Hot tub or cold plunge? Experts say there are benefits — and risks — to both.
It’s hard to scroll through social media right now without seeing a celebrity or influencer — among them, Jelly Roll, Kristen Bell, Bradley Cooper and Josh Brolin — rave about cold plunges, aka the practice of soaking in ice-cold water.
While cold plunges may be the wellness trend du jour, there's still something to be said for that other form of water therapy: the hot tub. In fact, new research highlights the benefits of taking a steamy soak — and shows how it compares to the chillier alternative.
What the study says
The study, which is being presented at the Integrative Physiology of Exercise conference, had young adult male athletes do 50 minutes of high-intensity interval running before soaking in a cold-water tub (at 59 degrees Fahrenheit), soaking in hot water (at 104 degrees Fahrenheit) or simply sitting, without being in water.
The researchers measured both how high the participants could jump and any changes in enzymes and proteins that can indicate muscle damage. The volunteers were asked to rate how sore their muscles felt.
The researchers found that participants had lower jump heights and squat positions with cold plunges than when they had used the hot tubs. There were no significant differences in creatine kinase and myoglobin levels between the two soaking methods.
As a result, the researchers concluded that the hot tub was better than cold plunging for exercise performance. But they also found that a cold plunge is more effective at easing inflammation, swelling and fatigue from exercise. Basically, one wasn’t better than the other — they were just different.
So, when should you do a cold plunge and when is soaking in hot water a better option? Experts explain.
What is a cold plunge, and what are its benefits?
A cold plunge is a type of cold therapy in which you partially or totally immerse yourself in water that’s below 60 degrees Fahrenheit for a short period, Dr. Joseph J. Ciotola, an orthopedic surgeon at Baltimore’s Mercy Medical Center, tells Yahoo Life. Ciotola studied with Wim Hof, an extreme athlete and cold plunge expert.
“It has been suggested that cold plunges can help with increasing mood, [providing] pain relief from workouts, lowering inflammation or activating the parasympathetic nervous system and minimizing stress responses,” Steven K. Malin, associate professor in the Department of Kinesiology and Health at Rutgers Robert Wood Johnson Medical School, tells Yahoo Life. “Some have even suggested improvements in health by way of better insulin sensitivity and blood pressure.” But, Malin stresses, “this evidence is highly mixed.”
There may be some perks of cold plunging, “but very little research has confirmed the advantages,” Dr. Tracy Zaslow, primary care sports medicine specialist at Cedars-Sinai Kerlan-Jobe Institute in Los Angeles and a team physician for Angel City Football Club and LA Galaxy, tells Yahoo Life. Zaslow says it’s not clear why cold plunging may help people. “Maybe it's changes in adrenaline or cortisol — or even dopamine,” she says.
One analysis of pre-existing studies published last year found that cold water therapy helps with soreness after exercise. Cold plunges may also help lower inflammation in the body, according to another study. But Zaslow says a lot of research still needs to be done.
What about the risks?
Cold plunging is an intense activity, and there are some risks to consider. Malin says there are concerns that people with cardiac conditions could experience potential heart or vascular issues in response.
“But even if they do not have pre-existing issues, the cold immersion under 60 degrees may raise breathing rate, heart rate and blood pressure — and promote drowning,” he says. “This is in part due to blood rushing away from arms and legs to the core of the body to keep the heart able to pump blood.” Hypothermia, which is an abnormally low body temperature, is also a concern.
“If done carefully, there are very little to no risks,” Ciotola says. “The biggest risk is staying in too long. Two minutes is all you need to get the benefit.”
What is hot water immersion, and what are its benefits?
Hot water immersion, also known as hot water therapy, involves fully or partially immersing yourself in hot water (by sitting in a hot tub, for example). “It’s used more for muscle relaxation and spasms,” Ciotola says.
Research has found that hot water therapy may help you perform better from an athletic standpoint. A study published in 2020 had athletes sit up to their necks in 102-degree water for 30 minutes right after a training session three times a week. At the end of three weeks, the researchers discovered the participants had a 3.2% improvement in their bodies' efficiency in using oxygen and up to a threefold improvement in the amount of oxygen their bodies needed to do a workout.
Research has also linked hot water therapy with lower levels of stress, improved muscle relaxation and even a lower risk of developing cardiovascular disease.
What are the risks?
There are a few things to keep in mind with hot water immersion. “Hot water, like cold water, can be uncomfortable and promote burns,” Malin says. “Temperature in many studies tends to be near 104 degrees Fahrenheit, but going well above that should be used with caution, to minimize risks.”
You can also develop dehydration, dizziness, lightheadedness and headaches from overdoing hot water immersion, Malin says.
When should you choose one over the other?
It’s important to point out that you don’t have to do cold plunges or hot water immersion if they don't appeal to you (or if you don't have access to either option). Malin stresses that more data is needed to assess both therapies.
As for overall fitness, Malin notes that exercise itself is still the best way to go. “This should be the focal point,” he says.
“Given the mixed evidence in the literature, ‘supplementing’ with hot or cold tub exposure could have subtle potential benefits,” Malin says. Ciotola also stresses that both of these practices have “different functions.”
If you have access to cold plunging and to a hot tub, Malin recommends trying both and seeing how you feel. “It might be that both are ultimately needed to target some of the different benefits,” he says. Or they just might make you feel good. Either way, the science doesn’t definitively say that one is better than the other.
