ABSTRACT
To investigate the influence of long-distance running on bone metabolism, we measured bone metabolism markers in eight healthy young men before and 4 months after the start of training program of 10 km running. Measurements were then taken the day before a marathon race, immediately after, and 1 day, 2 days and 5 days after.<BR>As a result of exercise, the levels of serum osteocalcin (OC), a bone formation marker, and urinary deoxypyridinolin (D-Pyr), a bone resorption marker, decreased significantly. After the marathon race, the OC level decreased further corresponding to an increase of hydrocortisone right after the race. However, from the day following the race, the OC level showed a slight increase. D-Pyr showed an increasing tendency immediately after the race, and the levels of OC and D-Pyr increased significantly 5 days after the race.<BR>Bone formation and resorption decreased as a result of light, low-frequency endurance exercise. However, both of them increased after intense physical stress. From this result, it is suggested that the intensity and frequency of exercise affect bone metabolism differently, even though the type of exercise load is similar.