BIOCHEMICAL MARKERS OF BONE METABOLISM DURING DISTANCE RUNNING IN HEALTHY, REGULARLY EXERCISING MEN AND WOMEN

The purpose of the present study was to evaluate the effects of long d istance running on bone metabolism, using the biochemical markers ICTP (the carboxyterminal cross-linked telopeptide of type I collagen), PI CP (the carboxyterminal propeptide of type I procollagen), osteocalcin and bALP (bone specific alkaline phosphatase) as well as parathyroid hormone (PTH) and serum calcium. Twenty healthy, regularly exercising individuals, 10 women and 10 men, participated in a running competitio n. The mean age was 38 (range 22-55) and 39 (range 22-53) years respec tively, the performed distance 15 (range 5-30) and 28 (range 15-30) km respectively, with a speed of 5:30, 5:02 per kilometer respectively. Fasting blood samples were drawn in the morning the day before the rac e, and also the day after and two days after. A decrease of PICP conce ntrations among women was evident the day after the competition (from 170+/-17 mu g/l to 158+/-17 mu g/l) which returned to pre-exercise lev els two days after the race (167+/-19 mu g/l). Furthermore, a decrease of osteocalcin could be seen in the men one day after the exercise (f rom 12.1+/-1.1 mu g/l to 10.3+/-1.1 mu g/l). In the men, there was als o an increase of ICTP concentrations two days after (3.98+/-0.35 mu g/ l) this long-term and demanding exercise, when compared with pre-exerc ise levels (3.67+/-0.28). One single bout of longterm, exhaustive runn ing exercise in well-trained men and women seems to induce a temporary inhibition of bone formation as well as a stimulation of bone resorpt ion.