Athletes often tear the anterior cruciate ligament (ACL) in the knee. ACL tears can be devastating. They most often require surgery. They generally require a long period of rehabilitation. Rehab can help return people to their sports and activities. But the reconstructed ACL almost never regains its full strength. Therapists are working to figure out better rehab programs after ACL repair.
As part of this effort, these authors studied how ACL repair affects the way patients do squat exercises. Squats are a big part of most ACL rehab programs. Squats use the common motions of sitting, standing, and lifting. Squats also involve coordinating joints in the knees, hips, and ankles. It has been thought that exercises that use multiple joints are better for rehab. This study casts some doubt on that theory.
Researchers tested eight people who had ACL repair less than a year before. They did squats using fairly low amounts of weight. Joint movements and muscle activity were monitored. Results from each subject’s injured leg were compared to results from the healthy leg.
The authors found differences in how subjects used their legs. They did the squats in a way that shifted the force away from the injured knee. In the healthy leg, the effort was divided evenly between hip muscles and knee muscles. In the injured leg, the effort was greater at the hip. It is also possible that more of the work was shifted to the healthy leg.
Shifting the effort away from the injured knee could slow recovery. To get stronger, the knee needs to take on its fair share of the work. This pattern of transferring the work could mean less strength in the injured knee. It could also set patients up for another injury. The authors say that therapists should maybe think again about ACL rehab programs. Perhaps the program shouldn’t involve only exercises that work multiple joints. These exercises may be making it too easy for patients to shift the work to other joints and muscles.