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

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 (W'(BAL)) 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) over dotO(2max), 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 W'(BAL), 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 (W'(ACT)) was compared with the amount of W' predicted to be available by the W'(BAL) model. Results: Although some differences between W'(BAL) and W'(ACT) were noted, these amounted to only -1.6 +/- 1.1 kJ when averaged across all conditions. The W'(ACT) was linearly correlated with the difference between (V) over dotO(2) at the start of CWR and (V) over dotO(2max) (r = 0.79, P < 0.01). Conclusions: The W'(BAL) 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) over dotO(2) can be minimized, leading to an enhancement of subsequent exercise tolerance. These results may have important implications for athletic training and racing.