Tried to upload the video, and after I did, it was immediately removed for copyright issues, even being unlisted, wtf!
Anyway, attached a picture with what's going on:
https://drive.google.com/file/d/0By8lzXoJJdmqSXlRT0tiZ1JWVnM/view?usp=sharing
To translate what's going on there, it's like this:
Sharp pain = neuron X stimulated, then after a short time neuron Y is fired and it inhibits neuron X, pain disappears
Chronic pain = neuron X stimulated, neuron Y is inhibited, neuron X keeps firing => chronic pain that doesn't stop
When you generate some acute pain ("rough" massage) you fire the acute pain pathway, neuron X gets stimulated through that pathway (it was already stimulated through the chronic pathway) but then neuron Y gets stimulated as well, and Y inhibits X. So you can force neuron Y to fire through this acute pain that you're inflicting, in turn making X to be turned off (hopefully).
from my neurology textbooks info its not 'slow pain vs fast pain' as such but tactile senstation vs pain. so you have
no stimulation: no pain activation (C/A𝛿 - slow/fast pain fibres), no tactile stim (Aβ) - both inactive and inhibitory neurone prevents activation of projection neurone (to brain).
tactile stim (Aβ): activates Aβ fibres, which activate the projectin neurone (p) but also the inhibitory neurone (i) which blocks p.
Painful stim: C/A𝛿 activate which activate P either directly or via excitory interneurone, not inhibition of inhibitory I as first thought.
now tactile stim (Aβ) in presence of painful stim, which activate the inhibitory interneurones in lamina II of spinal cord which then block the projection fibres and therefore pain. but its also thought does stuff higher up in the CNS to block pain from that side of things too.
this is proposed mech behind massage/accupunture/tens etc
this book also mentions 'not always useful in chronic pain as some forms of chronic pain invovle phenotypic chanes in properties of low threshold afferents, so that they behave more like nociceptors. In such cases acrivation may actually increase pain rather than alleviate.' - so basically hyperalgesia?
one of my physiology books says on the topic
'stim of large Ab type sensory fibres from perihperal tactile receptors can depress transmission of pain signals from same body area, presumably via local lateral inhibition in spinal cord. - likely explaining why 'rubbing' massage and and liniments are useful in pain relief.'
- kind of straying away from the topic of massage but the pain stuff raptor brought up is interesting.
