Swiss Federal Institute of Sport Magglingen

of Sport, Switzerland

Swiss Federal Institute of Sport Magglingen

of Sport, Switzerland
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Colombani P.C.,ETH Zurich | Mettler S.,Physiology and Behavior | Mettler S.,Swiss Federal Institute of Sport Magglingen
International Journal for Vitamin and Nutrition Research | Year: 2011

The previously separate dietary protein recommendations for strength and endurance athletes are no longer supported, and the daily intake for adult athletes suggested by most of the entities is about 1.5 g · kg -1 body mass with a range of perhaps 1.0 to 2.0 g · kg -1 body mass. This recommendation is a broad landmark that needs to be adapted to the individual circumstances of the athlete. Research of the past decade indicates a beneficial effect with respect to a positive net muscular protein balance if athletes ingest some protein before an exercise bout. The amount of protein to be ingested to elicit the highest benefit is about 10 to 20 g · h -1, but due to the insufficient amount of available data, it is not possible yet to rank different protein types or sources according to their anabolic potential. A simple way to translate the nutrient-based recommendations is the Swiss Food Pyramid for Athletes, which ensures a sufficient intake of energy, and all macro- and micronutrients in relation to the volume and intensity of the daily exercise. © 2011 by Hans Huber Publishers, Hogrefe AG, Bern.

Romann M.,Swiss Federal Institute of Sport Magglingen | Fuchslocher J.,Swiss Federal Institute of Sport Magglingen
BMC Medical Imaging | Year: 2015

The second-to-fourth digit-length ratio (2D:4D) may be a correlate of prenatal sex steroids, and it has been linked to sporting prowess. The aim of the study was to validate dual-energy X-ray-absorptiometry (DXA) as a technique to assess 2D:4D in soccer players under 15 years of age (U-15). Methods: Paired X-ray and DXA scans of the left hands of 63 male U-15 elite soccer players (age: 14.0 ± 0.3 years) were performed, and 2D:4D was then compared between the two techniques. The 2D:4D measurements were performed twice by two blinded raters. Intrarater and interrater reliability, as well as agreement between the X-ray and the DXA assessments, were tested. Results: Intrarater reliabilities of both raters using X-ray with intraclass correlation coefficients (ICCs) of 0.97 and 0.90 were excellent. Using DXA, the ICCs were 0.90 and 0.91 thus also showing excellent reliability. Interrater reliabilities were excellent using both the X-ray (ICC of 0.94) and the DXA (ICC of 0.90), assessments respectively. Bland-Altman plots demonstrated that the 2D:4D ratios of the two raters did not differ significantly between the X-ray and the DXA assessments. The standard errors of estimate were 0.01 for both techniques. The 95% limits of agreement of ±0.018 (±2.0%) and ±0.023 (±2.6%), respectively, were within the acceptable tolerance of 5%, and showed very good agreement. Conclusion: DXA offered a replicable technique for assessing 2D:4D in youth soccer players. Therefore, the DXA technique seems to be an alternative method for evaluating 2D:4D in youth sports. © Romann and Fuchslocher.

Birrer D.,Swiss Federal Institute of Sport Magglingen | Morgan G.,Swiss Federal Institute of Sport Magglingen
Scandinavian Journal of Medicine and Science in Sports | Year: 2010

The importance of psychological skills training (PST) in the development of athletic performance is widely recognized. This paper is a comprehensive review of PST in elite sports, with a special focus on high-intensity sports (HIS). The reviewed literature showed a lack of convincing evidence and theoretical underpinning concerning traditional psychological skills to enhance performance in HIS. Therefore, a model with three conceptual levels (psychological demands, skills and techniques) is presented. The model facilitates the identification of the psychological demands of a specific sport, which in turn enables distinguishing which psychological skills are required. This allows an expert to choose psychological techniques to improve the athlete's psychological skill. Considerations based on our model and the limited HIS-related literature available revealed self-skills, personal development and life skills, arousal-regulation skills, volitional skills, motivational skills and recovery skills as the most important skills to address in order to enhance performance. Development of harmonious passion, in-practice integration of volitional strategies, use of associative attentional techniques, pain management techniques, use of the mindfulness-acceptance approach and the facilitative interpretation of cognitive and somatic sensations are regarded as suitable to meet the psychological demands of HIS. They are recommended for systematic application by athletes and coaches. © 2010 John Wiley & Sons A/S.

Jimmy G.,Swiss Federal Institute of Sport Magglingen | Seiler R.,University of Bern | Mader U.,Swiss Federal Institute of Sport Magglingen
Measurement in Physical Education and Exercise Science | Year: 2013

The purpose of this study was to compare the validity and output of the biaxial ActiGraph GT1M and the triaxial GT3X (ActiGraph, LLC, Pensacola, FL, USA) accelerometer in 5-to 9-year-old children. Thirty-two children wore the two monitors while their energy expenditure was measured with indirect calorimetry. They performed four locomotor and four play activities in an exercise laboratory and were further measured during 12 minutes of a sports lesson. Validity evidence in relation to indirect calorimetry was examined with linear regression equations applied to the laboratory data. During the sports lessons predicted energy expenditure according to the regression equations was compared to measured energy expenditure with the Wilcoxon-signed rank test and the Spearman correlation. To compare the output, agreement between counts of the two monitors during the laboratory activities was assessed with Bland-Altman plots. The evidence of validity was similar for both monitors. Agreement between the output of the two monitors was good for vertical counts (mean bias =-14 ± 22 counts) but not for horizontal counts (-17 ± 32 counts). The current results indicate that the two accelerometer models are able to estimate energy expenditure of a range of physical activities equally well in young children. However, they show output differences for movement in the horizontal direction. © 2013 Taylor and Francis Group, LLC.

Romann M.,Swiss Federal Institute of Sport Magglingen | Fuchslocher J.,Swiss Federal Institute of Sport Magglingen
European Journal of Sport Science | Year: 2013

Relative age effects (RAEs) refer to age differences between children in the same selection year. The present study investigated the prevalence of RAEs and their link to playing positions in Swiss junior soccer. Swiss male junior soccer players (n=50,581) representing 11% of the age-matched population - members of extra-curricular soccer teams - were evaluated to determine the influence of RAEs on Swiss junior soccer. Subgroups were the national talent development programme (n=2880), and U-15 to U-21 national teams (n=630). While no RAEs were found for the self-selected extra-curricular soccer teams or for the U-20 teams (P>0.05), significant RAEs were found for talent development and the national U-15 to U-19 and U-21 teams (P<0.01). Additionally, defenders born early in the year were significantly overrepresented compared with goalkeepers, midfielders and strikers (P<0.05). In Switzerland, RAEs apparently have substantial influence on the talent identification process for U-15 to U-18 teams, significantly influencing the selection of players in talent development teams already at an early age, but do not influence self-selected participation in extra-curricular soccer. Additionally, the RAE bias may be a predictor of playing positions in national teams. To minimise RAEs in Swiss soccer, systematic education for all coaches regarding RAEs should be established, in addition to a slotting system with rotating calendar cut-off dates. © 2013 Copyright European College of Sport Science.

Rumo M.,Swiss Federal Institute of Sport Magglingen | Amft O.,TU Eindhoven | Troster G.,ETH Zurich | Mader U.,Swiss Federal Institute of Sport Magglingen
Physiological Measurement | Year: 2011

Regular physical activity (PA) is an important contributor to a healthy lifestyle. Currently, standard sensor-based methods to assess PA in field-based research rely on a single accelerometer mounted near the body's center of mass. This paper introduces a wearable system that estimates energy expenditure (EE) based on seven recognized activity types. The system was developed with data from 32 healthy subjects and consists of a chest mounted heart rate belt and two accelerometers attached to a thigh and dominant upper arm. The system was validated with 12 other subjects under restricted lab conditions and simulated free-living conditions against indirect calorimetry, as well as in subjects' habitual environments for 2 weeks against the doubly labeled water method. Our stepwise validation methodology gradually trades reference information from the lab against realistic data from the field. The average accuracy for EE estimation was 88% for restricted lab conditions, 55% for simulated free-living conditions and 87% and 91% for the estimation of average daily EE over the period of 1 and 2 weeks. © 2011 Institute of Physics and Engineering in Medicine.

Jimmy G.,Swiss Federal Institute of Sport Magglingen | Seiler R.,University of Bern | Maeder U.,Swiss Federal Institute of Sport Magglingen
Journal of Physical Activity and Health | Year: 2013

Background: Accelerometry has been established as an objective method that can be used to assess physical activity behavior in large groups. The purpose of the current study was to provide a validated equation to translate accelerometer counts of the triaxial GT3X into energy expenditure in young children.Methods: Thirty-two children aged 5-9 years performed locomotor and play activities that are typical for their age group. Children wore a GT3X accelerometer and their energy expenditure was measured with indirect calorimetry. Twenty-one children were randomly selected to serve as development group. A cubic 2-regression model involving separate equations for locomotor and play activities was developed on the basis of model fit. It was then validated using data of the remaining children and compared with a linear 2-regression model and a linear 1-regression model.Results: All 3 regression models produced strong correlations between predicted and measured MET values. Agreement was acceptable for the cubic model and good for both linear regression approaches.Conclusions: The current linear 1-regression model provides valid estimates of energy expenditure for ActiGraph GT3X data for 5-to 9-year-old children and shows equal or better predictive validity than a cubic or a linear 2-regression model. © 2013 Human Kinetics, Inc.

Melzer K.,Swiss Federal Institute of Sport Magglingen | Kayser B.,University of Lausanne | Schutz Y.,University of Lausanne
European Journal of Obstetrics Gynecology and Reproductive Biology | Year: 2014

Food intake increases to a varying extent during pregnancy to provide extra energy for the growing fetus. Measuring the respiratory quotient (RQ) during the course of pregnancy (by quantifying O2 consumption and CO 2 production with indirect calorimetry) could be potentially useful since it gives an insight into the evolution of the proportion of carbohydrate vs. fat oxidized during pregnancy and thus allows recommendations on macronutrients for achieving a balanced (or slightly positive) substrate intake. A systematic search of the literature for papers reporting RQ changes during normal pregnancy identified 10 papers reporting original research. The existing evidence supports an increased RQ of varying magnitude in the third trimester of pregnancy, while the discrepant results reported for the first and second trimesters (i.e. no increase in RQ), explained by limited statistical power (small sample size) or fragmentary data, preclude safe conclusions about the evolution of RQ during early pregnancy. From a clinical point of view, measuring RQ during pregnancy requires not only sophisticated and costly indirect calorimeters but appears of limited value outside pure research projects, because of several confounding variables: (1) spontaneous changes in food intake and food composition during the course of pregnancy (which influence RQ); (2) inter-individual differences in weight gain and composition of tissue growth; (3) technical factors, notwithstanding the relatively small contribution of fetal metabolism per se (RQ close to 1.0) to overall metabolism of the pregnant mother. © 2014 Elsevier Ireland Ltd.

Zimmermann-Sloutskis D.,Swiss Federal Institute of Sport Magglingen | Wanner M.,Swiss Federal Institute of Sport Magglingen | Zimmermann E.,University of Neuchatel | Martin B.W.,University of Zürich
International Journal of Behavioral Nutrition and Physical Activity | Year: 2010

Background: There is growing concern about physical inactivity in adolescents and young adults. Identifying determinants that are associated with low levels of physical activity and with changes in physical activity levels will help to develop specific prevention strategies. The present study describes the prevalence and potential determinants of physical activity behavior and behavior changes of young adults. The study is based on the Swiss Household Panel (SHP), a longitudinal study assessing social changes in a representative sample of Swiss households since 1999.Methods: Data is collected yearly using computer-assisted telephone interviews. Information is obtained from each household member over 14 years of age. Participants between 14 and 24 years entering the SHP between 1999 and 2006 were included (N = 3,068). "Inactive" was defined as less than 1 day/week of at least 30 minutes of moderate physical activity, "no sport" as exercising less than once a week. Age, gender, nationality, linguistic region, household income, education, membership in a sport club, reading, and Internet use were included as potential determinants of physical activity behavior and behavior change.Results: In both young men and young women, the prevalence of inactivity, "no sport", and non-membership in a sport club was increasing with age. Women were less active than men of the same age. From one wave to the following, 11.1% of young men and 12.1% of young women became active, and 11.9% of men and 13.7% of women became inactive, respectively (pooled data over all eight waves). Non-membership in a sport club was the strongest predictor for "no sport" (ORmen6.7 [4.9-8.9]; ORwomen8.1 [5.7-11.4]), but also for being inactive (OR 4.6 [3.5-6.0]; 4.6 [3.3-6.4]). Leaving a sport club (OR 7.8 [4.4-14.0]; 11.9 [5.9-24.1]) and remaining non-member (OR 7.8 [4.7-12.9]; 12.4 [6.4-24.1]) were the strongest predictors of becoming "no sport". Effects for becoming inactive were similar, though smaller (OR 5.9 [3.4-10.5] and 5.1 [2.7-9.6] for leaving a club, OR 5.1 [3.1-8.4] and 6.9 [4.0-11.8] for remaining non-member).Conclusions: The most important findings were the strong effects of sport club membership on general physical activity. The correlation between sport club membership and exercise was not surprising in its nature, but in its strength. © 2010 Zimmermann-Sloutskis et al; licensee BioMed Central Ltd.

Mettler S.,ETH Zurich | Mettler S.,Swiss Federal Institute of Sport Magglingen | Zimmermann M.B.,ETH Zurich | Zimmermann M.B.,Wageningen University
European Journal of Clinical Nutrition | Year: 2010

Background/Objectives: Iron deficiency and anemia may impair athletic performance, and iron supplements are commonly consumed by athletes. However, iron overload should be avoided because of the possible long-term adverse health effects. Methods: We investigated the iron status of 170 male and female recreational runners participating in the Zürich marathon. Iron deficiency was defined either as a plasma ferritin (PF) concentration <15 μg/l (iron depletion) or as the ratio of the concentrations of transferrin receptor (sTfR) to PF (sTfR: log(PF) index) of ≥4.5 (functional iron deficiency).Results: After excluding subjects with elevated C-reactive protein concentrations, iron overload was defined as PF >200 μg/l. Iron depletion was found in only 2 out of 127 men (1.6% of the male study population) and in 12 out of 43 (28.0%) women. Functional iron deficiency was found in 5 (3.9%) and 11 (25.5%) male and female athletes, respectively. Body iron stores, calculated from the sTfR/PF ratio, were significantly higher (P<0.001) among male compared with female marathon runners. Median PF among males was 104 g/l, and the upper limit of the PF distribution in males was 628 μg/l. Iron overload was found in 19 out of 127 (15.0%) men but only 2 out of 43 in women (4.7%). Gender (male sex), but not age, was a predictor of higher PF (P<0.001).Conclusions: Iron depletion was present in 28% of female runners but in <2% of males, whereas one in six male runners had signs of iron overload. Although iron supplements are widely used by athletes in an effort to increase performance, our findings indicate excess body iron may be common in male recreational runners and suggest supplements should only be used if tests of iron status indicate deficiency. © 2010 Macmillan Publishers Limited All rights reserved.

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