Physical activity from adolescence to young adulthood and bone mineral density in young adults from the 1982 Pelotas (Brazil) Birth Cohort

Abstract

Objective: To evaluate a prospective association between physical activity (PA) and bone mineral density (BMD) in young adults.

Method: Total body (TB), lumbar spine (LS) and femoral neck (FN) BMD were measured in participants from the 1982 Pelotas Birth Cohort by dual-energy X-ray absorptiometry at 30 y. PA was evaluated at 15, 18 (males) and 23 y.

Results: 3454 young adults were scanned (DXA) at least at one anatomical site. In males, PA at 15 y was associated with LS density (β=0.061 g/cm(2); 95% confidence interval (CI): 0.015; 0.108). A positive dose-response effect was found for the association between PA at 18 y and BMD. Males in the two highest quartiles of PA at 23 y had significantly greater BMD at all anatomical sites than males in the lowest quartile. We observed greater BMD at 30 y in boys who were active at least in one of the assessments (18 or 23 y) compared to inactive boys at both ages. Females in the highest quartile of PA at 23 y showed greater FN density at 30 y (β=0.020; 95%CI: 0.001; 0.039).

Conclusions: A physically active pattern is important to BMD across the first three decades of life. Potential beneficial effects of PA were not entirely lost with advancing age in male young adults.

Keywords: Bone density; Cohort studies; Physical activity; Young adults.