Exercise and osteoporosis-related fractures: perspectives and recommendations of the sports and exercise scientist.

Osteoporosis-related fractures represent a major health concern, particularly in elderly populations. Direct and indirect costs (amounting to nearly $17 billion in 2005), increased morbidity, and loss of independence place substantial burden on the health care system. Observational studies have shown that a physically active lifestyle is associated with a 30% to 50% decrease in vertebral or hip fractures, and a recent meta-analysis that determined the effects of exercise on fracture incidence further confirmed these results. However, because no randomized controlled exercise trials have selected fractures as a primary endpoint, causality between a sedentary lifestyle and fractures may be potentially confounded by participants' poor health status. With regard to fall reduction and bone strength as the main surrogates for fracture risk, many randomized controlled trials and corresponding meta-analyses have reported significant positive outcomes. Interestingly, no study that has assessed fall-related injuries has focused specifically on interventions that aimed to reduce fall impact. There is ongoing debate as to which factor, osteoporosis or falls, is more important for fracture prevention. This may be dependent on the region prone to fracture and the subjects' health status. In randomized controlled trials on exercise, the type, mode, and composition of exercise parameters are predictors of study outcome. Unfortunately, many exercise trials on fall prevention have not adequately described the exercise protocol used, which makes it difficult to determine which fall prevention protocol was most effective. A recent meta-analysis recommended Tai Chi and/or a mix of balance and resistance exercises for fall prevention. More sophisticated protocols are required to impact bone strength. Corresponding state-of-the-art protocols have focused on periodized high-impact/high-intensity resistance protocols performed at least twice per week. In the frail elderly, high-frequency/high-cycle number exercise programs with low-to-moderate strain intensity may also positively affect bone strength.