Local critical power is an index of local endurance
Résumé
The hypothesis thal critical power (CP) is significantly lower than the maximal aerobic power of the knec cxtensors has hccn tested in nine endurance-traincd subjccts, sevcn gymnasts and sevcn weight lirters. CP was calculated as heing equal to the slopc of the linear relationship bct\veen exhaustion lime and work pcrformcd at exhaustion on a knee-extcnsion ergometer. CP was comparcd with the power output at the end of a progressive knee-cxtension exercise (Prcnk) and the power outputs eorresponding to exhaustion times equal to 4 (P4 min), 6 (/\min), K (Px min) and 10 min (P 10 min), calculated according to the lincar relationship betwecn work and exhaustion time. The hypolhesis thal CP corresponds to a steady state in metabolic and physiological pararneters \vas testcd in the gymnasts and the \veight lillers hy comparing CP with the fatigue thresholds of the integratcd electromyog:ram (iEMGFT). lac-tate leve] (Lap 1). oxygen uptake (V0 2 IT) and heart rate (HR 1 Tl· The resulls of the present study demonstrate that the value of CP or a local cxercise cannot be con-sidcred as the equivalent of' the maximal aerobic power for general excrcises. The values or P4 1111 n, P6 min· Py, mirn P1o min and Pr~; 1 k wcre significantly higher than CP, and eorresponded to 13~, 126. 119, 115 and 151 "A, CP. re-spectivcly. The results of the present study indicatc that CP can be considcred as an index of muscular endurance. lndeed, LtF 1 , iEMG f-T· V0 2 FT and HRF· 1 vvere nol significantly different from CP. Ail of these fatigue thresholds wcre significantly correlatcd with CP (r > 0.92). Moreovcr. the highest coefficient of corre-Paris. /-rance lation (r = 0.71; P < 0.01) bctween the percentage of maximal aerobic power in cycling that corresponds to a blood lactate concentration of 4 mmol · 1-1 (OBLA 0 1Ô) and the difTerent local aerobic indices was observed with CP.