Changes in the power-duration relationship following prolonged exercise: estimation using conventional and all-out protocols and relationship to muscle glycogen
journal contributionposted on 2019-04-10, 14:05 authored by Ida E. Clark, Anni Vanhatalo, Christopher Thompson, Lee J. Wylie, Stephen BaileyStephen Bailey, Brett S. Kirby, Brad W. Wilkins, Andrew M. Jones
It is not clear how the parameters of the power-duration relationship (critical power (CP) and W′) are influenced by the performance of prolonged endurance exercise. We used severe intensity prediction trials (conventional protocol) and the 3-min all-out test (3MT) to measure CP and W′ following 2 h of heavy-intensity cycling exercise and took muscle biopsies to investigate possible relationships with changes in muscle glycogen concentration ([glycogen]). Fourteen participants completed a rested 3MT to establish end-test power (Control-EP) and work done above EP (Control-WEP). Subsequently, on separate days, immediately following 2 h of heavy-intensity exercise, participants completed a 3MT to establish Fatigued-EP and Fatigued-WEP and three severe-intensity prediction trials to the limit of tolerance (Tlim) to establish Fatigued-CP and Fatigued-W'. A muscle biopsy was collected immediately before and after one of the 2-h exercise bouts. Fatigued-CP (256 ± 41 W) and Fatigued-EP (256 ± 52 W), and Fatigued-Wʹ (15.3 ± 5.0 kJ) and Fatigued-WEP (14.6 ± 5.3 kJ), were not different (P>0.05), but were ~11% and ~20% lower than Control-EP (287 ± 46 W) and Control-WEP (18.7 ± 4.7 kJ), respectively (P<0.05). The change in muscle [glycogen] was not significantly correlated with the changes in either EP (r = 0.19) or WEP (r = 0.07). The power-duration relationship is adversely impacted by prolonged endurance exercise. The 3MT provides valid estimates of CP and W′ following 2 h of heavy-intensity exercise but the changes in these parameters are not primarily determined by changes in muscle [glycogen].
This study was supported by a research grant ST-07222 from Nike Inc.
- Sport, Exercise and Health Sciences