Relationships between global physical activity and bone mineral density in a group of male and female students.

Background: Peak of bone mass (PBM) is generally reached about the age of 18 both in boys and girls. Maximizing PBM during growth may contribute to fracture risk reduction in adulthood and in the elderly. The aim of our study was to evaluate the effects on bone mineral density (BMD) of global physical activity (PA), carried out in the past 15 years, in a population of 70 healthy, young male and female subjects aged 22 to 25.
Methods: BMD of the lumbar spine and total hip was measured using dual-energy X-ray absorptiometry (DEXA); global PA, resulting from sports-related, occupational and commuting PA, was evaluated using validated questionnaires.
Results: Women spent more time than men both in sports-related, occupational and commuting PA in the age range between 10-15 years. In the female group global PA positively correlated with BMD of the lumbar spine (r=0.38; P=0.02) and the total hip (r=0.36; P=0.04) and BMD of the lumbar spine was independently predicted by global PA and Body Mass Index.
Conclusions: Our retrospective cross-sectional study indicates that global PA, not only sports-related PA, performed during prepubertal age, is associated with a greater PBM in women.