The accuracy of the critical power test for predicting time to exhaustion during cycle ergometry

Dona J. Housh, Terry J. Housh, Sonja M. Bauge

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


The purpose of this study was to determine the relationship between actual time to exhaustion or time limit (ATLIM) during bicycle ergometry and predicted time to exhaustion (PTLIM from the Critical Power (CP) test Fourteen males (x¯ ± SD = 22·36 ± 2·13 years) volunteered as subjects for this investigation. The subjects visited the laboratory on seven occasions separated by at least 24 h. The first two visits were used for the determination of CP; during the remaining sessions the subjects rode a Monarch bicycle ergometer at power loadings of CP — 20%, CP, CP + 20%, CP + 40% and CP + 60% for the determination of ATLIM. Theoretically, power loadings les;CP can be maintained indefinitely without exhaustion and the PTLIM for power loadings > CP can be estimated from the results of the CP test. The accuracy of the CP test for estimating the time to exhasution during bicycle ergometry was determined by comparing ATLIM to PTLIM using correlation coefficients, standard error of estimates and related t-tests. The results of this study indicated that there were no significant (p > 0·05) differences between ATLIM and PTLIM for power loadings > CP (ATLIM vs PTLIM at CP + 20% = 8·19 ± 3·90 vs 7·13 ± 2·69min, t = 2·106, r =0·893, SEE = l·21min; CP + 40% = 3·60 ± 1·37 vs 3·46 ± 1·18min, t = 0·842, r = 0·882, SEE = 0·556min; CP + 60% = 2·36 ± 0·95 vs 2·32 ± 0·79min; t = 0·328 r = 0·841, SEE = 0·428min). Power curve analyses however, indicated that the CP test overestimated the power loading which could be maintained for 60 min by a mean of approximately 17%.

Original languageEnglish (US)
Pages (from-to)997-1004
Number of pages8
Issue number8
StatePublished - Aug 1989


  • Bicycle ergometry
  • Critical power

ASJC Scopus subject areas

  • Human Factors and Ergonomics
  • Physical Therapy, Sports Therapy and Rehabilitation


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