Physical activity could reduce risk
In a second, unrelated study, researchers found that moderate physical activity may have a modest effect on bone strength in older men, accounting for up to a 20% lower fracture risk, according to Lisa Langsetmo, PhD, primary investigator and a senior research associate at the University of Minnesota, Minneapolis. She and her colleagues studied physical activity and bone strength in 994 older men (mean age 83.9) participating in the Osteoporotic Fractures in Men (MrOS) Study, a longitudinal, observational study of musculoskeletal health in older American men that initially enrolled about 6,000 participants.
Dr. Lisa Langsetmo
Participants wore armband activity monitors for 5 days during their year-7 and year-14 assessments; investigators averaged their physical activity over the two time points and used armband data along with factors like height, weight, and smoking status to estimate total energy expenditure (TEE), total steps per day, and level of activity, from sedentary to at least moderate. The men also underwent bone microarchitecture assessments of the distal radius and tibia using high-resolution peripheral quantitative computed tomography (HR-pQCT), a technique that produces detailed pictures of the bones. Investigators used mathematical models to predict failure load, or the force required to break a bone – a predictor of osteoporotic fractures in men. They also computed total, cortical, and trabecular volumetric bone mineral density (BMD).
Overall, researchers found that time spent doing at least moderate activity versus time spent in sedentary activity was related to better bone strength at both sites, whereas time spent in light activity was not. The results suggest that at least moderate physical activity such as vigorous walking averaged over a period of time may have a modest effect on bone strength among older men, Dr. Langsetmo said.
“This is important for older men,” she said. “They may not be able to jog any more but they may be able to do more moderate activity.” Physicians should ask older male patients about their activity levels and any barriers to activity, or consider a referral to a physical therapist to keep them active, she said.
Higher TEE, step count, and peak 30-minute cadence (P30MC), a measure of vigorous activity, were each associated with higher failure load of the distal radius (effect size 0.08-0.13) but not higher volumetric or compartment-specific BMD. These measures also were associated with higher failure load of the distal tibia (effect size 0.19-0.21), higher volumetric BMD (effect size 0.08-0.15), higher trabecular BMD (effect size 0.07-0.11), and higher cortical BMD (0.09-0.13).
The first study was funded internally; Manitoba Health provided the data. The second study was funded by the National Institutes of Health. Dr. Morin and Dr. Langsetmo reported no relevant financial disclosures.