Some respiratory and metabolic effects of exercise in moderately obese men.

The effects of varying levels of exercise on oxygen uptake, CO2 production, blood pressure, arterial blood gasses, and arterial concentrations of glucose, insulin, and growth hormone were examined in ten normal weight and ten moderately overweight young men. At comparable external work loads with a bicycle ergometer, the lean men required less oxygen than the obese men. When oxygen uptakes were matched during exercise on a treadmill, the lean men were walking on a steeper grade or at a higher rate than the obese men. The efficiency of exercise as assessed by the relation between oxygen uptake and work did not differ between the two groups. Blood pressure rose more in the obese during exercise than in the lean. The fall in lactate and rise in bicarbonate was of greater magnitude during cycle ergometry than during treadmill exercise. Obese and lean men, however, showed similar changes. With each level of exercise, there was a fall in arterial insulin levels, but the concentrations in the blood of overweight men always remained significantly above that of the normal men. Growth hormones tended to be higher in the normal weight men, but the differences were usually not significant, and there was no significant rise with exercise in either group until the highest levels of work were achieved. Glucose concentrations tended to be higher in the obese men, but fell to constant levels in both groups during exercise. Blood pressure rose to a greater extent in the overweight men during exercise.