An Evaluation of the Maximal Anaerobic Capacity in Man

Abstract

Maximal anaerobic capacity, i. e., the maximal amount of energy released by anaerobic processes (E_an max, J · kg^-1), has been evaluated from maximal increase of plasma lactate concentration (Lâp) in eight male subjects of different physical fitness submitted to supramaximal runs of various intensity performed until volitional exhaustion (temps-limite, t_lim). As previously found (2), the interindividual differences of t_lim were reduced when exercise intensity was expressed by the anaerobic component of exercise defined as the difference between the overall energy requirement (Ė, W · kg^-1) and maximal aerobic power Ė_{ox max}, W · kg^-1). Within the range of intensity studied, Lâp did not vary significantly as a function of Ė-Ė_{ox max}. However, the performances achieved by the less fit subjects (group 1) remained lower than those achieved by the more athletic subjects (group 2). Mean Lâp were significantly higher in group 2 (17.2 mmol·l^-1) than in group 1 (13.7 mmol·l ^-1). The rate of increase of Lâp, defined by the ratio Lâp/t _lim, was a linear function of Ė-Ė_{ox max}. The energy equivalent of plasma lactate accumulation (β), given by the reciprocal of the slope of the equation describing the relationship Lâp/t_lim = f(Ė-Ė_{ox max}), amounts 56.8 J · kg^-1 when Lâp is increased by 1 mmol·l^-1. The energy released by anaerobic glycolysis was calculated by multiplying β by mean Lâp measured in the two groups of subjects. Assuming that the energy yielded by the anaerobic alactic processes amounts 260 J · kg^-1(1), mean E_{an max} values in group 1 and 2 were found to be equal to 1040 (range: 910-1110) and 1240 J · kg^-1(range: 1100-1330), respectively. In order to validate these results, we developed a model relating t_lim to E_{an max}, Ė_{ox max} and the overall energy cost of exercise on the basis of the energy conservation principle. As the theoretical relationships t_lim = f(Ė-Ė_{ox max}) derived from our model fitted the experimental results quite well, we concluded that E_{an max} has been correctly evaluated.

Key words

Maximal anaerobic capacity - supramaximal running - peak plasma lactate concentration - endurance time