Background: Physical performance of sea-level (SL) residents acutely exposed to altitude (ALT) is diminished and may improve somewhat with ALT acclimatization. Hypothesis: A large reduction in lean body mass (LBM), due to severe energy intake deficit during the first 21 d of ALT (4300 m) acclimatization, will adversely affect performance. Methods: At ALT, 10 men received a deficit (DEF) of 1500 kcal·d-1 below body weight (BW) maintenance requirements and 7 men received adequate (ADQ) kcal·d-1 to maintain BW. Performance was assessed by: 1) maximal oxygen uptake (V̇o2max); 2) time to complete 50 cycles of a lift and carry task (L+C); 3) number of one-arm elbow flexions (10% BW at 22 flexions·min-1; and 4) adductor pollicis (AP) muscle strength and endurance time (repeated 5-s static contractions at 50% of maximal force followed by 5-s rest, to exhaustion). Performance and body composition (using BW and circumference measures) were determined at SL and at ALT on days 2 through 21. Results: At SL, there were no between group differences (p > 0.05) for any of the performance measures. From SL to day 21 at ALT, BW and LBM declined by 6.6 ± 3 kg and 4.6 kg, respectively, for the DEF group (both p < 0.01), but did not change (both p > 0.05) for the ADQ group. Performance changes from day 2 or 3 to day 20 or 21 at ALT were as follows (values are means ± SD): V̇o2max (ml·min-1): DEF = +97 ± 237, ADQ = +159 ± 156; L + C (s): DEF = -62 ± 35*, ADQ = -35 ± 20* (*p < 0.05; improved from day 3); arm flex (reps): DEF = -2 ± 7, ADQ = +2 ± 8; AP endurance (min): DEF = +1.4 ± 2, ADQ = +1.9 ± 2; AP strength (kg): DEF = -0.7 ± 4, ADQ = -1.2 ± 2. There were no differences in performance between groups. Conclusions:A significant BW and LBM loss due to underfeeding during the first 21 d of ALT acclimatization does not impair physical performance at ALT.
|Number of pages||8|
|Journal||Aviation Space and Environmental Medicine|
|State||Published - 1 Jan 2002|
- Altitude anorexia
- Body weight loss
- Hypoxia exercise
- Lean body mass loss