Effects of physical activity on bone mineral density increases in adolescent girls: a systematic review and meta-analysis

INTRODUCTION: Peak bone mineral density (BMD) is affected greatly during the adolescent years and is an important determinant of future fracture and osteoporosis risk. This systematic review aimed to evaluate the potential contributions of physical activity according to the volume of bone mineral density increase at various sites during different periods of adolescence derived from the published literature.EVIDENCE ACQUISITION: Studies on the effects of physical activity on BMD increases in adolescent girls were collected from PubMed, Embase, Web of Science, Clinical Trials, Springer Link, and Chinese databases. Altogether, 12 studies were included in the final analysis.EVIDENCE SYNTHESIS: For pubertal girls, the BMD of both lumbar vertebrae 2-4and femoral neck were significantly increased by physical activity. lumbar vertebrae 2-4 bone mineral density was increased by both low-moderate PA and moderate-high PA, with no significant difference between the moderate-high and low-moderate PA groups. Femoral neck BMD was also increased by both low-moderate and moderate-high PA, with a significant difference in femoral neck BMD increase between the moderate-high and low-moderate PA groups, although the difference was limited. For prepubertal girls, the femoral neck BMD was significantly increased only by moderate-high PA (not low-moderate PA), suggesting that PA had positive effects on the BMD increase in adolescent girls.CONCLUSIONS: Low-moderate PA might be sufficient to promote bone mass increase in pubertal girls, whereas moderate-high PA was required to gain more bone mass in prepubertal girls.