Non-impacting exercises for runner's knee are aimed at helping improve your range of motion. They also strengthen the muscles around your knee without putting any force on the knee. While very few exercises succeed in being completely non-impacting, most low-impact exercises will help you recover from runner's knee without re-injuring yourself. Consult your doctor if your knee pain persists or worsens.
Icing and rest are the immediate response to runner's knee pain. Once the pain has subsided, begin slowly to restore flexibility and range of motion with stretches. Runner's knee stretches often focus on the quadriceps and hamstrings, two muscles that directly affect the amount of pressure put on your knee. Lie down on the ground with your knees bent and back flat on the floor. From this position, extend your right leg up and away from your body. Once it is extended, place both of your arms gently under your knee, bringing the leg up and in towards your body. Hold for several seconds before relaxing. Repeat with the left leg.
Swimming exercises are a non-impacting form of exercise that can help you strengthen your knee and the muscles around it. Swimming exercises range from regular freestyle swimming strokes to walking exercises in the water. To perform a basic kicking exercise, swim to the edge of the pool, placing both hands securely on the edge. From here, begin kicking your legs up and down in the water. Kick until you are fatigued, but stop if you feel any pain in your knee.
After several weeks of recovery, performing mild strengthening exercises for your knee is an essential part of full recovery. No-impact strengthening exercises range from leg lifts to leg dips. Lie down on your back with both legs extended and your arms at your sides. From this position, bend your left knee, placing your left foot flat on the floor. Tighten your abdominal muscles and lift your right leg up and off the ground, making sure it stays parallel to the floor as you do so. Hold for 10 seconds before relaxing. Repeat with both legs until fatigued.
Elliptical Machine Exercises
Exercise on an elliptical machine will place a low level of impact on your knee, but it is one of the lowest impact cardiovascular exercises you can perform. The gliding motion you repeat on the machine will help improve range of motion in your knees as well as restore strength to your legs. Start by walking slowly on the elliptical for several minutes at a time, focusing on posture and form over speed and endurance. As you improve, increase the amount of time you walk on the elliptical -- and add walking in reverse to further strengthen your leg muscles.