title: Effect of lowered muscle temperature on the physiological response to exercise in men.
abstract: The effect of low muscle temperature on the response to dynamic exercise was studied in six healthy men who performed 42 min of exercise on a cycle ergometer at an intensity of 70% of their maximal O2 uptake. Experiments were performed under control conditions, i.e. from rest at room temperature, and following 45 min standing with legs immersed in a water bath at 12 degrees C. The water bath reduced quadriceps muscle temperature (at 3 cm depth) from 36.4 (SD 0.5) degrees C to 30.5 (SD 1.7) degrees C. Following cooling, exercise heart rate was initially lower, the mean difference ranged from 13 (SD 4) beats.min-1 after 6 min of exercise, to 4 (SD 2) beats.min-1 after 24 min of exercise. Steady-state oxygen uptake was consistently higher (0.2 l.min-1). However, no difference could be discerned in the kinetics of oxygen uptake at the onset of exercise. During exercise after cooling a significantly higher peak value was found for the blood lactate concentration compared to that under control conditions. The peak values were both reached after approximately 9 min of exercise. After 42 min of exercise the blood lactate concentrations did not differ significantly, indicating a faster rate of removal during exercise after cooling. We interpreted these observations as reflecting a relatively higher level of muscle hypoxia at the onset of exercise as a consequence of a cold-induced vasoconstriction. The elevated steady-state oxygen uptake may in part have been accounted for by the energetic costs of removal of the extra lactate released into the blood consequent upon initial tissue hypoxia.
authors.affiliation: Department of Muscle and Exercise Physiology, Faculty of Human Movement Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Beelen
authors.forename: A J
authors.initials: AJ
authors.lastname: Sargeant
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology*; D003080:Cold Temperature; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007773:Lactates / Q000097:blood; D007866:Leg; D008297:Male; D009132:Muscles / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D012146:Rest / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology
chemical_list: D007773:Lactates