Two-Day Residence At 2500 M To 4300 M Does Not Affect Subsequent Exercise Performance At 4300 M

Purpose To determine the efficacy residing for 2 d at various altitudes while sedentary (S) or active (A; similar to 90 min hiking 2 d) on exercise performance at 4300 m. Methods Sea-level (SL) resident men (n = 45) and women (n = 21) (mean +/- SD; 23 +/- 5 yr; 173 +/- 9 cm; 73 +/- 12 kg; VO2peak = 49 +/- 7 mL center dot kg(-1)center dot min(-1)) were randomly assigned to a residence group and, S or A within each group: 2500 m (n = 11S, 8A), 3000 m (n = 6S, 12A), 3500 m (n = 6S, 8A), or 4300 m (n = 7S, 8A). Exercise assessments occurred at SL and 4300 m after 2-d residence and consisted of 20 min of steady-state (SS) treadmill walking (45% +/- 3% SL VO2peak) and a 5-mile, self-paced running time trial (TT). Arterial oxygen saturation (SpO(2)) and HR were recorded throughout exercise. Resting SpO(2) was recorded at SL, at 4 and 46 h of residence, and at 4300 m before exercise assessment. To determine if 2-d altitude residence improved 4300 m TT performance, results were compared with estimated performances using a validated prediction model. Results For all groups, resting SpO(2) was reduced (P < 0.01) after 4 h of residence relative to SL inversely to the elevation and did not improve after 46 h. Resting SpO(2) (similar to 83%) did not differ among groups at 4300 m. Although SL and 4300 m SS exercise SpO(2) (97% +/- 2% to 74% +/- 4%), HR (123 +/- 10 bpm to 140 +/- 12 bpm) and TT duration (51 +/- 9 to 73 +/- 16 min) were different (P < 0.01), responses at 4300 m were similar among all groups, as was actual and predicted 4300 m TT performances (74 +/- 12 min). Conclusions Residing for 2 d at 2500 to 4300 m, with or without daily activity, did not improve resting SpO(2), SS exercise responses, or TT performance at 4300 m.