By strengthening your quadriceps muscles-the large muscles in front of your thighs-you can protect against cartilage loss, slow progression of knee arthritis, and ease pain. "All muscle groups around the knee are important for supporting the knee joint, but the quadriceps muscles are the most important," says Mary-Blair Matejczyk, M.D., an orthopaedic surgeon at Cleveland Clinic. "If your quadriceps become weak, your knee can buckle and give out. Strengthening your quads will dramatically improve function. Youll need less effort to get out of a chair or manage stairs. Most important, it will help prevent falls."