Influence of low muscle temperature on muscle metabolism during intense dynamic exercise

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Abstract
Males (8) performed intense leg cycle exercise at a constant rate of work averaging 350 W, according to 3 different protocols: cold exhaustive exercise (initial muscle temperature (Tm) = 29.degree. C); warm non-exhaustive exercise (initial Tm = 34.degree. C); and warm exhaustive exercise (initial Tm = 34.degree. C). In 5 subjects the concentration of various muscle metabolites was determined before and immediately, 1 min and 5 min after exercise. Blood lactate concentration was determined before and repeatedly after exercise. At low Tm maximal work time was considerably shorter for all subjects compared to normal Tm, 1.3 and 2.1 min, respectively. The O2 deficit and decrease in ATP and CP [creatine phosphate] content were the same in the 2 experiments. There was a significantly higher concentration of glucose-6-phosphate 17.6 .+-. 10.1 and 8.0 .+-. 6.2 mmol .cntdot. kg dw-1, respectively and a tendency to higher lactate concentration 60 .+-. 36 and 33 .+-. 14 mmol .cntdot. kg dw-1, respectively, immediately after exercise in the cold exhaustive exercise. Peak blood lactate concentration appeared significantly later after cold exhaustive exercise indicating a slower elimination rate of lactate from the muscle compared to warm non-exhaustive exercise. The reduction in performance observed at low Tm may partially be explained by an increased accumulation rate of lactate in 4 of 5 subjects.