Following anterior cruciate ligament (ACL) injury, people tend to develop a persistent quadriceps weakness and osteoarthritis (OA) of the knee. In order to maintain function in ACL deficient individuals, rehabilitation must address both of these problems.

In the experiments described here, ACL transected rabbits underwent maximal and submaximal electrical stimulation strength training protocols followed by assessment of quadriceps strength, muscle mass and OA progression.

Maximal training did not improve strength imbalances compared to untrained controls, whereas sub-maximal training did alleviate the imbalances. The maintenance of strength imbalance was attributed to a strong contralateral effect in the maximal training protocol, a hypothesis that was supported by tests on maximally trained rabbits with intact knees, in which pre-existing imbalances were maintained. Neither protocol was found to be safe for the integrity of the knee:​ both accelerated the development of OA.