Cold plunges are the latest workout trend. Do they actually have benefits?

Cold water therapy is not new, but it is all the rage right now, especially cold plunges and soaks.

On TikTok, the hashtag #coldplunge on TikTok has over a billion views and features countless videos of people shivering and braving the cold water. Cold plunges are a favorite among many celebrities, athletes and influencers.

The supposed benefits of cold water immersion include reducing inflammation, relieving muscle soreness, aiding with recovery after exercise, boosting immunity and improving sleep, among others. Some claim the cold water has mental health benefits, such as improving clarity or reducing depression, anxiety and stress.

Unsurprisingly, cold plunges do not come without risk. The practice has been criticized by some experts for being risky or downright dangerous.

What does the science say about cold plunges? What, if any, are the benefits of cold water immersion? We spoke to experts about cold plunges about what people should know before jumping in.

What is a cold plunge?

A cold plunge involves fully submersing the body in cold water — whether that's a bathtub, tank, pool or a natural body of water, such as a lake or the ocean. It’s also called cold-water immersion or cold-water swimming. Ice baths are an extreme type of cold water immersion, on the lower end of the temperature spectrum.

Although cold plunges have surged in popularity in recent years, the practice has been around pretty much as long as humans have been near water, Mike Tipton, a professor of human and applied physiology at the University of Portsmouth, tells TODAY.com.

“Going back to Hippocrates and even Thomas Jefferson, Darwin and Florence Nightingale were all doing cold-water immersion,” says Tipton, who leads research on cold-water swimming at the University of Portsmouth’s Extreme Environments Laboratory.

More recently, cold plunges have been associated with Wim Hof, a Dutch extreme athlete and founder of the "Wim Hof Method," which combines cold-water therapy and breathing exercises to boost mental and physical health.

How to cold plunge

A cold plunge involves immersing the body in cold water — either quickly in and out, or for up to 10 minutes. During a cold plunge, the water is typically between 50 to 70 degrees Fahrenheit or 10 to 20 degrees Celsius, Dr. Kristi Colbenson, a sports medicine and emergency physician at the Mayo Clinic, tells TODAY.com.

In general, cold plunges typically last between five and 10 minutes, Colbenson adds. The length of a cold plunge will vary depending on the water temperature and a person's comfort level.

The colder the water, the shorter the immersion should be, the experts note, and the water should be no colder than about 53 degrees Fahrenheit or 12 degrees Celsius. At this point, the risk of damage to the skin and tissues or other adverse health events increases, the experts note.

The ideal temperature for cold water swimming is a bit warmer, or between about 65 to 75 degrees. Many cold water swimmers wear wetsuits to preserve their core body temperature.

How long to cold plunge

A quick dip in and out of the water counts as a cold plunge, but how long does it take for the cold water to work? It takes three to five minutes for the cold to penetrate beyond the skin, Colbenson says, at which point it starts to have a neuromuscular effect.

Most cold plunges typically last between five to 10 minutes, she adds. Tipton cautions that staying in the water for longer than 10 minutes increases the chances of being harmed by the cold.

People may be able to tolerate cold water swimming for longer periods of time depending on the water temperature and their experience level.

People have long-touted the benefits of cold water but also warned of the risks, says Tipton, and throughout history it has been deemed both a cure-all and a health hazard. So what do we know now about how cold water immersion affects the body?

Cold plunge benefits

From a physiological standpoint, the most significant benefit from cold water immersion seems to be improvement in recovery, the perception of pain and delayed muscle soreness, says Colbenson.

A systematic review published in the journal Sports Medicine in February 2022 suggested that cold-water immersion was an effective recovery tool after high-intensity exercises, specifically HIIT exercises, TODAY.com previously reported.

Cold plunges may also reduce inflammation in the body. When the body enters cold water, this causes the blood vessels to constrict, especially in the extremities, to conserve heat at the core of the body near the heart, the experts explain.

"It slows down and inhibits blood flow to the legs and the arms and pushes (the blood) more towards the central aspect of the body," says Colbenson. "In doing so, you decrease the natural inflammatory response that occurs after exercise."

“When you look at the literature, it does help with recovery and inflammation, especially if you’re a competing or training athlete,” Colbenson adds. However, the anti-inflammatory effects of a cold plunge are likely temporary, the experts note.

A cold plunge can also induce a heightened state of stress, or send the body and brain into "fight or flight" mode, Colbenson notes. In response to low temperatures, the body will release a surge of norepinephrine and cortisol, the stress hormone, she adds.

The gasping, hyperventilating and increased heart rate after jumping into frigid water is also known as a "cold shock response." This response can be dangerous, but it may also be the basis of some of the physical benefits of cold plunges, says Tipton.

“The belief is that if you consistently expose yourself to stress in a meaningful and structured way, your body will actually respond by improving its ability to respond to everyday stress,” says Colbenson.

However, the evidence that cold-water immersion improves the body's immune function is lacking, the experts note.

"From an immunologic standpoint, or your ability to fight infection, I give caution to that. ... There hasn’t been a good study that says there is a decreased propensity of getting infection if you use cold-water immersion," Colbenson adds.

The lack of robust scientific evidence is a running theme. “Whilst we know a lot about the science of the hazards, we know much less about the science of the benefits,” says Tipton, adding that more studies like randomized controlled trials (the gold standard in research) are needed to understand the physical health benefits.

Can cold plunges boost mental health?

The mental health benefits of cold-water immersion are even less studied and understood, the experts note. However, there are many theories and anecdotal testimonies about the mind-boosting effects of cold water.

In the short-term, cold plunges can increase levels of dopamine and endorphins, says Colbenson, which can contribute to a feeling of euphoria and heightened clarity or focus immediately afterwards.

"That's how our body responds to stimuli that threatens us — we are ready to be clear in our ability to react," Colbenson adds. However, the mental clarity after a cold plunge seems to be short-lived, she adds, and there isn't literature showing this is sustained over time.

The anti-inflammatory effects of cold water may also play a role. “There may well be, according to some models, an inflammatory component in depression, and we know that repeated cold immersions decreases (inflammation),” Tipton adds.

Similarly, the theory that repeated cold water exposures can make the body better able to deal with stress may apply to mental health obstacles, says Tipton, who co-authored a case study on a 24-year-old woman whose depression was treated with cold-water swimming.

The patient felt an immediate improvement in mood after each immersion, the authors note, and experienced a gradual and sustained reduction in symptoms. One year after starting routine cold-water swimming, the patient was reportedly depression-free and off medication, says Tipton. "Something's going on," he adds, but exactly what that is remains unclear.

“Even if it’s a placebo effect, that’s still an effect,” he adds.

Several other factors may impact a persons mental state after cold plunging. “They’re doing some exercise, they’re getting a sensation of overcoming a challenge and a sense of achievement,” says Tipton, adding that cold plunges can also be a social activity.

“There’s lots of potential things that could be going on, and we need more experiments to isolate the active ingredient,” says Tipton.

Cold plunge risks

There's a right way and many wrong ways to do a cold plunge, and certain people should avoid cold-water immersion entirely.

"We've spent probably 40 years looking at the hazards associated with going in cold water — from drowning to sudden cardiac death," says Tipton.

The surge in the hormone norepinephrine from cold water increases the heart rate, blood pressure and breathing rate, says Colbenson. For healthy people, that may be tolerable, she adds, but for people with any history of heart disease or cardiac problems (such as arrhythmias), it can be deadly.

People with any cardiac history, vascular disease or underlying conditions, like high blood pressure, should avoid cold plunges, Colbenson says. Regardless, everyone — especially people over 65 — should check with their doctor before trying cold-water immersion to be safe, the experts note.

"It’s a very significant challenge to the body, and you need to make sure that you’re fit and healthy enough to do it," says Tipton.

People should avoid doing cold plunges or cold-water swimming alone, Tipton warns. "We want to make sure that people do it safely, and that means doing it in a controlled environment with other people or supervised," says Tipton.

Some people may be tempted to take things to the extreme, but the experts caution against overdoing it. "Colder is not necessarily better, and the cold shock response is potentially dangerous," says Tipton. "That response maximizes between 10 and 15 degrees Celsius, so you do not need to be going into ice water," he adds.

Plunging for longer than 10 minutes is not inherently better either either. "There's a greater chance you'll become physically incapacitated by the cold," Tipton warns.

Practicing cold water immersion in a sensible and risk-minimizing way maximizes the chance of it being beneficial to your health, the experts note.

This article was originally published on TODAY.com