EFFECTS OF SHORT-TERM MAXIMAL WORK ON PLASMA CALCIUM, PARATHYROID-HORMONE, OSTEOCALCIN AND BIOCHEMICAL MARKERS OF COLLAGEN-METABOLISM

Physical activity is most probably an important factor to increase bon e mass. The exact mechanisms by which this takes place are not complet ely understood. During the last years methods have become available ma king it possible to study the metabolism of type I collagen in bone in more detail. In this study seven male athletes were studied before an d after a short-term maximal work (a modified Wingate test at a retard ation of 7.5% of body weight) during 30 seconds. Blood samples were dr awn before the test and 5 and 60 minutes after. Serum concentrations o f type I procollagen carboxyterminal propeptide (PICP) and carboxyterm inal telopeptide of type I collagen (ICTP) were measured, as were seru m calcium, parathyroid hormone and osteocalcin. Serum PICP and ICTP re flect synthesis and degradation of type I collagen, respectively and m ainly bone collagen metabolism. A significant increase of ionized calc ium and lactate was noted while PTH and total serum calcium did not ch ange. No significant alterations of either ICTP, PICP or osteocalcin w ere registered. We conclude from this study that the short-term maxima l work performed by means of the modified Wingate test failed to show any significant changes in bone metabolism (osteocalcin and metabolite s of type I collagen). A short experimental period and lactacidosis mi ght contribute to the unaltered bone metabolism. The results mainly in dicate that there is no pool of bone biochemical markers in young athl etic males that is washed out by short bursts of intense exercise.