Energy Balance And Body Composition In Elite Alpine Skiers During Training At Altitude And Across The Competitive Season

Alpine skiing is characterized by phases of demanding on-snow glacier training and competitions in extreme environments, where maintaining body composition (BC) is crucial for performance and may play a role in injury prevention. However, sport-specific literature on energy balance (EB) and strategies to avoid unfavorable changes in BC are still lacking. PURPOSE: To analyze EB and BC during a training camp at altitude and over the course of a competitive season. METHODS: In a prospective observational study, active male (n = 9, 27 ± 2.9 yrs) and female (n = 10, 25 ± 3.0 yrs) international skiers, competing in either speed (SPEED; n = 10) or technical (TEC; n = 9) disciplines, completed a 7 to 15-day training camp at altitude (base: 1800 m, glacier: 3500 m). BC (displacement plethysmography and bioelectrical impedance) was assessed at baseline, directly before and after the camp and at the end of the season. At altitude, food intake was assessed directly and indirectly, urine samples were collected for estimation of energy expenditure (doubly labelled water isotope method). RESULTS: During the training camp, an overall increase in body mass (BM, p = 0.011) and fat mass (FM, p < 0.001) was observed, whereas FFM remained unchanged. Increases in FM were prominent in men (p < 0.001) and SPEED (p = 0.002), but not in women or TEC. An average total daily energy expenditure (TEE) of 4088 ± 895 kcal/d and an energy intake (EI) of 4375 ± 1223 kcal resulted in an overall positive EB. EE in SPEED was significantly higher than in TEC (p = 0.03), with the highest EE observed in male speed athletes (~5900 kcal). Moreover, EB differed (p = 0.01) between men (760 ± 890 kcal/d) and women (-138 ± 490 kcal/d). Over the course of a season, FFM (p = 0.007) and skeletal muscle mass (SMM, p = 0.05) decreased significantly. Whereas women tended lose more SMM than men (p = 0.09), reductions in BM tended to be greater in male when compared to female athletes (p = 0.07). CONCLUSION: The findings indicate that alpine skiers are able to meet the high energy demands during a short-term training camp, but not over the course of a competitive season. Therefore, BC should be monitored during key training and competition phases to identify athletes at risk and -if necessary- nutritional support should be provided to avoid being in a negative EB.