Comparison of Critical Power and W' Derived From 2 or 3 Maximal Tests

Int J Sports Physiol Perform. 2017 Jul;12(6):825-830. doi: 10.1123/ijspp.2016-0371. Epub 2016 Dec 5.


Purpose: Typically, accessing the asymptote (critical power; CP) and curvature constant (W') parameters of the hyperbolic power-duration relationship requires multiple constant-power exhaustive-exercise trials spread over several visits. However, more recently single-visit protocols and personal power meters have been used. This study investigated the practicality of using a 2-trial, single-visit protocol in providing reliable CP and W' estimates.

Methods: Eight trained cyclists underwent 3- and 12-min maximal-exercise trials in a single session to derive (2-trial) CP and W' estimates. On a separate occasion a 5-min trial was performed, providing a 3rd trial to calculate (3-trial) CP and W'.

Results: There were no differences in CP (283 ± 66 vs 282 ± 65 W) or W' (18.72 ± 6.21 vs 18.27 ± 6.29 kJ) obtained from either the 2-trial or 3-trial method, respectively. After 2 familiarization sessions (completing a 3- and a 12-min trial on both occasions), both CP and W' remained reliable over additional separate measurements.

Conclusions: The current study demonstrates that after 2 familiarization sessions, reliable CP and W' parameters can be obtained from trained cyclists using only 2 maximal-exercise trials. These results offer practitioners a practical, time-efficient solution for incorporating power-duration testing into applied athlete support.

Keywords: cycling; performance; power-duration; time trial.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Bicycling
  • Exercise Test / methods*
  • Fatigue*
  • Female
  • Humans
  • Male
  • Physical Endurance*