The effects of exercise on the maximal istantaneous muscular power of man

The maximal instantaneous anaerobic power (w), as determined during a high jump off both feet on a force platform, was measured on eight subjects starting from 1) a resting base line; 2) a base line of steady-state cycloergometric exercise requiring 30, 50, and 70% of individual maximum O2 consumption (V̇(O2max)); and 3) a base line of maximal and supramaximal exercise (100 and 120% of V̇(O2max)). In addition, 4) w was also measured during the V̇(O2) transients from rest to each of the above work loads. Blood lactate concentration ([La(b)]) was determined before and 8 min after the end of each priming load. After the onset of any priming load, w decreases with time reaching in 2 min a steady level that is lower the higher the V̇(O2). For the three lowest work rates, the steady w level is unchanged by increasing the duration of the priming exercise up to 30 min. For low work levels, the decrease of w as a function of V̇(O2) is essentially parallel to that of estimated muscle concentration of ATP ([ATP]). For work levels >60% of V̇(O2max) involving a substantial accumulation of lactate, the decrease of w becomes smaller than the estimated drop of muscle [ATP]. This finding is tentatively attributed to an increase of either the mechanical equivalent or of the velocity constant of ATP splitting brought about by the lowering of intracellular muscle pH after lactate accumulation. The dynamic assessment of w during the rest-to-work transients is viewed as an indicator of the changes of V̇(O2) at the muscle level and can be approximated by an exponential with a half time on the order of 20 s.