Changes of bone turnover markers after marathon running over 245 km

We evaluated bone turn over markers, cortisol and parathyroid hormone (PTH) levels in male athletes after 245 km of marathon running. Sixteen athletes were studied five days before, immediately after, and 1, 3, and 5 days after the run. We used T-test and Pearson correlation for statistical analysis. Osteocalcin levels were significantly decreased from 4.6 microg/lit to 3.8 microg/lit (p < 0.05). Activity of b-ALP was significantly decreased from 66 U/lit to 61.5 U/lit (p < 0.05). PICP levels were also significantly decreased from 168 microg/lit to 153 microg/lit (p < 0.05). Hydroxyproline levels decreased after the run from 70 mmol/min to 65 mmol/min (p < 0.05). ICTP levels increased after the run but without being statistically significant, from 6.62 microg/lit to 7.0 microg/lit. Urine calcium decreased significantly by 68 %, immediately after the run. Cortisol increased from 212 ng/ml to 455 ng/ml, and PTH levels increased from 12 pg/lit to 16 pg/lit immediately after the race (p < 0.05). Cortisol levels were significantly negatively correlated with osteocalcin (r = - 0.61, p < 0.05) and b-ALP (r = - 0.98, p < 0.05). PTH levels were significantly negatively correlated only with serum osteocalcin (r = - 0.8, p < 0.05). These findings suggest a transient suppression in osteoblast function during the marathon run probably due to cortisol and PTH levels elevation.