data tables of single food items. Additionally the calculation of the composition of raw food mixtures based on the data included in the database is realized by this electronic version.
This article reviews The Essential Physics of Medical Imaging, Third Edition. by J. T. Bushberg, J. A. Seibert, E. M. Leidholdt, J. M. Boone
In 1985, Silver et al. published a cadaver study which determined the relative order of strength of the muscles in the calf. Muscle strength, which is proportional to volume, was obtained by dissecting out the individual muscles, weighing them, and then multiplying by the specific gravity. No similar studies have been performed using {\it in vivo} measurements of muscle volume.
Ten normal subjects underwent 3-Tesla MRI's of both lower extremities using non-fat-saturated T2 SPACE sequences. The volume for each muscle was determined by tracing the muscle contour on sequential axial images and then interpolating the volume using imaging software.
The results from this study differ from Silver's original article. The lateral head of the gastrocnemius was found to be stronger than the tibialis anterior muscle. The FHL and EDL muscles were both stronger than the peroneus longus. There was no significant difference in strength between the peroneus longus and brevis muscles.
This revised order of muscle strengths in the calf based on in vivo MRI findings may assist surgeons in determining the optimal tendons to transfer in order to address muscle weakness and deformity.
The goal of these studies was to evaluate acute changes in protein metabolism in skeletal muscle in response to contractile activity. Rates of protein synthesis were measured by following L-[U-14C]phenylalanine incorporation into protein in muscles of the perfused rat hindlimb at rest, during 10 min of maximal isometric muscle contractions, and during 10 min of recovery. Synthesis measurements were carried out under conditions that ensured that the specific radioactivity of the tRNA-bound precursor amino acid was equal to that of extracellular phenylalanine. Protein degradation was estimated by measuring the release of Nt-methylhistidine. Rates of synthesis were markedly inhibited in response to muscle contractions in tibialis anterior, gastrocnemius, and plantaris but were unaffected in soleus. Rates of synthesis returned toward those observed in the resting condition during the recovery period. Rates of degradation were also markedly inhibited in response to muscle contractions. Decreased rates of synthesis correlated with reduced tissue contents of ATP and creatine phosphate, a reduced ATP/ADP, and an elevated tissue content of lactate. The results demonstrate that isometric contractions in muscles consisting of a high proportion of fast glycolytic fibers result in a marked depression in rates of protein synthesis that may be due to an altered energy state.
This study investigates the impact of protein coingestion with carbohydrate on muscle protein synthesis during endurance type exercise. Twelve healthy male cyclists were studied during 2 h of fasted rest followed by 2 h of continuous cycling at 55% W(max). During exercise, subjects received either 1.0 g·kg(-1)·h(-1) carbohydrate (CHO) or 0.8 g·kg(-1)·h(-1) carbohydrate with 0.2 g·kg(-1)·h(-1) protein hydrolysate (CHO+PRO). Continuous intravenous infusions with l-[ring-(13)C(6)]phenylalanine and l-[ring-(2)H(2)]tyrosine were applied, and blood and muscle biopsies were collected to assess whole body protein turnover and muscle protein synthesis rates at rest and during exercise conditions. Protein coingestion stimulated whole body protein synthesis and oxidation rates during exercise by 22 ± 3 and 70 ± 17%, respectively (P < 0.01). Whole body protein breakdown rates did not differ between experiments. As a consequence, whole body net protein balance was slightly negative in CHO and positive in the CHO+PRO treatment (-4.9 ± 0.3 vs. 8.0 ± 0.3 μmol Phe·kg(-1)·h(-1), respectively, P < 0.01). Mixed muscle protein fractional synthetic rates (FSR) were higher during exercise compared with resting conditions (0.058 ± 0.006 vs. 0.035 ± 0.006%/h in CHO and 0.070 ± 0.011 vs. 0.038 ± 0.005%/h in the CHO+PRO treatment, respectively, P < 0.05). FSR during exercise did not differ between experiments (P = 0.46). We conclude that muscle protein synthesis is stimulated during continuous endurance type exercise activities when carbohydrate with or without protein is ingested. Protein coingestion does not further increase muscle protein synthesis rates during continuous endurance type exercise.
Energy turnover was assessed in two conditions of mixed ultra-endurance exercise. In Study 1, energy expenditure and intake were measured in nine males in a laboratory over 24 h. In Study 2, energy expenditure was assessed in six males during an 800-km Adventure race (mean race time 152.5 h). Individual correlations between heart rate and oxygen uptake (VO(2)) were established during pre-tests when kayaking, cycling, and running. During exercise, energy expenditure was estimated from continuous heart rate recordings. Heart rate and VO(2) were measured regularly during fixed cycling work rates to correct energy expenditure for drift in oxygen pulse. Mean energy expenditure was 18,050 +/- 2,390 kcal (750 +/- 100 kcal h(-1)) and 80,000 +/- 18,000 kcal (500 +/- 100 kcal h(-1)) in Study 1 and Study 2 respectively, which is higher than previously reported. Energy intake in Study 1 was 8,450 +/- 1,160 kcal, resulting in an energy deficit of 9,590 +/- 770 kcal. Body mass decreased in Study 1 (-2.3 +/- 0.8 kg) but was unchanged in Study 2. Fat mass decreased in Study 2 (-2.3 +/- 1.5 kg). In Study 1, muscle glycogen content decreased by only 60%. Adventure racing requires a high energy expenditure, with large inter-individual variation. A large energy deficit is caused by inadequate energy intake, possibly due to suppressed appetite and gastrointestinal problems. The oxygen pulse, comparing start to 12 h of exercise and beyond, increased by 10% and 5% in Study 1 and Study 2 respectively. Hence, estimations of energy expenditure from heart rate recordings should be corrected according to this drift.
We investigated whether male triathletes in an Ironman triathlon lose body mass in the form of fat mass or skeletal muscle mass in a field study at the Ironman Switzerland in 27 male Caucasian non-professional Ironman triathletes. Pre- and post-race body mass, fat mass and skeletal muscle mass were determined. In addition, total body water, hematological and urinary parameters were measured in order to quantify hydration status. Body mass decreased by 1.8 kg (p< 0.05), skeletal muscle decreased by 1.0 kg (p< 0.05) whereas fat mass showed no changes. Urinary specific gravity, plasma urea and plasma volume increased (p< 0.05). Pre- to post-race change (Delta) in body mass was not associated with ? skeletal muscle mass. Additionally, there was no association between Delta plasma urea and Delta skeletal muscle mass; Delta plasma volume was not associated with Delta total body water (p< 0.05). We concluded that male triathletes in an Ironman triathlon lose 1.8 kg of body mass and 1 kg of skeletal muscle mass, presumably due to a depletion of intramyocellular stored glycogen and lipids.
This study investigated fluid and electrolyte balance in well-trained male and female swimmers during 2 training sessions. Participants were 17 nationally ranked swimmers measured during a period of intensive training. Sweat loss was assessed from changes in body mass after correction for fluid intake and urine collection. Sweat composition was measured from waterproof absorbent patches applied at 4 skin sites. Air and pool-water temperatures were 36 degrees C and 27.4 degrees C, respectively. Training lasted 105 min in each session. All measured variables were similar on the 2 testing days. Mean sweat-volume loss was 548 +/- 243 ml, and mean sweat rate was 0.31 +/- 0.1 L/hr. Mean fluid intake was 489 +/- 270 ml. Mean body-mass loss was 0.10 0.50 kg, equivalent to 0.1% +/- 0.7% dehydration. Mean pretraining urine osmolality was 662 +/- 222 mOsm/kg, which was negatively associated with both mean drink volume consumed (p = .044, r = .244) and mean urine volume produced during training (p = .002, r2 = .468). Mean sweat Na+, K+, and Cl- concentrations (mmol/L) were 43 +/- 14, 4 +/- 1, and 31 +/- 9, respectively; values were not different between males and females and were not different between days except for a marginal difference in K+ concentration. The average swimmer remained hydrated during the session, and calculated sweat rates were similar to those in previous aquatic studies.
We investigated whether ultraendurance runners in a 100-km run suffer a decrease of body mass and whether this loss consists of fat mass, skeletal muscle mass, or total body water. Male ultrarunners were measured pre- and postrace to determine body mass, fat mass, and skeletal muscle mass by using the anthropometric method. In addition, bioelectrical impedance analysis was used to determine total body water, and urinary (urinary specific gravity) and hematological parameters (hematocrit and plasma sodium) were measured in order to determine hydration status. Body mass decreased by 1.6 kg (p < .01), fat mass by 0.4 kg (p < .01), and skeletal muscle mass by 0.7 kg (p < .01), whereas total body water increased by 0.8 L (p < .05). Hematocrit and plasma sodium decreased significantly (p < .01), whereas plasma urea and urinary specific gravity (USG) increased significantly (p < .01). The decrease of 2.2% body mass and a USG of 1.020 refer to a minimal dehydration. Our athletes seem to have been relatively overhydrated (increase in total body water and plasma sodium) and dehydrated (decrease in body mass and increase in USG) during the race, as evidenced by the increased total body water and the fact that plasma sodium and hematocrit were lower postrace than prerace. The change of body mass was associated with the change of total body water (p < .05), and we presume the development of.
To examine the improvement in swimming (3.8 km), cycling (180 km), running (42.2 km), and overall performances at the Hawaii Ironman Triathlon of elite males and females between 1981 and 2007.
Trends across years, gender differences in performance times in the three disciplines, and overall winning times of the top 10 males and females were analyzed.
Overall performance time in the ironman decreased rapidly from 1981 but has remained stable since the late 1980s. From 1988 to 2007, linear regression analysis showed that change in swimming, cycling, running, and total performance for both males and females was less than 1.4% per decade, except for females' running time, which decreased by 3.8% per decade. Since 1988, the mean (SD) gender differences in time for swimming, cycling, running, and total event were 9.8% (2.9), 12.7% (2.0), 13.3% (3.1), and 12.6% (1.3), respectively.
After an initial phase of rapid improvement of performances during the 1980s, there was a relative plateau, but at least in running and cycling, there were small improvements. Over the last two decades, gender difference in swimming remained stable while it slightly increased in cycling and decreased in running. The gender difference in ironman total performance is unlikely to change in the future.
Large stores of intramuscular substrates are found in the different fiber types of human skeletal muscle, and with prolonged exercise both glycogen and triglyceride stores are utilized. The contribution from intramuscular glycogen stores is greatest at higher work intensities while triglyceride stores are utilized at moderate intensities. In man all fiber types have a similar glycogen content whereas the highest lipid content is found in the more oxidative fibers. The muscle metabolism is well adapted to the supply of substrate as well as to the demand for energy. Among several regulatory mechanisms, changes in citrate concentration seems to be an important factor in the interplay between carbohydrate and lipid metabolism.
Indirect calorimetry is the method by which the type and rate of substrate utilization, and energy metabolism are estimated in vivo starting from gas exchange measurements. This technique provides unique information, is noninvasive, and can be advantageously combined with other experimental methods to investigate numerous aspects of nutrient assimilation, thermogenesis, the energetics of physical exercise, and the pathogenesis of metabolic diseases. Since its use as a research tool in metabolism is growing, the theoretical bases of indirect calorimetry are here reviewed in a detailed and orderly fashion. Special cases, such as the occurrence of net lipid synthesis or gluconeogenesis, are formally considered with derivation of explicit stoichiometric equations. The limitations of indirect calorimetry, both theoretical and technical, are discussed in the context of circumstances of clinical interest in metabolism.
19 subjects performed prolonged heavy arm and leg exercise after which they had a protein and fat diet for three days. Thereafter they switched to a carbohydrate enriched diet during a 4-day period. The measurements were performed on the 3rd day and then repeated on the 7th day. The glycogen concentration in the thigh and the arm muscles was 4.5 and 2.6 g/kg wet muscle on the 3rd day and increased with the carbohydrate enriched diet to 19.9 and 16.9 g/kg wet muscle, respectively. Body weight increased 2.4 kg during this period of 4 days. The total body water increased 2.2 1 which is assumed to be caused by the glycogen storage in the muscles and the liver. The amount of glycogen stored was calculated to be at least 500 g, which means that 3—4 g of water is bound with each gram of glycogen.
We have used the primed constant infusion of di-[15N]urea and [1-13C]leucine to determine the effects of mild exercise (approx 30% Vo2max for 105 min) on urea production and leucine metabolism in human subjects. The oxidation of plasma leucine was distinguished from the oxidation of leucine that never entered the plasma pool ("intracellular" leucine) by means of determining the enrichment of alpha-ketoisocaproic acid (alpha-KICA). Total leucine oxidation increased from 0.38 +/0 0.05 to 1.41 +/- 0.14 micromol . kg-1 . min-1 during exercise due to increases in the oxidation of plasma leucine (150%) and intracellular leucine (600%). Plasma leucine flux decreased slightly, but not significantly (0.1 greater than P greater than 0.05), and the percent of alpha-KICA derived from plasma leucine dropped significantly (P less than 0.05) from 79.5 +/- 4.3 at rest to 62.0 +/- 5.3% over the last 30 min of exercise. Despite the increase in leucine oxidation during exercise, urea concentration and production did not change. Thus in exercise urea production does not accurately reflect all aspects of amino acid metabolism.
We evaluated the Miles Inc., Clinitek Atlas Automated Urine Chemistry Analyzer for 11 tests: bilirubin, color, glucose, ketones, leukocyte esterase, nitrite, occult blood, pH, protein, specific gravity, and urobilinogen. The instrument uses a roll of reagent strips affixed to a clear plastic support; urine specimens are automatically pipetted onto these strips. The instrument measures the pads' color using reflectance colorimetry. Specific gravity is measured using a fiberoptic refractive index method. Four hospitals participated in the evaluation, and tests were performed only on fresh urine samples. We found the instrument easy to use; it has walk-away capability with up to 40-specimen loading capacity plus spaces for STATs, calibrators and controls. We found good comparability with chemical tests and other nonreagent strip procedures, as well as good agreement with the Miles Inc. Clinitek 200+ urine chemistry analyzer and visual reading of the Miles Inc. Multistix Reagent Strips. The Clinitek Atlas is rugged and reliable, and is suitable for a high-volume urinalysis laboratory.
Evidence in human studies of the association of long term habitual exercise with bone mineral content (BMC) and density (BMD) largely comes from studies in athletes. In young adults, the highest BMC and BMD values have been found in strength and power-trained athletes, while endurance activities such as long distance running and swimming seem less effective with regard to peak bone density. Intensive endurance training may even be associated with amenorrhoea and decreased trabecular bone density in young females. However, after menopause female athletes show greater bone mass indicating that they do not share the accelerated decline in BMC observed in a nonathletic population. Middle-aged and elderly male athletes from various sports have significantly higher BMC and BMD than controls, especially in trabecular bone sites, but higher cortical BMC has also been found in the dominant/nondominant arm comparisons with unilateral exercises such as tennis. The differences found between female athletes and controls have generally been less pronounced than those among men, but a number of studies suggest that in women long term physical training may counteract the low BMC and BMD associated with reduced bone mass. Although the interpretation of results of cross-sectional studies should be treated with caution, studies in athletes serve as an economical alternative approach to experimental trials with their long term follow-up and exercise compliance problems. The differences found in BMD between those who have devoted themselves to life-long training and those who have been much less active should not be underestimated.
We examined water gains and water losses in a group of athletes after an ultra-endurance event. Thirteen male triathletes competed in a triathlon consisting of 21 km canoeing, 97 km cycling, and 42 km running. Water loss determinations included sweat rate (940 +/- 163 g.h-1), urine output (41 +/- 38 g.h-1), and respiratory water loss (88 +/- 10 g.h-1). Water gain measurements included water intake (737 +/- 137 g.h-1) and the water content of the food intake (10 +/- 7 g.h-1), and we estimated the water of metabolism for carbohydrate (49 +/- 5 g.h-1) and fat (41 +/- 5 g.h-1) and the water released after glycogen utilization (104 +/- 64 g.h-1). Total water gain averaged 940 +/- 160 g.h-1, while the total water loss averaged 1069 +/- 163 g.h-1. Body weight changed from 69.87 +/- 7.14 kg before the race to 66.65 +/- 6.75 kg after the race (-4.61 +/- 2.94%). The sum of the exogenous water gains and the endogenous water gains (940 g.h-1) replaced almost 90% of the total water loss (1069 g.h-1). The difference (1334 g) represented a loss of about 1.9% of the initial body mass (69.87 kg). The exogenous water gains alone (747 g.h-1) replaced about 70% of the total water loss, and the difference represented a loss of over 4% of the initial body mass. Because of the nature of the endogenous sources of water gain, the total amount of water gain almost replaces the total amount of water loss (difference approximately 12%) even in the presence of a reduction in body mass (> 4%).
The purpose of this investigation was to validate that in vivo measurement of skeletal muscle attenuation (MA) with computed tomography (CT) is associated with muscle lipid content. Single-slice CT scans performed on phantoms of varying lipid concentrations revealed good concordance between attenuation and lipid concentration (r(2) = 0.995); increasing the phantom's lipid concentration by 1 g/100 ml decreased its attenuation by approximately 1 Hounsfield unit (HU). The test-retest coefficient of variation for two CT scans performed in six volunteers was 0.51% for the midthigh and 0.85% for the midcalf, indicating that the methodological variability is low. Lean subjects had significantly higher (P < 0.01) MA values (49.2 +/- 2.8 HU) than did obese nondiabetic (39.3 +/- 7.5 HU) and obese Type 2 diabetic (33.9 +/- 4. 1 HU) subjects, whereas obese Type 2 diabetic subjects had lower MA values that were not different from obese nondiabetic subjects. There was also good concordance between MA in midthigh and midcalf (r = 0.60, P < 0.01), psoas (r = 0.65, P < 0.01), and erector spinae (r = 0.77, P < 0.01) in subsets of volunteers. In 45 men and women who ranged from lean to obese (body mass index = 18.5 to 35.9 kg/m(2)), including 10 patients with Type 2 diabetes mellitus, reduced MA was associated with increased muscle fiber lipid content determined with histological oil red O staining (P = -0.43, P < 0. 01). In a subset of these volunteers (n = 19), triglyceride content in percutaneous biopsy specimens from vastus lateralis was also associated with MA (r = -0.58, P = 0.019). We conclude that the attenuation of skeletal muscle in vivo determined by CT is related to its lipid content and that this noninvasive method may provide additional information regarding the association between muscle composition and muscle function.
To study fluid and sodium balance during overnight recovery following an ultradistance triathlon in hyponatremic athletes compared with normonatremic controls. CASE CONTROL STUDY: Prospective descriptive study.
1997 New Zealand Ironman Triathlon (3.8 Km swim, 180 Km cycle, 42.2 Km run).
Seven athletes ("subjects") hospitalized with hyponatremia (median sodium [Na] = 128 mmol L(-1)). Data were compared with measurements from 11 normonatremic race finishers ("controls") (median sodium = 141 mmol L(-1)).
None.
Athletes were weighed prior to, immediately after, and on the morning after, the race. Blood was drawn for sodium, hemoglobin, and hematocrit immediately after the race and the following morning. Plasma concentrations of arginine-vasopressin (AVP) were also measured post race.
Subjects were significantly smaller than controls (62.5 vs. 72.0 Kg) and lost less weight during the race than controls (median -0.5% vs. -3.9%, p = 0.002) but more weight than controls during recovery (-4.4% vs. -0.8%, p 0.002). Subjects excreted a median fluid excess during recovery (1,346 ml): controls had a median fluid deficit (521 ml) (p = 0.009). Estimated median sodium deficit was the same in subjects and controls (88 vs. 38 mmol L(-1), p = 0.25). Median AVP was significantly lower in subjects than in controls. Plasma volume fell during recovery in subjects (-5.9%, p = 0.016) but rose in controls (0.76%, p = NS).
Triathletes with symptomatic hyponatremia following very prolonged exercise have abnormal fluid retention including an increased extracellular volume, but without evidence for large sodium losses. Such fluid retention is not associated with elevated plasma AVP concentrations.
The maximum tetanic tension of skeletal muscle (P(0)) is often estimated based on calculation of physiological cross-sectional area (PCSA). PCSA depends on muscle volume, pennation angle, and fiber length. Studies documenting PCSA in fixed human muscles usually compute muscle volume by dividing muscle mass by density. These studies use a density value of 1.0597 g/cm(3), which was originally based on unfixed rabbit and canine muscle tissue. Due to the dehydration effects of different fixation methods, the variable hydration that occurs when fixed tissue is stored in buffered saline, and the potential for species-specific muscle density, this value may be incorrect and an accurate value for fixed human muscle density is needed. To obtain an accurate density and water content values, 4% formaldehyde-fixed (n=54) and 37% formaldehyde-fixed (n=54) cadaveric human muscle samples were divided into 6 groups (0, 6, 12, 18, 24, or 30 h) for hydration in phosphate buffered saline (PBS). Measurements of volume, water content, and mass were made enabling calculation of muscle density. Additionally, water content was measured in living muscle (n=4) to determine the appropriate hydration time in PBS. Comparisons among groups demonstrated a significant increase in muscle water content and muscle volume over time, reaching living tissue levels after 24h, but, interestingly, the hydration process did not affect muscle density. These data yield a density value (mean+/-SE) of 1.112+/-0.006 g/cm(3) in 4% formaldehyde-fixed muscle and 1.055+/-0.006 g/cm(3) in 37% formaldehyde-fixed muscle. These results indicate that the use of inappropriate hydration times or density values can produce PCSA errors of 5-10%.
The effect of carbohydrate intake before and during exercise on muscle glycogen content was investigated. According to a randomized crossover study design, eight young healthy volunteers (n = 8) participated in two experimental sessions with an interval of 3 wk. In each session subjects performed 2 h of constant-load bicycle exercise ( approximately 75% maximal oxygen uptake). On one occasion (CHO), they received carbohydrates before ( approximately 150 g) and during (1 g.kg body weight(-1).h(-1)) exercise. On the other occasion they exercised after an overnight fast (F). Fiber type-specific relative glycogen content was determined by periodic acid Schiff staining combined with immunofluorescence in needle biopsies from the vastus lateralis muscle before and immediately after exercise. Preexercise glycogen content was higher in type IIa fibers [9.1 +/- 1 x 10(-2) optical density (OD)/microm(2)] than in type I fibers (8.0 +/- 1 x 10(-2) OD/microm(2); P < 0.0001). Type IIa fiber glycogen content decreased during F from 9.6 +/- 1 x 10(-2) OD/microm(2) to 4.5 +/- 1 x 10(-2) OD/microm(2) (P = 0.001), but it did not significantly change during CHO (P = 0.29). Conversely, in type I fibers during CHO and F the exercise bout decreased glycogen content to the same degree. We conclude that the combination of carbohydrate intake both before and during moderate- to high-intensity endurance exercise results in glycogen sparing in type IIa muscle fibers.
Male cyclists have been found to have low BMD in cross-sectional studies. Changes in BMD values over 1 yr of training and competition were studied in 14 male cyclists. BMD decreased significantly at the total hip, neck, trochanter, and shaft regions but not the lumbar spine. This first prospective study of cyclists showed a decrease in BMD over the course of 1 yr.
Cross-sectional studies have shown that some endurance athletes, and cyclists in particular, have low BMD. Whether vigorous cycle training is causally related with low BMD remains unknown.
Changes in BMD values over 1 yr of training and competition were studied in 14 male road cyclists, 27-44 yr of age. Subjects were randomized to receive 1500 (500 mg with meals) or 250 mg of supplemental calcium citrate daily. BMD measurements were obtained at pre-, mid-, post-, and off-season time points over 1 yr. Dermal calcium loss during exercise was estimated using a patch collection technique to examine calcium loss as a potential mediator of changes in BMD.
Using paired t-tests, BMD was found to decrease significantly from pre- to off-season at the total hip, neck, shaft, and trochanter regions (relative changes of -1.5 +/- 2.1%, -0.7 +/- 2.1%, -0.9 +/- 2.1%, and -1.0 +/- 1.2%, respectively, all p < 0.05). The 1.0 +/- 1.2% decrease in BMD at the lumbar spine failed to reach statistical significance (p = 0.079). There were no differences in changes in BMD between the calcium supplementation groups. The 2-h dermal calcium loss was estimated at 136.5 +/- 60.5 mg. Higher dermal calcium losses were associated with lower baseline BMD values at the total hip, neck, and shaft (all p < 0.05), but were not significantly associated with changes in BMD.
This study suggests that high intensity cycle training may adversely affect BMD. Excessive dermal calcium loss during exercise may be a contributing factor, but mechanisms remain to be elucidated.
Exercise biochemistry
- Mougios
Effect of exercise and recovery on muscle protein synthesis in human subjects National athletic trainers' association position statement: fluid replacement for athletes
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- Rosenblatt J Wh
- Wolfe
- Armstrong Dj Le Casa
- Hillman
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- Montain
- Reiff Rv Sj
- Roberts Wo
- Stone
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F, Suart CA, Hartl WH, Rosenblatt J, Wolfe RR (1990) Effect of exercise and recovery on muscle protein synthesis in human subjects. Am J Physiol 259(4 Pt 1):E470–E476 Casa DJ, Armstrong LE, Hillman SK, Montain SJ, Reiff RV, Rich BSE, Roberts WO, Stone JA (2000) National athletic trainers' association position statement: fluid replacement for athletes. J Athl Train 35:212–224