Data on the women's weight, percentage of body fat, energy expenditure, breast-milk volume and composition, total energy output, and energy intake are shown in Table 2Table 2Anthropometric Measures, Energy Expenditure, Volume and Composition of Breast Milk, and Energy Intake in the Exercise and Control Groups.. Weight declined significantly in both groups during the study; there was no significant difference in the amount of weight lost or in the change in the percentage of body fat between the exercise and control groups. The exercise program significantly improved aerobic capacity, however; maximal oxygen consumption increased by 25 percent among the exercising women (from 27.0 ±4.8 to 33.8 ±4.4 ml of oxygen per kilogram per minute), as compared with only 5 percent among the control women (from 27.6 ±3.9 to 28.9 ±4.4 ml of oxygen per kilogram per minute; P