Chondroprotective action of glucosamine, a chitosan monomer, on the joint health of athletes

It has been reported that cartilage metabolism (type II collagen degradation) is enhanced in endurance athletes with intense joint loading. Notably, glucosamine, a chitosan monomer, exhibits a chondroprotective action on osteoarthritis by inhibiting type II collagen degradation. Here, we evaluated the action of glucosamine on cartilage metabolism in soccer and rugby players with intense joint loading. In soccer and rugby players, the urine level of type II collagen degradation maker (CTX-II) was significantly increased compared with non-athlete control, indicating that cartilage metabolism is enhanced in these athletes. In contrast, the urine level of type II collagen synthesis maker (CPII) was almost the same as in non-athletes. These findings suggest that type II collagen degradation is relatively increased compared with type II collagen synthesis in these athletes. Interestingly, the administration of glucosamine-containing diet significantly decreased the CTX-II level but not the CPII level in these athletes. These observations suggest that cartilage metabolism (type II collagen degradation) is increased in endurance athletes (such as soccer and rugby players), and glucosamine demonstrates a chondroprotective action on these athletes by preventing type II collagen degradation but maintaining type II collagen synthesis.