THE EFFECT OF PRIOR EXERCISE ON THE &OV0622;O2 SLOW COMPONENT AND MUSCLE TEMPERATURE

Abstract

It has been reported that the O2 slow component is reduced after heavy exercise. In one study it was found that an increase in muscle temperature (Tm) produced by wearing hot water-perfused pants, induced a decrease in O2 slow component of heavy exercise. Therefore the aim of this study was to investigate whether the effect of prior heavy exercise on the O2 slow component of subsequent heavy exercise could be related to the warming-up of the exercising limbs. Six male subjects (22 ± 2 yrs, O2peak: 3835 ± 382 ml min−1) completed an exercise protocol consisting of two constant-load work bouts (EX-1 and EX-2) at 90% O2peak, separated by 6 min of rest. Seven days later, subjects completed a second exercise protocol consisting of a passive warming-up of the upper legs (parafango) 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. O2 was measured on a breath-by-breath basis (Oxycon Jaeger system). O2(6–3) was used as an index of the O2 slow component. Tm was measured by a sterile thermistor (Duowrap Kapton HS/D30KK+CNN 21200) that was inserted 3 cm into the vastus lateralis muscle. Tm reached comparable levels at the start of EX-2 and EX-3 (see table). O2(6–3) was significantly reduced by 75% after prior heavy exercise while the reduction after prior passive warming-up (8%) did not reach the significant level (see table). The results of this study indicate that the reduction in O2 slow component observed after prior heavy exercise can not be explained by an increase in muscle temperature of the upper legs.Table