I'm concerned about my 14-year old son. When it comes to sports and activity, he never stops. Is it possible he could wear his joints out before he reaches adulthood?

Increased weight-bearing and repetitive joint loading in active teens is a good thing. Research shows that the volume and thickness of joint cartilage actually increases in athletes and adolescents with activity.

There are three main types of cartilage: elastic, articular or hyaline, and fibrocartilage. Articular cartilage is the smooth cartilage that lines the joints. It makes smooth, coordinated joint motion possible.

The more repetitive loading the athlete experiences, the healthier the function of the articular cartilage. However, it is true that too much of a good thing can lead to problems. There is a threshold of activity beyond which damage to the articular cartilage can occur.

Chronic microtrauma and/or acute injury in the high-impact athlete can damage the articular cartilage. Symptoms of articular cartilage can be fairly vague. Activity-related pain or swelling around the joint should be examined sooner than later. The same is true for any reports of joint clicking, catching, or locking.