Strengthening the muscles around your knee joints reduces the force placed upon your knees as you walk, run, jump, change directions and lift weights because your muscles are more conditioned to absorb and react to the force. The knee joints are composed of primarily bone, cartilage and ligaments though they can be strengthened by training your quadriceps and hamstring muscles.
Strengthen the section of your quadriceps muscles just above your knee joints with the leg extension machine. Slide into the machine, ensuring the pivot point for your knees is in line with the center of your knee joint. Adjust the back of the chair forward or backward as needed. Change the ankle pads so it rests just above your ankles.
Do leg extensions with both legs at the same time by contracting your quads to straighten your legs completely, holding the contraction for two seconds. Bend your knees to return to the start position and repeat.
Incorporate a few sets of leg extensions using one leg only; change the weight you are lifting between two-leg extensions and one-leg extensions.
Perform four to six sets of six to 12 repetitions on the leg extension machine.
Slide face-down into the leg curl machine, ensuring the pivot point for your knees is in line with the center of your knee joint; your knees must be slightly off of the pad of the machine. Adjust the ankle pad of the machines till it is just above your ankles.
Do leg curls with both legs at the same time by contracting your hamstrings to curl the leg attachment toward your buttocks, drawing your feet close to your body. Straighten your leg and repeat.
Incorporate a few sets of leg curls using one leg only; change the weight you are lifting between should two-leg curls and one-leg curls.
Do four to six sets of six to 12 repetitions on the leg curl machine.
Stand with your feet together and hold a dumbbell in each hand.
Step your right leg forward, then lower your body until your front thigh is parallel to the floor. Your hip joints and knee joints should be nearly 90 degrees with your trunk in a fairly upright position.
Push through your right foot and contract the muscles of your right leg to stand up straight, moving your left leg forward into another lunge. Push through your left foot and contract the muscles of your left leg to stand up straight, moving your right leg forward into a lunge again.
Alternate forward legs, completing 10 lunges per leg. Rest for one minute and repeat using slightly heavier dumbbells for three more sets of lunges.