Knee Strengthening Exercises for ACL Damage


The knee, as the largest and most complex joint of your body, is extremely vulnerable to injuries. Bearing your body weight places a great deal of force on your knee. Adding motion, especially landing after being airborne, magnifies the force up to four times. Ligaments are tissues connecting your femur, the thigh bone, to your tibia, the shin bone. Injuries to your anterior cruciate ligament, ACL, decreases knee strength and stability. Rehabilitation of an ACL joint consists of exercises to mobilize and strengthen your ACL.


The ACL is one of four ligaments crossing the knee joint, connecting your thigh to your shin. The ACL crosses from the back of your leg, just above your knee, to the front of your leg, just below your knee, providing stability to your knee joint. The term cruciate refers to the cross shape of the ligament as it wraps around the knee joint. The ACL functions to guide and control rotational movement and prevent hyperextension of the knee joint.

ACL Injuries

ACL injuries occur with sudden stopping or twisting movements of the knee, common in sports such as football and basketball. Sudden movements such as directional changes, hyperextension and overflexion can rupture, or tear the ligament. There may be a popping sound at the point of injury. Initial symptoms include severe pain, swelling and diminished knee stability making it difficult to bear weight. ACL injuries are more common in female athletes due to structural problems causing joint instability.

Initial Treatment

Initial treatment includes rest, ice, compression, elevation and pain-reducing medication. In severe cases, surgery is necessary. In the past, ACL injuries required months of rehabilitation. Since 2000, treatment and rehabilitation starts immediately after pain and swelling has diminished.

During the first six weeks, mobility exercises restore movement to the knee joint along with improved balance, strength and coordination. Exercises such as thigh contractions in a standing and seated position increase strength. Calf raises and squats performed only 1/4 of the way down are done just using body weight without additional weight. Adduction and abduction exercises in a seated position using resistance tubing are recommended during the first six weeks.

Ongoing Treatment

During the second six weeks, lateral motion and additional weight-bearing movements continue to strengthen the knee joint. Squats and lunges performed through a full range of motion are suggested starting with body weight and progressing to adding additional weight. Single leg lunges and leg presses place an increase demand on the affected knee joint and are recommended for progression. Stair climbing and running programs are included in the treatment program when the joint is close to full stability and strength.