Quantitative reviews find that exercise interventions, including mainly aerobic or weight-bearing activities, are effective in promoting bone growth in both premenopausal and postmenopausal women. Less consensus exists for the effectiveness of resistance training on bone strength in women and no quantitative reviews have been conducted on the topic. Further, no reviews have included unpublished studies in their analysis.
To quantitatively summarize the effects of resistance training on bone strength in women.
Studies were located through searches of electronic databases and reference sections of major reviews on the topic. The determination of which studies to include in the analysis was based upon specific inclusion criteria. That is, studies had to include experimental and control groups in a repeated measures design. Further, since the majority of research on bone has been done with women, the analysis was limited to studies including women only or where data specific to women could be obtained. Once studies were identified for inclusion, they were collected, coded for moderator effects, and an estimate of treatment effect (d) was calculated. Fifty-six studies (45 published, 11 unpublished) revealing 189 effect sizes were included in the analysis. The three most frequently measured sites were L2-L4 (spine), the femoral neck (hip), and total body.
The effect of resistance training on bone strength was significant but small as measured at the spine (d = 0.14), hip (d = 0.16), and total body (d = 0.28). Menopausal status moderated the influence of resistance training on total body bone strength in that postmenopausal women experienced significantly larger increases in bone mass density than did premenopausal women.
Resistance training can bring about small increases in bone strength in women of all ages. However, in comparison to the findings of previous reviews, resistance training alone may not be the most effective activity in promoting bone growth or slowing bone loss.