Hemoglobin Mass and Aerobic Performance at Moderate Altitude in Elite Athletes.

Fore more than a decade, the live high-train low (LHTL) approach, developed by Levine and Stray-Gundersen, has been widely used by elite endurance athletes. Originally, it was pointed out, that by living at moderate altitude, athletes should benefit from an increased red cell volume (RCV) and hemoglobin mass (Hbmass), while the training at low altitudes should prevent the disadvantage of reduced training intensity at moderate altitude. VO2max is reduced linearly by about 6-8 % per 1000 m increasing altitude in elite athletes from sea level to 3000 m, with corresponding higher relative training intensities for the same absolute work load. With 2 weeks of acclimatization, this initial deficit can be reduced by about one half. It has been debated during the last years whether sea-level training or exposure to moderate altitude increases RCV and Hbmass in elite endurance athletes. Studies which directly measured Hbmass with the optimized CO-rebreathing technique demonstrated that Hbmass in endurance athletes is not influenced by sea-level training. We documented that Hbmass is not increased after 3 years of training in national team cross-country skiers. When athletes are exposed to moderate altitude, new studies support the argument that it is possible to increase Hbmass temporarily by 5-6 %, provided that athletes spend >400 h at altitudes above 2300-2500 m. However, this effect size is smaller than the reported 10-14 % higher Hbmass values of endurance athletes living permanently at 2600 m. It remains to be investigated whether endurance athletes reach these values with a series of LHTL camps.

Differences in horizontal vs. uphill running performance in male and female Swiss world-class orienteers.

In orienteering, athletes must choose the quickest route from point to point, considering if they want to run a longer flat distance rather than a shorter distance with an incline to reach the next point. Our aim was therefore, to determine an athlete's equivalence factor (EF, ratio between horizontal and uphill running performance) enabling coaches to provide individual route choice recommendations during orienteering competition. Ten male and 8 female orienteers performed 1 horizontal (MST(horizontal); 0% incline) and 1 uphill (MST(uphill); 22% incline) maximal running stage test to exhaustion on a treadmill in randomized order. The EFs were calculated based on maximal speeds achieved in both tests (MRV(horizontal/uphill)). In addition, VO2peak was measured. MRV(horizontal) was 20.4 ± 0.6 and 17.3 ± 0.8 km · h, and MRV(uphill) was 8.8 ± 0.7 and 7.2 ± 0.5 km · h (men and women). The EF was 6.3 ± 0.7 and ranged between 5.2 and 7.4. Relative VO2peak(uphill) was 69.2 ± 5.7 and 59.1 ± 3.7 m l · kg · min, whereas VO2peak(horizontal) was lower 66.4 ± 3.5 (p < 0.05) and 55.7 ± 3.1 ml · kg · min (p < 0.01) than in VO2peak(uphill). Relative VO2peak(uphill) correlated strongly with MRV(uphill) (men: r = 0.85, p < 0.01; women: r = 0.84, p < 0.01), whereas relative VO2peak(horizontal) showed no strong correlation with MRV(horizontal) (men: r = 0.51, p = 0.12; women: r = 0.41, p = 0.32). These data show that there are relevant differences in the relation between uphill and horizontal running capacity in these athletes. Tailoring the route selection to the athletes' advantage based on the relation between their uphill and horizontal running performance and individual EF may positively impact on overall performance in orienteering competition.

The level of physical activity affects adrenal and cardiovascular reactivity to psychosocial stress.

Physical activity plays a key role in the control of neuroendocrine, autonomic, and behavioral responses to physical and psychosocial stress. However, little is known about how the level of physical activity modulates stress responsiveness. Here, we test whether different levels of physical activity are associated with different adrenal, cardiovascular, and psychological responses to psychosocial stress. In addition, competitiveness is assessed as a personality trait that possibly modulates the relationship between physical activity and stress reactivity. Eighteen elite sportsmen, 50 amateur sportsmen, and 24 untrained men were exposed to a standardized psychosocial laboratory stressor (Trier Social Stress Test). Repeated measures of salivary free cortisol, heart rate, and psychological responses to psychosocial stress were compared among the 3 study groups. Elite sportsmen exhibited significantly lower cortisol, heart rate, and state anxiety responses compared with untrained subjects. Amateur sportsmen showed a dissociation between sympathetic and hypothalamic-pituitary-adrenal responsiveness to stress, with significantly reduced heart rate responses but no difference in cortisol responses compared with untrained men. Different levels of competitiveness among groups did not mediate stress reactivity. Our results are in line with previous studies indicating reduced reactivity of the autonomic nervous system to psychosocial stress in trained individuals. More importantly, these findings imply a differential effect of the level of physical activity on different stress-related neurophysiological systems in response to psychosocial stress.

Trained men show lower cortisol, heart rate and psychological responses to psychosocial stress compared with untrained men.

Physical activity has proven benefits for physical and psychological well-being and is associated with reduced responsiveness to physical stress. However, it is not clear to what extent physical activity also modulates the responsiveness to psychosocial stress. The purpose of this study was to evaluate whether the reduced responsiveness to physical stressors that has been observed in trained men can be generalized to the modulation of physiological and psychological responses to a psychosocial stressor. Twenty-two trained men (elite sportsmen) and 22 healthy untrained men were exposed to a standardized psychosocial laboratory stressor (Trier Social Stress Test). Adrenocortical (salivary free cortisol levels), autonomic (heart rate), and psychological responses (mood, calmness, anxiety) were repeatedly measured before and after stress exposure. In response to the stressor, cortisol levels and heart rate were significantly increased in both groups, without any baseline differences between groups. However, trained men exhibited significantly lower cortisol and heart rate responses to the stressor compared with untrained men. In addition, trained men showed significantly higher calmness and better mood, and a trend toward lower state anxiety during the stress protocol. On the whole, elite sportsmen showed reduced reactivity to the psychosocial stressor, characterized by lower adrenocortical, autonomic, and psychological stress responses. These results suggest that physical activity may provide a protective effect against stress-related disorders.

Live high-train low for 24 days increases hemoglobin mass and red cell volume in elite endurance athletes.

The effect of live high-train low on hemoglobin mass (Hbmass) and red cell volume (RCV) in elite endurance athletes is still controversial. We expected that Hb(mass) and RCV would increase, when using a presumably adequate hypoxic dose. An altitude group (AG) of 10 Swiss national team orienteers (5 men and 5 women) lived at 2,500 m (18 h per day) and trained at 1,800 and 1,000 m above sea level for 24 days. Before and after altitude, Hbmass, RCV (carbon monoxide rebreathing method), blood, iron, and performance parameters were determined. Seven Swiss national team cross-country skiers (3 men and 4 women) served as "sea level" (500-1,600 m) control group (CG) for the changes in Hbmass and RCV. The AG increased Hbmass (805+/-209 vs. 848+/-225 g; P<0.01) and RCV (2,353+/-611 vs. 2,470+/-653 ml; P<0.01), whereas there was no change for the CG (Hbmass: 849+/-197 vs. 858+/-205 g; RCV: 2,373+/-536 vs. 2,387+/-551 ml). Serum erythropoietin (P<0.001), reticulocytes (P<0.001), transferrin (P<0.001), soluble transferrin receptor (P<0.05), and hematocrit (P<0.01) increased, whereas ferritin (P<0.05) decreased in the AG. These changes were associated with an increased maximal oxygen uptake (3,515+/-837 vs. 3,660+/-770 ml/min; P<0.05) and improved 5,000-m running times (1,098+/-104 vs. 1,080+/-98 s; P<0.01) from pre- to postaltitude. Living at 2,500 m and training at lower altitudes for 24 days increases Hbmass and RCV. These changes may contribute to enhance performance of elite endurance athletes.

Validity of four short physical activity questionnaires in middle-aged persons.

PURPOSE: Self-administered questionnaires continue to be the most widely used type of physical activity assessment in epidemiological studies. However, test-retest reliability and validity of physical activity questionnaires have to be determined. In this study, three short physical activity questionnaires already used in Switzerland and the International Physical Activity Questionnaire (IPAQ) were validated. METHODS: Test-retest reliability was assessed by repeated administration of all questionnaires within 3 wk in 178 volunteers (77 women, 46.1+/-14.8 yr; 101 men 46.8+/-13.2 yr). Validity of categorical and continuous data was studied in a subsample of 35 persons in relation to 7-d accelerometer readings, percent body fat, and cardiorespiratory fitness. RESULTS: Reliability was fair to good with a Spearman correlation coefficient range of 0.43-0.68 for measures of continuous data and moderate to fair with Kappa values between 0.32 and 0.46 for dichotomous measures active/inactive. Total physical activity reported in the IPAQ and the Office in Motion Questionnaire (OIMQ) correlated with accelerometry readings (r=0.39 and 0.44, respectively). In contrast, correlations of self-reported physical data with percent body fat and cardiorespiratory fitness were low (r=-0.26-0.29). Participants categorized as active by the Swiss HEPA Survey 1999 instrument (HEPA99) accumulated significantly more days of the recommended physical activities than their inactive counterparts (4.4 and 2.7 d.wk, respectively, P<0.05). However, compared with accelerometer data, vigorous physical activities were overreported in investigated questionnaires. CONCLUSION: Collecting valid data on physical activity remains a challenging issue for questionnaire surveys. The IPAQ and the three other questionnaires are characterized to inform decisions about their appropriate use.

A school-based physical activity program to improve health and fitness in children aged 6-13 years ("Kinder-Sportstudie KISS"): study design of a randomized controlled trial [ISRCTN15360785].

BACKGROUND: Childhood obesity is the result of a long lasting imbalance between energy intake and energy expenditure. A major contributing factor is physical inactivity which is closely linked to bone health, cardiovascular disease risk, fitness and psychological factors. The school seems to provide an excellent setting to enhance levels of physical activity (PA). However, there is insufficient data from previous school-based intervention trials on how to enhance overall PA. It is also unknown whether an intervention aimed at increasing PA is effective in improving the children's health. The purpose of this paper is to outline the design of a school-based randomized, controlled trial (RCT) aiming to increase overall PA and to improve fitness and health in 6- to 13-year-old children. METHODS/DESIGN: 15 schools were randomized to the intervention (n = 9) or the control (n = 6) group, stratified by geographic region (urban vs. rural) and by age (1st and 5th grade). Participation was given for all children in the intervention group since in this group the intervention was part of the normal school curriculum. The intervention during one academic year consisted of: 1. two additional physical education classes per week given by trained physical education teachers adding up to a total of five PA classes per week, 2. short PA breaks (2-5 min each) during academic lessons, 3. PA home work, and 4. adaptation of recreational areas around the school. All children underwent anthropometric measurements, blood pressure assessment, fitness testing, measurement of PA and they filled out questionnaires. At least 70% of all children agreed to blood sampling and measurements of body composition and bone mineral measurements by dual energy x-ray absorptiometry. The primary endpoints of the study after one year were an increase in total PA by accelerometry, an increase in aerobic fitness measured by the 20 m shuttle run, a decrease in percent body fat derived from skinfold measurements and an increase in quality of life as assessed by the child health questionnaire in the intervention group compared to the control group. Secondary outcomes were overall fitness, differences in body composition including body fat distribution, cardiovascular risk factors, psychosocial health, bone mineral content and density of femur, lumbar spine and total body and food intake. DISCUSSION: Our preliminary data suggest that the children were representative of Swiss children with respect to sex, socio-demographic status, and body mass index. Short-term results can be expected by the beginning of 2007. We hypothesized that our intervention will lead to an increase in PA, fitness and overall health. Based on our data, we aim to provide important information regarding the influence of such an intervention on these outcome measures in school-aged children and to provide nationwide guidelines to improve PA in children.

The public perception of doping in sport in Switzerland, 1995-2004.

The article reports findings on the perception of doping and anti-doping policies from four representative population surveys carried out in 1995, 1998, 2001, and 2004, as well as from a 2005 - 2006 survey of top-level athletes in Switzerland. The results show a growing public awareness for doping issues and increasing support for a comprehensive anti-doping strategy in Switzerland. The vast majority of the Swiss population and top-level athletes are strongly against doping and support a strategy that combines strict prohibition and sanctioning with informational and educational efforts. The perception of the doping issue and the strategic preferences in fighting doping stated by the public are largely in line with the current anti-doping strategy followed by the Swiss authorities. The results thus suggest a successful use of information resources by the authorities to create public awareness and to communicate its strategy.

Effects of drop jumps added to the warm-up of elite sport athletes with a high capacity for explosive force development.

The purpose of this study was to evaluate the immediate influence of eccentric muscle action on vertical jump performance in athletes performing sports with a high demand of explosive force development. In this randomized, controlled crossover trial, 13 Swiss elite athletes (national team members in ski jump, ski alpine, snowboard freestyle and alpine, ski freestyle, and gymnastics) with a mean age of 22 years (range 20-28) were randomized into 2 groups. After a semistandardized warm-up, group 1 did 5 jumps from a height of 60 cm, landing with active stabilization in 90 degrees knee flexion. One minute after these modified drop jumps, they performed 3 single squat jumps (SJ) and 3 single countermovement jumps (CMJ) on a force platform. The athletes repeated the procedure after 1 hour without the modified drop jumps. In a crossover manner, group 2 did the first warm-up without and the second warm-up with the modified drop jumps. Differences of the performance (jump height and maximal power) between the different warm-ups were the main outcomes. The mean absolute power and absolute height (without drop jumps) were CMJ 54.9 W.kg(-1) (SD = 4.1), SJ 55.0 W.kg(-1) (SD = 5.1), CMJ 44.1 cm (SD = 4.1), and SJ 40.8 cm (SD = 4.1). A consistent tendency for improvement with added drop jumps to the warm-up routine was observed compared with warm-up without drop jumps: maximal power CMJ +1.02 W.kg(-1) (95% confidence interval [CI] = +0.03 to +2.38), p = 0.045; maximal power SJ +0.8 W.kg(-1) (95% CI = -0.34 to +2.02), p = 0.148; jump height CMJ +0.48 cm (95% CI = -0.26 to +1.2), p = 0.182; SJ +0.73 cm (95% CI = -0.36 to +1.18), p = 0.169. Athletes could add modified drop jumps to the warm-up before competitions to improve explosive force development.