The Effect of Energy Deficit on Physical Performance at Sea Level and 4,300 M Altitude
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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We investigated the effect on physical performance of 3 weeks of severe deficit energy intake at sea level SL and high altitude HA, 4300 m. Twenty-six young healthy men range 18 to 34 yrs were assigned for 3 weeks to one of 3 dietary and environmental groups. One group consumed adequate kcalday to maintain body weight while living at HA ADQ, n 7 and two groups consumed 1500 kcalday less than needed to maintain body weight while living at SL HYPO, n 9 or HA DEF, n 10. For all groups, physical performance was assessed at SL prior to dietary phase assignment i.e., baseline, and on days 2, 10 and 20 of the dietary phases. The physical performance tasks were 1 maximal oxygen uptake VO2max, 2 time to complete 50 lift and carry cycles, 3 number of one-arm elbow flexions 10 body weight at 22 flexionsmin, and 4 adductor pollicis muscle exercise repeated 5 sec static contractions at 50 of maximal force 5 sec rest. After 3 weeks, relative to the baseline phase, the HYPO and DEF groups lost nearly 5 and 8 body weight, respectively and 3 and 6 lean body mass, respectively. The body weight and lean body mass losses of the HYPO and DEF groups were significantly greater than those of the ADQ group P 0.01, who lost neither body weight nor lean body mass P 0.05. VO2max was not impaired during body weight loss for the HYPO group P 0.05 whereas VO2max declined by 30 on day 2 of HA exposure compared to the SL baseline phase for the ADQ and DEF groups. However, VO2max for either the ADQ or DEF group did not change with continued HA exposure P 0.05. Time to complete the lift and carry task was impaired for the ADQ and DEF groups on day 2 of HA exposure P 0.05 but subsequently improved P 0.05 for both groups similarly with continued HA exposure. One-a elbow flexion and adductor pollicis muscle performance tasks did not differ among groups either before or during the dietary phases P 0.05.
- Anatomy and Physiology