Stack cold exposure, exercise, and sauna to recreate the evolutionary experience of your ancestors.
Summary
Science isolates experimental interventions to study their effects separately, but our ancient ancestors typically experienced them in combination.
The most important of evolutionary environmental experiences contrasted wet cold with dry heat, exercise with rest, and sunlight with darkness.
Integrating separate research studies with an up-to-date understanding of human evolution suggests new combination protocols for antifragility.
Could combining ice bath, then exercise, then dry heat sauna boost benefits to levels greater than those obtained when practiced individually?
A new antifragile workout stack?
Evolution at the water's edge
Dr. Jack Kruse recently recommended a wonderful academic research book titled Human Brain Evolution: The Influence of Freshwater and Marine Food Resources (Cunnane & Stewart 2010) that describes the environmental conditions under which Homo sapiens were most likely to have evolved. In my earlier article How cold water immersion shaped human evolution, I described the features of human anatomy that support the Aquatic Ape Hypothesis (Hardy 1960). For example, unlike the chimpanzees and bonobos with whom we share 99% of our DNA, I argued that humans:
are streamlined for swimming & diving with less body hair,
walk upright to facilitate foraging thru shallow waters with our heads above water,
have subcutaneous fat (just under the skin) to help keep us warm and buoyant in cold water,
have downward facing nostrils to allow diving without forcing water up our noses, and most importantly,
are born knowing how to swim, because our ancient grandmothers likely labored in cold water.
However, the one aspect of human anatomy that most distinguishes humans from every other creature is our enormous brain. While I talked about the necessity of water birth to ease the difficulty of passing a big baby brain through a narrow human pelvis, I didn't go into depth about the evolutionary and geographic conditions on which our brains depend.
That geography is aquatic.
Of necessity and convenience, early hominids would have made use of the aquatic food chain thereby making possible the spectacular evolution of the brain and brain size.
It goes without saying that fresh water had always been essential for survival... . We may reasonably infer that an even closer proximity between man and water would have been of intense survival value. I envisage such a close relationship would have involved not only water for drinking and keeping cool, but also increased dependence on aquatic food resources. - Prof. Philip V Tobias (p. ix, 2010)
There were at least two reasons for the intimate human relationship with the water:
Only aquatic food resources (e.g., shellfish) can provide the omega-3 fatty acids that are necessary to support development of the enormous human brain, and these were not available in the grasslands of the savanna, and
During the Ice Ages, the human populations were squeezed between advancing equatorial glaciers and the coasts. As ice built up over the continents — including the equatorial glaciers of East Africa — sea levels dropped and humans moved into the areas of land that were uncovered by the receding coastline. The fossil remains of those ancient human communities are now underwater, but the consequences of those periods on human evolution were likely profound.
While we think of Africa as a warm continent, it's easy to forget that there are three modern mountain-top glaciers near the equator in East Africa, including Mount Kilimanjaro in Tanzania where Wim Hof makes his record-breaking, shirtless hiking expeditions in the snow. So, despite our expectation that human beings must've evolved in a hot place that was without winter, it must also be true that there was no shortage of streams and rivers fed by melting snow. In short, the water in the African metaphorical Garden of Eden where the first human women gave birth must have been cold, given the hydro-geography of that region at the time.
Moreover, as climate fluctuations drove growth and recession of the African glaciers, a burgeoning humankind experienced what are called population bottlenecks. During an Ice Age bottleneck, habitable areas are geographically confined to the coast by inhospitable cold. For example, the super-eruption of the Toba volcano in Sumatra only 70,000 years ago likely spewed so much ash into the upper atmosphere that it partially blocked the sun for several years. Global temperatures dipped, and glaciers advanced. During that time, the total human population may have been reduced to as few as 4,000, all living in equatorial regions, subsisting on fish and whatever else the aquatic ecosystem could provide because “Toba could have been responsible for six years of relentless volcanic winter, substantial lowering of plant biomass, and disastrous famine" (Ambrose 1998). That is, no matter whether your ancestors hailed from the North Sea (as mine did) or from the equator, the early evolutionary experiences shared by all human ancestors likely shaped our anatomy to need cold water immersion on a regular basis. In this respect, cold water immersion is like exercise and sunshine. To thrive, human beings need some of all three.
Combination therapies for anti-fragility
Just like our bodies are evolved to expect sunshine and exercise, we get sick if we're not getting enough of cold-water immersion. That is, an expectation of whole-body, cold-water immersion is likely in our ancient DNA.
There are at least three elements of the ancient ancestral environment that were likely experienced together, although they are typically studied separately by modern science. The three elements are:
temperature: hot vs cold,
exercise: active vs resting, and
light: ultraviolet vs infrared, sunlight vs darkness.
The myriad of possibilities makes systematic investigation of each an expensive and laborious undertaking. Whereas scientists typically isolate study of one variable at a time, everything is experienced by human beings in some variation and combination.
Variation
In Antifragile: Things That Gain From Disorder, philosopher Nassim Nicholas Taleb suggests that it is not just eating Mediterranean foods that confers health benefits, but also the religious custom among Mediterranean people to abstain from certain foods for as much as 180 days out of each year (Taleb 2012). In other words, the benefits of the diet come from both the feast and the fasting that are customary to the diet -- which is a good example of variation.
What is true for diet is also true for sunlight and exercise. We need the dark to benefit from the light. We need the rest to benefit from the workout. Most scientists working in phototherapy and exercise physiology understand this principle of variation and there are several studies that look at them together. However, when it comes to deliberate cold exposure, almost no one looks at the advantages of thermal contrast therapy (ice bath and sauna), even though tradition often employs them in variation.
Combination
With three different variables and at least two different settings for each, there more than 8 different ways to combine hot/cold, exercise/rest, and light/darkness. While the possibilities might be mind-boggling, returning to our evolutionary narrative likely provides us with some insights.
A typical Ice Age day for our ancient ancestors might look like what we would now call a Maine lobster bake. For example, suppose our ancestors spent the afternoon wading thru the water, hunting for lobsters, clams, or other shellfish. That's some cold water and some sunshine combination therapy. Early in the evening, our ancestors might make a fire so they could cover hot rocks with wet seaweed to steam the lobsters and clams. That's a dry heat and red/infrared therapy combination. Finally, they'd stuff themselves on lobster meat before nodding off to sleep under a dark sky. That's some recovery and darkness combination therapy.
My own childhood experiences by the coast include all of these experiences: swimming, fishing, grilling, and napping on the beach at night. I remember them joyfully.
Could they have been so bad for me?
Ice bath, exercise, sauna protocols
Susanna Søberg, PhD has advocated for 11 minutes/week of whole-body cold-water immersion and 57 minutes/week of sauna. However, her published research focuses on winter swimming, and does not examine the combination of cold and hot. Moreover, her public recommendations to always end with cold when practicing thermal contrast therapy seem to be motivated by maximization of caloric expenditure during rewarming – even though we know that calorie consumption may not be the primary goal of thermal contrast therapy (Søberg et al. 2021).
What if there's an even better way to do it?
The most prolific thermal contrast therapy researchers in the world in Finland, at both the University of Turku west of Helsinki near the Baltic coast, and the University of Oulu, further north on the Gulf of Bothnia. Sometimes they publish studies in obscure journals like the International Journal of Circumpolar Health, but their work also appears in top-ranked journals and has global implications. In paper titled ‘Effects of heat and cold on health, with special reference to Finnish sauna bathing’ they write that “a typical duration of sauna bathing can vary between 5 and 20 minutes and is often intermittent, including shorter periods in colder environments” (Heinonen & Laukkanen 2018).
While the researchers are aware that Finnish custom is to combine dry heat exposure at 80C (or more, up to nearly 100C -- or 210F) with a brief plunge in a frozen lake, fjord, Gulf, or at least a naked roll in the snow, they also write that “the combined and possibly additive effects of alternating heat and cold exposures, such as sauna plus cold water immersion, on human health are currently not well known.”
To my knowledge, five years later, there are still no systematic studies of sauna and cold exposure together. Nonetheless, our intuition suggests certain hypotheses. For example, we know from the chapters on sports and performance that precooling exercise will boost peak muscle power, extend endurance, and stimulate testosterone production in men. We also know that sauna after exercise will boost blood volume and improve endurance (Scoon et al. 2007), as well as reduce oxidative stress from exercise (Sutkowy et al. 2014).
In aggregate, these studies suggest the following thermal contrast protocol:
Begin with two to four minutes of whole-body, cold-water immersion at a temperature cold enough to make you gasp. Those naive to deliberate cold exposure may find that 50F is sufficient to initiate the gasp reflex, and that 4 minutes is long enough to induce shivering thermogenesis. If you’re just starting out, go cold enough to gasp and long enough to shiver. However, experienced cold plungers will be acclimated to lower temperatures and are less likely to experience shivering in their muscles, due to the increased non-shivering thermogenesis in their brown fat. Because it takes a week to ten days of daily plunging to recruit new brown fat, a good strategy as you gain experience is to reduce the temperature of your water over time until you get below 39F.
Once you’ve attained temperatures in the 30’s, don’t worry so much about whether you shiver. Two to four minutes will be sufficient to induce vasoconstriction and some superficial neuromuscular cooling. What I’ve been hearing from several readers is that they still obtain the anabolic benefits of the protocol as long as they still feel cold when they begin the next step.
Follow your cold exposure with some light, easy exercise. The goal of this step is to stimulate anabolic gains, return circulation to your limbs, and rewarm the distal regions of your body. Body weight exercises, kettlebells, and a steel mace all work well in this respect. Pull ups, lunges, squats, and pushups are among my favorite rewarming exercises. Wim Hof teaches a rhythmic, back-and-forth sort of dance in horse stance, coordinated with some deep breathing and that looks like good advice to me. I’ve also heard from readers who have success rewarming with a brisk walk, and I’ve had success with that, too. Twenty minutes on a stationary bicycle will do. It doesn’t take much exercise.
Do your regular workout. Whether you’re into yoga, heavy lifting, running, cycling, ARX Fitness, or nothing – whatever your routine is, now is the time to do it. You’re probably going to notice that your body feels stronger and more powerful and that your workout comes easier to you.
Follow your workout with dry, Finnish sauna (>80C, or about 180F). While studies from Japan show that an infrared sauna provides vascular benefits, I’ve noticed that at the lower temperatures (e.g., 140F) obtained, it takes a long time to induce sweating whenever I’m using sauna after my ice bath. The colder my skin when I enter the sauna, the more heat it takes to warm my body. Partly that’s because the mechanisms of thermoregulation (e.g., redistribution of blood throughout the body) that are strengthened by cold exposure can also improve thermoregulatory function in the heat, but I suspect that it’s mostly because of the precooling effect of the ice bath. A good rule of thumb is to go hot enough, for long enough, to begin sweating. That’s how you know you’ve induced vasodilation and you may consider your thermal contrast therapy complete.
Mike Mutzel of High Intensity Health recently posted a video summarizing some of the Finnish research on sauna after exercise that claims superior cardiovascular benefits.
Exercise during sauna?
One of my personal favorites methods of recovery from an ice bath is hot yoga. There are several studios available in Phoenix AZ and they have different approaches that typically involve performing traditional yoga poses in a room heated to a little more than 100F. To put that in perspective, summer outdoor temperatures in Phoenix typically exceed 110F (43C), so on some days I get more heat exposure walking around the Arizona State University campus than I do in a typical hot yoga class – but my case is unusual. The principal benefit of stacking of heat and exercise after my ice bath is that I get the benefits of both sauna and a workout, and it rewarms my body faster than either one alone. However, the risk of heat overexposure can create a serious medical emergency – even death. When symptoms of heat exhaustion first appear, it is essential to discontinue exercise and seek refuge from the heat.
Cold & exercise
Most people have experience with combining cold and exercise in winter sports. Cross-country skiing, downhill skiing, figure skating, hockey, snowshoeing, football, or even just underdressing during a winter walk or run are all popular winter past times in northern states. In addition to the recreational benefits, exercising in the cold boosts metabolism, improves insulin sensitivity, can improve sleep, and may promote weight loss. The more extreme form of cold-exercise combination is competitive winter swimming. Dr. Nicolas Iconomidis’ (2023) book Cold Water Swimming is the most comprehensive guide yet available, although there have also been some scientific studies of the practice (Knechtle et al. 2020). The International Ice Swimming Association organizes a regular schedule of competitions and has published rules and safety standards. Although winter sports are the most obvious combination of cold and exercise, there are also technological options. Vasper, which is a recumbent exercise machine that uses a cooling vest to intensify the workout, is one of the oldest. However, I’ve also met with an entrepreneur in Phoenix who proposed to build a gym machines inside a walk-in freezer, allowing athletes to perform weight-lifting and other exercises in a cold air environment.
Heat & light
By far the most popular combination of therapies is the far infrared sauna. There are many forms, some of which incorporate near infrared and red light. The benefits are well documented in studies of heat therapy, and a detailed review is outside the scope of this book, but it’s worth mentioning because there is an enormous gap in the marketplace for saunas that combine heat, red light, and ultraviolet light. Exposure to ultraviolet light via tanning lamps or beds has a myriad of benefits beyond the aesthetic. For example, the stimulation of Vitamin D photosynthesis by ultraviolet radiation in the UVB region (about 310nm) on the skin is associated with improved health, stronger bones, and protects against infectious disease. Matching ultraviolet exposure to skin pigmentation confers considerable benefits without the risks of overexposure (Holick 2016). Moreover, preconditioning the skin with red light prior to ultraviolet light exposure has been shown to protect against, and speed recovery from, sunburn due to ultraviolet overdose (Jantschitchs et al. 2009).
Cold & light
If you look closely in the background of the videos I post from my ice bath, you’ll often see the little Mito Red Light I keep on top of my Morozko. Mito Red is a company founded by my friend Scott Chaveri, who advocates for red and near infrared light exposure on the skin to stimulate mitochondria and speed healing. I often use my little red light on my face or the back of my head when I’m plunging to create a feeling of warmth on the only part of my body that isn’t underwater, but many of my readers report that they use larger red lights during their rewarming.
The red and near infrared lights are a little bit different from the far infrared sauna lights. They aren’t warm when measured by a thermometer, but they feel warm when they’re shining on the skin. Red light penetrates several centimeters below the skin to stimulate mitochondrial function. In this way, it may promote endothelial function, production of nitric oxide for vasodilation, and non-shivering thermogenesis. My readers report that the red light speeds their body’s natural rewarming process after the ice bath, and Ben Greenfield wrote that exposing his testicles to red light encourages testosterone production (Greenfield 2021). Although I’m not aware of any scientific studies that have investigated the combination of cold exposure and red light, these experiences suggests that an ice bath followed by a red light session could be a powerful metabolic therapy.
The best red light therapy is sunshine – especially at dawn and dusk, when the long path of the sunlight through the atmosphere attenuates shorter, blue and ultraviolet wavelengths. At northern latitudes, artificial lights may be the best substitute for sunshine during the winter. However, in the summer, rewarming in the sunshine has some big advantages. For example, exposure to ultraviolet light causes a cascade of neurochemical responses that ignite sexual passion. In mouse models, males experience an increase in testosterone. Females become more receptive to male advances and spend more time grooming the males. Questionnaires indicate that the mouse findings likely translate to humans as well, with increased romantic interactions and attractiveness associated with greater UVB exposure (Parikh et al. 2021).
Cold, exercise, sunlight, & heat
The ultimate modern combination of ancestral exposure therapies may be a day of surfing that culminates in a seafood cookout around a campfire on the beach. The cold ocean, the paddling & swimming, the sunshine, and the heat of the fire at the end of the day replicate many of the exposures that ancient human beings must have experienced as a matter of their survival. They may not have been surfing, per se – but they undoubtedly spent their days in the water fishing, and their nights by the fire cooking, eating, making music, and telling stories.
References
Cunnane S, Stewart K, editors. Human brain evolution: the influence of freshwater and marine food resources. John Wiley & Sons; 2010.
Greenfield B. The power of photobiomodulation. https://bengreenfieldlife.com/article/red-light-therapy-routine-explained/; 2021.
Holick MF. Can you have your cake and eat it too? The sunlight D‐lema. British Journal of Dermatology. 2016 Dec 1;175(6):1129-31.
Iconomidis N. Cold Water Swimming. BoD - books on demand; 2023.
Jantschitsch C, Majewski S, Maeda A, Schwarz T, Schwarz A. Infrared radiation confers resistance to UV-induced apoptosis via reduction of DNA damage and upregulation of antiapoptotic proteins. Journal of Investigative Dermatology. 2009 May 1;129(5):1271-9.
Knechtle B, Waśkiewicz Z, Sousa CV, Hill L, Nikolaidis PT. Cold water swimming—benefits and risks: A narrative review. International journal of environmental research and public health. 2020 Jan;17(23):8984.
Parikh R, Sorek E, Parikh S, Michael K, Bikovski L, Tshori S, Shefer G, Mingelgreen S, Zornitzki T, Knobler H, Chodick G. Skin exposure to UVB light induces a skin-brain-gonad axis and sexual behavior. Cell Reports. 2021 Aug 24;36(8).
Scoon GS, Hopkins WG, Mayhew S, Cotter JD. Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport. 2007 Aug 1;10(4):259-62.
Søberg S, Löfgren J, Philipsen FE, Jensen M, Hansen AE, Ahrens E, Nystrup KB, Nielsen RD, Sølling C, Wedell-Neergaard AS, Berntsen M. Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men. Cell Reports Medicine. 2021 Oct 19;2(10).
About the Author
Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience. Subscribe to https://seagertp.substack.com/ for more information from Seager on taking charge of your own physical & mental health.