Serum concentration of cartilage oligomeric matrix protein (COMP) is sensitive to physiological cyclic loading in healthy adults

Objective: To test the hypothesis that physiological cyclic loading during a 30-min walking exercise causes an increase in serum cartilage oligomeric matrix protein (COMP) concentration in a healthy population. Methods: Blood samples (5 ml) were drawn from 10 physically active adults immediately before and after, and 0.5 h, 1.5 h, 3.5 h and 5.5 h after a 30-min walking exercise on a level outdoor walking track at self-selected normal speed. On a separate day, blood samples were drawn from the same 10 subjects during 6 In while they were resting in a chair. Serum COMP concentrations were determined using a commercial enzyme-linked immunosorbent assay (COMP(R) ELISA). An activity monitor was used to record basic time-distance measurements of gait. Serum COMP concentrations within the exercise protocol and within the resting protocol were compared using separate repeated measures analyses of variance (alpha = 0.05). Results: In the exercise protocol, a first increase (9.7%; P = 0.003) occurred immediately after the walking exercise. A second increase in serum COMP concentration (7.0%; P = 0.024) occurred 5.5 h after the walking exercise. In the resting protocol, the concentration at baseline was significantly higher than at all subsequent time points (8.2%; P < 0.050). Serum COMP concentration decreased from the 3.5-h to the 5.5-h sample (-4.8%; P = 0.012). Conclusions: Even a moderate walking activity can significantly influence serum COMP concentration. The immediate response points to a diffusion time of COMP fragments from cartilage to the blood of 30 min or less. The response at 5.5 h indicates a metabolic delay for COMP in the range of 5 h to 6 h. (C) 2004 OsteoArthritis Research Society International. Published by Elsevier Ltd. All rights reserved.