Cold plunges, even popular among Hollywood stars, raise safety concerns

While cold plunging, or the act of immersing oneself in a body of frigid water to promote muscle recovery, might seem like a relatively new trend, it’s actually been around for centuries. Dating back to 3500 BC, cold-water immersion has long been used for various therapeutic, medicinal, and analgesic purposes.^[][]

Now, you can find cold plunge centers in almost every major metropolitan city. You can buy an ice bathtub off Amazon or, as a cheaper alternative, head to your local beach or lake in the thick of winter. While the buzz is all about the potential health benefits, some risks come with cold plunging, too—especially when it’s done in wild waters, such as rivers, lakes, ponds, and oceans. In Massachusetts, for example, a 31-year-old man recently died after wading into the freezing-cold ocean in Salem, MA. The American Heart Association (AHA) also warns that suddenly submerging in cold water can put a strain on the heart and, in some individuals, trigger life-threatening health complications.^[][]

While a dip in icy water may very well help muscles heal, health experts agree that the trend has outpaced the research. There’s a lot we don’t know about cold plunging. “While cold plunging is a hot health trend right now, there simply is not enough scientific evidence to either support or debunk the practice,” Tracy Zaslow, MD, a 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, told MDLinx.

What we know about the benefits of cold plunging

While many people claim that cold plunging is key to relieving muscle soreness, aiding recovery from fatigue, and boosting the immune system, the literature on the intervention’s effectiveness is mixed. 

Some scientific reports suggest that dunking in frigid water makes people feel more active, inspired, and alert. A large meta-analysis found that cold baths improved muscle soreness and perceived recovery in people who played a sport or were physically active. Another analysis, however, concluded that regular cold-water immersion actually harmed resistance training, and a report conducted on a small group of participants found that it attenuates muscle hypertrophy. Of all the possible benefits, Dr. Zaslow says soothing sore muscles has been backed with the most evidence.^[][] 

It’s unclear how long people should plunge for or the ideal temperature, though that’s currently being studied, according to Dr. Zaslow. On top of that, scientists are unsure why cold-water immersion seems to help some people. They suspect the frosty temperatures cause changes to adrenaline, cortisol, or dopamine—all hormones that impact emotional regulation, stress management, and reward centers. However, more research is needed to understand better why cold plunging has this effect. “Until there is significant data for clinicians to review, we can’t definitely say one way or the other,” Dr. Zaslow said.^[][][]

The bulk of studies have been conducted in small groups of participants, making it difficult for researchers to draw firm conclusions about the practice. “Research on the pros and cons of cold-water exposure is still very limited, and as is the case with so many health trends, when touted by celebrities or professional athletes, people believe it is safe enough for them to try before consulting with their physician,” Dr. Zaslow added.^[]

What we know about the risks associated with cold plunging 

As the research catches up, it’s becoming clear that cold plunging isn’t risk-free. The National Center for Cold Water Safety states that suddenly entering water colder than 60 degrees can cause someone to die in less than one minute. It can lead to a quick increase in breathing along with a rapid spike in heart rate and blood pressure. “The shock of cold water can cause an involuntary gasp, potentially leading to drowning,” says Erik Natkin, DO, medical director and provider at R2 Medical Clinic in Denver, CO.^[][]

Furthermore, while some studies have found that swimming in freezing waters can reduce inflammation, others have determined that those who regularly do so have higher levels of troponin—a protein that indicates there’s been damage to the heart. “Cold plunging is not free from risk,” Dr. Zaslow said.^[][]

Here’s how to safely try cold plunging

It’s recommended that people gradually build up their tolerance. “Begin with short immersions of a minute or two, and listen to your body to avoid pushing too hard,” Dr. Natkin says. He adds that it’s best to get acclimated in a controlled environment, such as at a spa or medical facility that offers cold plunging. Typically, one minute is sufficient for those trying out cold plunging for the first time, according to Dr. Ng.

Always monitor how long you’re plunging for. Dr. Zaslow recommends that even experienced plungers limit their dips to 10 to 15 minutes. Warming up properly afterward will minimize the risks. When you exit the cold water, put on warm, dry clothes and drink something warm. Don’t hop in a hot shower right away, Dr. Zaslow warns, as that can cause your blood vessels to dilate and you could faint.

And if you’re headed to the wilderness, it’s best to bring a friend along. “When plunging in wild waters, always have a safety plan, never do it alone, and stay close to an exit point,” Dr. Natkin said.