Bone mineral density of the calcaneus in 70- to 81-yr-old male athletes and a population sample.

Bone mineral content (BMC/W) and density (BMD) were studied in 70- to 81-yr-old active male endurance-trained (long-distance runners, cross-country skiers, N = 67), strength-trained (throwers, weight-lifters, N = 14), and speed-trained (sprinters, jumpers, N = 16) athletes. A population sample of similar age (N = 42) served as a control group. The measurements were performed at the calcaneus by single-energy photon absorption. The endurance-trained athletes had higher bone width and depth, and the strength and speed-trained athletes higher bone depth than the control subjects. The three groups of athletes showed 19-28% higher BMC (g.cm-1) and BMC/W (g.cm-2) than the control group (P less than 0.01-0.001). When the results were corrected for bone depth by assessing BMD (g.cm-3), the mean differences between the athletes and controls were 11-16% (P less than 0.05-0.01, not significant for the strength group). The highest BMD values were associated with moderate training for running and cross-country skiing. BMD did not correlate with serum total testosterone, but there was a negative correlation between BMD and sex hormone binding globulin and a positive correlation between BMD and the free androgen index in the endurance group. The results indicate that athletes having a long-term training history and being still active at over 70 yr of age preserve superior trabecular bone mass compared with the average male population of the same age.