| Getting Hot For Recovery

Author / Hunter Waldman

5-7 min read

Mathematician and hair model Isaac Newton once stated that for every action, there is an equal and opposite reaction. For hard charging athletes, every training session has (or should have) a reciprocal recovery session. The “bread and butter” for recovery methods include getting sufficient quality and quantity (7-8 h) of sleep per night, sufficient protein post-workout (~40 g), and a passive-cool down immediately post-exercise (Power Athlete Cool-Down, anyone?). However, once an athlete has taken care of these recovery essentials, it is not uncommon to find athletes then turning their attention to recovery methods like soft-tissue work (e.g., foam rollers, massage guns, or manual manipulation), electronic muscle stimulators (EMS), and the ever popular cold-exposure. Interestingly, cold exposure may not be as effective as the social influencers are making it out to be (sorry Hof fans), and there may be a method that has yet to be examined in pop culture, but that new research is demonstrating as an effective means for reducing soreness and muscle damage post-training.

Don’t Cry over Cryotherapy

With a new focus on cold exposure, popular methods you’ve probably seen online include cryotherapy and cold-water immersion (re: every person ever on Instagram with a picture of themselves in a bath with ice-cubes talking about philosophy). Look, muscle temperature manipulation is not something new…although it would appear to be the next great thing. A graduate student of mine from the Ukraine once told me that all infants from his small town are immediately dipped into ice water in the creek by their hospital, because they believe it creates a strong immune system and builds character. While maybe not as impressive as your 2-min in the ice bath you created for yourself, there are certainly benefits to cold exposure, which include small improvements to one’s androgen profile, an increase in brown fat conversion, increased energy expenditure, and possibly better glucose management for those who need it (1). However, when it comes to recovery and the focus of this blog post, the data are mixed. With attention specifically on cryotherapy, and at the risk of making angry all Joe Rogan readers of this post, the purported benefits of enhanced recovery and reducing muscle soreness are beginning to conclude the benefits for cryo are over-exaggerated…and may even reflect a simple placebo effect (2-3).

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Chill, Bro

With respect to cold water immersion, the conclusion from research is that if the water is at an appropriate temperature (8-15°C), and it is under continual circulation to avoid a thermal barrier from building, then cold water immersion is effective in reducing muscle soreness and increasing recovery time (4). The only problem, and it’s a big problem, is the timing of this recovery modality. If done too close to the workout window, cold water immersion is known to mitigate the anabolic responses that take place during muscle recovery…aka much less gainz obtained over time (5). In fact, most all of the current research on cold-water immersion right after training shows it either has null or detrimental effects to training adaptations. Not good! What about when performed several hours pre or post training? To be honest, we need more research. I’ve listened to some well-respected individuals talk about the benefits of cold-water immersion on other aspects of health, but 1) the benefits tend to be blown out of proportion, 2) there’s currently not enough research on the best duration for cold-water immersion exposure and recovery, and 3) we simply need more data points to draw further conclusions.

A good example of the “benefits” of cold water immersion is often the cited increase in testosterone in men following cold-water immersion. Based on the current research and one highly cited article from 1991 (6), the increase in testosterone tends to be about ~10%. To put this in perspective, normal ranges of total test is somewhere between the range of 400 – 1200 ng/dL. If we shoot the middle and say a male has a test concentration of ~600, a 10% increase takes that male acutely from 600 to 660 ng/dL. I’d argue you would get a larger increase in test levels if I simply took you to Miami and let you look around the beach for ~10 seconds. While my intention is not to put down cold-water immersion (because I do believe there are other benefits which extend beyond recovery), I’m simply saying we don’t have enough data to conclude the need just yet for you to go and build yourself an ice bath in January if the goal is recovery.

Recovery – Its So Hot Right Now

All of this said, there is one method that I’ve seen in the literature that is gaining some hard evidence as a manner for increasing recovery, and which can be done immediately after training: hot water immersion, or thermotherapy. Although the mechanisms are still be worked out, the current thought is that during hot water immersion, heat shock proteins are activated and accumulate in the damaged muscle (7). This accumulation of heat shock proteins then assist in the repair and recovery of those muscles, thus speeding up recovery for the trained athlete. And while taking a picture in a hot-bath may not gain you as many Instagram followers, those jacked muscles following a proper recovery routine will! It is important that I point out that the evidence in this area is also limited, but promising so far. We do know that localized heating appears to do nothing really for recovery, while whole body heating appears to not only enhance recovery, but may even increase anabolic signaling (8). An important note though – prolonged hot water immersion (>30 min) can lend itself to orthostatic intolerance, which is that dizziness you get when you stand up too quickly. Just like with cold-water immersion, the dose here is the medicine. Too long and you risk injury and not long enough, and the stimulus is too low to result in anything at all.

When it comes to hot-water immersion, the water temperature should be at least 96.8°F and no greater than 105°F. Keep in mind this is not hot-sauna bathing, where temperatures can exceed >160°F. There is a difference in heating air and heating water which then comes into contact with your skin. In addition, the ideal duration appears to be somewhere 10-30 min. If you are not acclimated to hot-water immersion, general guidelines would suggest start around ~10 min, and slowly build up to 30 min over a period of 3-4 weeks. Further, hot water immersion can be done daily or throughout the week as you see fit. Finally, always (ALWAYS) have with you some form of hydration beside the bath, as prolonged hot-water immersion can start to result in mild dehydration if those liquids are not put back.

In conclusion, you’ll all start hearing soon about hot-water immersion once the next influencer catches on. You can get ahead of the curve and start playing around with the water temperature and duration yourself, and see what works best for you. Remember, its never how much work you did in the gym or on the field that matters, but how much you can recover before the next session.

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1) Ivanova YM, Blondin DP. Examining the benefits of cold exposure as a therapeutic strategy for obesity and type 2 diabetes. J Appl Physiol (1985). 2021 May 1;130(5):1448-1459. doi: 10.1152/japplphysiol.00934.2020. Epub 2021 Mar 25. PMID: 33764169. 2) Nadarajah S, Ariyagunarajah R, Jong ED. Cryotherapy: not as cool as it seems. J Physiol. 558 2018;596(4):561-2. 3) Cheng AJ. Cooling down the use of cryotherapy for post-exercise skeletal muscle recovery. Temperature. 2018;5(2):103-5. 4) Petersen, A. C., & Fyfe, J. J. (2021). Post-exercise cold water immersion effects on physiological adaptations to resistance training and the underlying mechanisms in skeletal muscle: a narrative review. Frontiers in sports and active living, 3, 660291. 5) Malta, E. S., Dutra, Y. M., Broatch, J. R., Bishop, D. J., & Zagatto, A. M. (2021). The effects of regular cold-water immersion use on training-induced changes in strength and endurance performance: a systematic review with meta-analysis. Sports Medicine, 51, 161-174. 6) Sakamoto K, Wakabayashi I, Yoshimoto S, Masui H, Katsuno S. Effects of physical exercise and cold stimulation on serum testosterone level in men. Nihon Eiseigaku Zasshi. 1991 Jun;46(2):635-8. doi: 10.1265/jjh.46.635. PMID: 1890772 7) Paulsen G, Vissing K, Kalhovde JM et al. Maximal eccentric exercise induces a rapid accumulation of small heat shock proteins on myofibrils and a delayed HSP70 response in humans. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 584 2007;293(2):R844-R53. 8) Ihsan M, Deldicque L, Molphy J, Britto F, Cherif A, Racinais S. 596 Skeletal muscle signaling following whole-body and localized heat exposure in humans. Frontiers in physiology. 2020:839.


Hunter Waldman

Hunter Waldman is a former DII collegiate linebacker who found his passion in Nutrition and Exercise Physiology during his undergraduate years. After working as a Strength and Conditioning coach/personal trainer for several years, Hunter pursued his doctorate in Exercise Physiology while also serving as a Sweat Scientist for the Gatorade Sport Science Institute (GSSI) in Florida. Hunter is now a Professor of Exercise Science at the University of North Alabama, Researcher, Director of the Exercise Biochemistry Laboratory, and Power Athlete Block-1 Coach. Hunter's research area is in Nutrition and Metabolic Health/Performance, where his lab is attempting to understand how to increase cell stress resiliency via nutrition, supplements, and exercise.

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