[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.

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.

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.

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]

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 ± 10.9 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.

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.

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.

[Factors Associated with the Use of Protective Gear among Adults during Recreational Sledging]

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 ± 14.4 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]

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 ± 1.75 with significant differences between female and male via ferrata climbers (3.79 ± 1.37 vs. 4.53 ± 1.88).

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]

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 ± 14.4 years were interviewed. Interviewed persons reported that they perform about 20.6 ± 16.0 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.

[Current incidence of accidents on Austrian ski slopes]

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 ± 17.8 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?]

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 ± 0.21 per hour and that among snowboarders was 0.429 ± 0.70 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.

Effects of massage under hypoxic conditions on exercise-induced muscle damage and physical strain indices in professional soccer players

Reports based on experiences from masseurs and players, mostly without any scientific background, suggest that the combination of a classical regeneration method (i.e. massage) with exposure to hypoxia may enhance regeneration in soccer. The aim of this study was to evaluate whether this specific combination could affect blood parameters related to muscle damage and physical strain after a soccer game. Approximately 15 hours after two separate championship games, 10 professional male outfield players of the first Austrian division were exposed to normobaric hypoxia (FiO2 13.5% ∼ 4000m) or normoxia for 1 hour (30 minutes rest followed by 30 min massage) (cross-over design). Creatine kinase (CK), urea and uric acid (UA) were measured 4 days before the first game, and 15 and 63 hours after the two games. Match play increased CK values independently of the intervention. No effect of the massage in combination with hypoxia was seen. A trend was found between Δ UA ([UA] 48 hours after exposure minus [UA] before exposure) in response to hypoxia and SaO2 measured in hypoxia (r=0.612, p=0.06). Results show that massage under hypoxic conditions had no additional positive effect on the measured parameters compared to massage alone. Solely the trend of a relationship for Δ UA and SaO2 might indicate that redox alterations are a potential consequence of hypoxic exposure.

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.

Does listening to music with an audio ski helmet impair reaction time to peripheral stimuli?

With the recent worldwide increase in ski helmet use, new market trends are developing, including audio helmets for listening to music while skiing or snowboarding. The aim of this study was to evaluate whether listening to music with an audio ski helmet impairs reaction time to peripheral stimuli. A within-subjects design study using the Compensatory-Tracking-Test was performed on 65 subjects (36 males and 29 females) who had a mean age of 23.3 ± 3.9 years. Using repeated measures analysis of variance, we found significant differences in reaction times between the 4 test conditions (p=0.039). The lowest mean reaction time (± SE) was measured for helmet use while listening to music (507.9 ± 13.2 ms), which was not different from helmet use alone (514.6 ± 12.5 ms) (p=0.528). However, compared to helmet use while listening to music, reaction time was significantly longer for helmet and ski goggles used together (535.8 ± 14.2 ms, p=0.005), with a similar trend for helmet and ski goggles used together while listening to music (526.9 ± 13.8 ms) (p=0.094). In conclusion, listening to music with an audio ski helmet did not increase mean reaction time to peripheral stimuli in a laboratory setting.

Short-term supplementation with alpha-ketoglutaric acid and 5-hydroxymethylfurfural does not prevent the hypoxia induced decrease of exercise performance despite attenuation of oxidative stress

Reactive oxygen species are thought to partly be responsible for the hypoxia induced performance decrease. The present study evaluated the effects of a broad based antioxidant supplementation or the combined intake of alpha-ketoglutaric acid (α-KG) and 5-hydroxymethylfurfural (5-HMF) on the performance decrease at altitude. 18 healthy, well-trained males (age: 25±3 years; height: 179±6 cm; weight: 76.4±6.8 kg) were randomly assigned in a double-blind fashion to a placebo group (PL), a α-KG and 5-HMF supplementation group (AO1) or a broad based antioxidant supplementation group (AO2). Participants performed 2 incremental exercise tests to exhaustion on a cycle ergometer; the first test under normoxia and the second under hypoxia conditions (simulated altitude, FiO2=13% ~ 4 300 m). Supplementation started 48 h before the hypoxia test. Maximal oxygen uptake, maximal power output, power output at the ventilatory and lactate threshold and the tissue oxygenation index (NIRS) were measured under both conditions. Oxidative stress markers were measured before the supplementation and after the hypoxia test. Under hypoxia conditions all performance parameters decreased in the range of 19-39% with no differences between groups. A significant change from normoxia to hypoxia (p<0.001) and between groups (p=0.038) were found for the tissue oxygenation index. Post hoc test revealed significant differences between the PL and both, the AO1 and the AO2 group. The oxidative stress parameter carbonyl protein changed from normoxia to hypoxia in all participants and 4-hydroxynonenal decreased in the AO1 group only. In conclusion the results suggest that short-term supplementation with an antioxidant does not prevent the performance decrease at altitude. However, positive effects on muscle oxygen extraction, as indicated by the tissue oxygenation index, might indicate that mitochondrial functioning was actually influenced by the supplementation.

Short-term intermittent hypoxia reduces the severity of acute mountain sickness

Intermittent hypoxia (IH) is a promising approach to induce acclimatization and hence lower the risk of developing acute mountain sickness (AMS). We hypothesized that a short-term IH protocol in normobaric hypoxia (7 × 1 h to 4500 m) effectively increases the hypoxic ventilatory response (HVR) and reduces the incidence and severity of AMS. Therefore, 26 men (25.5 ± 4.4 years), assigned in a double-blinded fashion to the hypoxia group (HG) or placebo group (PG), spent 8 h at 5300 m before (PRE) and 2 days after cessation of the IH protocol (POST). Measurements included the evaluation of the Lake Louise Score (LLS) and the HVR. The severity of AMS decreased from PRE to POST in the HG (from 6.0 ± 2.7 at PRE to 4.1 ± 2.1 at POST), whereas the LLS in the PG stayed high (from 5.7 ± 2.9 to 5.5 ± 2.8, respectively). The HVR in the HG increased from 0.73 ± 0.4 L/min/% at PRE to 1.10 ± 0.5 L/min/% at POST and did not increase in the PG. The reduction of the LLS was inversely related to the changes in the HVR (r = -0.434), but the AMS incidence was not different between the HG and the PG at POST. In conclusion, short-term IH reduced the severity of AMS development during a subsequent 8-h exposure to normobaric hypoxia.

Effects of supervised exercise on gamma-glutamyl transferase levels in patients with isolated impaired fasting glucose and those with impaired fasting glucose plus impaired glucose tolerance

AIM

To study the effects of a supervised exercise program on serum gamma-glutamyl transferase (GGT), glycemic control and cardiovascular risk factors in pre-diabetic patients with isolated impaired fasting glucose (IFG) and those with IFG plus impaired glucose tolerance (IGT).

METHODS

Out of 60 pre-diabetic patients (30 with isolated IFG and 30 with IFG + IGT) 24 were randomly assigned to the supervised exercise program (1 h twice a week) and 36 only obtained counselling on the risk of diabetes and its prevention. Patients have been followed over a 12-month period.

RESULTS

The main findings were that patients with IFG + IGT had increased GGT levels at baseline (49.2±27.4 U/L) compared to subjects with isolated IFG (28.1±21.9 U/L) (p<0.01), and that GGT levels improved only after the supervised exercise intervention within the IFG + IGT subjects ( - 17.7±19.6 U/L). Similarly, baseline triglyceride levels were also higher in IFG + IGT patients (p<0.001) and there was a decrease through exercise intervention in these patients only (p<0.05).

CONCLUSION

GGT is an unspecific marker of oxidative stress and both high plasma glucose and triglycerides levels may produce oxidative stress. Thus, patients with IFG + IGT seem to have higher levels of oxidative stress than those with isolated IFG. Based on the known association between GGT levels and cardiovascular risk factors, IFG + IGT patients may be at higher risk for the development of cardiovascular diseases. The specific effect of regular exercise on GGT in pre-diabetic patients may contribute to the understanding of the preventive effects related to exercise.

Effects of the performance level and the FIFA "11" injury prevention program on the injury rate in Italian male amateur soccer players

AIM

Soccer is characterized by high injury rates that necessitate interventions for its reduction. The "11" is a multi-modal preventive program that was developed to reduce injury rate. However, outcomes on the effectiveness of the program are not unambiguous and data for the largest group at risk (i.e., male adult amateur players) are missing. The study aims to assess the injury rate in male adult amateur soccer players of different levels and to evaluate the effectiveness of the prevention program the "11".

METHODS

Three amateur soccer teams participated in the study during the first round of a competition season. Two teams played at a regional level (6th Italian league) and one team at a provincial level (7th Italian league). The regional league is of a higher skill level compared to the provincial league. Duration and frequency of training and match sessions and the occurrence of time-loss injuries were recorded. One team of the 6th league performed an injury prevention program.

RESULTS

The total injury rate for the intervention and the control team in the 6th league was 3.3 (CI 0.7-5.9) and 4.3 (CI 1.3-7.3) injuries/1000 h, respectively (P=0.841). The 6th league control team tended to have a lesser injury rate compared to the 7th league team (P=0.081). The relative risk was 2 fold higher in the 7th compared to the 6th league team (P=0.0285 one tailed).

CONCLUSION

Present results show that injury rate in amateur soccer depended rather on the skill level than the prevention program. In this study the prevention program the "11" was not shown to be highly effective in soccer player of intermediate level (i.e., 6th Italian league).

Changes in cardiac autonomic activity during a passive 8 hour acute exposure to 5 500 m normobaric hypoxia are not related to the development of acute mountain sickness

Alterations in the autonomic nervous system after ascent to high altitude may be related to the development of acute mountain sickness (AMS). So far, the time course of cardiac autonomic modulation in relation to AMS development during the early hours at altitude is not well established. As AMS develops sometimes as early as 1 h and typically within 6 to 10 h at altitude, evaluating this time period provides information on cardiac autonomic responses with regard to AMS development. Prior studies exclusively investigated autonomic modulations in hypobaric hypoxia. Because barometric pressure per se might influence autonomic nervous system activity, the evaluation of cardiac autonomic alterations caused by hypoxia alone might give new insights on the role of the autonomic nervous system in AMS development. To assess the early responses of acute hypoxia on cardiac autonomic modulation and its association to the development of AMS, 48 male subjects were exposed for 8 h to acute normobaric hypoxia (FiO2 11.0%, 5 500 m respectively). Heart rate variability (HRV) was determined by 5-min recordings of successive NN-intervals in normoxia and after 2, 4, 6 and 8 h in hypoxia. Compared with normoxia, acute exposure to hypoxia decreased total power (TP), high frequency (HF) and low frequency (LF) components as well as the standard deviation of all NN intervals (SDNN), the root mean square of differences of successive NN intervals (rMSSD) and the proportion of differences between adjacent NN intervals of more than 50 ms (pNN50). LF:HF ratio, heart rate (HR) and blood lactate (LA) were augmented, indicating an increase in cardiac sympathetic activity. No differences were found between those who developed AMS and those who did not. Our results confirm reduced HRV with a shift towards sympathetic predominance during acute exposure to hypoxia. However, changes in cardiac autonomic modulations are not related to AMS development in acute normobaric hypoxia.

[Attitudes of winter sport participants toward ski helmet mandatory]

The aim of this study was to examine attitudes of winter sport participants toward a ski helmet mandatory. In total, 959 persons who had to estimate statements regarding ski helmet and helmet mandatory with the aid of a five level Likert scale were interviewed. About 85 % of interviewed persons totally agreed that a ski helmet reduces head injury risk although only 64 % are wearing a ski helmet. Significant more helmet wearers and females compared to non-wearers and males totally agreed that all winter sport participants should wear ski helmets on slopes as well as that all children on slopes should wear a ski helmet. Also, significant more helmet wearers and females compared to non-wearers and males totally agreed that a ski helmet mandatory for all people has to be recommended as well as that a ski helmet mandatory for children under 16 years has to be recommended. However, the acceptance for a helmet mandatory for all people as well as for children was significantly lower compared to recommendations for helmet use irrespective of helmet use or gender. Therefore, we conclude that preventive helmet campaigns possibly attain a higher acceptance leading to a higher helmet use compared to a helmet mandatory.

Impact of environmental factors on knee injuries in male and female recreational skiers

In alpine skiing, the knee represents the dominant injury location with marked gender differences. Snow, slope and weather conditions as well as altitude and low temperatures are thought to influence the prevalence of knee injuries. Therefore, ski patrol injury reports were used to compare gender-specific prevalence of knee injuries with regard to several environmental factors including the actual air temperatures. A total of 1039 non-contact knee injuries were reported with a corresponding prevalence of knee injuries of 44.4% (males: 30.1%; females: 57.4%). Temperature quartiles of all recorded injuries were calculated to compare gender-specific prevalence of knee injury with regard to temperatures. Comparing the first quartile (mean temperature -11°C) with the fourth quartile (mean temperature +3°C), the prevalence of knee injury in female skiers was higher at low ambient temperatures (61% vs 50%, odds ratio: 1.60, 95% confidence interval: 1.16-2.22; P=0.005) while no such association was found for male skiers. Additionally, knee-injured females showed a twofold prevalence when skiing during snowfall compared with females with other injuries (15.4% vs 8.6%; P=0.001). No other environmental factor showed a significant association with the gender-specific prevalence of knee injury. In conclusion, low ambient temperature and snowfall are important environmental risk factors for knee injuries in female skiers.

Changes in hydration status of soccer players competing in the 2008 European Championship

AIM

Body composition is highly modifiable through exercise and may be changed by the physical stress of soccer training and competition. Especially body water as a constituent of body composition is assumed to be subjected to changes. It is speculated that during the most important soccer championship the combination of heat and the strenuous competitive program could lead to the development of a chronic state of hypohydration. However, no one tested this hypothesis. Therefore, the purpose of present work was to investigate the impact of the European Soccer Championship 2008 on players' body composition.

METHODS

Participants were 14 players of one team, split into Starters (N.=7) and Non-Starters (N.=7). Starters participated in the games, while Non-Starters served as substitutes, with marginal playing times. Body composition was examined by bioelectrical impedance analysis before the championship and 36 hours after the first and second game.

RESULTS

After the first game, Starters and Non-Starters showed decreased extra-cellular mass (-3.3% and -5.5%) and body cell mass (-4.1% and -6.1%) compared to prechampionship measurements. The impedance vector graph showed a significant lengthening in both groups (Starters T²=30.5, P=0.000; Non Starters T²=39.0, P=0.000). After the second game, extra-cellular mass (-3.4%) and body weight (-1.1%) decreased in Starters only. ANOVA revealed a significant difference in extra-cellular mass between Starters and Non-Starters (P=0.027). The impedance vector graph was lengthened in the Starters only (T²=17.5, P=0.000). The distance covered during the games was correlated to the percent drop in extra-cellular mass between the end of games 1 and 2 (r=-0.602; P=0.023).

CONCLUSION

Players competing in the European championship games experienced a decrease in extra-cellular mass and body weight. The impedance vector graph showed a lengthening, indicating fluid loss. Therefore, proper hydration of players requires diligent attention.

Effects of intermittent hypoxia on running economy

We investigated the effects of two 5-wk periods of intermittent hypoxia on running economy (RE). 11 male and female middle-distance runners were randomly assigned to the intermittent hypoxia group (IHG) or to the control group (CG). All athletes trained for a 13-wk period starting at pre-season until the competition season. The IHG spent additionally 2 h at rest on 3 days/wk for the first and the last 5 weeks in normobaric hypoxia (15-11% FiO2). RE, haematological parameters and body composition were determined at low altitude (600 m) at baseline, after the 5 (th), the 8 (th) and the 13 (th) week of training. RE, determined by the relative oxygen consumption during submaximal running, (-2.3+/-1.2 vs. -0.3+/-0.7 ml/min/kg, P<0.05) and total running time (+1.0+/-0.9 vs. +0.4+/-0.5 min, P<0.05) changed significantly between the IHG and CG only during the first 5-wk period. Haematological and cardiorespiratory changes indicate that the improved RE was associated with decreased cardiorespiratory costs and greater reliance on carbohydrate. Intermittent hypoxia did not affect RE during the second 5-wk period. These findings suggest that the effects of intermittent hypoxia on RE strongly depend on the training phase.

Intermittent hypoxia increases exercise tolerance in patients at risk for or with mild COPD

The effects of repeated short-term hypoxia on exercise tolerance in patients at risk for, or with mild COPD were investigated. Eighteen patients (10 males, 8 females; 33-72 years) were randomly assigned in a double-blind fashion to receive 15 sessions of intermittent hypoxia (FiO(2): 0.15-0.12) or normoxia within 3 weeks. Three weeks of intermittent hypoxia increased total haemoglobin mass (+4% vs. 0%, p<0.05), total exercise time (+9.7% vs. 0%, p<0.05) and the exercise time to the anaerobic threshold (+13% vs. -7.8%, p<0.05) compared to controls. Changes in the total exercise time were positively related to the changes in total haemoglobin mass (r=0.59, p<0.05) and changes in the time to the anaerobic threshold were positively related to the changes in the lung diffusion capacity for carbon monoxide (r=0.48, p<0.05). Intermittent hypoxia treatment may be a valuable addition to therapy designed to improve exercise tolerance in patients at risk for, or with mild COPD.

Frontal plane leg alignment and muscular activity during maximum eccentric contractions in individuals with and without patellofemoral pain syndrome

PURPOSE

The role of frontal plane tibiofemoral alignment in subjects with patellofemoral pain syndrome (PFPS) is controversial and rarely discussed in the literature. As well, little research has been done on the effects of the hamstrings muscles on PFPS. The aim of the current study was to determine whether, in individuals with PFPS, frontal plane tibiofemoral alignment or muscular activity of the index knee's crossing muscles is altered during maximum eccentric leg press exercise.

METHODS

This cross-sectional study involved 19 patients with PFPS and 19 control subjects who were matched according to gender, age, and physical activity. During eccentric leg press action, frontal plane tibiofemoral alignment was assessed with a motion analysis system based on skin markers. Simultaneously, surface-electromyography was used to assess the activity levels of the relevant knee crossing muscles. To assess the activity under functional conditions, a leg press with a footplate having variable stability was used for barefoot testing.

RESULTS

The PFPS subjects did not have significantly different frontal plane leg alignment compared to controls. On electromyography (EMG), PFPS patients had significantly lower levels of hamstring activity during eccentric leg exercise. The differences between the two groups (%; absolute differences normalized EMG) ranged from 20% (semitendinosus; stable footplate; p=0.017) to 21% (biceps femoris; unstable footplate; p=0.019) and 32% (semitendinosus; unstable footplate; p=0.002).

CONCLUSIONS

PFPS is not linked to altered frontal plane leg alignment during eccentric leg pressing. However, PFPS is associated with eccentric under-activation of the hamstrings, which may be a compensatory strategy that maintains patellofemoral joint pressure within bearable levels.

Risk Factor Profile for Sudden Cardiac Death During Mountain Hiking

Mountain hiking is associated with a death rate of about 4 deaths per 100,000 hikers annually. About 50 % of all fatalities during mountain hiking are sudden cardiac deaths (SCDs). But there are only few data available regarding risk factors and triggers associated with SCD during mountain hiking. Thus, a case-control analysis between persons who died suddenly during mountain hiking and randomly selected controls was carried out. Risk factor profiles of 179 males over the age of 34 who suffered SCD during mountain hiking were compared to those of 537 matched controls. Hikers who died suddenly during mountain hiking were much more likely to have had a prior MI (17% vs. 0.9%; p < 0.001), known coronary artery disease (CAD) without prior MI (17 % vs. 4%; p < 0.001), diabetes (6% vs. 1 %; p < 0.001), hypercholesterolemia (54 % vs. 20%; p < 0.001), and were less engaged in regular mountain sports activities (31% vs. 58%; p < 0.001) compared to hikers from the control group. Based on the reported relationship between traditional risk factors and coronary plaque morphology, acute plaque rupture with thrombus formation and subsequent lethal arrhythmias may be assumed to be a dominant mechanism precipitating SCD during hiking. In contrast, in skiers especially non-occlusive plaques may precipitate ischemia leading to an imbalance between oxygen demand and supply and subsequent lethal arrhythmias. As preventive measures recommended to hikers at risk, adaptation to regular mountain sports activities by an adequate training program and pharmacological interventions, e.g. lipid lowering drugs, aspirin, and beta-blockers, should be considered.

Frequency of Cardiovascular Diseases among Ski Mountaineers in the Austrian Alps

In recent years, mountain sports, especially ski mountaineering, are practised by increasing numbers. Although a high percentage of elderly with cardiovascular diseases is estimated, little is known about the real frequency of cardiovascular diseases among ski mountaineers. The goal of this study was to provide data on the frequency of cardiovascular diseases (coronary artery disease with and without myocardial infarction, hypertension, arrhythmias), collected among a representative sample of 937 ski mountaineers in the Austrian Alps. Data of 934 questionnaires were included into the evaluation. Regarding the whole sample, 5.8 % (95 % CI: 4.3 - 7.3 %) of the ski mountaineers are afflicted with at least one cardiovascular disease. The frequency of cardiovascular diseases is age dependent and more pronounced in men. Hypertension is the dominant cardiovascular disease in ski mountaineers. All persons with coronary artery disease with or without prior myocardial infarction and 79 % of the persons with cardiovascular diseases in general are males over the age of 40 years. Scientific research should provide the basis of an optimal risk management for this group of persons.

Effects of short-term acclimatization to altitude (3200 m) on aerobic and anaerobic exercise performance

Aerobic exercise performance decreases upon ascent to altitude whereas anaerobic performance remains unchanged. Although the effects of 1 - 3 wk of altitude acclimatization on both aerobic and anaerobic exercise performance have been well studied, the effects of short-term altitude acclimatization (i.e., 45 h) on these parameters have not been well defined. Therefore, both aerobic and anaerobic exercise performance was evaluated in five healthy men (51.4 +/- 7.7 years, 175 +/- 4.2 cm, and 73.8 +/- 6.1 kg) at low altitude (LA, 600 m), upon acute exposure (approximately 1 - 3 h) to 3200 m (HA1) and on the third day of altitude exposure (HA3, 3200 m). Subjects performed three consecutive exercise tests, separated by approximately 1 - 3 h of rest, of various durations (i.e., 30 s, 5 min, and 50 min) on a cycle ergometer in each environmental condition. Anaerobic cycling performance (i. e., 30 s) was the same at LA, HA1, and HA3. Aerobic cycling performance (i. e., 5 min and 50 min) was reduced by 12.0 and 11.3 %, respectively, upon acute exposure to altitude. There was no change in the 5-min cycling performance but the 50-min cycling performance improved by 5.7 % from HA1 to HA3 which implies a 50 % recovery of the initial loss. These findings are important for individuals going to high altitude for work, for athletic competition, or recreation.

Effects of aspirin during exercise on the incidence of high-altitude headache: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate the efficacy of aspirin for headache when exercising during acute high-altitude exposure.

BACKGROUND

Aspirin effectively prevents headache when mostly resting during acute high-altitude exposure. However, the majority of individuals exposed to high altitude perform mountaineering activities, which might trigger headache.

DESIGN

Randomized, double-blind, placebo-controlled trial.

METHODS

Thirty-one healthy volunteers (20 men, 11 women; aged 22 to 59 years) were transported to an altitude of about 3000 meters and climbed up to 3800 meters. They then descended to a mountain hut at 3480 meters and spent 2 nights there. Tablets (placebo or 320 mg aspirin) were administered three times at 4-hour intervals, beginning 2 hours before arrival at high altitude. Headache scoring and measurements of heart rate, blood pressure, and arterial oxygen saturation were performed.

RESULTS

Ninety-three percent (14 of 15) of the placebo group and 56% (9 of 16) of the aspirin group developed headache when mountaineering activities were performed during acute exposure to high altitude (P<.05). Five hours after arrival at high altitude, mean resting oxygen saturation was 86.1% +/- 2.1% with aspirin and 85.7 % +/- 2.8% with placebo (P =.66). However, subjects in the aspirin group developed headache at saturation values less than or equal to 86%, while those in the placebo group developed headache at saturation values less than 90%.

CONCLUSIONS

Although the prophylactic intake of about 1 gram of aspirin reduced the headache incidence when exercising during acute high-altitude exposure, the incidence of headache was higher than previously shown for resting conditions. Aspirin resulted in tolerance to lower arterial oxygen saturation without development of headache; exercise had the opposite effect.