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The aim of this study is to investigate the effect of a 3-day high-carbohydrate diet (≥75% of total calories) on body composition using dual-energy X-ray absorptiometry (DXA). Twenty non-obese young men (age 22.7 ± 2.6 years, BMI 23.5 ± 2.1 kg/m(2)) completed the study. Two DXA tests were performed for the measurement of total body weight, body mass index (BMI), body fat percentage as well as total, appendicular and central lean body mass (LBM) before and after a high-carbohydrate diet for 3 days. In addition, the participants completed a food diary during the 3-day high-carbohydrate diet to determine the mean percentage of carbohydrates consumed from total kilocalories. The mean percentage of carbohydrate intake over 3 days was 83.7 ± 8.4%. Our results showed a significant increase in total body weight, BMI as well as total and appendicular LBM after the high-carbohydrate diet (p < 0.01). In addition, we observed a strong tendency for lower body fat percentage values after the intervention (p = 0.05). No significant difference was observed for central LBM. These results indicate that the effect of an acute high carbohydrate diet seems to affect body composition values using DXA, such as total LBM. This study may lead to the need of standardizing a diet prior to using DXA. © 2015 S. Karger AG, Basel.
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... 22 This acute gain in lean body mass in week 11 is not entirely uncommon, considering 3 days of HC feeding and rest is associated with increased body mass (0.6 kg, p=0.001) and estimations of lean body mass (0.9 kg, p<0.0001) within nonobese men using a DXA scanner. 38 In contrast, Vargas et al demonstrated recreationally trained men consuming a non-KD increased lean body mass to a greater extent when compared to a KD group following an 8-week training intervention. 27 Baseline dietary assessment was absent, therefore, it is unknown if the non-KD group increased or sustained carbohydrate intake, thereby potentially impacting DXA reliability, for reasons previously outlined. ...
... 27 Baseline dietary assessment was absent, therefore, it is unknown if the non-KD group increased or sustained carbohydrate intake, thereby potentially impacting DXA reliability, for reasons previously outlined. 38 In addition, groups were instructed to consume a hyper-caloric diet to promote greater gains in lean body mass, however, mean body weight decreased within the KD group (−1.4 kg, TxG, p=0.016). Therefore, an appropriate synopsis is, a hypocaloric KD decreased fat mass, and maintained lean body mass (Table 4B). ...
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Fionn T McSwiney,1,2 Lorna Doyle,3 Daniel J Plews,4 Caryn Zinn4 1School of Health and Human Performance, Dublin City University, Dublin, Ireland; 2Setanta College, Thurlus, Tipperary, Ireland; 3Department of Sport and Exercise Science, Waterford Institute of Technology, Waterford, Ireland; 4Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New ZealandCorrespondence: Caryn ZinnAUT University, Sports Performance Research Institute New Zealand (Mail code P-1), Private Bag 92006, Auckland 1142, New ZealandTel +64 9 921 9999Fax +64 9 921 9960Email caryn.zinn@aut.ac.nzAbstract: The impact of a ketogenic diet (KD) (<50 g/d carbohydrate, >75% fat) on athletic performance has sparked much interest and self-experimentation in the past 3–4 years. Evidence shows 3–4-week adaptations to a KD in endurance-trained athletes were associated with maintenance of moderate (46–63% VO2max) and vigorous intensity (64–90% VO2max) endurance exercise, while at intensities >70% VO2max, increases in fat oxidation were associated with decreased economy (increased oxygen consumption), and in some cases, increased ratings of perceived exertion and heart rate. Two investigations in recreationally active endurance athletes noted no vigorous intensity exercise decrement following 3- and 12-week adaptations. Moderate (70–85% one repetition maximum) and near-maximal to maximal intensity (>85% 1RM) strength performance experienced no decrement following a 3-12-week KD adaptation. Beneficial effects were noted for 2000 m sprint and critical power test completed for short duration at vigorous intensity, while two additional tests noted no decrement. For sprint, near-maximal exercise (>91% VO2max), benefit of the KD was observed for six-second sprint, while no decrement in performance was noted for two additional maximal tests. When protein is equated (grams per kilogram), one investigation noted no decrement in muscle hypertrophy, while one noted a decrement. One investigation with matched protein noted the KD group lost more body fat. In conclusion, moderate-to-vigorous intensity exercise experiences no decrement following adaptation to a KD. Decreases in exercise economy are observed >70% VO2max in trained endurance athletes which may negate performance within field settings. Beneficial effects of the KD during short duration vigorous, and sprint bouts of exercises are often confounded by greater weight loss in the KD group. With more athletes pursuing carbohydrate-restricted diets (moderate and strict (KD)) for their proposed health benefits, more work is needed in the area to address both performance and health outcomes.Keywords: keto-adaptation, performance, endurance, strength, high intensity, low carbohydrate
... Biological variation may result from food and fluid ingestion or exercise prior to assessment and appears to influence most body composition methods, albeit to different degrees (Bone et al., 2017;Kerr et al., 2017). Other biological variables known to have an impact on estimates of body composition include body temperature and skin moisture (Fields et al., 2004), gastrointestinal contents (Bone et al., 2017), and muscle solutes (Rouillier et al., 2015). ...
... Raw measurements from SA (in millimeters) have been shown to be robust and unaffected by the biological variation caused by prior food and fluid ingestion or exercise (Kerr et al., 2017), yet this study included body mass to obtain estimates of FM and FFM using the Evans equation (Evans et al., 2005). It would be expected, then, that consecutive-day PE would be larger given that body mass is acutely influenced by hydration status, gastrointestinal tract contents, and muscle glycogen stores (Rouillier et al., 2015). Due to adopting previous recommendations of subject presentation, including overnight fasting, post bladder, and bowel evacuation with body measurements taken early in the morning in minimal clothing, the biological impact on precision was expected to be minimal (Kerr et al., 2017;Nana et al., 2015). ...
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Athletic populations require high-precision body composition assessments to identify true change. Least significant change determines technical error via same-day consecutive tests but does not integrate biological variation, which is more relevant for longitudinal monitoring. The aim of this study was to assess biological variation using least significant change measures from body composition methods used on athletes, including surface anthropometry (SA), air displacement plethysmography (BOD POD), dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance spectroscopy (BIS). Thirty-two athletic males (age = 31 ± 7 years; stature = 183 ± 7 cm; mass = 92 ± 10 kg) underwent three testing sessions over 2 days using four methods. Least significant change values were calculated from differences in Day 1 Test 1 versus Day 1 Test 2 (same-day precision), as well as Day 1 Test 1 versus Day 2 (consecutive-day precision). There was high agreement between same-day and consecutive-day fat mass and fat-free mass measurements for all methods. Consecutive-day precision error in comparison with the same-day precision error was 50% higher for fat mass estimates from BIS (3,607 vs. 2,331 g), 25% higher from BOD POD (1,943 vs. 1,448 g) and DXA (1,615 vs. 1,204 g), but negligible from SA (442 vs. 586 g). Consecutive-day precision error for fat-free mass was 50% higher from BIS (3,966 vs. 2,276 g) and SA (1,159 vs. 568 g) and 25% higher from BOD POD (1,894 vs. 1,450 g) and DXA (1,967 vs. 1,461 g) than the same-day precision error. Precision error in consecutive-day analysis considers both technical error and biological variation, enhancing the identification of small, yet significant changes in body composition of resistance-trained male athletes. Given that change in physique is likely to be small in this population, the use of DXA, BOD POD, or SA is recommended.
... Therefore, the protective associations of anthocyanidin on body composition might partly source from the benefit of vegetables and fruits as reported previously (32), and the associations were not adjusted for dietary intake of fruits and vegetables in our study in case of over adjustments. Several nutrients (fat, protein, carbohydrate, cholesterol, calcium, and vitamin D) were found to be associated with body composition or obesity before (33)(34)(35)(36). In our study, similar positive relationships with anthocyanidins were observed for the dietary intake of calcium (partly source from fruits and vegetables) and carbohydrate (r' = 0.102-0.202, ...
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Background: Previous animal and in vitro studies indicated that anthocyanidins might contribute to the prevention of obesity, while epidemiological evidences were scarce and had not been conducted in children. Objective: We explored the associations between anthocyanidins and body composition in children. Design: A cross-sectional study involving 452 children aged 6-9 years in Guangzhou, China, was carried out. Dietary information was collected using a 79-items food frequency questionnaire. Fat mass (FM), lean mass (LM), and fat mass percentage (FMP) at multi-sites (whole body, trunk, limbs, android area, and gynoid area) were measured using a dual-energy X-ray scan. Abdominal obesity was defined as an age- and sex-specific abdominal FM ≥ 85th percentile. Handgrip strength was measured using a hydraulic hand dynamometer. Results: After adjusted for several potential covariates, higher dietary intake of anthocyanidin (per one standard deviation increase) was associated with a 0.013-0.223 kg increase of LM, a 0.024-0.134 kg decrease of FM, and a 0.63-0.76% decrease of FMP at multi-sites (P < 0.05). Results were similar and more pronounced for delphinidin and cyanidin, but less significant for peonidin. Higher dietary anthocyanidin intake (per standard deviation increase) was associated with a 41.0% (OR: 0.59, 95%CI: 0.37, 0.94) decreased risk of abdominal obesity. However, no significant associations were observed between anthocyanidin and handgrip strengths. Conclusions: Higher dietary intake of anthocyanidin and its components tended to be associated with better body composition, but not handgrip strength, in Chinese children at early age.
... It is important to mention that most of them were done without concomitant resistance training. Pointed out by Rouillier et al. [25], there is a positive correlation between carb intake and LBM. Along with their net mass loss, there are waterbinding properties of glycogen stores [26] contributing to this overall loss of LBM recorded on bioelectrical impedance. ...
Article
Background & aims The aim of this paper was to investigate and compare the effects of two iso-energetic hypo-caloric ketogenic hyper-ketonemic and non-ketogenic low carbohydrate high fat high cholesterol diets on body-composition, muscle strength and hormonal profile in experienced resistance-trained middle-aged men. Methods Twenty non-competitive experienced resistance-trained middle-aged men were on the supervised calorie maintenance western diet and resistance-training regimen for 4 weeks and then divided into ketogenic and non-ketogenic groups for 8 weeks period. Keto bodies (β-hydroxybutyrate) levels were measured weekly, testosterone and insulin biweekly, strength and body-composition monthly, lipid profile and blood sugar level at the beginning and at the end of the study. Results Both groups lost a similar amount of lean body mass and fat tissue (from F = 248.665, p < 0.001 to F = 21.943, p = 0.001), but preserved maximal upper and lower body strength (from F = 1.772, p = 0.238 to F = 0.595, p = 0.577). Basal testosterone and free testosterone increased (from F = 37.267, p = 0.001 to F = 16.261, p = 0.005) and insulin levels decreased significantly in both groups (F = 27.609, p = 0.001; F = 54.256, p < 0.001, respectively). No differences in lipid profile and blood sugar level were found (from F = 4.174, p = 0.058, to F = 0.065, p = 0.802). Conclusions Ketogenic diet with sustained hyper-ketonemia above 1 mol/l has the same impact as low carbohydrate non-ketogenic diet on muscle strength, body-composition, and hormonal and lipid profile in hypo-caloric dietary conditions in strength-trained middle-aged men.
... DXA-based measurement of lean body mass by ~4.5 kg [22]. Similarly, three days of rest and CHO loading (8.1 g kg -1 ) increased body mass (+0.6 kg) and FFM (+0.9 kg) in non-obese men [37]. Due the present KD intervention being ad libitum caloric intake, and the limitations of DXA in measuring FFM under conditions where CHO intake is modulated, it is unknown if these participants were in a caloric deficit, and therefore, if loss of FFM observed was in the form of tissue mass or water, or a combination of both. ...
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Few studies have investigated the short-term effects of a very low carbohydrate ketogenic diet (KD) on body composition and substrate utilization in trained individuals. This study investigated effects on substrate utilization during incremental exercise, and changes in body composition, in response to seven days ad libitum consumption of a KD by athletes from endurance sports. Nine young trained males (age, 21.8 ± 1.9 y; height, 1.83 ± 0.11 m; body mass, 78.4 ± 13.8 kg; body fat, 14.9 ± 3.9%; VO2peak, 54.3 ± 5.9 mL kg-1 min-1) were assessed before (day 0; PRE) and after (day 7; POST) seven days of consuming an ad libitum KD. Following an overnight fast, body composition was measured by dual x-ray absorptiometry, and substrate utilization was measured during an incremental (3 min stages, 35 W increments) exercise test on a cycle ergometer. After KD, Wmax (PRE, 295 ± 30 W; POST, 292 ± 38 W) and VO2peak (PRE, 4.18 ± 0.33 L min-1; POST, 4.10 ± 0.43 L min-1) were unchanged, whereas body mass [-2.4 (-3.2, -1.6) kg; P < 0.001, d = 0.21], fat mass [-0.78 (-1.10, -0.46) kg; P < 0.001, d = 0.22] and fat-free mass (FFM) [-1.82 (-3.12, -0.51) kg; P = 0.013, d = 0.22] all decreased. The respiratory exchange ratio was lower, and rates of fat oxidation were higher, at POST across a range of exercise intensities. Maximal fat oxidation rate was ~1.8-fold higher after KD (PRE, 0.54 ± 0.13 g min-1; POST, 0.95 ± 0.24 g min-1; P < 0.001, d = 2.2). Short-term KD results in loss of both fat mass and FFM, increased rates of fat oxidation and a concomitant reduction in CHO utilization even at moderate-to-high intensities of exercise.
... • Inactif depuis au moins 6 mois ( < 2 heures d' AP structurée par semaine ou <3 heures d' AP libre (Garber, et al 2011) • Aucune contre-indication médicale à la pratique d'activité physique (avoir répondu non à toutes les questions du questionnaire sur l'aptitude à l'activité physique (Q-AAP) ou fournir une évaluation médicale à l'aptitude à l'activité physique (X-AAP) signée par un médecin). l'intervention), les participants étaient à jeun pour éviter que les facteurs alimentaires (tels que l'excès de glucides) influencent les mesures obtenues (Rouillier et al., 2015). La durée totale de la composition corporelle par DEXA prend environ 8 minutes et la dose de radiation émise lors de cette dernière était très faible (0,037 mrem). ...
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Introduction : Les complications métaboliques sont très communes chez les personnes âgées et surtout chez celles présentant une obésité. Pour les contrer, les bienfaits de l’exercice physique, plus spécifiquement l’entraînement par intervalles de haute intensité (EIHI), sont bien connus. Il a été suggéré que la citrulline, qui a des effets bénéfiques sur le tissu musculaire et le sur le métabolisme du tissu adipeux chez le rat, pourrait être une avenue intéressante. Objectif : Examiner si l’EIHI combiné à une supplémentation en citrulline améliorerait d'avantage la composition corporelle et les complications métaboliques chez des personnes âgées obèses comparé à l’EIHI sans aucune supplémentation. Méthodologie : Quatre-vingt-deux personnes âgées ont été randomisées aléatoirement et en double-aveugle dans 2 groupes : EIHI+citrulline (n=46 ; âge:68±4 ans) vs. EIHI+Placebo (n=36 ; âge:66±5 ans). Un EIHI de 12 semaines (30min/session/3xsem) et une supplémentation de citrulline ou placebo (ratio 1/1 ; l0g/j) ont été suivis par tous les participants. La composition corporelle, la capacité aérobie, la pression artérielle et les paramètres métaboliques sanguins (glycémie, HDL, LDL et triglycérides) ont été mesurés avant et après l’intervention. Résultats : Avant l’intervention, les groupes étaient similaires. Suite à l’intervention, l’ensemble des participants ont diminué leur tour de taille et leur pourcentage de masse grasse totale (p<0,05), en plus d’avoir augmenté leur masse musculaire (p<0,01) et leur capacité aérobie (p<0,01). Lorsqu’on compare le pourcentage de changements entre les deux groupes, le groupe citrulline a diminué davantage les taux de C-LDL (p=0.04) et a amélioré la qualité de sommeil (p=0.05) comparativement au groupe placebo. Aucun effet additif n’a été noté avec la supplémentation en citrulline sur d’autres paramètres. Discussion : L’EIHI améliore la composition corporelle, la capacité aérobie et diminue le tour de taille. La combinaison de l’EIHI avec la supplémentation en citrulline semble apporter de plus grandes améliorations au niveau des taux de C-LDL et de la qualité de sommeil que l’EIHI seul. De futures études avec des populations symptomatiques et un plus grand échantillon sont nécessaires.
... the present study found the administration of ccp along with either exercise regimen decreased BW and BF% similarly to previous research conducted on both males and females of diverse age groups (i.e., 21-51 years old). 7,9 however, a greater reduction in BF% was observed in p2 who performed Mrt compared to p1 who performed hrt ( Figure 1). Factors that may have contributed to this difference were p1 had a baseline BF% of 7.6, which is lower than the average range among athletes (9-15%) 10 and consumed more energy compared to p2. therefore, during hrt, the primary source of energy for p1 was cho 4 which reduced lipolysis (i.e., utilization of stored body fat) during training sessions resulting in a 1.1% BF reduction, which is consistent with previous research. ...
Article
BACKGROUND Carbohydrate (CHO) resources are limited during moderate- to high-intensity resistance exercises (RE) which may limit performance. Increased intake of CHO prior to RE has been shown to enhance performance. The purpose of the study was to investigate the effect of self-implemented CHO cycling program (CCP) and RE on collegiate athlete body builders. METHODS Two body builders [males, participant-1 (P1):21 y and participant-2 (P2): 22 y] at a Division I University performed a dual energy X-ray absorptiometry scan before and after a five-week CCP to measure body fat percent (BF%) and bone mineral density (BMD). P1 performed high-intensity [60-90 mins, 75-90% of one repetition max (1RM)] resistance training (HRT) and P2 performed moderate-intensity (30-45 mins, 60-75%1RM) resistance training (MRT). RESULTS Total BF% was reduced by 1.1% in P1 and 3.6% in P2. The decrease in BF% among both the participants can be primarily attributed to the moderate- to high-intensity resistance exercise program. Although P2 performed MRT, a greater relative decrease in BF% was recorded (24.5%) compared to P1 (14.5%). However, P1 had a lower baseline BF% (7.6) than P2 (14.7). CONCLUSIONS Longer duration MRT may be more effective in reducing BF% if baseline values are at higher end of average athlete recommendation (9-15%).
... the present study found the administration of ccp along with either exercise regimen decreased BW and BF% similarly to previous research conducted on both males and females of diverse age groups (i.e., 21-51 years old). 7,9 however, a greater reduction in BF% was observed in p2 who performed Mrt compared to p1 who performed hrt ( Figure 1). Factors that may have contributed to this difference were p1 had a baseline BF% of 7.6, which is lower than the average range among athletes (9-15%) 10 and consumed more energy compared to p2. therefore, during hrt, the primary source of energy for p1 was cho 4 which reduced lipolysis (i.e., utilization of stored body fat) during training sessions resulting in a 1.1% BF reduction, which is consistent with previous research. ...
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BacKGroUNdː carbohydrate (cho) resources are limited during moderate-to high-intensity resistance exercises (re) which may limit performance. increased intake of cho prior to re has been shown to enhance performance. the purpose of the study was to investigate the effect of self-implemented cho cycling program (ccp) and re on collegiate athlete body builders. MethodSː two body builders [males, participant-1 (p1):21 y and participant-2 (p2): 22 y] at a division i University performed a dual energy X-ray absorptiometry scan before and after a five-week ccp to measure body fat percent (BF%) and bone mineral density (BMd). p1 performed high-intensity [60-90 mins, 75-90% of one repetition max (1rM)] resistance training (hrt) and p2 performed moderate-intensity (30-45 mins, 60-75%1rM) resistance training (Mrt). reSUltSː total BF% was reduced by 1.1% in p1 and 3.6% in p2. the decrease in BF% among both the participants can be primarily attributed to the moderate-to high-intensity resistance exercise program. although p2 performed Mrt, a greater relative decrease in BF% was recorded (24.5%) compared to p1 (14.5%). however, p1 had a lower baseline BF% (7.6) than p2 (14.7). coNclUSioNSː longer duration Mrt may be more effective in reducing BF% if baseline values are at higher end of average athlete recommendation (9-15%).
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Background: The association of dietary patterns and resting metabolic rate is still unclear. Aim: To study the relationship between the major dietary patterns, resting metabolic rate, and adiposity measures in Iranian adults. Methods: This is a cross-sectional study of 270 adults aged between 18–45 years old who lived in Tehran. Dietary intakes were achieved using food frequency questionnaire. Resting metabolic rate was measured using indirect calorimetry. Anthropometric measures were recorded using body composition analyzer. Results: Three major dietary patterns were identified by factor analysis labeled as healthy pattern (vegetables, fruits, and fruits juices, legumes, poultry, nuts, fish, egg, low fat dairy product, olive, and olive oil), mixed pattern (non-refined cereals, vegetables, vegetable oils, mayonnaise, high fat dairy product and, pickles), Western pattern (refined cereals, red or processed meat, soft drinks, sweets and desserts, Tea and coffee, salty snacks and French fries). After adjusting for covariates higher score of the Western dietary pattern was associated with lower resting metabolic rate ( p = 0.023). There was significant decreasing difference in means for fat free mass across tertiles of mixed pattern when the first tertile was compared to the third tertile ( p = 0.046). Higher adherence to healthy pattern was associated with lower body weight ( p = 0.034), body mass index ( p = 0.021), and higher resting metabolic rate ( p = 0.033). Conclusions: Higher adherence to the Western dietary pattern was associated with a lower amount of resting metabolic rate. Also higher adherence to the healthy dietary pattern was associated with higher resting metabolic rate and lower body weight and body mass index. Further studies are required to examine the causal relationship between dietary patterns and resting metabolic rate.
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Fat-free mass index (FFMI) is a height-adjusted metric of fat-free mass which has been suggested as a useful method of body composition assessment in athletic populations. The purpose of this study was to determine sport-specific FFMI values and the natural upper threshold of FFMI in female athletes. 372 female collegiate athletes (Mean±SD; 20.03±1.55 years, 167.55±7.50 cm, 69.46±13.04 kg, 24.18±5.48% bodyfat) underwent body composition assessment via dual-energy x-ray absorptiometry. FFMI was adjusted to height via linear regression and sport-specific reference values were determined. Between-sport differences were identified using one-way ANOVA with Tukey post-hoc tests. Average FFMI was 18.82±2.08 kg/m²; height-adjusted values were not significantly different (p<0.05) than unadjusted values. FFMI in rugby athletes (20.09±2.23 kg/m²) was found to be significantly higher (p<0.05) than in gymnastics (18.62±1.12 kg/m²), ice hockey (17.96±1.04 kg/m²), lacrosse (18.58±1.84 kg/m²), swim & dive (18.16±1.67 kg/m²), and volleyball (18.04±1.13 kg/m²). FFMI in cross country (16.56±1.14 kg/m²) and synchronized swimming (17.27±1.47 kg/m²) was significantly lower (p<0.05) than in Olympic weightlifting (19.69±1.98 kg/m²), wrestling (19.15±2.47 kg/m²), and rugby. The upper threshold for FFMI in female athletes (97.5th percentile) was 23.90 kg/m². These results can be used to guide personnel decisions and assist with long-term body composition, training, and nutritional goals.
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Background/objectives: We intended to (i) to compare the composition of weight loss and weight gain using densitometry, deuterium dilution (D₂O), dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging (MRI) and the four-compartment (4C) model and (ii) to compare regional changes in fat mass (FM), fat-free mass (FFM) and skeletal muscle as assessed by DXA and MRI. Subjects/methods: Eighty-three study participants aged between 21 and 58 years with a body mass index range of 20.2-46.8 kg/m(2) had been assessed at two different occasions with a mean follow-up between 23.5 and 43.5 months. Body-weight changes within < 3% were considered as weight stable, a gain or a loss of >3% of initial weight was considered as a significant weight change. Results: There was a considerable bias between the body-composition data obtained by the individual methods. When compared with the 4C model, mean bias of D₂O and densitometry was explained by the erroneous assumption of a constant hydration of FFM, thus, changes in FM were underestimated by D₂O but overestimated by densitometry. Because hydration does not normalize after weight loss, all two-component models have a systematic error in weight-reduced subjects. The bias between 4C model and DXA was mainly explained by FM% at baseline, whereas FFM hydration contributed to additional 5%. As to the regional changes in body composition, DXA data had a considerable bias and, thus, cannot replace MRI. Conclusions: To assess changes in body composition associated with weight changes, only the 4C model and MRI can be used with confidence.
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Background: With physical inactivity inextricably linked to the increasing prevalence of obesity, there is a need for validated methods that measure free-living energy expenditure (EE) within sedentary environments. While accelerometers enable these measurements, few studies have compared device accuracy in such settings. The aim of this study was to investigate the relative validity of the Actigraph, RT3 and SenseWear Armband (SWA). Methods: Twenty-three (11 male, 12 female) participants (age: 25.3 ± 6.3 yr; BMI: 22.6 ± 2.7) wore 3 accelerometers at designated sites during a 4-hour stay in the Whole Room Calorimeter (WRC). Participants performed 2 10-minute bouts of light-intensity exercise (stepping and stationary cycling) and engaged in unstructured sedentary activities. EE estimated by accelerometers was compared with WRC EE derived from measurements of gaseous exchange. Results: The Actigraph and SWA both accurately estimated EE during the stepping exercise. EE estimated by the RT3 during stepping was significantly lower than the WRC value (31.2% ± 15.6%, P < .001). All accelerometers underestimated cycling and unstructured activity EE over the trial period (P < .001). Conclusions: The Actigraph and SWA are both valid tools for quantifying EE during light-intensity stepping. These results provide further valuable information on how accelerometer devices may be appropriately used.
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Endurance sports are increasing in popularity and athletes at all levels are looking for ways to optimize their performance by training and nutrition. For endurance exercise lasting 30 min or more, the most likely contributors to fatigue are dehydration and carbohydrate depletion, whereas gastrointestinal problems, hyperthermia, and hyponatraemia can reduce endurance exercise performance and are potentially health threatening, especially in longer events (>4 h). Although high muscle glycogen concentrations at the start may be beneficial for endurance exercise, this does not necessarily have to be achieved by the traditional supercompensation protocol. An individualized nutritional strategy can be developed that aims to deliver carbohydrate to the working muscle at a rate that is dependent on the absolute exercise intensity as well as the duration of the event. Endurance athletes should attempt to minimize dehydration and limit body mass losses through sweating to 2-3% of body mass. Gastrointestinal problems occur frequently, especially in long-distance races. Problems seem to be highly individual and perhaps genetically determined but may also be related to the intake of highly concentrated carbohydrate solutions, hyperosmotic drinks, as well as the intake of fibre, fat, and protein. Hyponatraemia has occasionally been reported, especially among slower competitors with very high intakes of water or other low sodium drinks. Here I provide a comprehensive overview of recent research findings and suggest several new guidelines for the endurance athlete on the basis of this. These guidelines are more detailed and allow a more individualized approach.
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Objective methods to measure daily energy expenditure in studies of aging are needed. We sought to determine the accuracy of total energy expenditure (TEE) and activity energy expenditure (AEE) estimates from the SenseWear Pro armband (SWA) using software versions 6.1 (SWA 6.1) and 5.1 (SWA 5.1) relative to criterion methods in free-living older adults. Participants (n = 19, mean age 82.0 years) wore a SWA for a mean ± SD 12.5 ± 1.1 days, including while sleeping. During this same period, criterion values for TEE were assessed with doubly labeled water and for resting metabolic rate (RMR) with indirect calorimetry. AEE was calculated as 0.9 TEE - RMR. For TEE, there was no difference in mean ± SD values from doubly labeled water (2,040 ± 472 kcal/day) versus SWA 6.1 (2,012 ± 497 kcal/day, p = .593) or SWA 5.1 (2,066 ± 474 kcal/day, p = .606); individual values were highly correlated between methods (SWA 6.1 r = .893, p < .001; SWA 5.1 r = .901, p < .001) and demonstrated strong agreement (SWA 6.1 intraclass correlation coefficient = .896; SWA 5.1 intraclass correlation coefficient = .904). For AEE, mean values from SWA 6.1 (427 ± 304 kcal/day) were lower by 26.8% than criterion values (583 ± 242 kcal/day, p = .003), and mean values from SWA 5.1 (475 ± 299 kcal/day) were lower by 18.5% than criterion values (p = .021); however, individual values were highly correlated between methods (SWA 6.1 r = .760, p < .001; SWA 5.1 r = .786, p < .001) and demonstrated moderate agreement (SWA 6.1 intraclass correlation coefficient = .645; SWA 5.1 intraclass correlation coefficient = .720). Bland-Altman plots identified no systematic bias for TEE or AEE. Acceptable levels of agreement were observed between SWA and criterion measurements of TEE and AEE in older adults.
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The SenseWear Armband (SWA) has been shown to be a valid and practical tool to assess energy expenditure during habitual physical activity. However, previous studies have focused on low-to-moderate intensity activities. The purpose of this study was to assess the validity of the SWA during high intensity exercise. Twenty (ten males, ten females) endurance trained subjects, 24.3 (±2.8) years of age, performed three 10-min treadmill runs at 65, 75, and 85% of their VO(2max) each and also ran outside for 30 min at their preferred speed. Energy expenditure was measured with the SWA (software version 6.1) and a portable indirect calorimetry system (Jaeger Oxycon Mobile(®)). The SWA showed a ceiling effect around an intensity of ten METs. Since all subjects exceeded that intensity range during the exercise trials, the SWA significantly underestimated energy expenditure at high intensities. The intra-individual correlations between MET values calculated by the SWA and values derived from the Oxycon, however, were significant for all but two subjects (r = 0.390-0.933, mean = 0.66 ± 0.25). While providing accurate results for energy expenditure during low-to-moderate intensity physical activities, the SWA does not provide accurate estimates of energy expenditure at high intensity levels. The threshold for accurate measurements seems to be around an intensity of ten METs.
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