sore muscles

When you get two different answers to a question, sometimes even diametrically opposed, you can assume that there is no convincing evidence for either. One example is the seemingly age-old question: Shall I use heat or cold to treat muscle soreness? My answer is: It depends.

What does cold treatment do? First, it numbs the local pain neurons, so the sense of relief is immediate. It also reduces the local tissue temperature, which in turn reduces inflammation and swelling. The mechanism for that is by vasoconstriction, which reduces the blood flow and the release of inflammatory mediators into the site of injury. In the case of serious tissue injury, you want to reduce swelling and inflammation. This is not only reasonable, but also works for muscle strains. If you get a shooting pain during or immediately after an exercise, you have a muscle strain.

Woman straining muscle from exercise
Don’t do it — Injury guaranteed

But what if we are not dealing with injuries like muscle or tendon tears or strains? What about the run of the mill post-exercise muscle soreness?

Muscle soreness after exercise, otherwise known as delayed onset muscle soreness or DOMS, can hinder both your exercise routine and daily activities. If you feel a dull soreness starting about 8 hours and lasting for a few days after an intense bout of physical activity, it is likely that you are suffering from this common condition. What’s the treatment for it? Some “experts” say a cold bath or a cold compress. Others advocate a hot bath or warm compresses. Some cover all bases: Do cold first and follow with heat. Confused?

If you check the internet, you’d find so much nonsense that I can’t blame you for being confused. Here is an example of advice given in Fitness Magazine [Update: We noticed they removed the article]:

Question: “Will a hot bath help prevent muscle soreness after a workout?”

Answer: “Cold water is a better bet,” says Marty Jaramillo, CEO of the I.C.E. Sports Health Group. “Immersing yourself in chilled water is like an ice pack for your entire body,” he says.

When you exercise, your blood vessels open wider and stay that way for at least an hour afterward. Soreness occurs when waste products like lactic acid settle in your muscles through these dilated vessels. Colder temps constrict vessels, limiting the amount of waste product that accumulates,” explains Jaramillo.

You got it backward, Mr. Jaramillo. Lactic acid is not dumped by the circulation into the muscle—it is generated by the muscle and is removed from it by the blood vessels. So, constricting the vessels would actually accomplish the exact opposite of what is desired—it would reduce the rate of lactic acid removal. Besides, the theory that lactic acid causes the soreness has been proven wrong.

The soreness we experience after vigorous exercise is the result of micro-injuries to muscle fibers, and the repair process results in stronger muscles; precisely the reason why we exercise. So, a certain degree of soreness is actually good for you.

Like any healing, a certain amount of inflammation is required to repair the exercised muscle. White cells, rushing to the site of the injury, remove injured and dead tissue and release peptides, called cytokines and growth factors (fibroblast growth factor, epithelial growth factor, platelet-derived growth factor, to name a few), that, in a marvelously orchestrated fashion, go about repairing the damage. So why would you impede their access to the injury site with cold? It makes more sense to dilate the vessels to better allow the cells to reach the site and do their job.

Another reason why a cold bath or compress doesn’t make sense: After exercise, a muscle is contracted and only gradually does it return to its pre-exercise state. Cold will impede the relaxation. Heat relaxes the muscle and thus contributes to faster relief of the soreness.


Where is the evidence?

Amazingly, with all the hot/cold controversy, you’d expect somebody would do the study. I couldn’t find one (please send references, if you know of one). Such a study should be quite easy to do, you don’t even need human volunteers.

Run rats on a treadmill for a pre-determined period to induce micro-injuries in the quadriceps’ muscles. Then treat one group with heat, the other with cold, and a third untreated. Then take periodic blood samples to measure lactic acid and inflammatory mediators, as well as muscle biopsies, at different times after the exercise to document the histology of the injured muscle, and its rate of repair. Any sports scientist reading this?


Here’s what you should do

Until such an experiment is done, we need to just use common sense. So here is my routine:

I usually warm up before exercise by doing some stretching and light exercise, lasting about 10-15 minutes. After exercise, I stretch again and then take a hot bath for about 20 minutes. I used to regularly incur running and weight-lifting injuries. But through trial and error, and some common sense, I now manage to avoid injuries and heal faster using this simple recipe.

Bear in mind, though, this is a sample with N of 1. But at least for this experimental subject, it is 100% effective.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. Hey dov

    I’m just a kid trying to get in shape because of sports and I wanted to ask if changing my way of eating will help increase my muscle mass

  2. I have this problem where I do exercise I get sore muscles I take hot shower I feel tired and lazy for days and become unproductive and have reduced concentration .On the other hand when I take a cold shower after exercise I feel more energetic and have more concentration in expense of even more sore and tense muscles ! I don’t know how to treat my body ! Can someone help me please?!

  3. Hi Dov,

    Thanks for a great article.! After morning walk, I take bath in hot water. But, some articles on web tells that in morning its better to take cold shower.!!! I wanted to ask about the effect of seasons? e.g. whats your opinion about hot water bath in summers. I recently bought a hot tub after reading this article.

    Since summers are long here. I wanted to know if theres any downside sitting in hot tub in summers?


    • Maisie,
      Summer should not make any difference to the action of heat, such as hot bath or hot tub, on sore muscles. One caveat, drink a lot of water before and after the bath, especially in the summer, to forestall dehydration.

  4. Good news! You are NOT losing muscle mass. The achy muscles are are due to micro injuries that the muscle sustains after exercise. The healing process lasts a couple of days, and in the bargain you INCREASE muscle mass. To get maximum benefit, lay off exercising the aching muscles. If your biceps are sore, let them rest and do other exercises, such as triceps or pushups for pecs.

  5. I just got soaked dripping wet and had to sit for ten minutes before returning home, where I had a hot shower for about ten minutes. Now afterward, my muscles feel achy. I worked out yesterday. Do you think I will lose any muscle mass?

  6. Hi, I recently took a hot bath with bath salts for 10 mins after a workout and stretching, while my body was still hot. I started cramping in my arms and my face after a while. I guess I do medium level or exercise 2 times a week or so. I’ve never experienced this before.

    Any idea as to why my whole body started to cramp?
    Thank you!

    • You stumped me. Never heard of cramps in response to hot bath; it actually works the other way: heat relaxes cramping muscles.

  7. In lifting a tree limb after the hurricane Sandy, I felt a popping in the muscles of the rear of my right thigh. I never sought medical help. Fast forward: Now, several years later, I have trouble running, but can cycle and cross-country ski without problems. Hiking in the woods (uneven terrain) is definitely a problem. Even after a stretching warm-up, those muscles tighten up like knots after about 1/2 of hiking. The only relief is a heating pad—but, that really works. After reading your article, I am wondering if I should use heat before I go hiking–to start with very relaxed muscles—and see if I can hike further without pain. I intend to try this tomorrow and will post the results. Meanwhile, i welcome any comments sbout the notion of using heat before exercising.

  8. Nice article with a balanced understanding. While a study would deal with details, a solution that works is effective enough and the suggestion of hot for soreness and cold for numbing pains makes so much sense. Will try it out. Yoga too suggests cold water baths in general to charge up the body and mind system (it’s so refreshing on a dull day) whereas warm/hot water baths are suggested in case of even trivial illness or if the body immunity isn’t strong enough.

  9. I am sat in a piping red hot bath right here as I tpye… i usually go for the cold bath treatment (as i have been taught for a long time) and i am feeling so much more relaxed and tense less… defo hot baths will now be my future. Remember to take luke warm water to drink while your in the tub (not cold as the shock may get to you)… you do sweat.

  10. It works!! Thank you !! ..used to take hot showers in high school after practice. Last night, I took a hot tub and I felt good after leg day

  11. When I am excercising, it hurts to do squats because my shoulders are sore and icing it wasn’t helping. Also, I prefer showers over baths so I was wondering if there was an alternatives to getting rid of my muscle pain.

  12. OMG, OMG, OMG!!! Thought I’d share my two cents of experience. When I used to do competitive volleyball our coach would always tell us to shock our bods in a cold bath but then practices would be finished before dinner so I don’t mind. Then started rec and stopped baths of any sort completely just showers. Now that I’m doing rec, we don’t finish till 10pm and 11i have been experiencing a lot of strain no matter how many happy baby or child poses I do and I sure as hell won’t put my body into such cold shock or I would be up all night. So this week, I started my HOT BATH (just a cup og Epsom Salt) after practice and the following day was a complete revelation. I didn’t feel the knots or local pain I normally would in specific areas. Like WOW, It’s my 2nd time doing it now and I swear it’s like magic. I hope my body doesn’t get too spoiled and stopped being resilient but for now I’ll take it!!! And thinking of maybe competing again.

  13. I recently downloaded a boxer timer app and post workout do 3 minutes hot shower then 1 minute cold shower in an attempt to reduce soreness and promote faster recuperation.

    So good so far and very easy to do.

  14. We have been “blessed” with a few feet of wet heavy snow this weekend. I also have a driveway about 64 ft long. After doing the math, to shovel the entire thing was lifting a combined total of 5000 lbs. Took about an hour. After that I developed lower back pain. No injury, but soreness. Heat is the way to go. Keeps my muscles loose and relaxed. Not sure if it promotes quicker healing, but does provide short term relief of symptoms. I’m my general experience in life of athletics, heat soreness and ice injury and swelling. Knowing the difference is the key.

  15. I am a runner and the past two months due to injury I was stopped in my tracks. Just started back up and it was painful living after my first week of running, took the advice here and layed in hot tub for 20 minutes today after my run and it has been such a relive. Add me to #. Hot bath for sore muscles the way to go.

    • I agree that a warm bath helps in reducing pain of sore muscles. But let’s keep in mind that there is no real study (that I know of) that confirms it.

  16. There was a tele doctor recently that did a test of the effectiveness of both hot and cold bath therapies and found that the difference was marginal by 2-3% which is huge for professional athletes but not for your average person depends on how much you like your comfort. Also that of deep heat and deep freeze which he found useless… I will find and link when I can

  17. I completely concur with this view point. Post my last half marathon, I ended up having a nice hot bath (which I usually don’t , I stick to cold or room temperature baths) and was surprised to note that I didn’t experience any of the usual body soreness! I actually stumbled upon this, because I have been well schooled in the “cold bath or ice bath”is the best . Hot baths reduces soreness and body aches after excerise. My own experience ! You can add me to the “N” as well :)

  18. My son was working out the other day. As he was doing his work out routine he heard a pop in his shoulder. Ever since his arm is really really sore and he can’t lift his arm very high. I suggested to take a really hot bath with Epsom salts. He had also been icing and heating for 20 min intervals. Nothing seems to be working, any other suggestions would be greatly appreciated. Thanks

  19. I concur, after a long run or ride I often take a scalding hot bath, muscle aches and pains it just seem to greatly reduce. You can add me to the sample size

  20. Thank you, very informative, I have a question – has anyone tried shungite water? One of my friends advised me to try it, in his case it helped. If anybody faced this situation and tried it please advise.

  21. This is what I have always believed: If its just soreness from working out, then a bath as hot as you can stand is the way. It will relax the sore muscles. Cold baths are for injuries.

    • The only problem is that there doesn’t seem to be any evidence that cold is actually good for injuries. Sure, there is lots of evidence that it numbs pain, reduces inflammation and swelling, in addition to speeding return to action, BUT I can’t find any evidence that doing any of that is a good thing. Based on the available research, cold does not speed healing, but rather it stops it short, resulting in incomplete healing.

      • You are right, of course. The problem is that the whole field of sports medicine suffers from low quality research, not because there is anything wrong with the quality of the investigators -but because the field is woefully underfunded. this includes evidence that either cold or heat help in accelerating healing. So we have to resort to extrapolating from ancillary evidence, such as cold suppression of inflammation or heat causing vasodilation and increased blood flow to the area. Both of them “make sense” and also make you feel good right after the injury. But do they the injury heal faster? This requires a legitimate, long-term, rigorously -controlled study -and it costs money…


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