Biochemical markers of bone metabolism in healthy elderly men. The relationship to physical activity.

The purpose of the present study was to examine the serum levels of bone turnover markers and interleukin 1beta in healthy elderly men with different levels of habitual physical activity. The study was conducted on 40 healthy men aged between 65 and 85 years (mean 74.0 +/- 7.55 years). The study population was divided into two groups with respect to the level of physical activity: 22 less active subjects (energy expenditure related to physical activity below 1600 kcal per week) and 18 more active subjects (above 1600 kcal per week). To estimate the physical activity of the study population, weekly energy expenditure was measured in each subject with use of Caltrac accelerometer. In the blood serum levels of bone formation marker--osteocalcin and resorption marker--the C-terminal telopeptide of collagen I (ICTP), and interleukin-1beta were determined. Concentrations of osteocalcin and ICTP in less active subjects were significantly higher (by 3.62 ng/ml and by 1.21 mug/l respectively, p < 0.05), reflecting the higher bone turnover in comparison to values determined in more active subjects. Positive correlations between ICTP and osteocalcin levels (r = 0.5814 and r = 0.6526; p < 0.05), and between ICTP and IL-1beta (r = 0.5823 and r = 0.6040; p < 0.05) in less and more active men were found. On the ground of the presented study it can be concluded that the decreased bone turnover occurred in men with higher level of habitual physical activity. This study showed the relationship between serum level of IL-1beta and bone resorption but the habitual physical activity has no effect on this cytokine activity.