It's all about the Nerves

Hello everyone!

Over the past year or so, I have been reconsidering many of my rehab philosophies due to 3 realizations I’ve had. All three realizations have to do with how we train the body in a rehab setting, specifically the role that nerves play in rehab. It started for me when I began paying attention to how long athletes would continue to get consistent treatment. For the sake of this discussion, we won’t include surgical cases (though most of the points I want to discuss still apply to them).

To begin let’s consider an average injury, whether that is a lateral ankle sprain, hamstring strain, or indistinguishable shoulder pain that flips between presenting as impingement and rotator cuff irritation. Of course all injuries exist on a spectrum from “mild” to “severe”, however I am focusing on the bulk around the average. I don’t have concrete statistics available, but I think it would be fair to estimate around 75% of non-surgical injuries are resolved within a 3-6 week timeline. When I say “resolved” I am assuming an athlete is compliant for rehab and treatment coming into the athletic training room an average of 3x per week. So my first realization was that the majority of injuries seen in the athletic training room often clear up in 6 weeks or less.

My second realization came while having a conversation with a former classmate of mine discussing Dynamic Neuromuscular Stabilization (DNS) and its implication in the sports medicine field. He told me about an athlete he worked with who presented with rotator cuff weakness/pain. The athlete was a male swimmer with no previous history of shoulder injuries. The question my friend asked was how does a healthy, strong, D1 college athlete suddenly have a weak rotator cuff? I think it is safe to say this particular athlete didn’t suffer from sudden muscular atrophy so what would explain the weakness? We know that muscles don’t like to contract when swelling is around, so plausibly that could be the cause of the weakness for this athlete. So if the problem is weakness perhaps due to swelling around the area, why do we often prescribe “strengthening” exercises to solve the problem?

Strength has been shown to have a direct correlation to the cross sectional area (size) of the muscle. According to NASM muscular hypertrophy (growth) requires greater than 70% of 1 Rep Max for a minimum of 6 weeks. I know that most rehab exercises are designed to target one specific muscle at a time, but I have a feeling that 2-5 lbs is not 70% 1RM even for a smaller muscle such as the subscapularis. We can agree that in a healthy D1 athlete 2-5lbs is never going to be near 70% 1RM no matter what muscle we are talking about. For example, the subscapularis is responsible for moving the arm into internal rotation, is the arm not heavier than 5lbs? This was my third realization. Given the information we’ve discussed, I must pose this question; what is the point of prescribing an exercise that is 3 sets of 8-10 reps using only 2-5lbs? An exercise with those parameters being performed (on average, as previously mentioned) for less than 6 weeks wouldn’t cause muscular hypertrophy. Even if the exercise is progressed beyond 6 weeks, rarely if ever, will you come close to 70% 1RM. Despite all this, it is obvious that the athlete will make significant improvements over the course of a 4-6 week rehab protocol even if using only 2-5lbs. So what is happening there?

When I was in undergrad, I remember learning two basic things about nerves: they take the longest time to heal of any tissue in the body, and in a strength program that is shorter than 6 weeks most of the gains made are due to neuromuscular efficiency. Yet following my certification I would evaluate an athlete to find “muscular weakness” around the involved joint and then prescribe them rehab exercises to improve “strength”. Typically those exercises would be something like standing shoulder abduction (Ts) for 3x8 using 5lbs. With these parameters the exercise is clearly not causing muscular hypertrophy especially if, on average, this athlete will be back on the field in 6 weeks or less. Call me ignorant, but this was a big realization for me. Maybe it’s only a matter of perspective but let’s admit, we aren’t really rehabbing for strength gains.

What we are really addressing is neuromuscular efficiency and proper firing patterns.

Okay, so maybe this isn’t such a huge discovery on my part. Let’s go back to the case of the male D1 swimmer I spoke to my friend about. In that case, he mentioned using DNS to address his problem. He told me they never put a dumbbell in his hand, they never used any Therabands or resistance tubing. I am only vaguely familiar with DNS techniques so I apologize if I describe this incorrectly. Using DNS they reset his neurological firing patterns over the course of 2 weeks. The treatments involve specific pressure points while the patient moves through a guided motion that mimics rolling or crawling patterns similar to how infants first develop. I believe the principle behind the treatment is that with proper cues and movement patterns the clinician can force the body to revert to previous motor patterns that were first created as a developing infant. Anyways, the athlete was able to resolve his weakness and return to being asymptomatic in only 2 weeks of therapy with no strengthening exercises.

So what does this mean? How does any of this really apply to creating a rehab protocol? I’m still trying to answer this and I hope to get feedback from all of you. I’m not trying to discredit the rehab exercises I previously mentioned, because they still get results. I am raising my hand to say the results we achieve are not related to muscular hypertrophy and therefore not truly strength gains. Maybe if we recognize more of our rehab gains are coming from neuromuscular efficiency then we can better direct our interventions to maximize patient outcomes. I am starting to realize, its all about the nerves.

More next time,

Mark D.
@MarkDomATC