18 May 2009 03:40 pm
We’ve all known since the beginning of time that the application of heat appears to sooth away aches and pains, but up until now that so-called “knowledge” has been strictly anecdotal. We could demonstrate it and experience it for ourselves, but there was no real proof that the phenomenon was anything more than just the result of the placebo effect.
That is until I came across a press release this summer from London’s University College stating that researchers there have discovered scientific proof that heat alleviates pain.
Dr Brian King, of the UCL Department of Physiology, led the research that found the molecular basis for the long-standing theory that heat, such as that from a hot-water bottle applied to the skin, provides relief from internal pains, such as stomach aches, for up to an hour. 
Dr. King goes on to explain:
“The heat doesn’t just provide comfort and have a placebo effect – it actually deactivates the pain at a molecular level in much the same way as pharmaceutical painkillers work. We have discovered how this molecular process works.”
If heat over 40 degrees Celsius (104F) is applied to the skin near to where internal pain is felt, it switches on heat receptors located at the site of injury. These heat receptors in turn block the effect of chemical messengers that cause pain to be detected by the body. 
In the past it was easy to speculate that heat therapy seemed to work simply because it made us feel good and thus made the pain more bearable.
Add to the fact that the pain relief was only temporary, furthered the assumption that the effect was merely psychological and not really real. However, Dr. King’s research gives us physiological evidence that supports our past personal observations.
The team found that the heat receptor, known as TRPV1, can block P2X3 pain receptors. These pain receptors are activated by ATP, the body’s source of energy, when it is released from damaged and dying cells. By blocking the pain receptors, TRPV1 is able to stop the pain being sensed by the body.
Scientists made this discovery using recombinant DNA technology to make both heat and pain receptor proteins in the same host cell and watching the molecular interactions between the TRPV1 protein and the P2X3 protein, switched on by capsaicin, the active ingredient in chili, and ATP, respectively. 
And so we see that even the temporary aspect can be demonstrated at the molecular level.
What does this all mean for the future of pain research? Dr. King goes on to give his opinion on the matter…
“The problem with heat is that it can only provide temporary relief. The focus of future research will continue to be the discovery and development of pain relief drugs that will block P2X3 pain receptors. Our research adds to a body of work showing that P2X3 receptors are key to the development of drugs that will alleviate debilitating internal pain.” 
Not Just Anecdotal Any More
This, of course, means the physical therapists have been correct all along in their use of modalities such as heat and ice when treating back and neck pain. It also confirms what you and I have observed time and time again, that the relief only lasts a short while.
For those of us who prefer not to use pharmaceuticals if they can be avoided — and don’t mind settling for a temporary solution — this is interesting research and a chance to finally point to something other than anecdotal evidence.
So, if you don’t want to take a pill and all you’re looking for is something to help you get to sleep at night. Try applying a hot water bottle or one of those commercial heat packs just before bed.
It may just do the trick.
Till next time,
1. Press Release: Heat Halts Pain Inside The Body, University College London, July 5, 2006
2. BBC News: Heat ‘blocks body’s pain signals’