A primary cause of knee problems among women is weak quadriceps. This group of four muscles at the front of the thigh is known as the “quadriceps femoris.” The “rectus femoris,” which stretches from the pelvis to the kneecap, works to flex the hip and extend the knee. The three “vastus muscles,” which run from the thigh bone (femur) to the kneecap, are responsible for knee extension. The innermost vastus muscle (vastus medialis) also helps stabilize the kneecap, which is important because, if the kneecap moves laterally, it can produce sheer forces that can damage the cartilage that lines the back side of the kneecap. To help avert injury to the kneecap, leg raises are recommended to strengthen the quadriceps.