Impact plus lifting builds bone density in older adults

Bone mineral density declines with age, and the lumbar spine and femoral neck, the hip site most prone to fracture, are where that loss matters most. Exercise is widely promoted as a way to protect ageing bone, but exercise is not a single thing: protocols differ enormously in how much impact and loading they put through the skeleton. This analysis asked whether exercise genuinely increases bone density at these two critical sites in older adults, and whether the loading characteristics of the programme make a difference to the result.

The authors searched electronic databases and hand-searched selected journals up to February 2011 for randomised controlled trials testing impact exercise interventions on lumbar spine and femoral neck bone mineral density in older adults. Nineteen trials with 1577 participants qualified. Exercise protocols were categorised by their impact loading characteristics, from low-impact through odd-impact to combined programmes mixing impact activity with high-magnitude loading from resistance training. Weighted mean differences were pooled with random-effects models, trial quality was assessed, and publication bias was checked with funnel plots.

Exercise produced a significant increase in bone density at the lumbar spine of 0.011 g/cm² and at the femoral neck of 0.016 g/cm², though results varied moderately between trials. Combined programmes mixing impact activity with resistance training loading were effective at the spine, with the trials in full agreement. Odd-impact protocols, which load bone from unusual directions, raised density at both the spine, by 0.039 g/cm², and the femoral neck, by 0.036 g/cm², though those studies disagreed considerably. Low-impact and resistance-only protocols showed no significant change at either site, and there was no evidence of publication bias.

The result supports the broad claim that exercise builds bone in older adults, and adds useful texture: the benefit concentrated in programmes with meaningful or unusual impact, while gentler protocols and resistance training alone did not reach a clear effect. Trial quality was moderate to high, which strengthens confidence in the overall picture. Open questions include exactly which combination, dose and duration of loading works best, and whether the small density changes recorded here translate into fewer fractures, an outcome this analysis did not measure.

This is a reason to think that how you load your skeleton matters, not just whether you exercise. Programmes that combined impact work with resistance training, or that loaded bone from varied directions, were the ones that moved bone density in older adults, while low-impact activity alone was not enough to show a clear effect. The absolute changes were small, and the analysis says nothing about fracture rates, so this is evidence about a marker of bone health rather than a guarantee of protection.