Physical activity and fat-free and fat mass by bioelectrical impedance in 3853 adults

Objective: To determine the effects of regular physical activity on body co mposition, as measured by bioelectrical impedance analysis (BIA), in a larg e Caucasian population of healthy subjects between 15 and 64 yr of age, and to observe the cross-sectional changes in body composition with increasing age. Design: Cross-sectional comparison between sedentary and physically a ctive adults (nt least 3 h.wk(-1) at moderate or hard intensity level activ ity) during aging. Subjects: A total of 3853 healthy adults (1036 sedentary and 1019 physically active men, and 1280 sedentary and 518 physically acti ve women) between 15 and 64 yr of age. Measurements: Height, weight, body m ass index (BMI), and fat-free mass (FFM), fat mass, and % fat mass measured by 50-kHz BIA. Results: Higher weight in older sedentary adults was due to a higher fat mass. In 55- to 64-yr-olds compared with 25- to 34-yr-olds, f at mass was 55 kg (P < 0.0001) higher in sedentary and 0.6 kg (P < 0.3) hig her in physically active men, and 4.5 kg (P < 0.0001) and 2.0 kg (P < 0.04) higher in sedentary and physically active women, respectively. Physical ac tivity was able to limit fat mass and weight gain in men over 25 yr of apt and in women until 54 yr of age. Endurance type physical activity was not a ssociated with increased FFM. For the same BMI, sedentary men and women hav e < 0.7 kg (P < 0.001) higher fat mass than physically active men and women . Conclusion: Therefore, the benefits of physical activity seem to include maintenance or prevention of an increase of BMT that in turn correlates wit h prevention of a fat mass increase for physically active subjects.