Effect of prior exercise on VO2 slow component is not related to muscle temperature

Introduction: It has been widely reported that the (V)over dotO(2) slow component is reduced in the second of two bouts of heavy exercise. It has also been shown that an increase in muscle temperature (Tm) produced by wearing hot-water-perfused pants causes a reduction in the (V)over dotO(2) slow component. Therefore, the aim of this study was to investigate whether the effect of prior heavy exercise on the (V)over dotO(2) slow component of subsequent heavy exercise is related to the warming-up of the exercising limbs. Methods: Six male subjects completed an exercise protocol consisting of two constant-load exercise bouts (EX-1 and EX-2) at 90% (V)over dotO(2peak), separated by 6 min of rest. The Tot of the m. vastus lateralis was measured with an indwelling thermistor. Seven days later, the subjects completed a second exercise protocol consisting of a passive warming-up of the upper legs until the same Tm was reached as after EX-1, followed by a constant-load work bout (EX-3) identical to EX-1 and EX-2. Results: Tm reached comparable levels at the start of EX-2 and EX-3 (37.3 +/- 0.6degreesC and 37.2 +/- 0.3degreesC, respectively). The (V)over dotO(2) Slow component (measured as Delta(V)over dotO(2) ((6-2 min))) was reduced by 57% after prior heavy exercise (P < 0.05), whereas no significant reduction was observed after prior passive warming-up. Conclusions: The results of this study indicate that the reduction in (V)over dotO(2) slow component observed after prior heavy exercise cannot be explained by an increase in muscle temperature of the upper legs.