The Effect of Acute Hypoxia at Low Altitude and Acute Normoxia at High Altitude on Performance During a 30-s Wingate Test in Children

Abstract

The effect of acute hypoxia (FIO₂ = 0.137±0.001) at Low Altitude (LA: Clermont-Ferrand, 330 m) and acute normoxia (FIO₂ = 0.30610.006) 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), O₂ uptake during the 30 s (V̇O₂) and blood lactate accumulation (Δ[L]s) were measured. Compared to normoxia, acute hypoxia at LA did not alter PP (8.0±1.1 vs 7.9±1.3 W·kg^-1BW) and MP (6.1±0.7 vs 6.1±1.1 W·kg^-1BW). Similarly, compared to chronic hypoxia, acute normoxia at HA did not modify these parameters (PP: 7.4±1.5 vs 7.3±1.8; MP: 5.4±1.2 vs 5.5±1.1; W·kg^-1 BW). V̇O₂ and Δ[L]s were neither significantly changed by acute hypoxia at LA (520±50 vs 550±60 ml O₂; 5.3±1.7 vs 4.8±1.7 mmol·l^-1) nor by acute normoxia at HA (530±110 vs 500±90ml O₂; 3.4±1.3 vs 3.3±1.0 mmol·l^-1). When comparing HA and LA (chronic situation), V̇O₂ was similar at HA and LA but Δ[L]s was reduced at HA; however chronic hypoxia did not alter Wingate performances. Thus, in prepubertal children, modifications of O₂ fractions of inspired air did not alter MP, blood lactate accumulation and aerobic contribution to a 30-s Wingate test.

Key words

Anaerobic metabolism - prepubertal boys - acute hypoxia - acute normoxia - blood lactate