Overworked knee—

The researchers used MRI scans to monitor changes in the right knee cartilage of 205 participants, age 45 to 65 years old, over a span of four years. The study found that people who participated in high-impact activities such as basketball, tennis and running had increased cartilage deterioration in the knee. But so did people who hardly exercised at all. The research suggests that moderate, low-impact exercise is best for protecting knee cartilage.