Abstract des Autors

The effect of acute hypoxia (FI02 = 0.137+/-0.001) at Low Altitude (LA: Clermont-Ferrand, 330 m) and acute normoxia (FI02 = 0.306+/-0.006) at High Altitude (HA: La Paz, 3600 m) on performance during a 30-s Wingate test has been investigated in prepubertal children (Tanner stage 1). Twenty five boys (LA, n=10; HA, n=15) aged from 10.6 to 12.7 years performed two Wingate tests at random: at LA, one in normoxia (ambient air) and one in acute hypoxia and at HA, one in chronic hypoxia (ambient air) and one in acute normoxia. The subjects performed the two tests using the same calibrated cycle ergometer. Peak Power (PP), Mean Power (MP), 02 uptake during the 30s (V02) and blood lactate accumulation (delta[L]s) were measured. Compared to normoxia, acute hypoxia at LA did not alter PP and MP. Similarly, compared to chronic hypoxia, acute normoxia at HA did not modify these parameters. V02 and delta[L]s were neither significantly changed by acute hypoxia at LA nor by acute normoxia at HA. When comparing HA and LA (chronic situation), V02 was similar at HA and LA but delta[L]s was reduced at HA; however chronic hypoxia did not alter Wingate performances. Thus, in prepubertal children, modifications of 02 fractions of inspired air did not alter MP, blood lactate accumulation and aerobic contribution to a 30-s Wingate test. Verf.-Referat