Local critical power is an index of local endurance

The hypothesis that critical power (CP) is significantly lower than the max imal aerobic power of the knee extensors has been tested in nine endurance- trained subjects, seven gymnasts and seven weight lifters. CP was calculate d as being equal to the slope of the linear relationship between exhaustion time and work performed at exhaustion on a knee-extension ergometer. CP wa s compared with the power output. at the end of a progressive knee-extensio n exercise (P-peak) and the power outputs corresponding to exhaustion times equal to 4 (P-4 (min)), 6 (P-6 (min)), 8 (P-8 (min)) and 10 min (P-10 (min )), calculated according to the linear relationship between work and exhaus tion time. The hypothesis that CP corresponds to a steady stale in metaboli c and physiological parameters was tested in the gymnasts and the weight li fters by comparing CP with the fatigue thresholds of the integrated electro myogram (iEMG(FT)), lactate level (La-FT), oxygen uptake (VO2FT) and heart rate (HRFT) The results of the present study demonstrate that the value of CP of a local exercise cannot be considered as the equivalent of the maxima l aerobic power for general exercises. The values of P-4 (min), P-6 min, P- 8 min, P-10 min and P-peak were significantly higher than CP, and correspon ded to 138, 126, 119, 115 and 151% CP, respectively. The results of the pre sent study indicate that CP can be considered as an index of muscular endur ance. Indeed, La-FT, iEMG (FT), (V) over dot O-2FT and HRFT were not signif icantly different from CP. All of these fatigue thresholds were significant ly correlated with CP (r > 0.92). Moreover, the highest coefficient of corr elation (r = 0.71; P < 0.01) between the percentage of maximal aerobic powe r in cycling that corresponds to a blood lactate concentration of 4 mmol . l(-1) (OBLA%) and the different local aerobic indices was observed with CP.