A 1-year prospective study on the relationship between physical activity, markers of bone metabolism, and bone acquisition in peripubertal girls

We conducted a l-yr prospective study to evaluate the association between p hysical activity and biochemical markers of bone formation and resorption w ith bone mineral acquisition in 155 peripubertal Caucasian girls (51 gymnas ts, 50 runners, and 54 nonathletic controls). The bone mineral density (BMD ) of the femoral neck, the greater trochanter, and the lumbar spine were me asured by dual energy x-ray absorptiometry. Serum biochemical markers of bo ne formation (osteocalcin, bone-specific alkaline phosphatase, aminotermina l propeptide of type I procollagen) and bone resorption (degradation produc t of C-terminal telopeptide of type I collagen) were measured. The l-yr increase in BMD (adjusted for. age, height, Tanner stage, BMD at b aseline, and increases in height and weight) of the femoral neck was 0.037 g/cm(2).yr [95% confidence interval (CI), 0.019-0.051 g/cm(2).yr), and that of the greater trochanter was 0.020 g/cm(2).yr (95% CI, 0.003-0.039 g/cm(2 ).yr) greater in gymnasts than in controls. The corresponding figures for g ymnasts compared with runners were 0.038 g/cm(2).yr (95% CI, 0.009-0.041 g/ cm(2).yr) and 0.033 g/cm(2).yr (95% CI, 0.006 to 0.043 g/cm(2).yr). The fig ures for the lumbar spine did not differ significantly between study groups . The baseline serum concentrations of formation markers and resorption marke r accounted for 2.3-12.8% (P < 0.05) of the variation in the l-yr increase in BMD at the femoral neck and lumbar spine. However, there was no signific ant difference between the levels of adjusted baseline bone turnover marker s of the gymnasts, runners, and controls. The present data add considerable support to the argument that high impact mechanical loading is extremely important and beneficial for the acquisitio n of BMD of the hip during peripubertal years. Our results indicate also th at a high rate of bone turnover, reflected as elevated bone markers, is onl y weakly associated with the l-yr bone gain in peripubertal girls.