Practical Science on Movement and Pain
Practical Science on Movement and Pain
In the previous post I discussed the fact that chronic pain is sometimes not so much a problem with actual ongoing physical damage to the body, but instead due to issues with the way the central nervous system processes pain. In other words, the pain alarm system is just going off too often, too loud and too long for no good reason. If this is the case, then you need a pain relief strategy that targets the brain and not just the body.
This post lists some basic mechanisms that can help turn down the volume on the alarm system. Although you may not have heard of any of these mechanisms before, one or more of them almost certainly explain a great amount of the pain relief that people sometimes get from almost any type of therapy, including bodywork, feldenkrais, chiropractic, yoga, pilates, tai chi, acupuncture, etc. Here they are.
Creating Noise to Block the Pain Signal
One of the primary ways that movement, exercise or bodywork can reduce pain is the phenomenon of sensory gating. Sensory gating means that the processing and perception of sense information is reduced by the presence of other competing sense information. If your nervous system is busy trying to process signals resulting from movement or touching, it has less ability to perceive and process pain signals. Most people will instinctively take advantage of sensory gating by rubbing an area that has just been injured. The rubbing sends sensory signals to the brain which compete with the pain signals and reduce their processing and perception. An active muscle contraction will also serve to reduce the perception of normal or painful stimulus to the skin. In fact, during vigorous exercise and for 10-15 minutes after, pain perception is reduced. It appears that sensory gating and resulting pain relief will be greater where: the competing stimulus is closer to the area of pain; the competing stimulus is more interesting and novel; and the stimulus comes from active movement rather than passive movement or touching.
Based on these facts, we can conclude that sensory gating will be maximally effective with active movement that is novel, interesting, rich in proprioceptive and sensory information, and near the site of pain, without aggravating the pain. An example might be trying to reduce knee pain by doing slow, mindful, non-threatening, novel and interesting movements at the ankle and hip joint, without causing any pain in the knee. Sounds like Feldenkrais or Z-Health in a nutshell.
The gating theory is an excellent way to understand how movement, exercise or bodywork can make us feel better. In fact, a great amount of pain relief that occurs with any of these modalities is likely explained by this mechanism.
Refine Your Body Maps
Body maps are important. They are neuronal networks in the brain that act as representations or maps of body parts. They are in essence virtual bodies. As far as pain goes, the representation is the reality. If your brain map says that your left arm is on fire, you will feel like your left arm is on fire, even if you don’t have a left arm on fire, or even if you don’t have a left arm at all. Phantom limb pain is a very real and very common ailment for people with amputated limbs, and it is an example of the fact that the virtual body is just as important as the real body in determining what you feel.
Accordingly, we want to make sure that our maps are as clear and accurate as possible, so that the brain does not mistakenly put pain somewhere it doesn’t belong, or mistake normal sensory information for pain signaling, or otherwise just become threatened by the fact that it doesn’t really know where the body is or how to move it well. Recall that all pain is an alarm signal that occurs when the brain believes the body is under threat. We would guess that the brain would be inherently threatened by not having an accurate map of a certain joint, just as we would feel threatened by walking into a room without the lights on or by using a power tool with a blindfold. If you walked into a dark basement, and brushed up against some unknown thing, you might let out a scream even if you weren’t hurt. Similarly, the brain might create pain in a joint where it doesn’t have any accurate information about what is going on there.
Our body maps are developed and modified primarily from the sensory feedback that comes from movement and touching. The modifications can be sensed very quickly. Without looking, try to sense the exact direction that your right big toe is pointing. Now move the toe in a circular arc from the ankle for a few seconds, let it come to rest, and try to sense where it is pointing again. It should now be easier to sense the direction of the right toe compared to the left. If you spend a minute or two carefully and slowly writing the alphabet with your toes, you will find that the whole foot is now easier to sense and move in a coordinated fashion. The change is not to your foot, but to the virtual foot in your brain. The sensory information provided by the movement has filled in some gaps or blind spots in the brain maps. This is good, because if pain is an alarm system, more accurate sensation of what is going on in the foot will lead to fewer false alarms. We would further expect that the clearer map and enhanced movement skill would reduce threat coming from the ankle, which might reduce pain. In fact, many people who perform this exercise find that walking immediately feels softer, easier, more balanced and possibly less painful.
In my opinion, most of the benefits of most bodywork and movement therapies are due to changes in the body maps that occur with touching or movement. Pilates, yoga, and tai chi provide particularly interesting sensory feedback from movement that feeds the maps. Bodywork, massage, chiropractic, and acupuncture provide novel and interesting touch stimuli that has the same effect. I think one of the reasons I enjoy strength training is that for a day or two after a good session, the mild soreness of the workout provides me with a much clearer image of where my muscles are and what they are doing. It also makes me feel heeuuge, bro’.
So what is the best way to refine the body maps? Just as with sensory gating, refinements to the proprioceptive maps are more likely to occur with active movements that are mindful, novel, curious, exploratory, active, and purposeful. Babies develop their understanding of where their limbs are in space with exactly this type of movement. Moshe Feldenkrais developed the logic of his method with these ideas in mind, in order to develop what he called the self image.
Develop Movement Skills
Pain is often is related to a certain movement or posture. For example, there is no pain until you bend your knee a certain way, or twist your spine in a certain way, or sit in a chair in a certain way. For whatever reason, the CNS obviously thinks that the painful move or position is a bad idea, and it is sending you a pain signal to discourage you from making it again in the same way. One strategy to reduce the pain is to move in a subtly different way that does not threaten the CNS. In general, we can expect that the more you move with coordination, control and efficiency, the less threatened the CNS will feel about that movement. Therefore, improving your movement skill is a way to give the CNS some good news that will reduce perceived threat related to movement. This means that anything you can do to improve movement skills and physical capability will likely help with pain related to movement. So, another reason that pilates, yoga, tai chi, martial arts, dance, or weight training can reduce pain is due to improvement in movement skill that lowers threats related to movement.
Usually people will explain the therapeutic aspects of improved movement in purely physical or mesodermal terms – more efficient movement simply causes less wear and tear on the body which reduces pain. I think that is a valid argument but there is probably also a purely ectodermal or “virtual” benefit to improved coordination as well – it calms a threatened nervous system about the dangers of moving, even when actual tissue health is relatively unaffected.
I think the above three methods for reducing threat to the CNS – sensory gating, improving body maps and movement skills – account for a significant amount of the benefit seen in most bodywork or movement therapies. In the next post I will discuss some additional strategies that are also aimed directly at the ectoderm.