Strong knees are essential for staying active and performing simple functions such as sitting down or squatting. Your knees consist of bones, cartilage, ligaments, muscles and tendons, but these structures can weaken or become injured through accidents, repetitive motions or conditions such as arthritis and obesity. Certain exercises can strengthen your knees and improve function. However, consult your doctor before starting an exercise plan, and remember to warm up for at least five minutes before an exercise session.
Modified squats are a knee-strengthening exercise, one of the Twenty Exercises for Arthritis Management, or TEAM exercises, approved by the American Orthopaedic Society for Sports Medicine. To do the squat, stand in front of a chair. Place your feet about hip-width apart with your toes pointing out slightly. Keep your weight evenly distributed. Fold your arms over your chest and keep your shoulders back. Lower yourself into a squat as if you're about to sit on the chair. Hold the position for a few seconds, then return to a standing position. Do two sets of about eight to 12 repetitions. Rest for a minute between each set.
According to the American Academy of Orthopaedic Surgeons, you should feel this exercise in the back of your thighs. Hold on to a wall, desk or chair for balance. Tighten your tummy muscles. With your left leg planted on the floor, slowly lift your right foot, bringing your heel towards your buttocks until your leg is at about 45 degrees. Hold for three or five seconds then lower. Perform eight to 12 repetitions, and repeat with the other leg. Don't lock the knee of your supporting leg, advises the AAOS. As your legs and knees become stronger, add light ankle weights for more effect.
Another TEAM exercise you can try at home is a knee extension. Sit on a comfortable chair with your back and hips resting against the chair back. Keep your left leg at about 45 degrees and slowly lift your right foot off the floor until your right leg is parallel to the floor. Do not lock your knees. Hold the position for one or two seconds, and then slowly return your foot to the floor. Do two sets of 10 to 12 repetitions for each leg. Rest for about 30 seconds between each set.
To do single-leg dips, stand in a doorway and hold on to the frame with both hands. Take a small step forward so your arms are a little bit behind you. Slightly lift your right leg off the floor and lower yourself a few inches, while keeping your left leg planted for support. Don't let your left knee protrude over your toes. Hold for three to five seconds and then slowly return to a normal standing position. Do eight to 10 repetitions, then switch sides.