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

Abstract

The purpose of this study was to determine the relationship between actual time to exhaustion or time limit (AT_LIM) during bicycle ergometry and predicted time to exhaustion (PT_LIM 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 AT_LIM. Theoretically, power loadings les;CP can be maintained indefinitely without exhaustion and the PT_LIM 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 AT_LIM to PT_LIM 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 AT_LIM and PT_LIM for power loadings > CP (AT_LIM vs PT_LIM 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%.