Effect of Intermittent Recovery Periods on the Magnitude of the VO2 Slow Component During Heavy Intensity Exercise

Background The slow component of O-2 uptake (VO2SC) is attenuated when brief periods of recovery are initiated at exercise onset but the impact of introducing intermittent recovery periods after the primary increase in VO2 on the VO2SC are unknown. Purpose This study examined the effect of brief bouts of recovery initiated after the primary rise in VO2 on the amplitude of the VO2SC. Methods Seven healthy men [30 +/- 10 years, 179 +/- 8 cm, 89.2 +/- 8.2 kg (+/- SD)] performed 6 bouts of cycling exercise; 2 bouts of continuous exercise (CONT) and 4 bouts of intermittent exercise (INT, HINT) with work-recovery intervals of 10 s and 3 s. CONT and INT trials consisted of step-transitions from 20 W to a work rate (WR) corresponding to 50% of the difference between VO2peak and gas exchange threshold (Delta 50). The WR for HINT was calculated to match the total work performed in the CONT condition. Results The VO2SC, indicated by Delta VO2(6-3 min), was eliminated INT (-81 +/- 201 mL/min) compared to CONT (597 +/- 164 mL/min) and HINT (409 +/- 212 mL/min) although there were no differences between the phase II VO2 kinetic parameters. Conclusion Introducing 3 s of recovery every 10 s following 3 min of heavy intensity exercise eliminated the VO2SC in INT but had no effect on HINT. These findings demonstrate that introducing brief intermittent exercise-recovery periods during heavy intensity exercise lowers exercise intensity domain; however, work-matched intermittent heavy intensity exercise results in similar dynamics to CONT.