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I first noticed the sauna-and-cold-plunge combo becoming popular around a year ago, when an invitation to try a Manhattan bathhouse hit my work inbox. Then another arrived, and another, and another, and another. Suddenly, everyone I knew (not to mention the athletes I interviewed) was marinating in their own sweat and then submerging themselves in icy water as a form of self-care, paying a premium to toggle between overheating and freezing.
This custom—exposing your body to alternating temperature extremes for supposed health benefits like faster workout recovery, increased mental clarity, and a higher metabolic rate—is formally known as “contrast therapy.” While contrast therapy has long been popular in Scandinavia, it’s only recently infiltrated mainstream US culture, especially in big cities like New York and Los Angeles. Riding the wave of the larger wellness movement, sauna chains like Othership and Lore Bathing Club have all opened locations in the Big Apple. Even national gyms—like LA Fitness, EoS Fitness, and Crunch Fitness—are starting to install sauna facilities, Tyler McDonald, NASM-CPT, CNC, a certified personal trainer specializing in tennis and a senior brand marketing manager for the National Academy of Sports Medicine, tells SELF.
When I visited Othership, I found the experience invigorating, as promised, but I also wondered about the science of it all. Was there any research to support the myriad health claims floating around? To find out, I spoke with a few experts in the fitness space. Read on to learn whether contrast therapy is legit, and how to practice it for best results.
How does contrast therapy work?
In the fitness world, contrast therapy is a workout recovery modality designed to help pro athletes and everyday exercisers bounce back faster after a tough bout, according to McDonald. Generally, a routine consists of “10 to 15 minutes in the heat of the sauna, and then two to three minutes in the cold of the ice bath,” he says. “This does two things: The cold really reduces the inflammation, and then the heat increases the circulation and tissue elasticity of your muscles.”
Blood vessels expand and contract to allow more or less blood to flow through to vital organs like the heart. By triggering that expansion and contraction, contrast therapy essentially functions as “a vascular pump,” McDonald says. (In this sense, it has a similar effect to another popular recovery technique—compression therapy. In fact, the two are effectively different sides of the same coin, according to McDonald.)
How contrast therapy can improve athletic performance
Let’s start with the heat. High temps trigger vasodilation—the technical term for blood vessel expansion. “Your blood vessels are opening up, so you’re pumping more blood, which is allowing for a lot more blood to circulate throughout the entire body,” McDonald says. That, in turn, delivers oxygen “that helps repair the muscles you just damaged in the workout and build those new tissues as you’re gaining strength or working out at a harder level.”
By contrast, cold prompts vasoconstriction. During this process, McDonald explains, “the blood vessels are becoming smaller, which helps with the inflammation by taking away blood from that area.” Presto: None (or less) of the swelling and soreness “that you might [typically] have after a very tough workout.” (That said, don’t discount the importance of heat in this regard, either: While the cold “is what handles the immediate inflammation,” as you probably know if you’ve ever applied an ice pack to a rolled ankle, “the heat is what relaxes the knots and keeps the tissue flexible so you don’t feel like a stiff board the next morning,” McDonald says.)
Oscillating between vasodilation and vasoconstriction acts as a workout for your vascular system in the same way that bicep curls are a workout for your arms, Josh Hagen, MS, PhD, the faculty director of the Human Performance Collaborative at The Ohio State University, tells SELF. “You’re actually improving the strength and plasticity of your vasculature, which is super good for your cardiovascular health,” he says. McDonald offers a helpful analogy: “Think of your body like a thermostat,” he says. “When you jump from a 180°F sauna to a 45°F plunge, you are basically asking that thermostat to do a 100-meter dash.”
Depending on how often you do contrast therapy, you might also see what Dr. Hagen calls “environmental training” advantages. “The more time you spend in that sauna,” he explains, “the more you become resilient to heat”—a boon for physical performance in hot environments (not to mention broader well-being). In the same way, “you can get adapted to cold as well.” Some OSU sports teams, he adds, have even started to explore heat exposure as a means of boosting their athletic preparedness.
Besides the impact on your blood vessels, contrast therapy also aids in lymphatic drainage to support your body’s “trash collection” system, according to McDonald. By the end of your workout, “you have lots of byproducts and metabolites and things that just need to be cleared out of the body,” Dr. Hagen says, so contrast therapy serves as “a way to essentially flush all that out.”
How contrast therapy can enhance overall health and wellness
But that’s not all. In fact, Dr. Hagen says he’s actually more excited about the longer-term health and wellness benefits of contrast therapy than the recovery benefits alone. For one, “it’s just a really great mental reset for many athletes and everyday users,” McDonald says. “That cold water will definitely wake you up, no matter what you’re feeling.” Expect lower stress, reduced brain fog, and improved focus.
What’s more, Dr. Hagen notes, the proteins created in response to the environmental stress placed on your body by temperature extremes—“heat shock proteins” and “cold shock proteins”—can also lower your disease risk downstream. Studies have shown that heat shock proteins “can actually protect you from Alzheimer’s and dementia and other brain diseases because they actually help keep other proteins from folding,” preventing malfunctions, Dr. Hagen says. “So hot therapy alone is good, cold therapy alone is good, and contrast therapy is really just switching between those two.”
The final verdict? “For athletes who are doing this in a controlled space and aren’t generally being watched [for any health issues], I definitely would recommend doing contrast therapy,” McDonald says. And not just athletes, either: In fact, Dr. Hagen has made it a regular part of his wellness routine for better longevity. These days, he tries to hit the sauna and the cold plunge pool six to seven times and two to three times per week, respectively.
Does contrast therapy pose any health concerns?
While I didn’t notice any major side effects during my Othership classes—other than some dizziness in the sauna and numbness and tingling in the ice bath—I could definitely see the physical strain triggering more severe symptoms in people with existing vulnerabilities. Turns out my hunch was correct: “The juxtaposition of the extreme hot and extreme cold definitely carries some concern for medical risks,” McDonald says. By nature, “it’s affecting your cardiovascular system, much like exercise does,” Dr. Hagen adds.
To keep yourself safe, remember that the purpose of contrast therapy is to elicit a specific physiological response, not test your willpower. Spending more than 20 minutes in the ice bath, for example, “doesn’t give you ‘extra’ recovery; it just increases the risk of tissue damage or making your muscles feel stiff and ‘frozen’ rather than recovered,” McDonald says.
And if you have any heart or respiratory problems, you should talk to a doctor before taking the dip at all. For someone who has an underlying heart condition or high blood pressure, “that sudden squeeze from the cold can be dangerous,” McDonald says—prompting lightheadedness, fainting, or in rare cases, heart rhythm issues.
What to know before you try contrast therapy
McDonald recommends capping your sauna sesh at 10 to 15 minutes—20 max. Otherwise, you’re at risk of the “overbaked” effect: dehydration and heat exhaustion. “You’re sweating out electrolytes, and if you don’t replace them, you’ll end up with a pounding headache, dizziness, or muscle cramps,” he explains. “It’s like leaving a plant in the sun without water, it starts to wilt.”
Meanwhile, try to limit your cold plunge to two to five minutes so you minimize the potential for hypothermia or cold shock. “If your core temperature drops too low, your coordination goes out the window and your breathing becomes erratic,” McDonald explains.
While McDonald doesn’t recommend practicing contrast therapy after every workout, he does recommend it after every hard workout. When he dabbles after a tough tennis match, for instance, “the pain relief is almost instant,” he says.
Just keep a few things in mind. One, “make sure you actually need recovery,” Dr. Hagen says. Contrast therapy is “most beneficial for high-volume, high-intensity training sessions.” What’s more, it won’t be as effective for cardio as it is for strength training. Cardio emphasizes endurance more than muscle growth—and, to reiterate, one of the biggest benefits of contrast therapy is accelerating muscle repair and reducing muscle soreness. Simply put, you won’t see the same results for running, swimming, rowing, or cycling compared to squats, deadlifts, or bench presses.
Two, take a beat between the end of your workout and the start of your contrast therapy stint. Even though the cold of the ice bath will fight inflammation and alleviate soreness in the short term, spending too long in there can actually take that effect too far and “slow down the normal regenerative inflammation that the body needs to repair tissue and adapt to training,” McDonald says. “If you use it too aggressively or too soon right after the workout, it could actually delay the long-term recovery process.”
In fact, Dr. Hagen says that his team actually doesn’t recommend contrast therapy immediately after intense strength training for this exact reason—prompt cold exposure can stop the muscle growth process in its tracks. Instead, wait a few hours. And if you’re itching to get a head start on your recovery in the meantime, here are five stretches that can help curb tightness.
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Originally Appeared on Self