, Volume 52, Issue 3, pp 209-211

Marathon running accompanied by transient decreases in urinary calcium and serum osteocalcin levels

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We evaluated the effects of marathon running on bone metabolism in 23 noncompetitive athletes (15 women, 8 men, age range 23–55 years). The volunteers were studied 10 days before, immediately after, and 1, 3, and 5 days after the run. Serum osteocalcin levels were decreased on average by 20% (from 4.9 to 3.9 μg/liter, P=0.005) in men and by 10% (from 4.9 to 4.4 μg/liter, P<0.05) in women at the end of the marathon, with lowest osteocalcin levels (67–55% of the prerun levels) encountered 1 day after the marathon. The activity of bone alkaline phosphatase was decreased in women (from 66.3 to 62.3 U/liter, P<0.05) after the run, and this drop was detectable at each checkup after the run. Urinary excretion of calcium was lowered on average by 82% in men (from 2.8 to 0.5 μmol/minute, P<0.05) and by 76% in women (from 2.5 to 0.6 μmol/minute, P<0.005) after the run, but had already returned to prerun levels 1 day after the marathon. Urinary excretion of hydroxyproline tended to rise in both men and women, but the change did not reach statistical significance in either sex. These changes suggest a transient suppression in osteoblast function during the marathon.

Children's Hospital