The Big Picture of Pain
Pain can be a complex phenomenon, meaning that many different factors might contribute to pain, and that these factors can be interwoven in a way that makes it very hard to separate one from the other, either for purposes of explaining pain or intervening to treat it in some way.
This was the theme of a talk I did a few weeks ago at the Oslo PainCloud Convention, in which I argued that complex systems theory has many concepts that are useful in understanding the nature of pain.
One of those concepts is that complex systems are often nested. That means the system as a whole is composed of smaller subsystems, which are also composed of smaller subsystems and so forth.
For example, people are made up of organ systems (like the nervous system or musculoskeletal system), which are in turn composed of organs (like the brain and spinal cord, muscles and tendons), which are composed of cells (like nerve cells and muscle cells) and so forth. Further, people are parts of larger systems like families and communities and economies.
The reason this is interesting from a practical perspective is that each nested system provides a different level from which we can attempt to explain and treat pain.
Here’s a diagram to illustrate:
At the “lower” levels, you can view the health status of cells and organs like muscles, tendons, discs or nerves. For example, maybe your foot hurts because of a stress fracture. This is where you can find "issues in the tissues", which is where traditional pain treatment has focused most of its attention. This is often called the "biomedical approach" or the "bio" part of the biopsychosocial model. You find the structure that is damaged and work to repair it.
At the “higher” levels of analysis, such as the person or the environment, you are looking at more complex phenomena – the role of thoughts, emotions, or social relationships. These are the “psychosocial” issues that are known to have very important effects on chronic pain. Problems in these areas are often relatively subtle, more about dysregulation or imbalance than something being broken or injured. These issues are also invisible if you look for them at a lower level. For example, you can't see catastrophising by assessing a foot - you need to talk to a person.
Fields of Study
There are many different formal disciplines you could study to get a better understanding at each level. Note that they are very different from one another, and very few people will have significant knowledge at more than one level.
At the lower levels, you could study biomechanics, exercise physiology or neurodynamics. Each would give you a better understanding of how physical structures in the body respond to stress – either by breaking down and getting injured, or adapting to get stronger.
You could move up a level to study the behavior of a larger system like the nervous system, immune system or endocrine system. This would give you some understanding of how the body mounts a protective response to perceived physical threat. Pain is in the nature of an alarm. The nervous, immune and endocrine systems help set the sensitivity of the alarm, and determine the kinds of events that cause it to go off. “Pain science” is mostly education in the basic physiology of these systems as they relate to pain.
We can move up another level to the “person”, where we are studying the role of cognitions and emotions in pain. This is the realm of psychology, the relevance of which should be obvious - pain is a psychological event.
Psychological concepts can be very useful in understanding why movement and physical activity help with pain. For example, cognitive behavioral therapy can explain how exercise could extinguish fears or expectancies that might be contributing to pain. In many cases, this perspective is more helpful in choosing an exercise program than one focused on "lower level" concerns about muscle groups, reps and sets.
You could move yet higher to study the role of social and economic systems. Many social critics would argue that the real pathologies causing a wide variety of chronic diseases – including drug addiction, anxiety, depression, and even chronic pain - live more at the level of society than the individual. For example, low socioeconomic status is a big predictor of chronic pain. Most readers of this blog are not active in trying to solve problems at this level, but are quite aware that they have a big impact on clinical outcomes.
Comparing the Different Levels
The terms "high level” and “low level” don't reflect any value judgment. They merely indicate different perspectives: one is taking a “micro” view of relatively small and simple things like tendons or muscles, and the other is taking a “macro” or big picture look at larger complex things like nervous systems and emotions.
In general, if you’re moving down levels in your effort to explain some problem, you could call that "reductionist." And if you’re moving up, that might be called a more "holistic" or "systems thinking" approach.
Again, there is not necessarily any right or wrong here - the right level depends on the context. Some problems with pain, especially those related to acute injuries, benefit from a lower level approach - strengthen this, stretch that, do X sets of Y reps for Z weeks and then you will be fixed. Other pain problems can never really be "fixed", and may be hard to manage even with a whole team of psychotherapists, social workers, and attorneys.
Although each end of the spectrum has its costs and benefits, there is no doubt that until very recently, manual and movement therapists have spent way too much time at the lower levels, looking for issues in the tissues, while ignoring some very real human issues sitting right in front of them. If the "pain science revolution" means anything, it is trying to improve basic literacy at the higher levels.