Pain is about threat and is determined mostly by two things, one, Danger signals from nerves that are spread through your body like a spider web, and two, the sensitivity of your nervous system
Most of these danger signals are warnings that tissue damage has occurred or could occur. Additionally, you can have pain without tissue damage because your brain still is processing possible danger to your system.
There are many threats to a person such as mechanical, chemical, psychological or combination, but for this course we’ll focus on threats that can cause low back pain.
As your body receives an increased number of danger signals, and it feels threatened, the system gets more sensitive to danger. Why would this happen? It’s a learning process your brain and body have to better protect you. This sensitivity happens in the nerve tissue that’s spread throughout your body, in your spinal cord, and in some of the danger signal processing areas in your brain. This is a biological response your body builds up— often without your knowledge.
So let’s say you are going back to the gym, you want to work on those legs and glutes for the summer. The last time you did squats was this same time last year for a few months. Lets say you’re doing a sumo squat, nothing hard core. This exercise requires stretching and compressing some structures more than usual around the knee, hip joint and spine.
The joint mechanoreceptors, which are extensions of the nervous system, provide feedback on knee flexion and load at the various knee flexion angles.
The nervous system, joint structures and muscle have been functioning at a set point like a thermostat. New loads applied will trip the thermostat or in the case of the nervous system will produce sensations because it is not sure yet if the new loads are threatening. The mechanoreceptors provide feedback if it is okay to proceed on or not.
When a new activity is introduced the receptors relay that information to the brain to determine if the new activity is threatening.
For example when lifting a heavy box the thermostat is activated and the response will either be painful enough to stop or a milder discomfort or strain.
Then with enough exposure to the new activity, the thermostat will reset. The nervous system will adapt accordingly – either negatively or positively. This is what we call neuroplasticity.
The system has to adapt in an effort to survive the new loads.