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Changes in the power-duration relationship following prolonged exercise: estimation using conventional and all-out protocols and relationship to muscle glycogen

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posted on 10.04.2019 by Ida E. Clark, Anni Vanhatalo, Christopher Thompson, Lee J. Wylie, Stephen 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].

Funding

This study was supported by a research grant ST-07222 from Nike Inc.

History

School

  • Sport, Exercise and Health Sciences

Published in

American Journal of Physiology - Regulatory Integrative and Comparative Physiology

Volume

317

Issue

1

Pages

R59-R67

Citation

CLARK, I.E. ... et al, 2019. Changes in the power-duration relationship following prolonged exercise: estimation using conventional and all-out protocols and relationship to muscle glycogen. AJP - Regulatory, Integrative and Comparative Physiology, 317 (1), pp. R59-R67.

Publisher

© 2019, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology

Version

AM (Accepted Manuscript)

Publisher statement

This paper was accepted for publication in the journal American Journal of Physiology - Regulatory Integrative and Comparative Physiology and the definitive published version is available at https://doi.org/10.1152/ajpregu.00031.2019.

Acceptance date

08/04/2019

Publication date

2019-06-21

ISSN

0363-6119

eISSN

1522-1490

Language

en

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