H-15I Free Communication/Poster Bone Density: Age and Menopause
While it is clear that exercise has a positive impact on bone turnover in young adults, the influence of exercise training on bone turnover in older individuals is not as apparent. Further, numerous older individuals, while physically independent, may be limited in terms of functional ability.
This study was designed to determine whether bone turnover changes in response to different modes of training in functionally limited adults.
Seventy-two (53F, 19M, 65–92 yr.) functionally limited individuals were randomly divided into one of four treatment groups: aerobic training (AER; 11F, 7M), resistance training (RES; 12F, 5M), aerobic plus resistance training (AR; 14F, 3M) or control (CON; 16F, 4M). Fasting, morning blood samples were collected at baseline, 8-weeks and 16-weeks of training. Serum samples were stored at −70°C; all samples were analyzed together by ELISA. Bone formation was measured by osteocalcin (ng/mL) and resorption by cross linked N-telopeptides (nM BCE). Bone turnover was expressed as the uncoupling index (UI), calculated by subtracting the z-score of the mean formation values from the z-score of the mean resorption values.
The UI for the different treatment groups were as follows: AER, M: −.383, F: .106; RES, M: .253, F:.150; AR: M: −.0144, F: .113; CON: M: .983, F: −.238. A UI near zero is indicative of neither bone gain nor loss; positive values indicate more bone loss than gain. Analysis revealed a significant group by gender interaction, indicating that bone turnover of males and females responded differently to different modes of exercise.
Both men and women in the AR had bone turnover levels near zero, while subjects in the control group had much higher levels of bone turnover. These data suggest that a combination of aerobic and resistance exercise is most appropriate for maintaining bone in functionally limited men and women. Supported by NIH RO1 NR04929-01A1