Though the knee is a simple hinge joint moving in primarily one direction, it bears much of the weight of your body and the forces exerted during locomotion. The joint is made up mostly of ligaments and bone compared with your hip joints and shoulder joints, which are surrounded largely by muscles; this bony configuration predisposes your knee to injury. The small mass of muscles covering the posterior aspect of your knees include the gastrocnemius, popliteus and the tendinous ends of your hamstrings. Exercises for these muscles will strengthen the back of your knees.
One-Leg Cable Curls
Perform leg curls using the ankle attachment on a cable pulley machine by securing an ankle strap around each ankle. Lower the pulley to its lowest level near the floor then click the pulley to the right ankle; you should be facing the pulley bar.
Step about 1 foot back from the pulley and hold the bars of the machine for balance. Bend the joints of your left leg slightly, balancing on your left foot. Lift your right foot off of the floor, keeping the knees of both legs adjacent to each other.
Bend your right knee and draw your right foot toward your buttocks as you simultaneously rotate your right heel outward, strengthening the knee end of your hamstrings and gastrocnemius muscles along with your popliteus; you should still be able to keep your knees close together. Repeat for one set of 12 to 15 repetitions then switch legs to work your left knee. Complete three sets per leg.
One-Leg Calf Raises
Place a large weight plate on the floor next to a relatively immovable object such as an exercise machine.
Put the ball of your right foot at the edge of the weight plate, lifting your left foot off the floor. Hold on to the bar of an exercise machine for balance.
Contract your calf muscles to lift you as high up on your tip toes as possible, holding the contraction for 5 seconds. Focus on tightening your gastrocnemius as hard as possible, feeling the contraction as close to the back of your knee as possible.
Lower your heel just past the weight plate using a 2-second count, then immediately contract your calf to stand on your tip toes for another 5 seconds. Repeat for one set of 10 repetitions then switch legs. Do three sets per leg.