This study investigated the effects of preliminary exercise (warm-up) on glycogen degradation and energy metabolism during intense cycle ergometer exercise. After determination of [latin capital V with dot above]O2max, six male subjects were randomly assigned to perform warm-up (WU) and no warm-up (NWU) trials incorporating a 2 min standardized sprint ride (SR) at 120% of the power output attained at [latin capital V with dot above]O2max (POmax). Muscle biopsies and temperature (Tm) recordings were obtained from the vastus lateralis muscle. Tm was elevated above the resting level prior to the SR during the WU trial (37.7 +/-0.1 vs 35.4 +/- 0.4[degrees]C; P < 0.05) and remained higher than the NWU trial after the SR (38.6 +/- 0.2 vs 37.1 +/- 0.4[degrees]C; P < 0.05). Similar trends existed for rectal temperature (Tr). The increases in Tm and Tr during the SR were both greater in the NWU trial (P < 0.05). Muscle glycogen degradation was similar for the WU and NWU trials (30.8 +/- 3.7 vs 25.6 +/- 3.7 mmol[middle dot]kg-1, respectively). When blood and muscle lactate concentrations after the SR were expressed relative to values before the SR, the WU trial resulted in a lower accumulation of blood lactate (6.5 +/- 0.9 vs 10.7 +/- 0.8 mEq[middle dot]1-1; P < 0.01) and muscle lactate (20.1 +/- 0.1 vs 23.4 +/- 2.2 mEq [middle dot] kg-1 wet wt.; P < 0.05). Furthermore, oxygen consumption during the 1st min of the SR was higher in the WU trial (2.3 +/- 0.2 vs 1.9 +/- 0.2 1[middle dot]min-1; P < 0.05). The changes in Tm indicated a potential for a maintained active hyperemia in the vastus lateralis following the warm-up. These results suggest that a maintained active hyperemia following warm-up may improve blood flow at the onset of high intensity exercise and transiently increase the aerobic contribution to muscle energy metabolism. Nevertheless, warm-up did not spare muscle glycogen during intense exercise.
(C)1991The American College of Sports Medicine