[Adaptation to intermittent hypoxia-hyperoxia improves cognitive performance and exercise tolerance in elderly].

For improvements in exercise tolerance and cognitive function in geriatric patients Multimodal training programs (MTP) are used as combination of physiotherapy, occupational therapy and cardiovascular training. Intermittent Hypoxic-Hyperoxic Training (IHHT), a modified type of intermittent hypoxic training (IHT) is proposed to be included in MTP to elicit more pronounced beneficial effects in exercise tolerance and cognitive functions of geriatric patients likely by an additional pathway than a single MTP. Thirty four patients of the Geriatric Day Clinic aged between 64 and 92 years participated in the placebo controlled clinical trial. They were randomly assigned to receive MTP plus IHHT (experimental group - EG) or MTP plus placebo-breathing through a machine face mask (control group - CG) in a double blind fashion. Before and after the interventions course cognitive performance was assessed by the Dementia-Detection-Test (DemTect) and the Clock-Drawing-Test (CDT), and functional exercise capacity - by the total distance of 6-Minute-Walk-Test (6MWT). After IHHT combined with MTP cognitive performance (DemTect) increased significantly when compared to NG (+16,7 % vs. +0,39 %, p<0,001). The CDT indicated similar results with a significant increase in the EG while the score of the CG even decreased (+10,7 % vs. -8%, p=0,031). Concerning the functional exercise capacity, both groups improved the total distance in the 6MWT but with a significantly larger increase in the EG compared to the CG (+24,1 % vs. +10,8 %, p=0,021). In addition, there was a significant relationship between the changes of the 6MWT and the DemTect Scores and the CDT. IHHT contributed significantly to improvements in cognitive performance and exercise capacity in elderly performing MTP. IHHT sessions are considered to be easily applicable to and well tolerated by geriatric patients up to 92 years.

Acute effects of concentric and eccentric exercise on glucose metabolism and interleukin-6 concentration in healthy males.

Acute muscle-damaging eccentric exercise (EE) negatively affects glucose metabolism. On the other hand, long-term eccentric endurance exercise seems to result in equal or superior positive effects on glucose metabolism compared to concentric endurance exercise. However, it is not known if acute non-muscle-damaging EE will have the same positive effects on glucose metabolism as acute concentric exercise (CE). Interleukin-6 (IL-6) released from the exercising muscles may be involved in the acute adaptations of glucose metabolism after CE and non-muscle-damaging EE. The aim of this study was to assess acute effects of uphill walking (CE) and non-muscle-damaging downhill walking (EE) on glucose metabolism and IL-6 secretion. Seven sedentary non-smoking, healthy males participated in a crossover trial consisting of a 1 h uphill (CE) and a 1 h downhill (EE) walking block on a treadmill. Venous blood samples were drawn before (pre), directly after (acute) and 24 h after (post) exercise. An oral glucose tolerance test (OGTT) was performed before and 24 h after exercise. Glucose tolerance after 1 and 2 hours significantly improved 24 hours after CE (-10.12±3.22%: P=0.039; -13.40±8.24%: P=0.028). After EE only the 1-hour value was improved (-5.03±5.48%: P=0.043). Acute IL-6 concentration rose significantly after CE but not after EE. We conclude that both a single bout of CE and a single bout of non-muscle-damaging EE elicit positive changes in glucose tolerance even in young, healthy subjects. Our experiment indicates that the overall metabolic cost is a major trigger for acute adaptations of glucose tolerance after exercise, but only the IL-6 production during EE was closely related to changes in glycaemic control.

Anaerobic training in hypoxia: A new approach to stimulate the rating of effort perception.

This study compared subjective effort perception with objective physiological measures during high-intensive intermittent exercise performed in normoxia, moderate hypoxia (FiO2: 16.5%) and severe hypoxia (FiO2: 13.5%). Sixteen physically active subjects performed an equal training session on three different days. Training consisted of 6 "all-out" series of continuous jumps lasting for 15s each. Average power output during the jumps was similar in all three conditions (~3200W). Greater hypoxemia was observed in hypoxia as compared to normoxia. Likewise, a significantly higher value in perceived effort was observed after hypoxia training as compared to normoxia training (p<0.05). Whereas blood lactate concentrations immediately after training were not different between normoxia and hypoxia, creatine kinase increased in moderate (p=0.02) and severe (p<0.01) hypoxia compared to normoxia 24h after the training. Perceived fatigue was also significantly elevated 24h after hypoxic exercise only. Heart rate variability pre and 24h after exercise showed a tendency to sympathetic predominance in severe hypoxia as compared to moderate hypoxia and normoxia. In conclusion, a single session of anaerobic exercise can be executed at the same intensity in moderate/severe hypoxia as in normoxia. This type of hypoxic training may be considered as a method potentially to improve the ability tolerating discomfort and consequently also exercise performance.

Sports injuries and illnesses during the 2015 Winter European Youth Olympic Festival.

BACKGROUND: The prevention of injury and illness remains an important issue among young elite athletes. Systematic surveillance of injuries and illnesses during multi-sport events might provide a valuable basis to develop preventive measures, focusing especially on adequate information for youth athletes. AIM: To analyse the frequencies and characteristics of injuries and illnesses during the 2015 Winter European Youth Olympic Festival (W-EYOF). METHODS: All National Olympic Committees were asked to report daily the occurrence or non-occurrence of newly sustained injuries and illnesses on a standardised reporting form. RESULTS: Among the 899 registered athletes (37% female) with a mean age of 17.1±0.8 years, a total of 38 injuries and 34 illnesses during the 5 competition days of the W-EYOF were reported, resulting in an incidence of 42.3 injuries and 37.8 illnesses per 1000 athletes, respectively. Injury frequency was highest in snowboard cross (11%), Nordic combined (9%), alpine skiing (6%), and ice hockey (6%), taking into account the respective number of registered athletes. In snowboard cross, females showed a significant higher injury frequency compared to males (22% vs 4%, p=0.033). The lower back (16%), the pelvis (13%), the knee (11%), and the face (11%) were the most common injury locations. About 58% of injuries occurred in competition and about 42% in training. In total, 42% of injuries resulted in an absence of training or competition. The prevalence of illness was highest in figure skating (10%) and Nordic combined (9%), and the respiratory system was affected most often (53%). CONCLUSIONS: Four per cent of the athletes suffered from an injury and 4% from illnesses during the 2015 W-EYOF, which is about twofold lower compared to the first Winter Youth Olympic Games in 2012.

Body Water Status and Short-term Maximal Power Output during a Multistage Road Bicycle Race (Giro d'Italia 2014).

An investigation of whether body water changes during the Giro d'Italia affected average maximal mean power (MMP) of different time durations and to establish whether phase-angle and body cell mass (BCM) are related to MMP in elite cyclists. Approximately 2 h after each stage of the race, a bioelectrical impedance analysis was performed on 8 cyclists and analysed according to bioelectrical impedance vector analyses. Additionally, MMP of different time durations were recorded during each stage. Body mass increased (p<0.001), vector-length shortened (p<0.001) and MMP15 (maximal mean power for 15 s; p=0.043) decreased in the course of the Giro d'Italia. The shortening of the vector was negatively related to MMP10 (r=- 0.749, p=0.032) and MMP15 (r=- 0.735, p=0.038) during stage 16 (heavy mountain-stage) and MMP60 (r=- 0.751, p=0.032), MMP300 (r=- 0.739, p=0.036) and MMP1800 (r=- 0.769, p=0.026) during stage 19 (time-trial). Additionally, the baseline phase-angle and BCM were associated to MMP15 best (r=0.781, p=0.022 and 0.756, p=0.030, respectively). In the course of the Giro d'Italia, MMP15 decreased, indicating progressive fatigue. The vector-length shortening and to some extent the body mass increase indicate that cyclists gained body water during the race. This gain was positively associated with performance during the last stages, possibly due to improved thermoregulation. Furthermore, phase-angle and BCM, shown to be linked to cellular function and to represent metabolic active tissue, reflect individual MMP of short duration in professional road cyclists.

[Impact of Self-Reported Fatigue on ACL Injuries in Alpine Skiing: A Sex Comparison]. / Einfluss von subjektiver Ermüdung auf vordere Kreuzbandverletzungen beim alpinen Skifahren: Ein Geschlechtervergleich.

INTRODUCTION: In recreational alpine skiing, about one third of all injuries affect the knee joint, and the most common diagnosis in adult male and female skiers is a tear of the anterior cruciate ligament (ACL), which makes up 15 - 21 % of all injuries. General preventive recommendations to reduce the incidence of ski injuries include avoiding fatigue. However, it seems unclear to what extent ACL injuries in male and female recreational skiers are related to perceived fatigue. METHODS: This study was conducted as a prospective questionnaire-based investigation in two Austrian ski injury clinics during the five winter seasons between 2009/2010 and 2013/2014. In total, 588 skiers (67.9 % females) with a mean age of 42.1 ±â€Š10.9 years were interviewed about demographics, skiing ability, skiing behaviour, fitness, day and time of accident, skiing duration and perceived fatigue at the moment of accident. RESULTS: ACL injured males reported a significantly higher skiing ability and fitness level as well as a more risky behaviour on ski slopes compared to females. About one third of males and females injured their ACL within the first day of the ski trip and about 57 % within the first two days, with no sex differences. However, a significantly higher number of female skiers sustained an ACL injury during the first hour of skiing (28 vs. 17 %) as well as during the first two hours of skiing compared to males (52 vs. 44 %). About 81 % of males and females felt no fatigue or just a trace of fatigue in their legs at the time of accident, with no sex differences. CONCLUSION: Based on the findings of this study, fatigue does not seem to be a major risk factor for an ACL injury among male and female recreational skiers.

[Factors Associated with the Use of Protective Gear among Adults during Recreational Sledging]. / Einflussfaktoren auf das Tragen von Schutzausrüstung bei erwachsenen Rodlern.

BACKGROUND: Recreational sledging (tobogganing) is a very popular winter sport in the Alps. Therefore, injury prevention through the usage of protective gear seems important. Therefore, the aim of this study was to evaluate factors associated with the use of protective gear among adults during recreational sledging. METHODS: Adult recreational sledgers were interviewed during the winter seasons 2012/13 and 2013/14 at six sledging tracks in Austria on demographics, skill level, sledging frequency, risk taking behaviour, sitting alone or with another person on the sledge, previous sledging-related injuries, and use of protective gear, respectively. Interviews were conducted on all days of the week. RESULTS: A total of 1968 adult sledgers (49.4 % females) with a mean age of 37.1 ±â€Š14.4 years participated in this study. A (ski) helmet, sun or snow goggles, a back protector, and wrist guards were used by 42.3 %, 71.0 %, 5.9 %, 2.6 % of sledgers, respectively. Helmet use was significantly higher with increasing age and increasing skill level as well as when sitting alone compared to sitting together with another person. Females, Austrians, persons sitting alone on the sledge, a higher frequency of sledging and a higher skill level were significantly associated with an increasing use of goggles. A back protector was significantly more often worn by younger people, more risky sledgers, and persons with a previous sledging-related injury. Wrist guards were significantly more often used by persons with a previous sledging-related injury. CONCLUSION: During recreational sledging, the factors age, sex, nationality, skill level, sitting alone compared to sitting together with another person on the sledge, sledging frequency, and injury experience were associated with the frequencies of usage of different types of protective gear. These factors should be considered when implementing preventive measures for recreational sledging.

[Equipment, Risk Awareness and Safety-Relevant Behaviour of Via Ferrata Climbers]. / Ausrüstung, Risikobewusstsein und sicherheitsrelevantes Verhalten von Klettersteiggehern.

BACKGROUND: Climbing via ferrata routes is becoming more and more popular. The growing number of via ferrata climbers is associated with an increasing number of accidents. In addition to adequate equipment and its correct handling, knowledge of specific risks and safety-related behaviour play an important role for safety on via ferrata routes. The goal of this study was to collect data on equipment, via ferrata-specific risk knowledge, safety-related behaviour, and general risk-taking behaviour of via ferrata climbers. METHODS: In this survey, data of 332 climbers of different via ferrata routes in Tyrol (Austria) were collected using a standardised data entry form including socio-demographic data, the use of via ferrata-specific equipment and first aid equipment. Knowledge of via ferrata-specific risks was assayed by a questionnaire including 4 questions. Additionally, safety-related behaviour and general risk-taking behaviour of the via ferrata climbers were evaluated. RESULTS: 92 % of the interviewed persons were wearing a helmet and helmet use was significantly lower in females (86 %) compared to males (96 %). In total, 10 % of the via ferrata climbers used inadequate belaying equipment or no equipment at all. The 4 questions related to via ferrata-specific risks were correctly answered by an average of 46 % of the climbers. A partner check was carried out by 76 % before starting the tour. 96 % of the climbers stated they ask the climber ahead of them for the possibility to overtake and wait for a suitable and safe spot. 64 % reported that they would not pass without self-belay. General risk-taking behaviour was scored at 4.26 ±â€Š1.75 with significant differences between female and male via ferrata climbers (3.79 ±â€Š1.37 vs. 4.53 ±â€Š1.88). CONCLUSION: Although most of the via ferrata climbers use adequate equipment, helmet use could be optimised in females. Via ferrata climbers should be better informed of the risks of climbing via ferrata routes and safety-related behaviour. Preventive measures including information panels at the entrances of the via ferrata routes and broad information campaigns could contribute to reduce the number of accidents.

[Frequencies of injuries and causes of accidents during ski touring on ski slopes - a pilot study]. / Verletzungshäufigkeit und Unfallursachen beim Pistentourengehen - eine Pilotstudie.

INTRODUCTION: Ski touring along ski slopes (slope touring) increased in recent years on Austrian ski slopes. However, ascending on the border of the slope and skiing downhill on the slope might be associated with a certain injury risk. Thus, the aim of this pilot study was to evaluate frequencies of injuries, causes of accidents and potential risk factors during slope touring. METHODS: Slope-tourers were interviewed from March to April 2014 at the bottom of 4 Austrian ski areas. Interviews were conducted during the week and at the weekend from 7.30 a. m. to 8.45 p. m. RESULTS: A total of 451 slope-tourers (60.1 % males) with a mean age of 39.3 ±â€Š14.4 years were interviewed. Interviewed persons reported that they perform about 20.6 ±â€Š16.0 slope tours per season mainly with a partner (48 %) and during the day (51 %). Ski helmet use was 60 %. A total of 57 persons (12.6 %) reported that they suffered at least once from an injury during slope touring needing medical care. This corresponds to a rate of 6 injuries per 1000 slope tours. Main injury causes were a fall (78 %) and a collision with another person (15 %) and the main injured body part was the knee (36 %). Slope-tourers with an injury were wearing more often back protectors, and were falling more often during downhill skiing, and were abstaining less often from alcohol and were listening more often to music during downhill skiing compared to slope-tourers without an injury. CONCLUSION: Based on the findings of this pilot study we recommend abstaining from alcohol and not listening to music during downhill skiing to reduce the injury risk during slope touring.

Changes in hydration, body-cell mass and endurance performance of professional soccer players through a competitive season.

AIM: The aim of this paper was to determine changes of the bioelectrical impedance vector (BIVA) throughout a soccer season and to ascertain whether vector changes are associated with endurance performance changes. METHODS: Eighteen professional male soccer players (age=21.8±3.0 years, height=1.8±0.07 m, mass=7.2±6.5 kg) participated in the study. BIVA was conducted serially on 8 occasions throughout one soccer season. Endurance performance (Yo-Yo test) was assessed before the first training session of the preseason training, after the pre-season training and at the end of the season. RESULTS: Vector length shortened (p<0.05) during pre-season training and was associated with improvements in endurance performance (r=0.569, p=0.034). Vector length and phase-angle increased at mid-season compared to post pre-season training (p<0.05). Vector length at end-season was lower compared to mid-season (p<0.05). No further changes in endurance performance occurred. CONCLUSION: Bioimpedance vector variations from baseline indicate that fluid-gains occur during the pre-season training, possibly due to plasma volume expansion and enhanced glycogen storage, accompanied by improvements in endurance performance. The vector migration and the increase in phase angle during the competitive season indicate fluid-loss and an increase in body cell mass without effects on performance. At the very end of the season, when training volume and intensity are reduced, body fluid increases again.

Are self-reported risk-taking behavior and helmet use associated with injury causes among skiers and snowboarders?

Over the last 10 years, ski helmet use has steadily increased worldwide. According to the "risk compensation theory," however, studies found that up to one third of skiers and snowboarders self-reported to engage in more risk taking when wearing a ski helmet. Therefore, to evaluate whether self-reported risk taking and ski helmet use affect accident causes on ski slopes, more than 2000 injured skiers and snowboarders were interviewed during the 2011/2012 winter season about accident causes and potential intrinsic and extrinsic risk factors. Chi-square tests revealed that ski helmet use did not significantly differ between self-reported risky and cautious people (81% vs 83%). Multivariate regression analysis revealed younger age groups [odds ratios (ORs) 1.8-1.9, P < 005], male sex (OR 2.4, P < 0.001), Austrian nationality (2.2, P < 0.001), higher skill level (1.7, P < 0.001), and off-slope skiing (OR 2.2, P = 0.060) to be predictive for a risky behavior on ski slopes. Neither the use of skis or snowboards nor accident causes were significantly associated with a riskier behavior on ski slopes. In conclusion, self-reported risk-taking behavior and ski helmet use seem not to be associated with accident causes leading to an injury among recreational skiers and snowboarders.

Effect of weekly hiking on cardiovascular risk factors in the elderly.

BACKGROUND: Hiking is one of the most popular activities among the elderly in Alpine regions. Due to the long-lasting, moderately intensive nature of this form of physical activity, hiking is generally considered to be beneficial to health. However, it is currently unclear whether once-weekly hiking--as commonly practiced at weekends--really does yield such positive effects in elderly persons aged 60 years and over. OBJECTIVES: This study investigated the effect of a single weekly mountain hiking session on cardiovascular risk factors. MATERIALS AND METHODS: A 9-month mountain hiking program was completed by 14 male (age 65.6 ± 2.7 years) and 10 female (age 66.2 ± 4.4 years) elderly participants. The program consisted of a single weekly hiking session with the goal of achieving a 500-m altitude increase within 3 h. Before and after the 9-month program, an electrocardiogram (ECG) was performed and blood pressure, glycated hemoglobin (HbA1c), high-density (HDL) and low-density lipoprotein (LDL) measurements were made. RESULTS: The elderly participants showed a normal cardiovascular risk profile at the start of the investigation. The estimated net energy expenditure for one hiking session was approximately 521 ± 91 kcal. Over the 9-month period, no changes were found in any of the investigated parameters for the entire group. However, participants with untreated hypertension showed a reduced systolic blood pressure. CONCLUSION: The present investigation showed that moderate-intensity activity only at weekends does not improve cardiovascular risk factors in elderly persons with a relatively normal cardiovascular risk profile. Conversely, elderly persons suffering from hypertension might profit from such a practice.

[Current incidence of accidents on Austrian ski slopes]. / Aktuelles Unfallgeschehen auf österreichischen Skipisten.

BACKGROUND: Alpine skiing and snowboarding are the most popular winter sports. These sports are also associated with a certain injury risk which, however, has steadily decreased during the past decades. During the winter season 2002/2003 the last large survey on ski injuries in Austria was performed. Among others, modern skiing equipment and optimized slope preparation may impact on the injury risk. We hypothesise that these changes may have led to a further decrease in ski injuries during the past decade. METHODS: In the winter season 2012/2013, skiing injuries were recorded in 26 Austrian ski areas. Data were collected from rescue personnel on ski slopes and by physicians in the hospital or doctors practice with the help of a questionnaire. RESULTS: A total of 7325 injured skiers and snowboarders (age: 34.8 ±â€Š17.8 years) were recorded (49 % males and 51 % females; 80 % skiers, 14 % snowboarders, 6 % others). The most frequent causes of injury were self-inflicted falls (87 %) and collisions with other skiers/snowboarders (8 %). Most affected injury locations among skiers were the knee (41 %; predominantly in female skiers, > 50 %), shoulder/back (18 %) and arms (10 %). Most affected injury locations among snowboarders were arms (38 %) and shoulder/back (23 %). Head injuries were found at the same frequency (8 %) in skiers and snowboarders. The calculated injury rate was about 0.6 injuries per 1000 skier days and has decreased by more than 50 % during the past decade. CONCLUSIONS: Modern skiing equipment and optimised slope preparation may be at least partly responsible for the decreased injury risk on ski slopes which is supported by the observation of a reduced falling frequency. Future preventive measures should focus on a reduction of knee injuries in female skiers.

[How frequent and why are skiers and snowboarders falling?]. / Wie häufig und warum stürzen Skifahrer und Snowboarder?

BACKGROUND: Injuries in alpine skiing and snowboarding are mainly caused by falls. In 2002, a study was conducted to gain insight into the risk factors for falls when skiing or snowboarding. Since then, the evolution of skiing, snowboarding and safety equipment, as well as slope preparation, may have altered the frequency of falls while skiing or snowboarding. METHODS: In total, 1436 male and female skiers and snowboarders from all age groups were interviewed from February until April 2012, in 6 Tyrolean ski resorts. The questionnaire was nearly identical to that used in 2002. It contained questions concerning personal characteristics, falls, equipment and risk taking behaviour. RESULTS: The incidence of falls among skiers was 0.076 ±â€Š0.21 per hour and that among snowboarders was 0.429 ±â€Š0.70 per hour. Age (OR: 0.96; CI: 0.95 - 0.97), soft snow conditions (OR: 4.1; CI: 1.9 - 8.8) and poor skiing skills (beginners and intermediates) (OR: 2.6; CI: 1.2 - 8.1) were predictive for falls during skiing. Poor snowboarding skills (beginners and intermediates) (OR: 8.3; CI: 3.1 - 27.4), wearing a helmet (OR: 2.3; CI: 1.2 - 4.6) and alcohol consumption (OR: 2.1; CI: 1.2 - 3.9) were predictive for falls during snowboarding. CONCLUSIONS: The incidence of falls among skiers and snowboarders was substantially lower when compared to that in 2002. Improvements in skiing and snowboarding equipment as well as slope preparation may have contributed to this favourable development. We strongly assume that the lowering in fall incidence may positively affect the injury incidence.

Effects of a 10-week conventional strength training program on lower leg muscle performance in adolescent boys compared to adults.

AIM: The use of resistance training by adolescents has been an area of controversy. The aim of the present work was therefore to evaluate the degree of strength trainability in adolescents compared to adults. METHODS: Thirteen healthy male adolescents (AL) and eight adults (AD) volunteered to participate in a 10-week training program. Subjects performed supervised exercises for the legs, calf raise, leg curl and leg extension three times a week. Maximal strength, explosive power and anaerobic power were assessed prior and after the 10-week training program. RESULTS: Significant interaction effects (time * age group) were found only for explosive strength as improvements of squat jump and counter movement jump performance (P<0.05) in favor of the AL group. No between-group changes were found for maximal strength and anaerobic power. However, significant time effects were observed for these parameters within both groups. CONCLUSION: Taken together, adolescents show distinct muscular adaptations by a higher gain in explosive power in response to resistance training when compared to adults. This might be related to peak height velocity (PHV) which is a "sensitive" period of trainability and accelerated adaptation to resistance training in adolescents.

Effect of wearing a ski helmet on perception and localization of sounds.

Helmet use on ski slopes has steadily increased worldwide over the past years. A common reason reported for helmet non-use, however, is impaired hearing. Therefore, an intra-subject design study was conducted to compare hearing thresholds and sound source localization of 21 adults with normal hearing in an anechoic chamber when wearing a ski helmet and ski goggles or wearing a ski cap and ski goggles to the condition head bare. Hearing thresholds while wearing a ski helmet (6.8 ± 1.6 dB HL) and ski cap (5.5 ± 1.6 dB HL) were significantly different (p = 0.030, d = 0.44). Compared to head bare (2.5 ± 1.2 dB HL), a significant difference was found for the ski helmet only (p = 0.040, d = 1.57). Regarding sound source localization, correct scores in the condition head bare (90%) showed a highly significant difference compared with those of condition cap (65%) and helmet (58%), respectively (p < 0.001; d > 2.5). Compared to the ski cap, wearing the helmet significantly reduced correct scores (p = 0.020, d = 0.59) irrespective of the tested sound pressure levels. In conclusion, wearing a ski helmet impairs hearing to a small though significantly greater extent compared with a cap, the degree, however, being less than what is termed as a hearing impairment. Compared to the condition head bare, wearing a ski cap or a ski helmet significantly reduced one's ability of sound source localization.

Different metabolic responses during incremental exercise assessed by localized 31P MRS in sprint and endurance athletes and untrained individuals.

Until recently, assessment of muscle metabolism was only possible by invasive sampling. 31P magnetic resonance spectroscopy (31P MRS) offers a way to study muscle metabolism non-invasively. The aim of the present study was to use spatially-resolved 31P MRS to assess the metabolism of the quadriceps muscle in sprint-trained, endurance-trained and untrained individuals during exercise and recovery. 5 sprint-trained (STA), 5 endurance-trained (ETA) and 7 untrained individuals (UTI) completed one unlocalized 31P MRS session to measure phosphocreatine (PCr) recovery, and a second session in which spatially-resolved 31P MR spectra were obtained. PCr recovery time constant (τ) was significantly longer in STA (50±17 s) and UTI (41±9 s) than in ETA (30±4 s), (P<0.05). PCr changes during exercise differed between the groups, but were uniform across the different components of the quadriceps within each group. pH during recovery was higher for the ETA than for the UTI (P<0.05) and also higher than for the STA (P<0.01). Muscle volume was greater in STA than in UTI (P<0.05) but not different from ETA. Dynamic 31P MRS revealed considerable differences among endurance and sprint athletes and untrained people. This non-invasive method offers a way to quantify differences between individual muscles and muscle components in athletes compared to untrained individuals.

Effects of exercise and hypoxia on heart rate variability and acute mountain sickness.

Acute mountain sickness (AMS) is a common condition among non-acclimatized individuals ascending to high altitude. Exercise, a characteristic feature of hiking and mountaineering, has been suggested to exacerbate AMS prevalence and to cause modifications of the autonomic nervous system. A reduction of the heart rate variability (HRV) is a common finding during acute hypoxia, however characteristics of HRV during exercise in subjects suffering from AMS are unknown. Therefore, the aim of the present study was to investigate the effects of acute normobaric hypoxia (FiO2=11.0% ≙ 5 500 m) at rest (PHE) and during exercise (AHE) on the cardiac autonomic function and the development of AMS in 20 healthy, male individuals. HRV recordings were performed during normoxia and after 2, 4, 6 and 8 h in hypoxia during PHE and AHE, respectively. AMS was assessed using the Lake Louise Score. During PHE 50% of participants developed AMS and 70% during AHE (p=0.22). The analysis of HRV data showed a significant reduction of total power (TP), high frequency (HF) and low frequency (LF) components and an increase of the LF:HF ratio during PHE, however without further modification during AHE. Exercise did not increase AMS prevalence or severity, but increased "non-gastrointestinal" symptoms including headache, fatigue and dizziness. HRV indices were not related to the overall incidence of AMS or the development of "non-gastrointestinal" symptoms but we detected significant correlations between gastrointestinal complaints and HRV components. Thus, we suggest that the cardiac autonomic modulation during acute normobaric hypoxia does not play an important role in the development of AMS, but seems to be related to gastrointestinal complaints at high altitude. However, the influence of moderate exercise on HRV and AMS is minor, only "non-GI" symptoms seem to be exacerbated when exercise is applied.