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

The slow component of O₂ 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.

This study examined the effect of brief bouts of recovery initiated after the primary rise in VO₂ on the amplitude of the VO₂SC.

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 VO_2peak and gas exchange threshold (Δ50). The WR for HINT was calculated to match the total work performed in the CONT condition.

The VO₂SC, indicated by ΔVO_{2(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.

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.