Bone, cartilage, muscles, ligaments and tendons come together to form your knees. Stress or damage to any of these body tissues can produce knee injuries. Knee injuries may produce swelling and pain within a few hours after a severe injury or more than 24 hours after less severe injuries. Muscular weaknesses can increase your risk of knee injuries by preventing these tissues from working together properly during leg extension activities.
Vastus Medialis Weakness
Your vastus medialis is the inner-most muscle in your quadriceps and helps stabilize your knee joint. According to ExRx.com, weakness in your vastus medialis can increase your risk of knee injury while performing leg extension activities. A weak vastus medialis may cause displacement of your patella and produce undesirable wear on other hard tissues that form you knee joint. This activity may produce pain during leg extension activities in which you bring your knees to greater than 20- to 30-degree angles.
Hamstring Weakness
Your hamstring muscles form the back of your thighs and extend from the base of your buttocks to the back of your knees. Your hamstrings help stabilize your knees and allow your legs to bend and extend. Weak hamstrings can increase your risk of knee injury during leg extension activities. Weak hamstrings may produce instability when you bend your knees at less than 90-degree angles during leg extension activities.
Vastus Medialis Strengthening
Strengthening your vastus medialis can help prevent knee injuries. Sportsinjurgyclinic.net recommends strengthening your vastus medilis with lunges. Stand with a split stance and place one or two fingers on the vastus medialis muscle on your front leg just above your knee. Bend your front knee and drop the back knee toward the floor. Push up and repeat by lowering the other knee to the floor. Increase the number of lunges you perform gradually, until you can complete 20. Use your finger to make sure you keep contracting your vastus medilis throughout the movement.
Hamstring Strengthening
Leg curl exercises can strengthen your hamstrings to help minimize your risk of knee injuries. Set the resistance on the lever of the leg curl machine at an amount that you can comfortably complete 20 repetitions with. Complete four sets of 20 to 25 repetitions. Increase the weight once you can complete 25 repetitions. Bodybuilding.com recommends training your hamstrings to produce at least 66 percent of the force that your quadriceps produce.
