However, I think one question that comes out of this discussion is why does this persist after an ACL reconstruction if they are doing rehab and what can we do to change it. Why does it persist? I think there are a lot of complexity to this question.
Grooms et al J Orthop Sports Phys Ther 2017 looked at 15 ACL reconstructed athletes who were cleared to return to sport and compared them to 15 matched controls. Each participant filled out an IKDC (which we talked about last week) and had a functional MRI. A functional MRI is an MRI that is done while the athlete is performing a task (pictured above). In this study, the task was performing knee extension while having an MRI.
What this study showed was that the athletes who had poor scores on the IKDC (their perceived functional ability of their knee) did in fact have diminished activity in the ipsilateral motor cortex and ipsilateral cerebellum. What does that mean? Essentially, this means that these athletes had altered activation in areas of their brains which is responsible for sensory, motor and sensory-visual-spacial processing. We are going to dive into this subject a lot more on the next blog series but this information clearly guides us on types of exercises we can add to our rehab and our performance training that is going to improve input in these areas resulting in improved performance and mitigating risk of injury.
I touch on this here, because this may be one reason that we see some of the things we do in rehab. For the athlete that has massive lateral shift (shifting weight to one side during squatting), this may be from these higher center neuroplastic changes. In addition, the changes in the primary motor cortex could be one additional reason that the quadriceps have difficulty firing and why an asymmetry in quadriceps develop continues even at the point of return to sport. So, how can we change this and can we use exercises to increase input to these higher centers?
Sadly, I think it is not as complex as we make it. Applying some simple concepts early on in the rehab process will aid in elevating a lot of this. Some examples:
- Correct a lateral shift ASAP. The first time you start any type of squats, partial, sit to stand or whatever it is, correct the lateral shift. Do not let this persist. Training this motion and allowing this lateral shift starts creating these movement patterns as the default movement pattern in the higher centers. This means this will be the movement they resort to when they sit, get down to the commode, sit in a car, on their bed ect. This will then be the movement pattern they will carry over to functional squatting, training activities and sport. WE must correct it and correct it right away.
- Start working recruitment of the quadriceps right away. If they can't do the motion concentrically, start them doing it eccentrically. Muscles are stronger eccentrically and I have often found we can use this to start recruiting muscles the athlete is having a difficult time recruiting. Try this technique. Take an athlete that can't do a long arc quad set or a straight leg. Raise their leg for them up to the end range of motion then have them hold it. Do this for a couple of reps then have them slowly lower it. Do that for 5 reps then have them do it immediately concentrically after completing an eccentric contraction. They can do it! Why? We have reengaged that synaptic pathway and got it firing again.
- Add BFR to your routine. Blood flow restriction training is a great tool we can use to recruit more of the muscle. By using BFR, you create a blockage of the venous return which causes a buildup of blood within the muscle (buildup of blood in the muscle resulting in back flow preventing more oxygenated blood from entering). As result, muscle gets super pumped up and creates a hypoxic state. This is due to less oxygenated blood coming in all while the task or load continues to be performed. This decrease in O2 causes a fatigue and an increase in motor unit recruitment and more whole muscle activation. This is how we get more of the muscle involved and greater recruitment of the whole muscle versus partial and hence more hypertrophy.
- BFR alone not enough - add electrical stimulation. We know that electrical stim (ES) can aid in recruiting more motor units within the muscle when done with low level exercise (leg raises, short arc quads, long arc quads). You can increase the impact of both the ES and the BFR by combining the two.
- Single limb performance - single leg activities are absolutely an essential part of your rehab
That concludes this series. Next week, we start to dive into some of the research related to the changes that occur in the higher brain centers and what specific strategies we can do to help retrain.. Stay tuned as I am super excited to share with you. Have you followed my instragram @bjjpt_acl_guy lately? If not, you are missing out. I am constantly posting the latest research in injury prevention and sports medicine. Don't miss out and please share with your colleagues, athletes and training partners and please be sure to follow us on instagrm @ bjjpt_acl_guy and twitter @acl_prevention. Train hard and stay well. #ViPerformAMI #ACLPlayItSafe