Doctors have known for many years that having weak quad muscles (in the front of your upper legs) increases risk for damage to the cartilage in your knees. A study from Purdue University showed that strengthening these muscles slows down knee cartilage damage and may even improve knee function (Arthritis & Rheumatism, October 2006). The researchers placed 221 adults in their sixties and seventies either on a program of strengthening their muscles in their upper legs or just moving their knees in a series of range-of- motion exercises. The subjects exercised three times per week (twice at a fitness facility and once at home) for 12 weeks. This program was followed by a transition to home-based exercise for 12 months. Older people weaken naturally with aging, but the range of motion exercisers lost more strength than those who exercised against progressive resistance. The strength training helped retain joint space, signifying that this group had less loss of cartilage.
The knee is like two sticks held together by four bands called ligaments. Strength training stabilizes the muscles that support the knee and helps to prevent loss of cartilage with aging. People with knee pain should get a diagnosis from their doctors. Most will be advised to do exercises that strengthen the knee, such as pedaling a bicycle or performing knee strengthening exercises that involve bending and straightening the knees against resistance. People with knee pain should avoid exercises that jar the joints, such as jumping or running.