The best way to prevent osteoarthritis as an adult may be getting plenty of exercise as a kid, say researchers in Australia.Previous studies suggest that exercise stress induces cartilage development before and in the early stages of puberty. An editorial on this topic was recently published in the British Journal of Sports Medicine.
In it the doctors conclude that, "vigorous activity during childhood promotes development of knee cartilage in the absence of significant injury and/or pain."
One study found that inactive children had 20 to 25 percent less cartilage development in just two weeks compared to kids who exercised. Even light exercise was beneficial for cartilage growth in the kids’ knees.
Articular cartilage is the smooth elastic tissue that covers the ends of bones in a joint, the site where the bones come together. A healthy joint glides easily without pain, thanks to cartilage; but over time the cartilage can wear away and become frayed and rough resulting in a condition called osteoarthritis.
In another study, pre-pubescent children were followed for almost two years. The researchers found that boys in the study had a 7 to 15 percent growth in knee cartilage while girls had a 4 to 10 percent growth. The kids who engaged in the most intense exercise regimens had gained almost twice as much cartilage as those who exercised the least.
This is why the American Academy of Orthopedic Surgeons encourages children to get 35 to 60 minutes of exercise everyday, even if it’s just walking. According to the Academy, only one in four American children is getting an adequate amount of physical activity each day. This is discouraging not only for cartilage development but also for bone strength, since exercise has also been shown to increase bone density — which can prevent osteoporosis later in life.
In the editorial, the Australian researchers also looked at how studies on limiting exercise in animals hindered cartilage development. They found that a certain amount of exercise was necessary for healthy development of cartilage in horses, and that limiting exercise adversely affected development. The same was true in rats when researchers eliminated weight-bearing exercise on these animals. The lack of stress on the joints prevented cells from producing cartilage.
But the caveat to exercise is avoiding injury, since childhood sports injuries can lead to post-traumatic knee arthritis as an adult.
The authors of the editorial suggest further research is needed to determine if exercise during childhood is truly preventative for arthritis later in life. Children would ideally be followed for decades to see who develops knee osteoarthritis and what their exercise levels were like before puberty.
