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Effects of exercise training on bone density in older men and women
J A Blumenthal1, C F Emery, D J Madden
1Department of Psychiatry, Duke University Medical Center, Durham, North Carolina 27710.
Objectives:
To determine the effects of up to 14 months of aerobic exercise on measures of bone density in older adults.
Design:
Randomized controlled trial with subjects assigned to either an aerobic exercise condition, non-aerobic yoga, or a wait list non-exercise control group for 4 months. Aerobic fitness and bone density were evaluated in all subjects at baseline (Time 1) and after 4 months (Time 2). A semi-crossover design was utilized with all subjects completing 4 months of aerobic exercise, followed by another evaluation (Time 3). All subjects were then given the option of 6 additional months of aerobic exercise, after which they had a fourth evaluation (Time 4).
Setting:
An outpatient exercise rehabilitation facility at a large, major medical center.
Subjects:
One-hundred-one healthy men (n = 50) and women (n = 51) over age 60 (Mean age = 67.0), recruited from the community.
Intervention:
The exercise program included stretching, cycle ergometry, and walking three times per week for 60 minutes throughout the course of the study.
Outcome Measures:
Aerobic fitness (VO2max) as assessed by cycle ergometry, and bone density (bone mineral content) measured by single photon absorptiometry.
Results:
Subjects achieved a 10%-15% increase in VO2max after 4 months of exercise training, and 1%-6% further improvement with additional training. Aerobic fitness was associated with significant increases in bone density in men, but not women, who maintained aerobic exercise for 14 months.