published 9/19/07, updated 7/12/10

Using Heat for Pain Problems

When and how to apply heat for therapy … and when not to!

by Paul Ingraham, Vancouver, Canada MORE
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Credentials and qualifications

I am a writer and retired Registered Massage Therapist (unusually well-trained for a massage therapist, a 3000-hour program). I’m almost done with a Bachelor of Health Sciences degree. I am a peer reviewer for The Natural Standard, and a copyeditor for Science-Based Medicine. My most important qualification is more than a decade of workaholic post-graduate study, clinical experience, and constant conversations with readers from around the world, including many experts who have provided countless suggestions and criticisms.

For more information, see: Who Am I to Say? More information about my qualifications, credentials and professional experiences for my readers and customers.

Not sure when to use ice or heat? Start with this super-short overview: The Great Ice vs. Heat Confusion Debacle. Please note that you should rarely (almost never) ice low back pain.

Therapeutic heating — “thermotherapy” for therapy geeks — is more useful than most people realize, because painful muscle problems are more common than most people realize. Pain caused by muscle spasm and muscular trigger points (muscle knots) is common and often severe, yet routinely mistaken for other kinds of problems. Consequently, one of the cheapest and best treatments — heat! — is routinely neglected.

Mustard plasters were widely used and probably brought about relaxation of muscle spasm through the heat generated by the plaster. Sometimes folk medicine is more sensible than ‘modern’ medicine. In any case, I suspect that the low-key, nonthreatening approach to back problems characterized by an earlier time helped to prevent the kind of long-term, disastrous courses that exist today.

John Sarno, Mind Over Back Pain: A radically new approach to the diagnosis and treatment of back pain

Everyone should understand heating the same way everyone knows how to put on a bandaid. It is a cheap, drugless way of helping an amazing array of pain problems related to muscle dysfunction, especially neck and back pain. Heat will not single-handedly “cure” such problems, but it is directly therapeutic, as opposed to “just” relieving symptoms.

What heat is for

Heat is primarily for muscle pain, and for stress relief.

The trick is knowing what muscle pain is. Muscle causes much more pain than most people are aware of. Some kinds of muscle pain are obvious enough — like the pain you get after the first ski trip of the season, or charlie horses in the night — but these are relatively isolated and obvious examples. Also, heat isn’t especially useful for them. Charlie horses are pretty fast, and for most people a rare problem, thankfully. And that post-exercise muscle soreness is virtually immune to any kind of therapy.

But muscle knots …

When you say that you have “knots in your muscles,” you are actually talking about trigger points. A trigger point is a small patch of contracted, stagnant, swampy muscle tissue. Instead of the whole muscle being in spasm, just a little piece of it is in spasm.

Trigger points are likely to be the most common cause of undiagnosed and unexplained aches and pains, especially stubborn or recurrent headaches, neck cricks and backaches. It is a much more common cause of pain than the more widely reported repetitive strain injuries (RSIs), nerve pain, or herniated disks. Trigger points also complicate essentially all other injuries: they usually appear in response to other kinds of pain and dysfunction, and then often begin to overshadow the original problem.

And heat is a good therapy for trigger points.

What heat is not for

Never apply heat to a fresh injury! Really. Just don’t do it! That’s what icing is for. Ice is for injuries.

And what’s a “fresh” injury? Any time tissue has been physically damaged, it will be inflamed for a few days, give or take, depending on the seriousness of the injury. If superficial tissue is sensitive to touch, if the skin is hot and red, if there is swelling, these are all signs that your injury is still fresh, and should not be heated.

Here’s an example of what can happen when you heat an inflamed injury:

When I was still in school, and my father had not yet learned to call me before asking a doctor about his aches and pains, he went to a drop-in clinic following a traumatic knee injury. The physician on duty prescribed heat! This is shockingly wrong, but the results spoke louder than any discussion of physiology: his knee swelled dramatically, outrageously, causing severe pain and immobility.
incident involving my father

Bear in mind that heating is for muscle knots or trigger points and muscle spasm, but not for physically injured muscle — muscle strains, pulled muscles, torn muscles. Damaged muscle is usually inflamed, not in spasm, and trigger points are a minor factor in the aftermath of the injury. It’s usually obvious that you’ve torn muscle because there is always a very clear, nasty “oh shit” moment of trauma, where you know — instantly — that something has gone quite wrong.

However, you may be understandably confused about the difference between spasms, knots, tears, etc., especially if you have back pain, where it can and does sometimes get all mixed together. People routinely believe that their backs and necks are injured when in fact they are just suffering from trigger points. I have other articles devoted to clearing up this confusion.

If you think you have a muscle strain, but you’re not sure, a great article for helping you sort it out is Save Yourself from Muscle Strain!

If back pain is your issue and your not sure what’s causing it, get thee to Save Yourself from Low Back Pain!

And the article (Almost) Never Use Ice on Low Back Pain! is specifically devoted to helping people understand why heating back pain is almost always better than icing it.

How heat works

It’s not scientifically clear exactly why heat is such a treat. However, a good guess is that there are several minor positive effects that add up to … therapy. Most of these effects are also beneficial in other ways. Not incredibly beneficial, and not even notably different from icing: for instance, a 2010 study showed quite clearly that both ice packs and hot packs were beneficial for neck and back pain, and about equally so.1 But a small therapeutic effect is still valuable even if it’s small, and there are probably situations where it works even better — after all, these were people with acute pain bad enough that they went to the hospital. They may have been a bit beyond the help of a hot pack!

Trigger points are known to be aggravated by stress (“fight or flight” hormones and neurology). As long as we aren’t overheated to begin with, being warm is a pleasant and comforting sensation. Our comfort zone is a warm place. Heat almost always relaxes you overall.

Overall relaxation usually reduces resting muscle tone. You can have “tight” muscles without actually being in spasm. There are many degrees of increasing muscle tone between relaxed and “spasm.” A true muscle spasm is very strong and painful, like a charlie horse. But many people live in a state of near spasm — their muscles always clenched and exhausted. This state is both uncomfortable in itself, causing the same kind of muscle discomfort that you have when you are exhausted from exercise … but without the endorphins. And of course it also aggravates trigger points. So any reduction in muscle tone is quite helpful. And the reduction in stress hormones makes it a more therapeutic (lasting) effect, as opposed to just momentary symptom relief.

Our comfort zone is a warm place. Heat almost always relaxes you overall.

Although scientists don’t really understand the physiology of why trigger points come and go, they have certainly identified why they hurt — the stagnant, swampy tissue fluids inside a trigger point are a disgusting bath for nerve endings. Heat facilitates circulation somewhat, helping to wash away metabolic waste products, and bring fresh oxygen and nutrients to the area. No one knows how strong this effect is.

As with everything about trigger points, there are many (many) variables, and consequently it is very hard to study, and everyone gets different results. But heat seems to have enough relevant benefits that many people get at least temporary, partial relief from trigger point pain by heating. And some people find it downright curative.

Local versus systemic

There are many ways to heat yourself. Local heating means specific heating: applying a hot water bottle, heating pad, heated gel pack or bean bag to a specific place on the body.

Systemic heating means raising the entire body temperature with a bath or jacuzzi, steam bath, or piping hot shower — basically creating an artificial fever!

I recommend seeking out a large-sized (14 × 27) Thermophore. Vastly superior to drugstore heating pads, Thermophores are the Rolls Royce of heating pads: they are large, heavy, thick, and produce a moist heat with “a special tightly-woven fleece blend cover which retains moisture from the air.” If you leave a Thermophore on a plastic surface, there will be beads of water under it five minutes later. The moisture captured from the air by the Thermophore conducts heat far more effectively than a dry heating pad. Luxurious! Both genuine Thermophores (roughly USD $50-100) and knock-offs (cheaper and probably nearly as good) can be ordered online from Relaxus.com, and are also available in some medical supply stores. Of course, Amazon.com has them, too.

Full-body heating in hot tubs, showers, saunas and steam rooms is also often the single most helpful factor in healing from conditions where emotional stress and/or knots in your muscles are the cause of your troubles, or a significant complicating factor — low back pain is the most obvious example. See A Better Hot Bath for tips on getting the most out of your bathtub or Jacuzzi. Believe it or not, many people do not really know how to take a bath! There are several simple tips that can definitely wring more therapeutic value out of the experience.

A bit more about DOMS

Perhaps the most popular therapeutic reasons to get into a hot tub is to try to beat the pain of DOMS (delayed-onset muscle soreness) — that nasty 24–28 hours of pain you get after unfamiliar exercise. DOMS is pretty much invincible. Researchers have proven over and over again that there really is no effective treatment for it.

On the other hand, the only scientific study to ever show any therapeutic effect on DOMS involved “warm underwater jet massage.” However, it was a small and flawed piece of research — and most people know from personal experience that a soak in a hot tub may “take the edge off it,” but hardly constitutes a miracle cure for DOMS.

It’s an interesting subject. For more information, see You Can’t Beat DOMS!.

Notes

Garra et al. Academic Emergency Medicine. 2010. What’s better for neck and back pain — ice or heat? This experiment, conducted at a university-based emergency department, compared the effectiveness of these two common treatments. Everyone studied received 400mg of ibuprofen orally and then thirty patients were given a half hour of either a heating pad or a cold pack.

The researchers concluded that adding heat or cold to ibuprofen therapy did not change the result. Both heat and cold resulted in “mild yet similar improvement in the pain severity.” They recommend that the “choice of heat or cold therapy should be based on patient and practitioner preferences and availability.” Return to text.