[Effect of physical exercise and heat on energy expenditure in obesity]

The effect of exercise and thermal stress on energy expenditure was studied in obese and lean subjects. The group of obese subjects comprised 20 women with body weight 81-159 kg, and the control group included 12 lean women weighing 51-58 kg. The energy expenditure was assessed by the method of indirect calorimetry with a Spirolyt II apparatus. The heart rate, the systolic and diastolic pressure were measured. The tested subjects were subjected to a 60 W (60 J/s) exercise on a cycle ergometer during 10 minutes, and immediately after it they were exposed to hot air in a chamber at about 60 degrees for 30 min. On the following day this sequence was reversed, with exercise following heat exposure. In the obese women the energy expenditure at rest was 93.4 +/- 17.5 W, and during exposure to heat after exercise it was 124.0 +/- 21.3 W. During exercise preceded by heat exposure it was 436.3 +/- 51.6 W. In lean subjects the corresponding values were lower: 77.5 +/- 6.5 W, 104.0 +/- 14.8 W, 376.8 +/- 36.1 W. After calculation of energy expenditure per 1 m2 of body area this expenditure was, however, lower in the group of obese subjects. The exposure to physical exercise before thermal stress increased significantly the energy expenditure in relation to that caused by each of these exposures separately. The heart rate and the systolic and diastolic blood pressures were higher in obese subjects. In both groups thermal stress increased the heart rate and systolic pressure but decreased the diastolic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)