Metabolic, thermoregulatory, and psychophysiological responses during arm and leg exercise

The present investigation compares metabolic, thermoregulatory, and psychophysiological responses during upper and lower body exercise in different environmental conditions. Eight males performed four, 60-min exercise bouts using either arm or leg ergometry in ambient temperatures of 23 degrees C (relative humidity = 75%) and 33 degrees C (relative humidity = 57%). Power output was 75 W for all experiments. Oxygen consumption, rectal and skin temperatures, heart rate (HR), and rating of perceived exertion were measured during exercise. Exercise oxygen consumption averaged 1.54 l.min-1 across all experiments and was equivalent to 60% of arm and 37% of leg peak values. Rectal temperature increased (P less than 0.001) an average of 0.43 degrees C and did not differ due to experimental conditions. Exercise performed in the heat resulted in higher skin temperature (P less than 0.001), regardless of whether the arms or legs were used. HR and rating of perceived exertion were greater (P less than 0.001) in arm (132.9 b.min-1, 14.4 units) than leg (108.9 b.min-1, 10.9 units) experiments. When arm exercise was performed in the heat, HR was 6 b.min-1 greater than when performed in the cool. Greater relative exercise intensity in arm work resulted in higher HR and rating of perceived exertion at the given power output. Similar rectal temperature increases in all experiments indicate that core temperature is controlled by absolute heat production, regardless of mode of exercise and ambient temperature.