RECOVERY PROCESSES AFTER REPEATED SUPRAMAXIMAL EXERCISE AT THE ALTITUDE OF 4,350 M

We tested the hypothesis that prolonged exposure to high altitude woul d impair the restoration of muscle power during repeated sprints. Seve n subjects performed two 20-s Wingate tests (WT1 and WT2) separated by 5 min of recovery, at sea level (N) and after 5-6 days at 4,350 m (H) . Mean power output (MPO) and O-2 deficit were measured during WT. O-2 uptake ((V) over dotO(2)) and ventilation ((V)over dotE) were measure d continuously. Blood velocity in the femoral artery (FBV) was recorde d by Doppler ultrasound during recovery. Arterialized blood pH and con centrations of bicarbonate ([HCO3-]), venous plasma lactate ([La-]), n orepinephrine ([NE]), and epinephrine ([Epi]) were measured before and after WT1 and WT2. MPO decreased between WT1 and WT2 by 6.9% in N (P < 0.05) and by 10.7% in H (P < 0.01). H did not further decrease MPO. O-2 deficit decreased between WT1 and WT2 in H only (P < 0.01). Peak ( V) over dotO(2) after WT was reduced by 30-40% in H (P < 0.01), but ex cess postexercise O-2 consumption was not significantly lowered in H. During recovery in H compared with N, (V) over dotE, exercise-induced acidosis, and [NE] were higher, [Epi] tended to be higher, [La-] was n ot altered, and [HCO3-] and FBV were lower. The similar [La-] accumula tion was associated with a higher exercise-induced acidosis and a larg er increase in [NE] in H. We concluded from this study that prolonged exposure to high altitude did not significantly impair the restoration of muscle power during repeated sprints, despite a limitation of aero bic processes during early recovery.