Belfry, G. R., Park, S.-J., Karelsen, W. J., Murias, J. M., Spencer, M. D., Kowalchuk, J. M., & Paterson, D. H. (2012). Effects of recovery duration from prior heavy exercise on VO2 kinetics and performance. Presentation 1338 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study examined the effect of recovery duration after heavy-intensity priming exercise (HVY1) on i) oxygen uptake (VO2 ) kinetics during a second heavy-exercise bout (HVY2), and ii) VO2 kinetics and endurance time during a third maximal exercise bout (VHVY) performed to fatigue. It was hypothesized that VO2 kinetics would be faster in the second heavy-exercise bout than in the initial heavy exercise bout, and that endurance time would be longer after the first priming heavy-exercise.

Healthy active Ss (M = 4; F = 5) performed a ramp (25 W/min) test to fatigue on a cycle ergometer on Day 1 to estimate lactate threshold and peak oxygen uptake (VO2peak). Ss returned on eight occasions to perform the exercise protocols. These included transitions from 20 W to HVY1, HVY2, and VHVY. Each transition was separated by the same recovery period lasting 5, 12, or 25 minutes that were randomly assigned for each visit. The power outputs for HVY1 and HVY2 corresponded to 50% of the difference between the VO2 at lactate threshold and VO2peak. The power output for the VHVY endurance test was 92% of VO2peak (271±77 W). Two repetitions of the protocol were performed for each of the three recovery periods. Two endurance-time tests with no priming exercise were also performed.

With five minutes of recovery, VO2 kinetics were faster in HVY2 (49 ± 10 seconds) and VHVY (47 ± 13 seconds) compared to HVY1 (63 ± 10 seconds). With 12 minutes of recovery, VO2 kinetics were faster during VHVY (57 ± 8 seconds) than in HVY1 (64 ± 14 seconds). Endurance time was greater after 25 minutes of recovery (323 ± 94 seconds) than no priming exercise (245 ± 61 seconds), five minutes of recovery (226 ± 62 seconds), and 12 minutes of recovery (255 ± 65 seconds).

Implication. After heavy-intensity priming exercise, VO2 kinetics during subsequent heavy exercise are faster when the recovery time is shorter. Improvements in endurance time in very heavy-intensity exercise are observed with longer recovery when enhanced VO2 kinetics are not seen. At exercise intensities above the lactate threshold, benefits from faster VO2 kinetics are reduced by the production of fatigue-inducing metabolites that may require a longer recovery time to minimize their effects.

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