Muscle damage slows oxygen uptake kinetics during moderate-intensity exercise performed at high pedal rate

This study aimed to investigate the dependence of oxygen uptake (VO₂) kinetics on pedal cadence during moderate-intensity exercise following exercise-induced muscle damage (EIMD). Twenty untrained males were randomly assigned to a 50 revolution per minute (rpm) (age, 23.3 ± 1.8 years; VO₂(max), 38.9 ± 2.8 mL·kg⁻¹·min⁻¹) or 100 rpm group (age, 24.4 ± 3.5 years, VO₂(max), 42.9 ± 4.3 mL·kg⁻¹·min⁻¹). Participants completed "step" tests to moderate-intensity exercise from an unloaded baseline on a cycle ergometer before (baseline) and at 24 and 48 h after muscle-damaging exercise (10 sets of 10 eccentric contractions performed on an isokinetic dynamometer with a 2-min rest between each set). Pedal cadence was kept constant throughout each cycling trial (50 or 100 rpm). There were no changes in phase II pulmonary VO₂ kinetics following EIMD for the 50 rpm group (baseline = 35 ± 4 s; 24 h = 35 ± 7 s; and 48 h = 36 ± 9 s). However, the phase II VO₂ was significantly greater at 24 h (59 ± 27 s) compared with baseline (39 ± 6 s) and 48 h (40 ± 9 s) for the 100 rpm group. It is concluded that the effects of EIMD on phase II VO₂ kinetics during moderate-intensity cycling exercise is dependent on pedal cadence. The slower VO₂ kinetics after muscle damage suggests that type II fibers are involved during transition to moderate-intensity exercise at high pedal cadence.