Exercising Too Much (or Too Little) Can Harm Your Knees

Here's how to find the right balance between healthy exercise and damaged knees.

A man with cartilage deterioration in his knee grips the damaged knee in pain.

Medically reviewed in September 2021

Whether you’re training for a marathon or barely getting off the couch after work, you could be doing a real number on your knees. Both intense exercise and a lack of activity can speed up cartilage deterioration of middle-aged knees, say investigators from the University of California, San Francisco. 

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 participants kept track of their physical activity with a questionnaire, and some used an accelerometer to track their exercise. The 2012 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. 

Cartilage deterioration is the hallmark of osteoarthritis (OA), a condition that affects 32.5 million American adults, according to the Centers for Disease Control and Prevention. It causes bones to rub together, leading to stiffness and pain. Increasing age, obesity, joint injuries and weak thigh muscles all can increase the risk of OA. 

What you can do 
The right kind of exercise  can be key to preventing OA. If you’re at risk, consider these exercise changes to help protect your knees from damage: 

  • Try lower-impact activities. Take a walk, go for a swim or try Tai Chi. You’ll still get a good workout without the stress on your knees. 
  • Alternate your workouts. You don’t always have to do high-intensity workouts to see results. In fact, adding a variety to your routine increases your benefits. 
  • Stretch it out. Stretching can help maintain flexibility in your joints.

More On