SAN FRANCISCO — Three years of yoga practice did not change bone mineral density in 31 postmenopausal women, compared with bone densities in 31 inactive women.
Proponents of yoga have wondered whether it might produce bone benefits similar to those seen with weight-bearing exercises. Previous data have shown skeletal tissue responds to site-specific stresses.
Yoga consists of movements and poses using body weight as a form of resistance, and contorts the joints with torque and strain. Results of the current cross-sectional study suggest yoga doesn't provide enough of a stimulus to increase bone mineral densities to levels significantly above those in inactive women, Millie Sweesy-Barger and associates said in a poster presentation at the annual meeting of the International Society for Clinical Densitometry.
Women in the yoga group had a 3-year history of practicing yoga at least twice a week in sessions of 60 minutes or longer. Those in the inactive group reported less than 2 hours of physical activity a week over the past 3 years. Participants underwent dual-energy x-ray absorptiometry (DXA) scans of the lumbar spine, left and right femurs, nondominant distal radius, and whole body. The mean age of the women was 60 years in the inactive group and 58 years in the yoga group. The cohort included 59 whites and 3 Asian Americans.
No significant differences between groups were seen in bone mineral densities at any sites. Higher mean bone mineral density in the distal radius in the inactive group, compared with the yoga group, became statistically insignificant after controlling for the effects of age, height, body mass, body mass index (BMI), percent body fat, fat mass, lean body mass, and calcium intake, said Ms. Sweesy-Barger, a student in the department of kinesiology and physical therapy at California State University, Long Beach. The yoga group had significantly lower mean measurements of body mass, percent body fat, fat mass, and BMI, compared with the inactive group, she added.
There is substantial evidence showing significant physical and psychological benefits of exercise programs for older adults, 55% of whom in the United States either have osteoporosis or are at risk of developing the disease, Ms. Sweesy-Barger noted. “To the aging, nonathletic postmeno- pausal woman, the question becomes, which activities are most effective for mitigating the loss of bone?”
Understanding how bone adapts to various forms of physical activity will help inform public health strategies to prevent and manage osteoporosis, she said.