[Show abstract][Hide abstract] ABSTRACT: The assessment of heart rate variability (HRV) thresholds (HRVTs) as an alternative of Ventilatory thresholds (VTs) is a relatively new approach with increasing popularity which has not been conducted in cross-country (XC) skiing yet. The main purpose of the present study was to assess HRVTs in the five main XC skiing-related techniques, double poling (DP), diagonal striding (DS), Nordic walking (NW), V1 skating (V1), and V2 skating (V2).Ten competitive skiers completed these incremental treadmill tests until exhaustion with a minimum of one to two recovery days in between each test. Ventilatory gases, HRV and poling frequencies were measured. The first HRV threshold (HRVT1) was assessed using two time-domain analysis methods, and the second HRV threshold (HRVT2) was assessed using two non-time varying frequency-domain analysis methods. HRVT1 was assessed by plotting the mean successive difference (MSD) and standard deviation (SD) of normalized R-R intervals to workload. HRVT1 was assessed by plotting high frequency power (HFP) and the HFP relative to respiratory sinus arrhythmia (HFPRSA) with workload. HRVTs were named after their methods (HRVT1-SD; HRVT1-MSD; HRVT2-HFP; HRVT2-HFP-RSA). The results showed that the only cases where the proposed HRVTs were good assessors of VTs were the HRVT1-SD of the DS test, the HRVT1-MSD of the DS and V2 tests, and the HRVT2-HFP-RSA of the NW test. The lack of a wider success of the assessment of HRVTs was reasoned to be mostly due to the high entrainment between the breathing and poling frequencies. As secondary finding, a novel Cardiolocomotor coupling mode was observed in the NW test. This new Cardiolocoomtor coupling mode corresponded to the whole bilateral poling cycle instead of corresponding to each poling action as it was reported to the date by the existing literature.
[Show abstract][Hide abstract] ABSTRACT: Although the mechanisms of G-induced stresses on the spinal structure of military pilots are well understood, less is known about relationships between the intensity of physical activity, fitness, occupational musculoskeletal symptoms, and the degree of resulting disabilities. During an aeromedical examination, Finnish military pilots answered a questionnaire on their flying experience, the occurrence of flight duty-related pain, the degree of resulting disabilities, and the intensity of physical activity they conducted. 195 males were selected for further analysis. They were divided into three groups, designated high G, low G, and HQ, according to their current flight duty profile. 93% of pilots who had passed fighter lead-in training reported flight duty-induced musculoskeletal disorders. The high-G group exhibited the highest aerobic capacity (p < 0.001) and muscular fitness scores (p < 0.001). The fittest individuals suffered markedly fewer disabilities than their less fit counterparts (p = 0.005). Flight hour accumulation among the subjects in the high-G group was associated (p = 0.010) with the occurrence of flight duty-induced disabilities. The fittest pilots flew aircraft that induce the heaviest accelerations. They also reported more musculoskeletal pain than the other pilots. Yet they seemed to experience fewer disabilities, which highlights the importance of physical training in the maintenance of operational readiness.
[Show abstract][Hide abstract] ABSTRACT: Santtila, M, Pihlainen, K, Viskari, J, and Kyröläinen, H. Optimal physical training during military basic training period. J Strength Cond Res 29(11S): S154-S157, 2015-The goal for military basic training (BT) is to create a foundation for physical fitness and military skills of soldiers. Thereafter, more advanced military training can safely take place. Large differences in the initial physical performance of conscripts or recruits have led military units to develop more safe and effective training programs. The purpose of this review article was to describe the limiting factors of optimal physical training during the BT period. This review revealed that the high volume of low-intensity physical activity combined with endurance-type military training (like combat training, prolonged physical activity, and field shooting) during BT interferes with optimal development of maximal oxygen uptake and muscle strength of the soldiers. Therefore, more progressive, periodized, and individualized training programs are needed. In conclusion, optimal training programs lead to higher training responses and lower risks for injuries and overloading.
Full-text · Article · Oct 2015 · The Journal of Strength and Conditioning Research
[Show abstract][Hide abstract] ABSTRACT: Friedl, KE, Knapik, JJ, Häkkinen, K, Baumgartner, N, Groeller, H, Taylor, NAS, Duarte, AFA, Kyröläinen, H, Jones, BH, Kraemer, WJ, and Nindl, BC. Perspectives on aerobic and strength influences on military physical readiness: Report of an international military physiology roundtable. J Strength Cond Res 29(11S): S10-S23, 2015-Physical fitness training of military recruits is an enduring focus of armies. This is important for safe and effective performance of general tasks that anyone may have to perform in a military setting as well as preparation for more specialized training in specific job specialties. Decades of studies on occupationally specific physical requirements have characterized the dual aerobic and strength demands of typical military tasks; however, scientifically founded strategies to prepare recruits with a good mix of these 2 physiologically opposing capabilities have not been well established. High levels of aerobic training can compromise resistance training gains and increase injury rates. Resistance training requires a greater commitment of time and resources as well as a greater understanding of the science to produce true strength gains that may be beneficial to military performance. These are critical issues for modern armies with increased demands for well-prepared soldiers and fewer injury losses. The actual physical requirements tied to metrics of success in military jobs are also under renewed examination as women are increasingly integrated into military jobs previously performed only by men. At the third International Congress on Soldiers' Physical Performance, a roundtable of 10 physiologists with military expertise presented comparative perspectives on aerobic and strength training. These topics included the physiological basis of training benefits, how to train effectively, how to measure training effectiveness, considerations for the integration of women, and the big perspective. Key discussion points centered on (a) the significance of findings from research on integrated training, (b) strategies for effective strength development, and
Full-text · Article · Oct 2015 · The Journal of Strength and Conditioning Research
[Show abstract][Hide abstract] ABSTRACT: Vaara, JP, Kokko, J, Isoranta, M, and Kyröläinen, H. Effects of added resistance training on physical fitness, body composition, and serum hormone concentrations during eight weeks of special military training period. J Strength Cond Res 29(11S): S168-S172, 2015-A high volume of military training has been shown to compromise muscle strength development. We examined effects of added low-volume resistance training during special military training (ST) period, which took place after basic training period. Male conscripts (n = 25) were assigned to standardized ST with added resistance training group (TG, n = 13) and group with standardized ST only (control) (CG, n = 12). Standardized ST with added resistance training group performed 2 resistance training sessions per week for 8 weeks: hypertrophic strength (weeks 1-3), maximal strength (weeks 4-6) and power training (weeks 7-8). Maximal strength tests, load carriage performance (3.2 km, 27 kg), and hormone concentrations were measured before and after ST (mean ± SD). Both groups improved similarly in their load carriage performance time (TG: 1,162 ± 116 seconds vs. 1,047 ± 81 seconds; CG: 1,142 ± 95 seconds vs. 1,035 ± 81 seconds) (p < 0.001) but decreased maximal strength of the lower extremities (TG: 5,250 ± 1,110 N vs. 4,290 ± 720 N; CG: 5,170 ± 1,050 N vs. 4,330 ± 1,230 N) and back muscles (TG: 4,290 ± 990 N vs. 3,570 ± 48 N; CG: 3,920 ± 72 N vs. 3,410 ± 53 N) (p ≤ 0.05). Maximal strength of the upper extremities improved in CG (1,040 ± 200 N vs. 1,140 ± 200 N) (p ≤ 0.05) but not in TG. Maximal strength of the abdominal muscles improved in TG (3,260 ± 510 N vs. 3,740 ± 75 N) (p ≤ 0.05) but not in CG. Testosterone concentration increased in CG (15.2 ± 3.6 nmol·L vs. 21.6 ± 5.0 nmol·L) (p < 0.01) but not in TG (18.6 ± 4.3 nmol·L vs. 19.5 ± 9.4 nmol·L). In conclusion, interference with strength gains might be related to the high volume of aerobic activities and too low volume of resistance training during ST. To develop strength characteristics, careful periodization and individualization should be adopted in ST.
No preview · Article · Oct 2015 · The Journal of Strength and Conditioning Research
[Show abstract][Hide abstract] ABSTRACT: Vaara, JP, Kalliomaa, R, Hynninen, P, and Kyröläinen, H. Physical fitness and hormonal profile during an 11-week paratroop training period. J Strength Cond Res 29(11S): S163-S167, 2015-Physical fitness and serum hormone concentrations have been shown to change during military training. The purpose was to examine these chronic changes in paratroopers (n = 52 male conscripts) during an 11-week training period, including acute changes induced by strenuous 5-day military field training. Hormonal profiles, body mass, maximal strength, muscle endurance, and 12-minute running test were assessed at several time points during paratrooper training. In the latter part of the training period, conscripts were involved in strenuous military field training (5 days). At week 7, during specialized military training period, aerobic performance decreased (3,146 ± 163 m) but recovered back to a baseline level (3,226 ± 190 m) at the end of the study period (p < 0.001). Standing long jump decreased at week 7 (242 ± 13 cm) (p < 0.001) from the baseline value (248 ± 13 cm), whereas push-up (52 ± 11, 60 ± 13 repetitions per minute) and sit-up (54 ± 6, 56 ± 7 repetitions per minute) performances increased (p < 0.001). No changes were observed in maximal strength and body composition, neither mostly in hormone concentrations, although cortisol decreased but increased back to baseline value at the end of the study period (p ≤ 0.05). Acute responses after the 5-day military field training included decreased maximal strength of the lower extremities and body mass, as well as changes in androgen hormone concentrations ([INCREMENT]testosterone: -46%, [INCREMENT]insulin-like growth factor-1: -28%, [INCREMENT]sex hormone-binding globulin: +25%) compared with all other measurements (p ≤ 0.05). The first 4 weeks of parachute military training decreased maximal aerobic capacity and neuromuscular performance of the lower body, whereas muscular endurance increased. Moreover, 5-day military field training resulted in dramatic changes in hormone concentrations. These findings highlight the importance of periodizing paratrooper training and underline the need for sufficient recovery immediately after military field training.
No preview · Article · Oct 2015 · The Journal of Strength and Conditioning Research
[Show abstract][Hide abstract] ABSTRACT: Taipale, RS, Heinaru, S, Nindl, BC, Vaara, J, Santtila, M, Häkkinen, K, and Kyröläinen, H. Hormonal responses to active and passive recovery after load carriage. J Strength Cond Res 29(11S): S149-S153, 2015-Military operations often induce fatigue resulting from load carriage. Recovery promotes military readiness. This study investigated the acute effects of AR vs. PR after load carriage on maximal isometric leg extension force (MVC) and serum hormonal concentrations. Male reservists (27 ± 3 years, 180 ± 7 cm, 74 ± 11 kg, V[Combining Dot Above]O2max 64 ± 9 ml·kg·min) completed PR (n = 8) or AR (n = 8) after 50 minutes of loaded (16 kg) uphill (gradient 4.0%) treadmill marching at individual anaerobic threshold. No differences were observed between groups in relative changes in MVC during the marching loading, after AR or PR or the next morning. Significant differences in relative responses to AR and PR postmarching loading were observed in serum testosterone (T), cortisol, and sex-hormone binding globulin immediately post AR and PR; however the next morning, all serum hormone concentrations had returned to normal. This study did not reveal any significant differences between the effects of AR and PR after an hour-long marching protocol at approximately anaerobic threshold on MVC or serum hormones the morning after the experimental marching protocol. Thus, based on the variable measured in this study, marching performed by physically fit army reservists at an intensity at or below anaerobic threshold may not necessitate specialized recovery protocols.
No preview · Article · Oct 2015 · The Journal of Strength and Conditioning Research
[Show abstract][Hide abstract] ABSTRACT: The primary aim of the present study was to investigate the acute gene expression responses of PGC-1 isoforms and PGC-1α target genes related to mitochondrial biogenesis (cytochrome C), angiogenesis (VEGF-A), and muscle hypertrophy (myostatin), after a resistance or endurance exercise bout. In addition, the study aimed to elucidate whether the expression changes of studied transcripts were linked to phosphorylation of AMPK and MAPK p38. Nineteen physically active men were divided into resistance exercise (RE, n = 11) and endurance exercise (EE, n = 8) groups. RE group performed leg press exercise (10 × 10 RM, 50 min) and EE walked on a treadmill (~80% HRmax, 50 min). Muscle biopsies were obtained from the vastus lateralis muscle before, 30 min, and 180 min after exercise. EE and RE significantly increased the gene expression of alternative promoter originated PGC-1α exon 1b- and 1bxs'-derived isoforms, whereas the proximal promoter originated exon 1a-derived transcripts were less inducible and were upregulated only after EE. Truncated PGC-1α transcripts were upregulated both after EE and RE. Neither RE nor EE affected the expression of PGC-1β. EE upregulated the expression of cytochrome C and VEGF-A, whereas RE upregulated VEGF-A and downregulated myostatin. Both EE and RE increased the levels of p-AMPK and p-MAPK p38, but these changes were not linked to the gene expression responses of PGC-1 isoforms. The present study comprehensively assayed PGC-1 transcripts in human skeletal muscle and showed exercise mode-specific responses thus improving the understanding of early signaling events in exercise-induced muscle adaptations.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to compare activation of cellular signaling pathways regulating protein synthesis and glucose uptake in skeletal muscle between resistance and endurance exercise. Moreover, the effect of resistance exercise volume was examined.
Three groups of male volunteers (26 ± 3 years) were examined: 5 × 10 repetition maximum (RM) resistance exercise (RE) with leg press device (5 × 10 RE; n = 8), 10 × 10 RE (n = 11), and endurance exercise (strenuous 50-min walking with extra load on a treadmill; EE; n = 8). Muscle biopsies were obtained from m.vastus lateralis 30 min pre- and post-exercise.
Downstream markers of mTORC1, p-p70S6K(Thr421/Ser424) and p-rpS6(Ser240/244), increased more after 10 × 10 RE than after 5 × 10 RE (p < 0.05) and EE (p < 0.01-0.001). Exercise-induced changes in p-IRS-I(Ser636/639) that inhibit IRS-I signaling via negative feedback from hyperactivated mTORC1 signaling were greater (p < 0.05) after 10 × 10 RE compared with 5 × 10 RE and EE. The changes in energy sensor p-AMPKα(Thr172) were greater after 10 × 10 RE and EE (p < 0.05-0.01) than after 5 × 10 RE. A major regulator of glucose uptake in muscle, p-AS160(Thr642), increased more after 10 × 10 RE than after 5 × 10 RE (p < 0.01) and EE (p < 0.05).
10 × 10 RE induced greater activation of important signaling proteins regulating glucose uptake (p-AS160) and protein synthesis (p-p70S6K, p-rpS6) than 5 × 10 RE and EE. The present findings further suggest that, especially after 10 × 10 RE, IRS-I signaling is downregulated and that AS160 is activated through AMPK signaling pathway.
[Show abstract][Hide abstract] ABSTRACT: Study aim: to develop and estimate the validity of non-exercise methods to predict VO2max among young male conscripts entering military service in order to divide them into the different physical training groups.
Material and methods: fifty males (age 19.7 ± 0.3 years) reported their physical activity before military service by IPAQ and SIVAQ questionnaires. Furthermore, Jackson’s non-exercise method was used to estimate VO2max. Body mass and height were measured, body mass index calculated and VO2max measured directly in a maximal treadmill test. Subjects were randomly divided into two groups. The results of the Group 1 (N = 25) were used to develop a regression equation to estimate VO2max. The results of the Group 2 (N = 25) were used to evaluate the validity of the developed non-exercise methods and Jackson’s non-exercise methods to estimate VO2max by Bland and Altman plot. The validity was further evaluated by comparing the results to 12-minute running test performed by 877 male conscripts (age 19.6 ± 0.2 years).
Results: the developed models explained 68–74% of the variation in VO2max. Mean difference between directly measured and estimated VO2max was not significant, while Jackson’s method overestimated VO2max (p < 0.001). Both developed models were equally valid to divide conscripts into tertile group of fitness. However, 5% of the conscripts were classified into the highest fitness group based on both methods, but they were actually in the lowest fitness group based on a running test.
Conclusion: in practice, these findings suggest that developed methods can be used as a tool to divide conscripts into different fitness groups in the very beginning of their military service.
Full-text · Article · Jan 2015 · Biomedical Human Kinetics
[Show abstract][Hide abstract] ABSTRACT: Aim: Physical fitness can be used as a marker of health and abilities to carry out activities of daily living. Since fitness measurements are challenging in epidemiological studies, the study aimed at analysing whether a single question on self-estimated physical fitness can be used as a surrogate measure for fitness measurements representing several components of fitness. Methods: Study population consisted of a representative sample of 18-30 year-old reservists (N.=764). Self-estimated fitness was assessed by asking the reservists to rate their fitness in comparison to their peers. Fitness measurements included figure-eight run, grip strength, repeated push-ups, sit-ups and squats, and an indirect maximal cycle ergometer test. Body mass index and waist circumference (WC) were also assessed. Results: Men estimating their fitness as worse than that of their peers had higher body mass index, larger WC and they also performed all fitness tests, except grip strength, more poorly. Correspondingly, men estimating their fitness as equal, performed the tests more poorly than those estimating their fitness as better. Self-estimated fitness was not sensitive enough to identify individuals with the poorest measured fitness. Large WC explained the association between self-estimated and measured fitness, especially among the men with poor perceived health. Conclusion: Self-estimated fitness is associated with measured fitness, but it cannot identify individuals with the poorest fitness accurately, especially among the participants with poor health and overweight.
[Show abstract][Hide abstract] ABSTRACT: Study aim: the purpose of the present study was to survey the impact of a social media platform on physical fitness, physical activity levels and daily sitting time.
Material and methods: a total of 2039 users (1445 women and 594 men) of the social media service (HeiaHeia, Helsinki, Finland) voluntarily participated in the study by answering an online questionnaire provided by a survey.
Results: about 63.8% of the participants reported that the service has advanced their perceived level of physical fitness, while 36.2% reported no impact on their fitness. Most participants (71.3%) with BMI over 25 reported that the service had helped them to improve their physical fitness. Participants with BMI over 35 reported a more positive impact than in any other weight range groups. One-third of the participants (32.3%) sat for more than seven hours a day; 23.5% sat less than five hours a day. More than half of the participants (56.8%) were encouraged to be physical active during the day and aimed to reduce sitting time at their jobs during the workday.
Conclusions: there seems to be a positive impact of web services that promote physical activity on the physical fitness among social media users. Although the present service is not merely well suited for physically active and physical fit users, it motivates users of all fitness levels to exercise. However, more studies are needed to clarify effects of social media on physical activity, fitness and health.
Full-text · Article · Oct 2014 · Biomedical Human Kinetics
[Show abstract][Hide abstract] ABSTRACT: The purpose of the study was to examine the effects of exercise on total leukocyte count and subsets, as well as hormone and cytokine responses in a thermoneutral and cold environment, with and without an individualized pre-cooling protocol inducing low-intensity shivering. Nine healthy young men participated in six experimental trials wearing shorts and t-shirts. Participants exercised for 60 min on a treadmill at low (LOW: 50% of peak VO2) and moderate (MOD: 70% VO2peak) exercise intensities in a climatic chamber set at 22uC (NT), and in 0uC (COLD) with and without a pre-exercise low-intensity shivering protocol (SHIV). Core and skin temperature, heart rate and oxygen consumption were collected continuously. Blood samples were collected before and at the end of exercise to assess endocrine and immunological changes. Core temperature in NT was greater than COLD and SHIV by 0.460.2uC whereas skin temperature in NT was also greater than COLD and SHIV by 8.561.4uC and 9.362.5uC respectively in MOD. Total testosterone, adenocorticotropin and cortisol were greater in NT vs. COLD and SHIV in MOD. Norepinephrine was greater in NT vs. other conditions across intensities. Interleukin-2, IL-5, IL-7, IL-10, IL-17, IFN-c, Rantes, Eotaxin, IP-10, MIP-1b, MCP-1, VEGF, PDGF, and G-CSF were elevated in NT vs. COLD and/or SHIV. Furthermore, IFN-c, MIP-1b, MCP-1, IL-10, VEGF, and PDGF demonstrate greater concentrations in SHIV vs. COLD, mainly in the MOD condition. This study demonstrated that exercising in the cold can diminish the exerciseinduced systemic inflammatory response seen in a thermoneutral environment. Nonetheless, prolonged cooling inducing shivering thermogenesis prior to exercise, may induce an immuno-stimulatory response following moderate intensity exercise. Performing exercise in cold environments can be a useful strategy in partially inhibiting the acute systemic inflammatory response from exercise but oppositely, additional body cooling may reverse this benefit.
[Show abstract][Hide abstract] ABSTRACT: Purpose:
To examine acute responses of force production and oxygen uptake to combined strength (S) and endurance-running (E) loading sessions in which the order of exercises is reversed (ES vs SE).
This crossover study design included recreationally endurance-trained men and women (age 21-45 y; n=12 men, 10 women) who performed ES and SE loadings. Force production of the lower extremities including countermovement-jump height (CMJ) and maximal isometric strength (MVC) was measured pre-, mid-, and post-ES and -SE, and ground-reaction forces, ground-reaction times, and running economy were measured during E.
A significant decrease in CMJ was observed after combined ES and SE in men (4.5%±7.0% and 6.6%±7.7%, respectively) but not in women (0.2%±8.5% and 1.4%±7.3% in ES and SE). MVC decreased significantly in both men (20.7%±6.1% ES and 19.3%±9.4% SE) and women (12.4%±9.3% ES and 11.6%±12.0% SE). Stride length decreased significantly in ES and SE men, but not in women. No changes were observed in ground-reaction times during running in men or women. Performing S before E caused greater (P<.01) oxygen uptake during running in both men and women than if E was performed before S, although heart rate and blood lactate were similar between ES and SE.
Performing S before E increased oxygen uptake during E, which is explained, in part, by a decrease in MVC in both men and women, decreased CMJ and stride length in men, and/or an increase in postexercise oxygen consumption.
No preview · Article · Oct 2014 · International journal of sports physiology and performance
[Show abstract][Hide abstract] ABSTRACT: The aim was to study associations of maximal strength and muscular endurance with inflammatory biomarkers independent of cardiorespiratory fitness in those with and without abdominal obesity. 686 young healthy men participated (25±5 years). Maximal strength was measured via isometric testing using dynamo-meters to determine maximal strength index. Muscular endurance index consisted of push-ups, sit-ups and repeated squats. An indirect cycle ergometer test until exhaustion was used to estimate maximal aerobic capacity (VO2max). Participants were stratified according to those with (>102 cm) and those without abdominal obesity (<102 cm) based on waist circumference. Inflammatory factors (C-reactive protein, interleukin-6 and tumour necrosis factor alpha) were analysed from serum samples. Maximal strength and muscular endurance were inversely associated with IL-6 in those with (β=-0.49, -0.39, respectively) (p<0.05) and in those without abdominal obesity (β=-0.08, -0.14, respectively) (p<0.05) adjusted for smoking and cardio-respiratory fitness. After adjusting for smoking and cardiorespiratory fitness, maximal strength and muscular endurance were inversely associated with CRP only in those without abdominal obesity (β=-0.11, -0.26, respectively) (p<0.05). This cross-sectional study demonstrated that muscular fitness is inversely associated with C-reactive protein and IL-6 concentrations in young adult men independent of cardiorespi-ratory fitness.
Full-text · Article · Sep 2014 · International Journal of Sports Medicine
[Show abstract][Hide abstract] ABSTRACT: Cheung, Stephen S, Niina E. Mutanen, Heikki M. Karinen, Anne S. Koponen, Heikki Kyröläinen, Heikki O. Tikkanen, and Juha E. Peltonen. Ventilatory chemosensitivity, cerebral and muscle oxygenation, and total hemoglobin mass before and after a 72-day Mt. Everest expedition. High Alt Med Biol. 15:000–000, 2014.—. doi:10.1089/ham.2013.1153. Sept. 11, 2014, epub ahead of print.
Background: We investigated the effects of chronic hypobaric hypoxic acclimatization, performed over the course of a 72-day self-supported Everest expedition, on ventilatory chemosensitivity, arterial saturation, and tissue oxygenation adaptation along with total hemoglobin mass (tHb-mass) in nine experienced climbers (age 37±6 years, 55±7 mL·kg−1·min−1).
Methods: Exercise-hypoxia tolerance was tested using a constant treadmill exercise of 5.5 km·h−1 at 3.8% grade (mimicking exertion at altitude) with 3-min steps of progressive normobaric poikilocapnic hypoxia. Breath-by-breath ventilatory responses, Spo2, and cerebral (frontal cortex) and active muscle (vastus lateralis) oxygenation were measured throughout. Acute hypoxic ventilatory response (AHVR) was determined by linear regression slope of ventilation vs. Spo2. PRE and POST (<15 days) expedition, tHb-mass was measured using carbon monoxide-rebreathing.
Results: Post-expedition, exercise-hypoxia tolerance improved (11:32±3:57 to 16:30±2:09 min, p<0.01). AHVR was elevated (1.25±0.33 to 1.63±0.38 L·min−1.%−1 Spo2, p<0.05). Spo2 decreased throughout exercise-hypoxia in both trials, but was preserved at higher values at 4800 m post-expedition. Cerebral oxygenation decreased progressively with increasing exercise-hypoxia in both trials, with a lower level of deoxyhemoglobin POST at 2400, 3500 and 4800 m. Muscle oxygenation also decreased throughout exercise-hypoxia, with similar patterns PRE and POST. No relationship was observed between the slope of AHVR and cerebral or muscle oxygenation either PRE or POST. Absolute tHb-mass response exhibited great individual variation with a nonsignificant 5.4% increasing trend post-expedition (975±154 g PRE and 1025±124 g POST, p=0.17).
Conclusions: We conclude that adaptation to chronic hypoxia during a climbing expedition to Mt. Everest will increase hypoxic tolerance, AHVR, and cerebral but not muscle oxygenation, as measured during simulated acute hypoxia at sea level. However, tHb-mass did not increase significantly and improvement in cerebral oxygenation was not associated with the change in AHVR.
Full-text · Article · Sep 2014 · High altitude medicine & biology
[Show abstract][Hide abstract] ABSTRACT: Aim:
There is limited evidence available regarding the relationship between physical fitness, especially muscular fitness, and the mental well-being among young healthy men. Therefore, the aim of the present study was to investigate the impact of measured cardiovascular and muscle fitness and self reported leisure time physical activity (LTPA) on outcomes of stress and mental resources in Finnish young men.
In a cross-sectional study, 831 men (mean age 25 y) underwent cardiovascular and muscle fitness test and completed LTPA and Occupational Stress Questionnaires (OSQ). For analysis, the subjects were divided to LTPA, CVF and MFI tertiles.
The group with low LTPA reported 6% and 13% more stress (ANCOVA using age, body mass index, smoking and alcohol use as covariates, P<0.05 in both) and 6% and 12% (P<0.05 in both) less mental resources than the moderate and high LTPA groups, respectively. The group having low cardiovascular fitness experienced 8% and 9% (P<0.001 in both) more stress and 7% and 7% (P<0.05 in both) less mental resources than moderate and high cardiovascular fitness groups. The low muscle fitness index (MFI) group reported 7% (P<0.01) less mental resources than those with moderate MFI and 8% (P<0.001) more stress and 8% (P<0.001) less mental resources than those with high MFI.
Both good aerobic and muscular fitness together with high LTPA are associated with low stress and high mental resources.
Full-text · Article · Aug 2014 · The Journal of sports medicine and physical fitness
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to investigate the effects of a four-week weight reduction period (WRP) with high protein and reduced carbohydrate intake on body composition, explosive power, speed, serum hormones and acid-base balance in male track and field jumpers and sprinters. Eight participants were assigned to a high weight reduction group (HWR; energy restriction 750 kcal / day), and seven to a low weight reduction group (LWR; energy restriction 300 kcal / day). Energy and carbohydrate intake decreased significantly (p ≤ 0.05) only in HWR by 740 ± 330 kcal / day and 130 ± 29 g / day, respectively. Furthermore, total body mass and fat mass decreased (p ≤ 0.05) only in HWR by 2.2 ± 1.0 kg and 1.7 ± 1.6 kg, respectively. Fat-free mass (FFM), serum testosterone, cortisol, and SHBG did not change significantly. Caion and pH decreased (p ≤ 0.05) only in HWR (3.1 ± 2.8 % and 0.8 ± 0.8 %, respectively), whereas HCO3- declined (p ≤ 0.05) in both groups by 19.3 ± 6.2 % in HWR and by 13.1 ± 8.5 % in LWR. The counter-movement jump and 20-m sprint time improved consistently (p ≤ 0.05) only in HWR, by 2.6 ± 2.5 cm and 0.04 ± 0.04 s, respectively. Finally, athletes with a fat percentage 10% or over at the baseline were able to preserve FFM. In conclusion, altered acid-base balance but improved weight bearing power performance was observed without negative consequences on serum hormones and FFM after a four-week weight reduction of 0.5 kg / week achieved via reduced carbohydrate but maintained high protein intake.
No preview · Article · Jul 2014 · The Journal of Strength and Conditioning Research
[Show abstract][Hide abstract] ABSTRACT: Dynamic exercise and whole-body cooling independently increase skeletal muscle tissue deoxygenation, yet their combined effects in muscular circulation are unknown. We investigated the effects of a cold environment on skeletal muscle blood volume and deoxygenation in eleven participants at 50% (walking) or 70% (running) of their peak VO2 for 60 min, in 22°C (NT), and 0°C without (CO) and with (PC) a pre-exercise whole-body cooling, which induced an increase in VO2 to 15%VO2peak. Near-infrared spectroscopy (NIRS) derived signals for hemoglobin changes were measured continuously with NIRS on the vastus lateralis (VL) and the gastrocnemius (GM) muscles to determine changes in oxygenated (O2Hb), deoxygenated (HHb: indicating deoxygenation) and total (tHb: indicating blood volume) myo/hemoglobin concentrations (ΔµM.L-1). Total Hb was lower in PC (-10.1±5.9 and -8.0±7.1 µM.L-1) compared to NT (-3.9±3.1 and -1.8±4.8 µM.L-1) and CO (-3.9±6.6 and 1.9±6.3 µM.L-1) in walking and running respectively, in the VL but not in GM (p≤0.001). This change in tHb was matched by O2Hb (p≤0.001). No differences between conditions were observed in HHb. In conclusion, pre-exercise whole-body cooling decreased skeletal muscle blood volume which limited oxygenated hemoglobin availability but deoxygenation of the muscle during submaximal exercise was unaffected by the cold.
[Show abstract][Hide abstract] ABSTRACT: Full text: http://www.tandfonline.com/eprint/6WNS9HjT5iaSAFY6hDXs/full
Participating in competitive sport increases the risk for injuries and musculoskeletal pain among adolescent athletes. There is also evidence that the use of prescription drugs has increased among sport club athletes. The purpose of this study was to evaluate the use of painkillers among young male ice hockey players (IHP) in comparison to schoolboys (controls) and its relation to the prevalence of musculoskeletal pain and problems during activities and sleeping. Information was gathered through a questionnaire, completed by 121 IHP and compared to the responses of 618 age-matched controls. Results showed that monthly existing pain was at 82% for IHP, and 72% for controls, though IHP had statistically more musculoskeletal pain in their lower limbs (56% versus 44%), lower back (54% versus 35%), and buttocks (26% versus 11%). There were no group differences in the neck, upper back, upper limb, or chest areas. The disability index was statistically similar for both groups, as musculoskeletal pain causing difficulties in daily activities and sleeping was reported by a minority of subjects. Despite this similarity, IHP used more painkillers than controls (18% versus 10%). Further nuanced research is encouraged to compare athletes and non-athletes in relation to painkillers.