Hot Off the Press! Cold vs. Heat: Which is Best For Muscle Soreness?

Let's say you've just finished an intense conditioning session. Your body is aching and you know that soreness and stiffness will inevitably set in, making walking up and down stairs a nightmare for the next several days. So you decide on a post-workout rehab method to help stave off soreness and get your tissues ready for the next workout. Do you hop in an ice bath (as athletes have done for generations), which some studies show may increase free radicals in the body? Or do you opt for some heat therapy, which  until now  has not been proven effective at reducing muscle soreness? Do you ice, hoping that the cold prevents local inflammation and numbs muscle pain? Or do you heat, in order to increase vasodilation and blood flow to the tissues in need of repair?

Many coaches and trainers have strong opinions one way or the other, and for good reason: the issue is directly applicable to how well and how quickly athletes can recover from a tough workout. But although the problem seems cut-and-dry (only one method can be the clear winner!), previous research on the subject is, as Loma Linda University scientists observed in a recent Journal of Strength and Conditioning Research article, “in total confusion” (3250). Studies on the subject of heat vs. cold therapy are controversial, often either contradicting each other or showing no actionable results at all. The Loma Linda team, led by Jerrold S. Petrofsky, set out to prove, once and for all, which modality is superior at reducing muscle soreness and increasing the rate of tissue repair.

The researchers studied the effect of heat and cold on 100 subjects aged 20-29, all with similar BMI, height, weight, and training background. They selected an exercise protocol guaranteed to elicit DOMS (delayed onset muscle soreness)  5 minutes of continuous bodyweight squats, repeated for 3 sets  and coached the participants through the session. Some participants were given heat or ice immediately after exercise, some 24 hours after exercise, and some no modality at all (the control group). The research team also took measurements from the participants before the exercise bout, directly after, and for a few days beyond that  measuring subjective muscle soreness (which participants self-reported on a scale-type rubric), maximum muscle strength, hemoglobin levels in the blood (elevated levels indicate muscle tissue damage), and passive range of motion. And what they discovered flies in the face of today's standard practices for rehabbing athletes.

Petrofsky's team found that heat applied to muscles immediately after exercise was the superior to all other methods at preserving muscle strength and limiting damage to muscle tissue.

The researchers conclude, “For some reason in athletics, it is believed that cold after exercise is the best modality to prevent swelling and damage to muscle. At least for this age group, this is not true. There is a definite advantage of heat after exercise, if applied or used immediately” (3250). In my eyes, these findings are pretty revolutionary! 

BUT! There are a few caveats. 

  1. Cold therapy (applied to muscles immediately post-exercise AND 24 hours post-exercise) was better at reducing the participants' subjective soreness. Both heat protocols were also effective at reducing soreness, just to a lesser extent.
  2. The specific modalities used to apply heat and cold matter. Cold (in the form at ThermaCare ice wraps) were applied for 20 minutes, as is consistent with industry standards. Heat (ThermaCare heat wraps), on the other hand, was applied for 8 hours. 8 hours! That's an awful long time. The reason is it takes a long time for heat to penetrate deep tissue through layers of fat and skin, and must be low enough in temperature so as not to burn the skin. The study didn't specify if the participants could move around during the heat therapy  my guess is that they could, with the heat wraps strapped to them  but if they had to sit still during the heat application, that just isn't practical for life outside the lab.
  3. It is important to note that the participants studied were non-athletes. And while human muscle tissue should respond similarly across our species, it bears mentioning that this study was not conducted on well-trained athletes, which may affect the applicability of the findings.

Here is my personal takeaway on this article.

While I have questions about the practical application of the results, this research seems to take the heat vs. cold discussion to a new level. My hope is that, from here, scientists can begin to research new heat therapy methods (maybe ones that don’t as long to be effective), better cold therapy methods, and the effects of these modalities on athletes. In the meantime, this article is making some headway in the search for the most effective (and implementable) way to help muscle tissue recover more quickly from strenuous exercise. 

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Christye Estes, CSCS, is one of the regular contributors to the Volt blog. She is an NSCA-certified strength coach and a Sport Performance Specialist at Volt.
Learn more about Christye and read her other posts | @CoachChristye