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 distance running on bone metabolism, using the biochemical markers ICTP (the carboxyterminal cross-linked telopeptide of type I collagen), PICP (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 competition. The mean age was 38 (range 22-55) and 39 (range 22-53) years respectively, 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 race, and also the day after and two days after. A decrease of PICP concentrations among women was evident the day after the competition (from 170 +/- 17 micrograms/l to 158 +/- 17 micrograms/l) which returned to pre-exercise levels two days after the race (167 +/- 19 micrograms/l). Furthermore, a decrease of osteocalcin could be seen in the men one day after the exercise (from 12.1 +/- 1.1 micrograms/l to 10.3 +/- 1.1 micrograms/l). In the men, there was also an increase of ICTP concentrations two days after (3.98 +/- 0.35 micrograms/l) this long-term and demanding exercise, when compared with pre-exercise levels (3.67 +/- 0.28). One single bout of long-term, exhaustive running exercise in well-trained men and women seems to induce a temporary inhibition of bone formation as well as a stimulation of bone resorption.