What drove me into physical therapy was 2 ACL reconstructions when I was 13 and 15. My passion to better understand not only why these injuries occur, how we can prevent them but when they happen how can we rehab them better. Looking back based off of what I know now, I cringe at many aspect of my rehab. I focused on alot of things that werent important and ignored many of the most important parts.
One of the biggest things I was told during my initial rehab my right leg which had received the surgery had countless precautions, I was told to avoid training my left leg as well. The explanation was that it would create an even larger imbalance between the legs than there already would be.
Makes sense…. However, like most things in the human body…. the easy to understand explanation is probably not correct
More and more research has come out to support the idea of crossover phenomenon. Crossover training or education is the idea training the healthy limb while the immobilized or injured limb is unable to train. Crossover training has been shown to improve strength on the injured limb by only training the healthy limb. This phenomenon has been explained by cross activation theory. This explains that working the healthy limb stimulates both sides of the cortical motor areas of the brain. Although, the stimulation is less on the untrained side, it is still receiving stimulation and create connections. Continuing training will also have systemic hormonal benefits
Here is what some of the research has said:
This meta-analysis suggests that unilateral strength training produces adaptations in the opposite limb….there seems to be a direct relationship between the training load applied and the effect achievedCirer-Sastre R, Beltrán-Garrido JV, Corbi F. Contralateral Effects After Unilateral Strength Training: A Meta-Analysis Comparing Training Loads. J Sports Sci Med. 2017;16(2):180-186. Published 2017 Jun 1.
Previous meta-analyses and systematic reviews have determined that the average contralateral strength gain from cross education is approximately 8–12%Lara A. Green & David A. Gabriel (2018) The effect of unilateral training on contralateral limb strength in young, older, and patient populations: a meta-analysis of cross education, Physical Therapy Reviews, 23:4-5, 238-249, DOI: 10.1080/10833196.2018.1499272