The anterior cruciate ligament, or ACL, is the smallest ligament in the knee and connects the tibia to the femur. The ACL is responsible for anterior stability of the lower leg bone and plays a pivotal role in movement. Any activity requiring twisting, turning, changing direction or jumping can stress the ACL. The NCAA has recognized there are gender differences between men's and women's ACLs. Women tend to have smaller ligaments in the knee, making them four times more likely to develop an injury to the ACL. Once a ligament has been injured, it may not heal as strong as before the injury. Rehab after an ACL injury is necessary to regain as much stability as possible.
Isometric Contraction
In the initial stages of recovery from an ACL injury, it may not be advised to perform load-bearing exercises, or exercises that require you to bend the knee. One of the first exercises usually recommended by physical therapists is isometric contraction of the quadriceps. This tenses the quadriceps muscles, effectively working them without requiring a change in joint position. Begin by sitting on the floor with your injured leg straight and your noninjured leg bent at the knee. Contract the quadriceps muscles on your injured leg without moving your knee. Hold for 10 seconds and relax. Repeat this exercise for 10 to 15 repetitions.
Passive Extension
Passive knee extension involves more of a stretch than it does a contraction of the leg muscles. The purpose is to stretch the hamstrings without placing unnecessary pressure on the knee capsule. Begin by sitting in a chair with your injured leg resting on another chair or surface of equal height. With your heel on the chair in front of you, relax your leg and let your knee straighten under the weight of your thighs. Hold this position for 30 seconds. Complete this exercise several times a day.
Half Squat
Once your knee has gained the ability to hold your body weight, you are ready for more advanced exercises. Begin by standing up straight with your feet shoulder-width apart and both knees slightly bent. Hold on to a wall or table for stability. Using only your body weight, slowly bend both knees and squat as if you were about to sit in a chair. Squat halfway to parallel and return to the starting position. Perform two to three sets of 15 to 20 repetitions.
Active Leg Extensions
Active leg extensions place more direct pressure on the joint capsule of the knee and is considered more of an advanced rehab exercise for ACL injuries. Knee extensions can be used with resistance from a machine, exercise band or ankle weights. However, begin by using only the weight of your lower leg. Sit on the edge of a sturdy table or elevated chair so your feet are off the ground. With your injured leg, slowly extend your knee until it is straight, contracting your quadriceps throughout the movement. Hold for five seconds at peak contraction before lowering your leg to the starting position. Repeat for 15 to 20 repetitions. When your ACL becomes strong enough, you can advance to using resistance.
References
- Info Sports; Female Athletes and Anterior Cruciate Ligament Injuries; Richard Parker, M.D.
- "Physiology of Sport and Exercise"; Jack H. Wilmore and David L. Costill; 2004
