Effects of prior heavy exercise, prior sprint exercise and passive warming on oxygen uptake kinetics during heavy exercise in humans

Prior heavy exercise (above the lactate threshold, Th-1a) increases the amplitude of the primary oxygen uptake ((V)over dot(V)over dotO(2)) response and reduces the amplitude of the (V)over dotO(2) slow component during subsequent heavy exercise. The purpose of this study was to determine whether these effects required the prior performance of an identical bout of heavy exercise, or if prior short-duration sprint exercise could cause similar effects. A secondary purpose of this study was to determine the effect of elevating muscle temperature (through passive warming) on (V)over dotO(2) kinetics during heavy exercise. Nine male subjects performed a 6-min bout of heavy exercise on a cycle ergometer 6 min after: (1) an identical bout of heavy exercise; (2) a 30-s bout of maximal sprint cycling; (3) a 40-min period of leg warming in a hot water bath at 42degreesC. Prior sprint exercise elevated blood [lactate] prior to the onset of heavy exercise (by congruent to5.6 mM) with only a minor increase in muscle temperature (of congruent to0.7degreesC). In contrast, prior warming had no effect on baseline blood lactate concentration, but elevated muscle temperature by congruent to2.6degreesC. Both prior heavy exercise and prior sprint exercise significantly increased the absolute primary (V)over dotO(2) amplitude (by congruent to230 ml(.)min(-1) and 260 ml(.)min(-1), respectively) and reduced the amplitude of the and reduced the amplitude of the (V)over dotO(2) slow component (by congruent to280 ml(.)min(-1) and 200 ml(.)min(-1), respectively) during heavy exercise, whereas prior warming had no significant effect on the 02 response. We conclude that the 02 response to heavy exercise can be markedly altered by both sustained heavy-intensity submaximal exercise and by short-duration sprint exercise that induces a residual acidosis. In contrast, passive warming elevated muscle temperature but had no effect on the (V)over dotO(2) response.