Effect Of Work Intensity On The Kinetics Of W’

Abstract

PURPOSE: To assess the effect of work intensity on the W’BAL model during intermittent exercise METHODS: After determining VO2max, critical power (CP), and W’, 10 untrained subjects completed three separate exercise tests on a cycle ergometer on different days, and in random order. In each case, subjects were asked to perform severe-intensity work intervals lasting 60s, followed by 30s of recovery at 20W. The intervals were repeated until volitional exhaustion. The work interval power was different during each visit, and was set using the 2-parameter CP model. Subjects were exercised at either the power predicted to result in exhaustion at 1.5, 3, or 4 min (P1.5, P3, P4). All subjects completed all trials. These data were entered into a continuous integrating equation predicting balance of W′ remaining, assuming exponential reconstitution of the W′ (W’BAL model; Skiba 2012). The time constant (τW′) was varied by iterative process until the remaining modeled W′ = 0 at the time of athlete exhaustion. τW’ was compared across trials, and predicted τW’ was compared to calculated τW’, using ANOVA. Results are reported as group means ± SD. RESULTS: Calculated τW′ was not significantly different between trials (mean P1.5 =507 ± 547s, P3 = 436 ± 266s, P4 = 463 ± 268s, p = 0.91). Model predicted τW′ (mean = 443 ± 45) was not significantly different from the calculated τW′ in any of the experimental trials (p = 0.96). However, considerable inter-individual variability was noted, resulting in high SD. In particular, three subjects showed unexpectedly slow recovery of the W’ during the experimental trials. CONCLUSIONS: These data suggest that the recovery of the W’ is insensitive to work intensity within the power ranges studied. These data provide further support for the utility of the W’BAL model over a variety of work intensities, but also suggest the possible need to develop athlete specific models with a customized τW′.