Comparison between maximal power in the power-endurance relationship and maximal instantaneous power

The purpose of this study was to analyze the relevance of introducing the maximal power ( P _m) into a critical-power model. The aims were to compare the P _m with the instantaneous maximal power ( P _max) and to determine how the P _m affected other model parameters: the critical power ( P _c) and a constant amount of work performed over P _c ( W ′). Twelve subjects [22.9 (1.6) years, 179 (7) cm, 74.1 (8.9) kg, 49.4 (3.6) ml/min/kg] completed one 15 W/min ramp test to assess their ventilatory threshold (VT), five or six constant-power to exhaustion tests with one to measure the maximal accumulated oxygen deficit (MAOD), and six 5-s all-out friction-loaded tests to measure P _max at 75 rpm, which was the pedaling frequency during tests. The power and time to exhaustion values were fitted to a 2-parameter hyperbolic model (NLin-2), a 3-parameter hyperbolic model (NLin-3) and a 3-parameter exponential model (EXP). The P _m values from NLin-3 [760 (702) W] and EXP [431 (106) W] were not significantly correlated with the P _max at 75 rpm [876 (82) W]. The P _c value estimated from NLin-3 [186 (47) W] was not significantly correlated with the power at VT [225 (32) W], contrary to other models ( P <0.001). The W ′ from NLin-2 [25.7 (5.7) kJ] was greater than the MAOD [14.3 (2.7) kJ, P <0.001] with a significant correlation between them ( R =0.76, P <0.01). For NLin-3, computation of W _{P >P c}, the amount of work done over P _C, yielded results similar to the W ′ value from NLin-2: 27.8 (7.4) kJ, which correlated significantly with the MAOD ( R =0.72, P <0.01). In conclusion, the P _m was not related to the maximal instantaneous power and did not improve the correlations between other model parameters and physiological variables.