The effects of exercise training in the cold and heat on hyperthermic hyperpnea and cutaneous vasodilation during exercise in the heat

 

Naoto Fujii¹, Yasushi Honda¹, Takeshi Ogawa^1,2, Bun Tsuji¹, Narihiko Kondo³, Shunsaku Koga⁴, and Takeshi Nishiyasu¹

¹Institute of Health and Sports Science, University of Tsukuba, Tsukuba, Japan; ²Faculty of economics, Tokuyama University, Yamaguchi, Japan; ³Faculty of Human Development, Kobe University, Kobe, Japan; ⁴Applied Physiology Laboratory, Kobe Design University, Kobe, Japan

 

We investigated whether hyperthermic hyperpnea is changed after exercise training in the cold and heat in exercising humans. Subjects performed exercise-heat tests before and after exercise training in the cold (EC, n = 10) and heat (EH, n = 10). During the training period, subjects performed 4 bouts of 20-min exercise at 50% peak oxygen uptake (V_O2peak) separated by 10-min rest in the cold (10 °C) in EC and in the heat (37 °C) in EH for 6 days. In the exercise-heat tests, subjects exercised on the cycle ergometer for 40 to 60 min at 50% V_O2peak in the heat (37°C). After exercise training, Esophageal temperature (T_es) threshold for the onset of increased forearm vascular conductance (FVC) was significantly lowered by 0.3°C in both EC and EH. Further, in EH, the slope and peak values of relating FVC and T_es were significantly increased by exercise training. Unlike cutaneous vascular response, slope of regression line relating minute ventilation and T_es was not significantly different before and after exercise training in both EC and EH. Our results suggest that in exercising humans in the heat, short-term exercise training in the cold and heat does not affect hyperthermic hyperpnea, although it does enhance cutaneous vasodilatory response known as thermoregulatory response.

 

Key words: exercise training, respiration, skin circulation