Regular Exercise May Reduce Risk for Osteoporotic Fracture in Older Men

June 25, 2007 — Regular exercise reduces the risk for osteoporotic fracture in older men, according to the results of a longitudinal, population-based study published in the June issue of PLoS Medicine.
"Data from previous studies are inconsistent, and it is therefore uncertain whether, to what extent, and at what level leisure physical activity influences the risk of osteoporotic fractures in men," write Karl Michaëlsson from the University Hospital in Uppsala, Sweden, and colleagues. "We therefore investigated the impact of physical activity on the risk of fracture in a population-based cohort of men followed over a 35-y period."
The study cohort consisted of 2205 men, aged 49 to 51 years at enrollment, who were followed up for 35 years. Leisure physical activity and other lifestyle habits were determined at enrollment and at ages 60, 70, 77, and 82 years. The investigators used Cox's proportional hazards regression to determine hazard ratios (HRs) of fracture associated with time-dependent physical activity habits and covariates.
During follow-up, 482 men had at least 1 fracture. Compared with men who participated in regular sports activities for at least 3 hours/week, men with a sedentary lifestyle or men who walked or bicycled only for pleasure had an increased adjusted risk for hip fracture (HR, 2.56; 95% confidence interval [CI], 1.55 - 4.24; and HR, 1.61; 95% CI, 1.10 - 2.36, respectively).
At the end of follow-up, hip fracture had occurred in 8.4% of men with a high level of physical activity, 13.3% of men with a medium level of physical activity, and 20.5% of men with a low level of physical activity. Based on estimates of population-attributable risk, one third of all hip fractures could be prevented by participation in regular sports activities. High level of activity was also associated with decreased overall fracture risk.
"Our data indicate that regular sports activities can reduce the risk of fractures in older men," the authors write. "As expected, those who maintained a high physical activity level had the lowest risk of hip fracture, but there was also a tendency towards a lower risk of fracture for those who increased their level of activity compared with those who reduced their level of activity, or compared with those who reported constant low activity."
The Swedish Research Council supported this study. The authors have disclosed no relevant financial relationships.
In an accompanying perspective article, Harri Sievänen and Pekka Kannus from the UKK Institute in Tampere, Finland, note that the best way to prove that physical activity prevents fragility fractures would be to conduct several adequately powered randomized controlled trials. However, such trials are almost impossible to perform for methodologic reasons.
"In Michaëlsson and colleagues' study, the effective 'dose' of exercise for reducing the risk of hip fracture was readily attained by recreational sports, heavy gardening, or other activities with similar intensity performed for at least three hours per week," Sievänen and Kannus write. "This volume of exercise is relatively easy to incorporate into everyday life. It is also fortunate that it is never too late to start exercising."
Sievänen and Kannus received no specific funding for this article and have disclosed no relevant financial relationships.
PLoS Med. 2007;4:e199, e222.