What Muscle Should Be Strengthened When You Tear Your ACL?

Stretch for success.

The anterior cruciate ligament, more commonly called the ACL, is the main stabilizing ligament in your knee. Injuries to the ACL, which runs from your shin bone up to your thigh bone, are common. Once you regain your range of motion following an ACL injury it’s important to strengthen the muscles around your knee to help prevent subsequent ACL problems. It’s also important to follow the directives of your doctor and physical therapist.


Initial strengthening focuses on your quadriceps muscles which run along the front of your thighs, according to Iowa State University. Quad sets are a common strengthening exercise prescription. To perform them lie on your back and put the heel of the leg you want to exercise on a surface that is raised about 2 inches from the ground, such as a book. When your leg is relaxed and extended fully, tighten your quad muscles as much as you can without lifting your leg. Hold for 10 seconds before relaxing for 10 seconds. Perform 10 repetitions.


Pulls to strengthen your hamstrings also are commonly prescribed following an ACL injury. To perform this, you need a piece of elastic tubing. Tie the ends of the tubing in a knot, place the knotted end behind a door and close the door to secure it. Sit in a chair facing the wall and loop the smooth end of the tubing around your heel. Pull your heel toward you slowly, activating the hamstring muscle that runs along the back of your thigh. Hold for 10 seconds before releasing slowly. Perform five repetitions, recommend the experts at the Montefiore Medical Center in New York.

Multi-Muscle Exercises

Your doctor may have you move on to performing quarter squats as your recovery progresses. Squats work your hamstrings and your quadriceps as well as your glutes. Anytime you perform squats, start with feet hip width apart, keep your chest up throughout the movement and make sure your core is engaged as you squat, advises Pete McCall of the American Council on Exercise. Also, keep your knees aligned over your second toes.

Post-Recovery Strengthening

Once you are fully recovered, do walking lunges to build strength that reduces risk for subsequent ACL injuries. Lunges work your hamstrings, quadriceps, glute and hip abductor muscles. Start with feet hip width apart. Step forward with your left foot, and contact the ground with your heel first. Transfer your weight to your left foot slowly, then lower your bodyweight onto that leg until your thigh is parallel to the ground and your shinbone has a very slight forward lean, or until you are in a comfortable position. Stand up on your left leg. Assist the motion by pushing your right foot into the ground and driving that knee forward. Continue moving your right foot forward into the next lunge.