The effect of impact exercise on bone mineral density: A longitudinal study on non-athlete adolescents

High impact exercise is known to induce osteogenic effects in the skeleton. However, less is known about the systemic effect of exercise practice in a potential adaptive mechanism of the skeletal accrual. This research aimed to assess the effect of impact exercise on bone mineral density (BMD) in the radius throughout adolescence.

This study evaluated 1137 adolescents, at 13 and 17 years old, as part of the population-based cohort EPITeen. BMD (g/cm²) was measured at the ultradistal and proximal radius of the non-dominant forearm by dual-energy X-ray absorptiometry (DXA) using a Lunar® Peripheral Instantaneous X-ray Image device. The practice of (extra-curricular) exercise was categorized as: no exercise, exercise with high impact and exercise with low impact. Regression coefficients (β) and respective 95% confidence intervals (CI_95%) were used to estimate the association between exercise practice categories at 13 years old and BMD at 13 and 17 years old and BMD gain between evaluations.

In boys, at 13 years, BMD was similar between the ones not practicing exercise and those practicing exercise with low impact, and the gain of BMD was also similar in both groups. Still in boys, at 13 years, those who practiced exercise with high impact presented higher mean (standard-deviation) of BMD, comparing to the other two groups (no exercise and low impact exercise), and also significantly increased the BMD gain between 13 and 17 years (β = 0.013; CI_95%0.003;0.023). In girls, no statistically significant differences on BMD were found between the categories of exercise at 13 years and BMD at 17 years of age.

This research shows that the practice of high impact exercise could help to increase BMD more than low impact exercise even in a nonweight-bearing bone during adolescence.