MedWire News: Becoming physically active is associated with an increase in bone mineral density (BMD) and a reduction in body mass index (BMI) in men and women, research shows.
"We have shown that increases in physical activity have the potential to decrease the obesity epidemic without increasing the risk of bone loss leading to osteoporosis," according to Jerilynn Prior (University of British Columbia, Vancouver, Canada) and colleagues in the journal Bone.
Physical activity is known to be a modifiable factor affecting BMD, bone accrual and loss, and the risk of fracture. Activity modulates bone remodeling through mechanical stimuli, and this results in increased mineralization and bone geometry.
Still, the evidence to support physical activity on bone health and fracture is derived from studies in postmenopausal women.
Using data from a large Canadian multicenter osteoporosis study, the researchers evaluated associations between physical activity and BMD in 2855 healthy men and 6442 healthy women.
At baseline, physical activity levels were inversely associated with BMI. From baseline to 5 years, increases in physical activity levels, measured by energy expended in total metabolic equivalents multiplied by minutes per day (MET*m/d), were associated with reductions in BMI.
For every 1000 MET*m/d, there was a BMI reduction of 0.41 and 0.40 kg/m2 in men and women, respectively.
In addition, for every 1000 MET*m/d expended, there were small but significant, increases in total hip BMD in men and women.
In women, increased physical activity was also related to increased lumbar spine BMD.
"For both men and women, the association between [physical activity] and BMD was modified by BMI, so that for a given BMI there was a positive association between higher [physical activity] and higher BMD in all cases except lumbar spine BMD among women," write Prior and colleagues.
The group adds that a wide range of exercise interventions, including walking and moderate activity, improve BMD.
"Thus, emphasis should be made on keeping active over the life span to prevent bone loss and to avoid weight gain," they conclude.
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