Are ice baths good for you? The benefits and risks of a cold plunge.

Yahoo

31-05-2025

Soothing sore muscles. Improving mood and sleep. Accelerating weight loss. Vagus nerve stimulation. Wellness enthusiasts, athletes, and maybe even your gym buddy are regularly praising ice baths for a wide range of benefits.
And today's fans of cryotherapy—the use of cold for therapeutic purposes—aren't on to anything new. Ancient Egyptians and Hippocrates all have touted the healing benefits of cold water. 'This has been around for a really long time,' says Dr. Georgine Nanos, a board-certified family physician and owner of Kind Health Group, in an interview with Popular Science.
But was Hippocrates onto something? Research shows that the effectiveness of ice baths depends on their intended purpose.
An ice bath or cold plunge typically involves immersing yourself in frigid water—either in a tub filled with ice or a naturally cold body of water. Even a cold shower can offer similar effects.
Especially for beginners, moderation is key, Nanos says. She recommends starting with water around 55 degrees to 60 degrees Fahrenheit, staying in for just 30 seconds, and then gradually increasing the duration to one to two minutes. Over a few weeks, and depending on how you feel, you can work up to three to five minutes. Benefits tend to plateau beyond five to six minutes, she points out.
Getting colder is possible, but extra caution is required. Nanos advises that anyone immersing themselves in water colder than 45 degrees should be supervised. Cold plunges, she notes, aren't for everyone, especially those with heart conditions, high blood pressure, or a history of arrhythmias or heart attacks.
An ice bath 'can worsen an arrhythmia, because when you're in the cold, it can increase oxidative stress and suppress short-term immune responses, and that can cause gasping and hyperventilation and acute cardiac strain,' Nanos explains.
From a scientific standpoint, cold water exposure triggers a series of internal changes in our body. It activates the sympathetic nervous system and releases a cascade of hormones called catecholamines, such as norepinephrine and dopamine, according to Nanos. 'Those are like our feel-good hormones,' she says, and their release can improve your mood and alertness.
When you plunge into cold water, your blood vessels also narrow—a process called vasoconstriction—to preserve heat, she says. When you come out, your vessels widen again—vasodilation—to bring your body temperature back to normal. Those changes could improve circulation, Nanos says.
What's more, cold exposure causes shivering, which is your body trying to generate heat. The theory is that shivering could temporarily raise your metabolism, which some believe could help with losing weight, she says. 'That's the scientific idea, but the evidence for that is not that great,' Nanos explains.
So, how do those physiological changes actually help us? Healthcare providers and experts have mostly relied on small clinical studies or observational data to support the potential health benefits of cold-water immersion, Nanos says. But systematic reviews of the research are beginning to shed light on the popular therapy, though everybody notes more study of the impacts is required..
A 2025 systematic review and meta-analysis of cold-water immersion, for example, examined the effects of cold-water immersion across 11 studies involving 3,177 participants. The interventions used either baths or showers with water between 45 degrees to 59 degrees Fahrenheit, lasting anywhere between 30 seconds and two hours.
The review found no immediate reduction in stress following cold-water immersion, but participants did report relief 12 hours later. In addition, there were improvements in sleep quality and overall quality of life, although no significant changes in mood were observed.
A separate 2023 meta-analysis of 20 studies homed in on how well ice baths help athletes reduce muscle soreness, fatigue, and damage after intense exercise. Researchers found that an ice plunge can help reduce muscle soreness and fatigue immediately after exercise.
But they also found that time in frigid water could reduce so-called explosive performance—such as the ability to jump high—immediately after getting out of cold water.
And, cautions Nanos, timing seems to matter when it comes to a post-workout ice bath. A 2024 review of eight studies found that cold-water bathing after resistance training could actually reduce muscle growth—a big downside for those seeking to bulk up.
'If you do it too soon, you're blunting muscle protein synthesis,' Nanos says. It's recommended to wait four to six hours after strength training to do a cold plunge—or even only stepping into frigid water on rest or cardio days, she said.
So, bottom line, if you enjoy an ice bath and experience benefits, go for it. 'And if it makes you miserable, stop,' Nanos advises . 'Some people just really have a strong aversion to being that cold and their bodies don't adapt, and they don't feel good or they panic. If you find that your body can't regulate, even after starting slowly, it's just not for you.'
However, if the cold water calls to you, dive in.
This story is part of Popular Science's Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall. Have something you've always wanted to know? Ask us.