The Effect of Increased Environmental Temperature during Anaerobic Activity in Heat Acclimatised Athletes

Finn, J.P., Wood, R.J., Travar, A.L., Marsden, J.F. The Effect of Increased Environmental Temperature during Anaerobic Activity in Heat Acclimatised Athletes. Proceedings of the 6th Applied Physiologist Conference, Canberra, Australia, Nov 1999.

While the deleterious effects of hot environmental conditions on aerobic power are well documented, there is a paucity of research on the effects of such conditions on anaerobic performance. Heat dissipation during hot conditions necessitates the redistribution of cardiac output that compromises oxygen delivery to the working muscles. Consequently, there can be an increased reliance on anaerobic metabolism (Young 1990) with higher blood lactate concentrations and increased rate of glycogen depletion (Claremont et al.1975; Fink et al. 1975).

The maximal accumulated oxygen deficit (MAOD) is the only measure of anaerobic capacity with the potential of being quantitative (Saltin 1990). It is striking that only one study has dealt with the effects of changes in body temperature on the oxygen deficit incurred during exercise (Claremont 1969).

Six heat acclimatised subjects (residents of Darwin, NT) were recruited from local triathlon and cycling clubs in order to compare their MAOD's for cycling in thermoneutral (22-23o C, 50-60% relative humidity) and hot/dry (29-30o C, 50-60% relative humidity) conditions. Skin and core temperatures, and heart rates, were recorded prior to, during exercise and recovery. Ear lobe capillary blood samples were taken pre and post exercise in order to determine pH, PCO2, PO2, Hb, Hct, plasma volume, lactate and electrolyte concentrations.

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