Heat therapy is when any sort of heat is used to help manage pain in the body on its own or in combination with analgesics.
Local heat - which is a device placed on a specific area of the body e.g. heat pack, wheat bag, hot water bottle
Systemic heat - heating the whole body e.g. hot shower, bath, sauna, jacuzzi
When to use heat?
Heat is mostly used for non-inflammatory pain. Ideal for:
muscle soreness from over exertion, delayed onset muscle soreness (DOMs)
muscle pain, spasms, cramping or stiffness
‘hurts everywhere’ sensitivity and pain from conditions like fibromyalgia
When not to use heat?
It is not recommended to use heat for an acute infection or acute inflammation e.g. arthritis or lupus acute flare in a joint, or fresh new injury like ankle ligament sprain or muscle strain. What for the inflammatory phase to pass before introducing heat.
How does heat help?
Heat is a comfort, it's soothing and this reassures the brain and thinks its safe, which acts like an analgesic reducing pain (this isn’t just a psychological affect, its about neurology!)
Heat can also affect the tissue directly and its thought cell processes are thought to speed up which can promote healing faster
Heat can help relax muscles – and reduce muscle spasm and tone by improving elasticity
It can increase blood flow to the area which is thought to help ‘flush’ out toxins – limited research on this
Risks of using heat
You can burn your skin with repeated use of heat packs in the same area, especially if you have decreased sensitivity. It is also common when using heat in the same area that you gradually feel the need to have the heat pack hotter and hotter to feel the same level of relief as your tolerance increases. This can be dangerous to your skin and lead to superficial skin burns.
EAI is a skin reaction caused by chronic exposure to infrared radiation aka heat. It creates a web type pattern that easily blanches (go white when you press it). Women are more likely to experience this than men and more common in the elderly with sensory issues, although it can be seen in other settings such as laptop burns too.