NET FLUXES OVER WORKING THIGH OF HORMONES, GROWTH-FACTORS AND BIOMARKERS OF BONE METABOLISM DURING SHORT LASTING DYNAMIC EXERCISE

The purpose of this study was to evaluate the responses of hormones, g rowth factors, and biomarkers involved in bone and muscle metabolism d uring exercise and in recovery. One leg knee-extension exercise and co ncomitant sampling from the artery and vein were performed. In 12 heal thy individuals (6 men and 6 women; age 21-36 years) blood was drawn f rom the femoral artery and vein at rest, after 10 minutes warm-up, aft er 15 minutes work at 61% of peak one leg VO2, and after 5 minutes wor k at peak one leg VO2, as well as 5, 30, and 60 minutes in recovery. B lood flow in the femoral vein was measured using the thermodilution te chnique. Arteriovenous differences were measured over working thigh fo r growth hormone (GH), insulin-like growth factor I (IGF-I), insulin-l ike growth factor binding protein 3 (IGF BP3), parathyroid hormone (PT H) and bone biomarkers, i.e., the carboxyterminal propeptide of type I procollagen (PICP), the carboxyterminal cross-linked telopeptide of t ype I collagen (ICTP), osteocalcin, and bone-specific alkaline phospha tase (b-ALP). There was an uptake of GH (3.1 +/- 1.2 mU . min(-1), P < 0.001; mean +/- SE) over thigh during exercise and a release of IGF-I at the end of exercise (60 +/- 36 mu g . min(-1) P < 0.01). PICP was also released after the maximal exercise (23 +/- 12 mu g . min(-1); P < 0.01) as well as ICTP (0.5 +/- 0.3 mu g . min(-1); P < 0.05) and b-A LP (0.2 +/- 0.1 mu kat . min(-1); P < 0.05). Osteocalcin, IGF BP3, and PTH revealed no clear-cut pattern. In the present study, exercise ind uces endocrine changes which point to anabolic effects on muscle and b one tissue.