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Temperature‐induced changes in metabolic and hormonal responses to intensive dynamic exercise

1986; Wiley; Volume: 127; Issue: 4 Linguagem: Inglês

10.1111/j.1748-1716.1986.tb07931.x

1365-201X

Eva Blomstrand, L. Kaijser, Arne Martinsson, Ulf Bergh, Björn Ekblom,

Thermoregulation and physiological responses

Seven male subjects performed intensive cycle exercise to exhaustion at subnormal muscle temperature (T m , 29 ± 2.8 °C). Exercise at exactly the same rate of exercise and duration (370 ± 34 W, 1.5 ± 0.15 min) was then repeated with normal T m (35 ± 0.9 °C). During exercise both the arterial (a) and femoral venous (fv) contents of oxygen were significantly higher at subnormal than at normal T m , because of the higher haemoglobin concentration, but the a‐fv oxygen difference was the same in the two situations. The rate of increase in lactate concentration in both arterial and venous blood during exercise was the same in the two situations. During exercise the plasma concentrations of adrenaline and noradrealine in arterial and venous blood were significantly higher at subnormal than at normal T m . At rest and after exercise the calf blood flow was significantly reduced at subnormal T m At the end of exercise the concentrations of glucose‐6‐phosphate and lactate in the muscle were significantly higher at subnormal T m than in the muscle of normal temperature. These findings suggest that there was a greater increase in glycolysis in the muscle of subnormal temperature during exercise, possibly as a result of impaired work efficiency and/or reduced blood flow in the cold muscle.