CHANGES IN BONE TURNOVER INDUCED BY AEROBIC AND ANAEROBIC EXERCISE INYOUNG MALES

Physical activity is considered an important factor in attaining bone mass. However, the mechanisms by which exercise affects bone metabolis m are not completely understood. The present study was performed to in vestigate the effects of aerobic and anaerobic exercise on bone turnov er. Twenty healthy young males (aged 20-29 years) were followed throug h an 8-week program of aerobic (n = 10) and anaerobic training (n = 10 ), Ten age-matched individuals served as controls. Serum bone-specific alkaline phosphatase (BAP), serum osteocalcin (OC), and urinary pyrid inoline (Pyd) and deoxypyridinoline (Dpd) were determined as indices o f bone metabolism, After 4 weeks of aerobic training, serum BAP and OC (p < 0.01), and urinary Pyd (p < 0.001) and Dpd (p < 0.01) were signi ficantly reduced. After 8 weeks, BAP and OC levels had returned to bas eline values, whereas the urinary cross-link excretion remained low. I n the anaerobic training group, elevated levels of BAP (p < 0.05 vs. w eek 4), OC (p < 0.05 vs. week 4), and Pyd (p < 0.01 vs, week 0) were o bserved after 8 weeks of exercise. Changes in urinary Pyd and Dpd (wee k 0 vs. week 8) were positively correlated with changes in the mean po wer level in the Wingate test, a parameter of the anaerobic performanc e capacity (r = 0.50 and r = 0.55, p < 0.01, respectively). In the con trols, no significant changes in biochemical markers were observed, We conclude that aerobic and anaerobic training excert different effects on bone metabolism, While aerobic training led to changes compatible with reduced bone resorption activity, anaerobic training seems to res ult in an overall accelerated bone turnover. Therefore, the impact of physical activity on bone turnover may depend on the kind of exercise performed.