Prolonged exercise causes an increase in the activity of galactosylhydroxylysyl glucosyltransferase and in the concentration of type III procollagen aminopropeptide in human serum.

The effect of prolonged heavy physical exercise on serum galactosylhydroxylysyl glucosyltransferase activity (S-GGT) and serum type III procollagen aminoterminal propeptide (S-Pro(III)-N-P) concentration was studied in healthy male long-distance runners. S-GGT increased gradually by about 70% (p less than 0.01) during a competitive 24-h run, and a rising trend was also observed in S-Pro(III)-N-P. After the termination of the run S-GGT was normalized in two days, but the increase in S-Pro(III)-N-P continued up to one day after the race, reaching nearly 40% (p less than 0.005). The alterations in S-GGT and S-Pro(III)-N-P showed no significant correlation with S-CK, S-LDH or the distance run. The most likely explanation for the increases in S-GGT and S-Pro(III)-N-P is that prolonged heavy exercise injures the collagen-synthesizing cells of the connective tissue, leading to a short-term increase in type III procollagen production.