The effect of an aerobic training program with two different training intensities on the energy intake, dietary composition and body composition of female subjects

Female subjects aged 18 to 40 began a running program with the goal of running a marathon. The subjects were randomly divided into two training groups. One group always trained at or below their lactate threshold, while the other group trained above their lactate threshold on alternate days. The subjects completed their weekly mileage in four to six days. Seven-day dietary records were kept at the onset of the study and at three month intervals throughout the study. Body weight and body fat data was also obtained at approximately the same intervals. Twenty-four women had dietary data at the onset of the study, with twenty-one remaining at six months. By this time the women were running twenty-four miles per week. Dietary records were analyzed using the Nutripractor nutritional analysis computer program for energy, macronutrients, and selected micronutrients. No significant differences were found in energy intake, macronutrients, or body composition between groups or aver time. Surprisingly, subjects maintained their body weight and body fat despite a large increase in activity level, with ma significant changes in caloric intake. The women, in general, consumed diets which did not meet the Recommended Daily Allowances (RDA) for calcium, magnesium, zinc, and iron across all three time periods. A trend analysis procedure showed significant quadratic trends in vitamin D intake, sodium intake, grams of fat consumed, and magnesium intake, and a significant linear trend downward in cholesterol intake. Individual responses were, however, highly variable. These results indicate that exercise training at either of the two intensities did not affect caloric intake, macronutrient mix, or body composition in this subject population.