Practical Science on Movement and Pain
Practical Science on Movement and Pain
Graded exposure is a key concept in understanding how to reduce pain caused by movement. It’s a very common sense idea, and one that most people kind of know at some level, because there is profound truth to it. But it’s also an idea that most people will probably fail to put into practice in a systematic way. Here’s a brief discussion of what it is, why it works and how to do it.
Graded exposure is a process by which you slowly and progressively expose yourself to some form of stress, in order to make you less sensitive to that form of stress. In the context of movement, it means the progressive introduction of threatening movements, in the right dosage and timing, in a way that makes them less painful. This might happen in one of two ways – through causing a change in the body, or a change in the way the nervous system perceives threats to the body.
There is some physiological truth to the idea that what doesn’t kill you makes you stronger. According to the SAID principle, the body will adapt to get better at withstanding specific forms of stress, provided they are experienced to a sufficient degree. For example, when the muscles are stressed enough by lifting weight, this causes micro damage that stimulates changes in muscle physiology. These changes will make the muscles stronger and less likely to get damaged by the same weight in the future. With this principle in mind, you can get stronger and stronger by progressively overloading your muscles over time. The trick is to expose yourself to stress in a graded manner – enough to stimulate adaptation, but not enough to cause injury or prevent healing.
The same principle can be applied to rehab injuries, especially overuse injuries like tendonosis. The difference is that in this context, getting the right timing and dosage is much more difficult, because the likelihood of injury or incomplete recovery is greatly increased. This makes it harder to find the “sweet spot” where you apply enough stress to cause adaptation, but not enough to cause or worsen injury. A careful and systematic approach is required.
For example, if you are currently experiencing pain in your foot after running a mile, you could try running just short of a mile, and then slowly inching your way upwards in distance, making sure that you are not making the pain worse. If you succeed, this might be a sign that you are applying enough stress to the tissues to get them to beneficially adapt, but not enough to cause injury or prevent them from healing. Most clients find this strategy fairly easy to understand, if not to apply.
The more complicated explanation for why graded exposure might reduce pain associated with a particular movement is that it makes the nervous system less threatened by the movement, even though the tissues are not really adapting in any meaningful way.
We experience pain in relation to movement when the nervous system perceives that the movement is threatening to the body. Like other perceptions, the perception of threat is an interpretation that is subject to change based on a wide variety of information. A program for graded exposure can offer the nervous system new information about a movement that might cause a change in perception. If you can find a way to perform a currently painful movement at a low enough intensity that it does not hurt, you are sending the nervous system feedback that the movement is safe. If you do this repeatedly, perhaps the nervous system will start to disassociate the movement from the pain. This is the same rationale underlying many treatments for anxiety and phobias.
Here’s an analogy to illustrate. If a child wanted to convince his overprotective mother that it was safe to play at the playground, he would first need to show her that he can play without getting hurt. A good strategy would be to start slowly with the safest activities, and then move to more dangerous ones, all the while showing Mom he is safe from injury or threat. Hopefully Mom will eventually chill out. You can go through a similar process of graded exposure to show your nervous system that a particular movement is safe. If running three miles causes panic, try running just one and see if that is acceptable. Then slowly inch the mileage upward and monitor the response.
A major goal of any program for movement health should be to send as much “good news” to the nervous system as possible about the state of the body, and its ability to withstand the stress of movement. Whether this is done by making the body stronger, or making the nervous system less concerned about the strength of the body is sometimes irrelevant. Either way, the formula for movement success is the same. Start moving how you want to move, make sure you’re not in pain during the process, and then move a little more next time. That’s graded exposure, and it’s how we get better at anything. Like many other ways to improve health, it’s simple but not easy.