The most important contraindication to cold plunge therapy is high blood pressure
Summary
Online critics of cold plunge, including the American Heart Association, fail to mention that hypertension (high blood pressure) is the most important contraindication to cold plunge.
The vasoconstriction induced by whole-body cold water immersion typically causes a temporary increase in blood pressure that may be dangerous for those with untreated hypertension.
The hypertensive effects of cold plunge may diminish with regular practice, as the body acclimates to regular cold exposure.
Nitrate ingestion, such as can be found in beet root juice, likely blunts the hypertensive effects of deliberate cold exposure.
Use a dry sauna to recover from exercise to maximize cardio-vascular gains that might reduce high blood pressures.
Critique of Cold Plunge Critics
A veritable chorus of cold plunge critics on social media were emboldened by the American Heart Association (AHA) when they published an article (Williamson 2022) called "You're Not a Polar Bear" advising against cold plunging. Although they never mentioned Joe Rogan, their article came out just a few days after he created a minor social media sensation by endorsing my method of precooling in his 6 Dec 2022 Joe Rogan Experience podcast with David Goggins.
Since then, there has been a proliferation of TikTok videos from influencers and other people claiming to be medical professionals, warning against the extreme dangers of cold plunge therapy. Most of them are hyperbolic, closed-minded, and ridiculous:
A surgeon recorded a TikTok video from his kitchen claiming that the cold plunge videos you see on Instagram must be fake, because "most of the time when you see people doing cold plunges, it's warm water with ice on top... because they're not crazy enough to get in the water that quickly and sit that long."
A medical doctor told Howie Mandel on YouTube that "Medically, I'm never going to recommend to my patient, ever in my life as a physician, to go do a cold plunge."
An anonymous Instagram influencer claimed that cold plunging is the "dumbest thing you can do" -- comparing an ice bath to a plane crash.
As far as I can tell, none of the people who have published these videos have ever tried a cold plunge, and you could say that given their views on how extremely dangerous it must be, why should they?
Except for one detail... if they're so worried about the dangers, then why do none of them ever mention the single most important contraindication to cold plunge therapy, ice bath, or whole-body cold water immersion? It's not adrenal fatigue, or heart arrhythmia, or some cold shock response.
The single most important contraindication to ice bath is hypertension (high blood pressure).
You'd think that the critics of cold plunge would want you to know that.
Blood Pressures in the Cold Plunge
I got text message from a Canadian reader this morning asking me about his blood pressure data recorded before and immediately after his ice bath. He said that he usually measures about 118/77, but the cold will spike his blood pressure to 160/100.
A persistent reading above about 140/90 could be sufficient to justify a diagnosis of hypertension. For example, when my ex-wife was struggling with a persistent anxiety, she recorded chronically high blood pressure readings. A medical doctor prescribed ACE inhibitors to reduce her blood pressure by prevent her body from narrowing her blood vessels. The idea behind an ACE inhibitor is that relaxing her blood vessels would create more room for her blood and lower blood pressure.
I don't know whether ACE inhibitors worked for her or not. She decided to quit drinking, clean up her diet, lose 15 pounds and quit taking her prescribed medication. Our kids and I agree that she's much better off from having made the lifestyle changes, regardless of the medication.
But what if she had decided to ice bath before getting her blood pressure down?
Short term effects of cold plunge on blood pressure
In Are You Getting Enough Vasoconstriction? I explained that cold exposure causes contraction of the smooth muscle tissues that control blood flow to the extremities. Redistributing blood from the limbs to the core helps minimize heat loss through the skin of the arms and legs, and maintain core body temperature.
However, shrinking blood vessels in the extremities will also increase blood pressure -- at least temporarily -- by doing exactly the opposite of what the ACE drugs my wife was taking were supposed be doing.
Several scientific studies have observed this temporary, hypertensive effect (Jdidi et al. 2024). For example, researchers at the University of Oulu in Finland studied 41 hypertensive men, aged 55-65 years, during 15 minutes of whole-body cold air exposure (−10°C, wind 3 m/s, winter clothes) and compared their blood pressure response to 20 men without hypertension. They discovered that short-term deliberate cold exposure elevated systolic blood pressure by 20 mm Hg or more Hintsala et al. (2013). Moreover, other studies have found similar results, even at more mild temperatures (e.g., +10°C, Korhonen et al. 2006). As a consequence, the Finnish researchers warn:
Short-term cold exposure increases central aortic blood pressure and cardiac workload in untreated hypertensive middle-aged men. Because of the higher baseline blood pressure among hypertensive subjects, the cold-induced rise in central aortic blood pressure may increase the risk of adverse cardiovascular health effects. - Hintsala et al. (2013)
The hypertensive effects of cold exposure are typically temporary. For example, more than forty years ago, researchers studying polar plungers observed a modest increase in blood pressure when exposed to cold air prior to the plunge, no significant further increase while plunging, and then a return to normal upon rewarming (Zenner et al. 1980).
Nevertheless, as cold plunging becomes more popular, it seems inevitable that someone, somewhere will experience an acute hypertensive episode resulting from untreated or unmonitored high blood pressure in the cold plunge. At least two medical professionals have reported such instances. One is my friend Stefan Hartmann, PA, who runs a primary care practice and a wellness club in Florida. He described to me a club member experiencing a temporary hypertensive crisis during an ice bath. The second is Dr. Nicolas Iconomodis, the French gastroenterologist who has been winter swimming for more than 30 years. He documents an example of severe hypertensive crisis in his book Cold Water Swimming: Heath Benefits & Risks:
A 61 year-old man, with a history of treated hypertension, presented hypertensive crisis at 210/100 mm Hg after swimming in cold water, with persistent hypertension averaging 170/100 mm Hg after the sauna. - Dr. Nicola Iconomodis (2023, p73)
An acute episode of sudden, elevated blood pressure with readings of 180/120 mm Hg or greater is typically considered a medical emergency when accompanied by symptoms of chest pain, back pain, shortness or breath, or visual disturbances. Such high blood pressure could damage blood vessels and body organs, including the heart, brain, kidneys and eyes.
Long term effects of cold exposure on blood pressure
There is comparably less published research on the long term effect of cold exposure on blood pressure. However, in a small study conducted by the US military, seven healthy males were placed through a cold acclimation program. The cold exposure consisted of daily 90-min cold water (18 degrees C or 64.5 F) immersions repeated five times a week for the length of the five week study. The researchers observed similar increases in blood pressure in the subjects during the first cold water immersion. However, after becoming acclimated to the cold, their blood pressure readings normalized -- suggesting some cardio-vascular adaptation had taken place (Muza et al. 1988).
Nitrates as a vasodilating agent
As my ex-wife discovered, lifestyle changes are usually sufficient to manage hypertension. However, one potential treatment goes against conventional medical wisdom: nitrates.
When I was a child, my Mother taught me that nitrates (like those found in cured meats) were bad for me and would give me cancer. As a child, that hardly diminished my appetite for bacon, although it did worry me that I my taste for salted fats was somehow hurting my Mother's feelings.
Nonetheless, after decades of vociferous bacon consumption I remain free of cancer and have come to know better. Recall that when I wrote Ice Bath for Better Sex, I described the essential role of mitochondria in the endothelial cells that produce the NO (nitric oxide) that initiates vasodilation.
Just like the ACE inhibitors prescribed for my ex-wife, nitric oxide production in the endothelial cells that line blood vessels will cause the smooth muscles tissues that control blood flow to relax. The precursor for NO production is L-arginine -- an amino acid that supports protein synthesis (Vallance & Hingorani 1999). In fact, recent clinical trials have demonstrated the efficacy of long-term, high-dose L-arginine supplementation for promoting blood flow to the penis and ameliorating erectile dysfunction (Menafra et al. 2022). According to one researcher, the benefits of L-arginine are so extensive, including cardio-vascular, sexual, and immune system functions, that "benefits of l-arginine show greater potential than any pharmaceutical or nutraceutical agent ever previously discovered" (Gad 2010).
As an amino acid, the chemical structure of L-arginine relies on nitrogen, and that nitrogen is typically sourced from proteins in the diet. However, nitrites and nitrates are also dietary sources of nitrogen.
Since the discovery of vasodilating properties nearly two hundred years, nitrates have been prescribed to manage cardiovascular diseases such as arterial hypertension, angina pectoris, acute coronary syndrome and heart failure. Dietary sources of nitrates may also be found in fresh produce such as beetroots, certain green leafy vegetables and as an additive in many processed meats. In particular, beetroot juice has been demonstrated in a number of studies to be beneficial for their effects on lowering blood pressure (Servo et al. 2013). There is evidently something about the ingestion of these nitrogen salts that also boosts NO synthesis for increased blood flow (Kurhaluk 2023).
Beetroot Juice Blunts Hypertensive Effects of Ice Bath
In a brand new study, an eclectic group of researchers from the United Kingdom and Japan decided to investigate whether beetroot juice could counteract the hypertensive effects normally associated with deliberate cold exposure. They recruited twelve men to visit their labs upon four occasions and gave them either straight beetroot juice, rich in nitrates, or a modified beetroot juice that had been stripped of nitrate content.
Then they exposed the men to mildly cool air (20°C/78°F) for three hours. They observed that the men who ingested the nitrate rich beetroot juice maintained the same systolic blood pressures in cool air that they had in warmer air, but that the men who did not drink the nitrates experienced increased blood pressures in the cool air ((Rowland et al. 2024). They concluded that:
Beetroot juice (nitrate) ingestion blunts the rise in blood pressure following acute cool air exposure, which might have implications for attenuating the increased cardiovascular strain in the cold. - Rowland et al. 2024.
Sauna effects on blood pressure
Considering that the opposite of the vasoconstriction induced by cold water immersion is the vasodilation induced by dry sauna. Then it stands to reason that a person experiencing a hypertensive crisis resulting from cold plunge might seek refuge and rewarming in the sauna.
As far as I know, there are no medical studies on the use of sauna for treating an acute hypertensive crisis. However, there's lots of good work on the cardiovascular benefits of a regular dry sauna practice. For example, when a research team in Montreal, Quebec exposed a group of sixteen patients with untreated hypertension to exercise and sauna, they measured an immediate improvement in blood pressure that lasted at least 24 hr (Gayda et al. 2012). However, the sauna alone had no significant effect. More recently, a FInnish team discovered that exercise and sauna were more effective for lowering blood pressure than exercise alone (Lee et al. 2022).
These studies suggest that a sauna after exercise is a powerful combination for maximizing the cardio-vascular benefits of either. However, they don't make obvious any particular recommendation for non-pharmacological treatment of an acute hypertensive crisis resulting from cold plunge.
In the two cases described by Hartman and Iconomodis respectively, both patients enjoyed a full recovery after a period of rest and rewarming. That is, their blood pressures came down after rewarming, just like the spin cycling reader who messaged me his blood pressure readings.
References
Gayda M, Paillard F, Sosner P, Juneau M, Garzon M, Gonzalez M, Bélanger M, Nigam A. Effects of sauna alone and postexercise sauna baths on blood pressure and hemodynamic variables in patients with untreated hypertension. The Journal of Clinical Hypertension. 2012 Aug;14(8):553-60.
Hintsala H, Kandelberg A, Herzig KH, Rintamäki H, Mäntysaari M, Rantala A, Antikainen R, Keinänen-Kiukaanniemi S, Jaakkola JJ, Ikäheimo TM. Central aortic blood pressure of hypertensive men during short-term cold exposure. American Journal of Hypertension. 2014 May 1;27(5):656-64.
Jdidi H, Dugué B, de Bisschop C, Dupuy O, Douzi W. The Effects of Cold Exposure (Cold Water Immersion, Whole-and Partial-Body Cryostimulation) on Cardiovascular and Cardiac Autonomic Control Responses in Healthy Individuals: A Systematic Review, Meta-Analysis and Meta-Regression. Journal of Thermal Biology. 2024 Apr 18:103857.
Korhonen I. Blood pressure and heart rate responses in men exposed to arm and leg cold pressor tests and whole-body cold exposure. International Journal of Circumpolar Health. 2006 Apr 18;65(2):178-84.
Lee E, Kolunsarka I, Kostensalo J, Ahtiainen JP, Haapala EA, Willeit P, Kunutsor SK, Laukkanen JA. Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trial. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 2022 Sep 1;323(3):R289-99.
Menafra D, de Angelis C, Garifalos F, Mazzella M, Galdiero G, Piscopo M, Castoro M, Verde N, Pivonello C, Simeoli C, Auriemma RS. Long-term high-dose l-arginine supplementation in patients with vasculogenic erectile dysfunction: a multicentre, double-blind, randomized, placebo-controlled clinical trial. Journal of endocrinological investigation. 2022 May;45(5):941-61.
Muza SR, Young AJ, Sawka MN, et al. Respiratory and cardiovascular responses to cold stress following repeated cold water immersion. Undersea Biomed Res. 1988 May;15(3):165-78. PMID: 3388627.
Rowland SN, O'Donnell E, James LJ, Da Boit M, Fujii N, Arnold JT, Lloyd AB, Eglin CM, Shepherd AI, Bailey SJ. Nitrate ingestion blunts the increase in blood pressure during cool air exposure. A double-blind, placebo-controlled, randomized, crossover trial. Journal of Applied Physiology. 2024 Apr 4.
Siervo M, Lara J, Ogbonmwan I, Mathers JC. Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis. The Journal of Nutrition. 2013 Jun 1;143(6):818-26.
Vallance P, Hingorani A. Endothelial nitric oxide in humans in health and disease. International Journal of Experimental Pathology. 1999 Dec;80(6):291.
Zenner R, De Decker D, Clement D. Blood-pressure response to swimming in ice-cold water. The Lancet. 1980 Jan 19;315(8160):120-1.