High-intensity exercise in female athletes: effects on bone mass and body composition

Abstract

We investigated bone mass and body composition in young healthy athletic women in order to determine the influence of high-impact physical activity on bone, fat and lean mass. In a case-control study, we studied 68 healthy women, aged 18–45 years, divided in two groups (age and body mass index matched): 39 sedentary women and 29 professional karate athletes. Family and medical histories and information on habits and dietary patterns were collected through a self-administered questionnaire. Bone mineral density (BMD, g/cm²) of whole body, lumbar spine and proximal femur was measured by means of dual energy X-ray absorptiometry (Hologic QDR 4500A scanner; Hologic,Waltham, USA; version 8.26). Total and subregional fat and lean whole body masses were also measured (grams). Significantly higher femoral and total body bone masses were found in active women compared to sedentary women (total femur: 1.00±0.09 vs. 0.95±0.10 g/cm², p<0.05; femoral neck: 0.94±0.11 vs. 0.87±0.11, p<0.05; trochanter: 0.77±0.10 vs. 0.70±0.08, p=0.002; intertrochanter: 1.17±0.09 vs. 1.11±0.12, p<0.05; total body: 1.19±0.06 vs. 1.14±0.08, p<0.05). Active women also had lower fat mass (total: 16510±4430 vs. 20736±7883 g, p=0.007; limbs: 9952±2779 vs. 11888±4147, p=0.027; trunk: 5807±1970 vs. 8325±4113 p=0.001) and higher limb lean mass (15574±2124 vs. 14532±2034 g, p=0.05). A significantly lower calcium intake was registered in active women. Oral contraceptive use appeared to significantly increase femoral bone density. Physical activity increased bone mass in young active women, and this effect seemed to be superior to that of dietary calcium intake.