Kyle Poland's Background
Kyle started his education at the University of Waterloo where he completed an Honours Bachelor of Science in Kinesiology, specializing in rehabilitation sciences. His passion for helping the injured with exercise grew leading him to become a certified strength and conditioning specialist, working with the public as a strength coach. Kyle then wanted to further his education to get a better understanding of how to better help others completing a Master's of Science in Biomechanics and Neurophysiology at the University of Guelph where his thesis focused on Central Sensitization, a neurological phenomenon of how pain can persist for so long. Kyle is currently teaching sciences and providing virtual training, empowering those with chronic pain to continue participating in exercise and favourite activities despite lingering injuries.
Kyle's Instagram: tactical_fit
Pain Physiology
● Pain is extremely complicated and not completely understood, which can make treatment extremely difficult.● The basic physiology is that you sense something in your internal environment, that information comes into your central nervous system (CNS), the CNS interprets the information deciding if there is a threat or not, which will dictate if pain is felt or not. ● Unfortunately, there are many factors which play into this communication from tissue to brain including sleep, nutrition. movement, mental perception, previous experiences, really any type of stress on the individual. These factors, and many more, influence the sensitivity of the nervous system, influencing the excitability of this response to the point where even non-painful stimuli can create pain.● It is then easy to see the complexity and oversimplification that there is one specific problem causing someones painful experience.
Is Pain an Alert System?
● In its most fundamental purpose yes, it lets individuals know there is a problem. This is especially true in acute cases where traumatic injury has occurred. Although, someones expectations of how painful an acute experience will be can influence the pain they feel during the stimuli and can even increase their likelihood of developing chronic pain● With chronic pain, even after tissue has healed, individuals can still experience the pain response. So why is the alert system still active even after the thing being alerted about has ceased?
Central Sensitization
● Essential a positive feedback loop where the more pain is perceived the better the body is at then feeling that pain. ● Due to the increase in impulses coming in from the nociceptor receptors (pain receptors) the CNS will increase the amount of neurons (C-fibers) in that response, more receptors for that signal (NMDA receptors), increase the Neurotransmitters involved in the communication (Glutamate), and another neurotransmitter, Substance P, is made by the neurons and can travel down the nerves (axoplasmic transport) and restimulate the receptors at this tissue.● This shows that the pain response is not always an alert system but is your bodies perception of a threat. This can work in the reverse, where your body will decrease the perception of pain to a stimulus to allow you to flee or fight (within the context of the sympathetic nervous system) when there is another threat greater at play.
How Does the Body Break This Cycle?
● If we think of this system evolutionarily or look to creatures in the wild, they have extremely limited capability to stay immobilized after injury. This would mean loading and moving recently injured tissues. In todays culture, it is much easier to not move after injury and survive.● This perpetuates the perception of the injured tissue and positive feedback loop of central sensitization as the CNS never learns that it is safe to move because the individual is avoiding movement. ● So the answer is movement!● It is still important to allow tissues the opportunity to heal through the inflammatory process but at some point those tissues need to be used again and the nervous system taught that they are safe to use.
What Part of the Brain is Responsible for Pain?
● There is no one part of the brain responsible for perceiving pain. This is a very distributed networking involving components of sensory integration (pressure, movement, temperature, etc), stress responses, emotional responses, memory and many more.● This is why many factors play into the perception of pain. ● The thalamus dictates what sensory information coming from the spinal cord gets perceived by the brain. If the body becomes fatigued, or if there are an increase in the amount of impulses coming from the spinal cord, the thalamus then allows more information to become perceived. This is a potential mechanism as to why we feel more pain when we are tired.
Pain and the Sympathetic Nervous system
● With a perceived threat, not only is the pain sensory response activated but also the sympathetic nervous system response. This increases heart rate, blood pressure, fills the skeletal muscles with blood, releases catecholamines and endorphines (which can inhibit pain)● Over time, however, the painful response can activate a connection in the spinal cord, which is generally inactive. Anatomically there are connections between C-fiber (pain neuron) stimulation and lateral grey horn stimulation. The lateral grey horn being the region of the spinal cord housing the sympathetic neuronal cells bodies. This then could led to an increase in the pain response and perpetuation of the sympathetic nervous system activation.
Referred and Projected Pain
● Referred pain is when there is a pain stimuli in one region or organ that is then felt in another. Classic examples of these are viscerosomatic reflexes where when an organ generates pain impulses, they are felt as pain coming from the musculoskeletal system. With heart attack, an individual usually feels pain in the chest, and down the medial aspect of the left upper limb. Looking at how the visceral pain sensory fibers travel from the heart, they travel with sympathetic fibers back to the T1-4 region. This is where nerves then travel toward and back from the upper limb. There is then some confusion from the CNS as where the pain stimulis is coming from and where it should be perceived. ● Projected pain is a simular phenomenon where impulses from one region are perceived in another. Science does not have an exact explanation for these changes in perception. However, looking back to central sensitization, some areas of the body may become more sensitized to the pain response, having a reduced resistance of perception. This is Head's law, where areas of low sensibility (high resistance) can refer pain to places of high sensibility (or low resistance). There is also the concept of sprouting, where as the central sensitization process is occurring and there is an increase in neurons and interneurons between them, the interneurons dont "wire" correctly creating connections where there shouldn't be. This again can create confusion in the perception of sensations.