First off, its important for patients to understand that our body is built on a bunch of thresholds. The body wants to stay within the threshold (called homeostasis). Even with influences put on it (exercise, heat, alcohol, just to name a few) it can do a remarkable job at keeping you within the thresholds. However if we are to leave the threshold (or even get close to it) the body will let us know. For example, put your hands near a campfire and you get a velvety warmth and the perfectly toasted marshmallow. However, get too close and you feel a quick and immense pain or shock that causes reflexive drawing away of the hands. Why did it do this? TO PROTECT YOU. Your sense of warmth (from nerves called thermoreceptors) in your hand registered that the heat was excessive and thus perceived as a threat to the system. So a noxious (painful or irritating) stimulus turns on your sense of pain (nociception) to protect you. Here is a simple pic to illustrate this phenomenon.
Similarly, our muscle, joints, and nervous tissues will let us know if we passed the threshold. And when the patient arrives in pain (and not exercise induced soreness) we can simply say "Pain occurs when some immeasurable threshold is reached where the brain perceives a sufficient enough threat to output [or register] pain. An injury can be viewed as the body’s failure to adapt to the imposed loads that exceed the threshold for positive tissue adaptability " Greg Lehman
Further, once we go beyond the threshold and we don't take immediate action our body will lower the threshold to ensure we're paying attention to it. This is why so many patient histories start with "it used to hurt just when I did "x" but now "it hurts with x and y and z...and a just a little x and at rest". Additionally, most patients' pain that begins insidiously/randomly can be explained with this 'threshold model'. The body's mechanoreceptors, proprioceptors, etc. slowly get worked to the threshold with aberrant movements or postures and/or repetitive strain. When the body moves via compensation, it increases the risk of loading tissue excessively or over facilitating muscle groups that eventually may fatigue. With fatigue, the noxious threshold comes faster, and injury often occurs.
Therefore our job is to:
1. Decrease the threat and back away from the threshold. Find the source or pattern that is causing the body to pass over the threshold and fix it. Since multiple factors influence this sensitivity, it is important to attempt to address all factors with the appropriate modality.
2. Increase the threshold, or tolerance, prior to nociception activation.
3. Ensure the understanding that pain in itself is not a bad thing. Would you really want to turn off your sensation to excessive heat and risk the chance of a burn? Of course not! Similarly, let's not rush to turn the system off with shots and medications. This may limit our ability to find the threat and get rid of it (i.e. find a directional preference).
Hopefully with a better understanding of pain our patients can know the importance of what their doing and thus improve their compliance.
