Variação diurna e resposta da cinética do Vo 2 de ciclistas durante exercício muito intenso

Abstract

The objective of the present study was to evaluate the influence of the time of day on the parameters of oxygen uptake kinetics of trained cyclists during high intensity exercise. Nine male volunteers repeated bouts at constant loads at 08:00, 13:00 and 18:00 h on different days. These exercise bouts were performed twice on each occasion, with an interval of 1 h between them. The load intensity used was 75%- (75% of the difference between the V̇O2 at the lactate threshold and the V̇O2max). The primary V̇O2 amplitude (2597 ± 273 ml.min-1, 2513 ± 268 ml.min-1 and 2609 ± 370 ml.min-1), the primary V̇O2 time constant (19.3 ± 2.5 s, 18.4 ± 3.0 s and 19.7 ± 3.9 s), the V̇O2 slow component (735 ± 81 ml.min-1, 764 ± 99 ml.min-1 and 680 ± 121 ml.min-1) and the mean response time (51.8 ± 4.2 s, 51.2 ± 4.2 s and 51.4 ± 3.4 s) did not present significant differences at the different times (08:00, 13:00 and 18:00 h), neither did the other parameters of the V̇O2kinetics. These results suggest that the response of the V̇O2 kinetics of cyclists exercising at high intensity (75%Δ) is not influenced by the time of day.