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Effect of Work and Recovery Durations on W′ Reconstitution during Intermittent Exercise


Medicine & Science in Sports & Exercise: July 2014 - Volume 46 - Issue 7 - p 1433–1440
doi: 10.1249/MSS.0000000000000226
Applied Sciences

Purpose We recently presented an integrating model of the curvature constant of the hyperbolic power–time relationship (W′) that permits the calculation of the W′ balance (WBAL) remaining at any time during intermittent exercise. Although a relationship between recovery power and the rate of W′ recovery was demonstrated, the effect of the length of work or recovery intervals remains unclear.

Methods After determining V˙O2max, critical power, and W′, 11 subjects completed six separate exercise tests on a cycle ergometer on different days, and in random order. Tests consisted of a period of intermittent severe-intensity exercise until the subject depleted approximately 50% of their predicted WBAL, followed by a constant work rate (CWR) exercise bout until exhaustion. Work rates were kept constant between trials; however, either work or recovery durations during intermittent exercise were varied. The actual W′ measured during the CWR (WACT) was compared with the amount of W′ predicted to be available by the WBAL model.

Results Although some differences between WBAL and WACT were noted, these amounted to only −1.6 ± 1.1 kJ when averaged across all conditions. The WACT was linearly correlated with the difference between V˙O2 at the start of CWR and V˙O2max (r = 0.79, P < 0.01).

Conclusions The WBAL model provided a generally robust prediction of CWR W′. There may exist a physiological optimum formulation of work and recovery intervals such that baseline V˙O2 can be minimized, leading to an enhancement of subsequent exercise tolerance. These results may have important implications for athletic training and racing.

1Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke’s Campus, University of Exeter, Exeter, Devon, UNITED KINGDOM; and 2Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, CANADA

Address for correspondence: Andrew M. Jones, Ph.D., Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke’s Campus, University of Exeter, Heavitree Road, Exeter, Devon EX1 2LU, United Kingdom; E-mail:

Submitted for publication October 2013.

Accepted for publication November 2013.

© 2014 American College of Sports Medicine