Effects of temperature on the maximal instantaneous muscle power of humans

Summary

The maximal instantaneous muscle power ($\dot w_{i,\max }$) probably reflects the maximal rate of adenosine 5′-triphosphate (ATP) hydrolysis ($A\dot TP_{\max }$), a temperature-dependent variable, which gives rise to the hypothesis that temperature, by affecting$A\dot TP_{\max }$, may also influence$\dot w_{i,\max }$. This hypothesis was tested on six subjects, whose vastus lateralis muscle temperature (T _muscle) was monitored by a thermocouple inserted approximately 3 cm below the skin surface. The$\dot W_{i,\max }$ was determined during a series of high jumps off both feet on a force platform before and after immersion up to the abdomen for 90 min in a temperature controlled (T=20±0.1°C) water bath. ControlT _muscle was 35.8±0.7°C, with control$\dot W_{i,\max }$ being 51.6 (SD 8.7) W · kg⁻¹. After cold exposure,T _muscle decreased by about 8°C, whereas$\dot w_{i,\max }$ 27% lower. The temperature dependence of$\dot W_{i,\max }$ was found to be less (Q ₁₀ < 1.5, whereQ ₁₀ is the temperature coefficient as calculated in other studies) than reported in the literature for$A\dot TP_{\max }$. Such a lowQ ₁₀ may reflect an increase in the mechanical equivalent of ATP splitting, as a consequence of the reduced velocity of muscle contraction occurring at lowT _muscle.