I would hazard a guess that if you’ve been to see a rehab professional for a shoulder issue, you will have been given an exercise that uses a resistance band of some type.
The bands themselves come in various colours according to the amount of resistance they provide. From very little, right through to extremely difficult to stretch.
What they all have in common is that the more you stretch them, the more resistance you encounter. Here in lies the problem.
Let’s take an exercise to illustrate the effect and the potential issue with this. If you’ve been diagnosed with a rotator cuff injury then I’m certain you’ve been recommended this exercise below.
What you’ll no doubt have noticed is that the last part of the exercise is the most difficult no matter which strength of band you’re using. The only difference will be exactly which part of the range the exercise begins to get difficult and then how much of the range you’re able to complete as a result.
There are several problems with this type of resistance profile. The first is that it doesn’t match that of the external shoulder rotators.
Where muscles are strong and weak.
Biomechanically muscles are typically strongest in their mid range position, before getting weaker at either end of their range.
From a nervous system perspective they are weakest in their shorter range position. This is particularly true of muscles that have been exposed to injury and inflammation.
So here you have an exercise that gets more difficult in precisely the range where you are weakest, both from a biomechanical stand point and a neuromuscular one.
That will feel something like this, very easy could do this all day, very easy pass me my cup of tea, very easy I’ll have a digestive as well, oh a little bit of resistance, quickly followed by damn that’s hard, I can’t go any further.
What this achieves in terms of improving the strength of the target muscles is minimal. There is precisely zero challenge in the muscle’s lengthened position, very little where the muscle is strongest and a very large challenge where the muscle is weakest.
Understanding the challenge is a challenge.
Not only that, it’s extremely difficult for anybody to gauge exactly what that challenge represents in terms of a consistent number.
In this paper involving the external rotation exercise mentioned above, the researchers found that changing the starting length of the same band could result in double the amount of tensile force being exerted by the person performing the exercise. That’s a huge difference and difficult to monitor.
Additionally, resistance bands are known to deform after a specific number of stretch cycles. Meaning that after a while they will provide anywhere between 5 and 15% less resistance no matter what strength they are to begin with.
These facts mean it’s very difficult to assess what the actual challenge to the muscles is and therefore monitor the load as you would with a resistance training machine for example. Not knowing precisely what the challenge is, naturally makes it very difficult to make that challenge either easier or harder.
An alternative approach.
It’s my experience that practitioners prescribe resistance band exercises both for their convenience and in the belief that very little harm can result. This is not the case. The dramatic ramping of force that occurs with a band, together with the huge difference the starting tension can make, leads to inconsistent results and can provoke symptom flares as these factors are rarely considered.
The image below shows the mid range position of a cable machine version of the resistance band exercise. This exercise provides a more favourable resistance profile to your external shoulder rotators and also reduces the challenge on your trunk, enabling you to better focus on the muscles being targetted.
The floor also provides you with an awareness of exactly where your shoulder blades are, ensuring as much as possible the motion is coming from the glenohumeral joint rather than any compensation at the scapula.
Like with strength training but perhaps more so, successful outcomes in injury rehab require an understanding of the forces being applied. It’s these forces that will determine the adaptation you are seeking to stimulate in order to get better.
Resistance bands have many uses but understanding their properties and the stimulus they provide is the key to deciding when and if to use them.