The smooth surfaces of cartilage in synovial joints like the knee allow for repeated movements with minimal wear and friction. If the joint is healthy to begin with, kept in good alignment, and free of injury, it is not likely that repeated movements would cause problems.

A recent study compared the thickness in knee cartilage between a group of triathletes and a group of people who had been inactive all their lives. There were hardly any differences at all. The knee cartilage of the triathletes did not appear to be negatively affected, despite the intense impact and repeated joint-loading commonly associated with this activity.