LOW BONE MASS AND HIGH BONE TURNOVER IN MALE LONG-DISTANCE RUNNERS

Running is a popular sport, but in some studies long distance running in women has been related to reduced bone mass and a potential risk of osteoporosis. To investigate the impact of running on bone mass in me n, 120 healthy, physically active men (19-56 yr old; running 0-160 km/ week) were studied. Bone mineral content was measured in the lumbar sp ine, total body, and proximal femurs by dual energy x-ray absorptiomet ry and in the forearm by single photon absorptiometry. Bone turnover w as assessed by urinary pyridinium cross-links, plasma osteocalcin, and serum alkaline phosphatase. Lumbar bone mineral content was negativel y correlated to the weekly distance run (r = -0.37; P < 0.0001), with a difference of 19 +/-5% (mean +/- SEM) between controls and elite run ners. A similar relation was found for all measurement sites. After ad justment for possible confounders, the correlations remained statistic ally significant in areas with a high proportion of trabecular bone. B one turnover parameters were 20-30% higher in the elite runners, where as sex hormone status was unrelated to running activity. We conclude t hat male long distance runners had reduced bone mass and increased bon e turnover compared to controls, which suggests accelerated bone loss. The pathophysiological explanation was not clear, but sex hormones di d not seem to play a key role.