Exercises to strengthen the knees

3. Prone Straight Leg Raises

Lie on your stomach with your legs straight. Tighten the muscles in your bottom and the hamstring of one leg, and lift toward the ceiling. Hold 3-5 seconds, lower, and repeat. Do 10-15 lifts and switch sides. You can add ankle weights as you gain strength. You shouldn’t feel back pain. If you do, limit how high you lift up. If it still hurts, stop and talk to your doctor.