What Is Cold Water Therapy? A Detailed Scientific Guide

Stepping into an ice-cold shower may seem like a rough way to start the day, but some research suggests it could benefit your health.

Here's a look at what cold water therapy entails, whether it's safe for you, and how to get started.

You can practice cold water immersion on your own at home or in a natural body of water. However, it's best to do it under the guidance of a healthcare professional if you're using it to recover from an injury, improve your athletic performance, or alleviate pain. Some fitness centers, physical therapy clinics, and specialty wellness studios offer hydrotherapy, including cold water immersion.

Immersing yourself in cold water may affect the body through a few different mechanisms:

• Vasoconstriction When you're cold, your blood vessels constrict, or narrow. This process, known as vasoconstriction, may help reduce inflammation.

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• Hydrostatic Pressure The gentle pressure water exerts on your body (known as hydrostatic pressure) similarly reduces pain and swelling, while boosting blood flow to the heart, says Sean Carpenter, DPT, a physical therapist with Memorial Hermann Health System in Houston.

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   “It's like a natural compression system for your muscles,” Carpenter says.
• Vasodilation When you warm up after a cold plunge or shower, blood vessels expand (vasodilation), Carpenter says. When that happens, the oxygen- and nutrient-rich blood gets pumped back to your tissues.

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• Inflammation Reduction Pain and swelling often stem from inflammation.

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  By reducing pro-inflammatory chemicals in the body, cold water therapy may help calm the body's response to injury or strain, Carpenter says.

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  “It's much like applying ice to a sprained ankle.”
• Nervous System Stimulation Entering frigid water prompts the brain to release endorphins — the same happy chemicals you get from a good workout. It also activates the sympathetic nervous system (SNS), stimulating a rise in noradrenaline (a hormone involved in the fight-or-flight response) and dopamine (the “happy hormone”) and a decrease in cortisol (the “stress hormone”).

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   “This can elevate your mood,” says Joseph Hribick, DPT, clinical assistant professor of physical therapy at Lebanon Valley College in Annville, Pennsylvania.

Options for cold water therapy include:

• Cold Water Immersion Like the name suggests, cold water immersion involves lowering yourself in cold water up to your neck or submerging a specific area of the body, like an arm or a leg. You can do this in a tub, basin, or natural body of water. There's no universal, official guidance for the optimal temperature or time limit, but most people use water that's at or below 59 degrees F and remain submerged for 10 minutes at most.

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• Contrast Water Therapy This method is similar to cold water immersion, except that it alternates exposure to cold water with exposure to hot water. There's no standard protocol, but most studies involve using temperatures between 50 to 59 degrees F (cold) and 100 to 104 degrees F (hot) for 1 to 2 minutes at a time.

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• Cold Showers Taking a frigid shower offers a way to ease into cold water therapy, though it may not be as beneficial as cold water immersion, says Scott J. Biehl, DO, an orthopedics and sports medicine physician at Rochester Regional Health in New York.

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   As with immersion, it's best to gradually turn down the temp, and stay in for 10 minutes at most.

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• Wim Hof Method The Wim Hof Method, invented by Dutch extreme athlete Wim Hof, combines cold water therapy, breath work, and commitment. By commitment, Hof means dedication to the practice and exercising self-control and willpower.

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1. May Aid Muscle Recovery

2. May Help Relieve Pain

“Its role in chronic pain management is not well supported by current research and it's rarely recommended as a long-term solution,” Dr. Raizman says. “Overall, it's best applied to short-term pain and post-workout fatigue rather than ongoing or chronic conditions.”

3. May Boost Your Mood

Cold water therapy is generally safe but could be risky if you are in the water too long or you have certain medical conditions, says Irvin Sulapas, MD, a sports medicine physician at UTHealth Houston.

If you plan to practice cold water immersion in an open body of water, be sure to take a partner with you — even if you're a strong, experienced swimmer — in case of emergency.

“Like many health-related activities, this can be hugely beneficial, but it's not for everyone, and even a person who responds positively to it may not experience those benefits all of the time,” says Jessica McManus, PT, owner of Full Circle Wellness in Newbury, Massachusetts.

If you're new to cold water therapy, hopping into a frigid lake or a tub filled with ice may be too much of a shock, so consider starting with cold showers.

“We recommend our athletes and patients start with a cold shower or an outdoor pool that's around 65 degrees F,” Gallucci says. At first, each session may be as short as 10 to 30 seconds. You can slowly increase the time over days (or weeks) as you build up tolerance. “Gradual acclimation is key to safely adapting to colder temperatures,” Gallucci says.

Once you're ready for a cold bath, simply fill your tub with the coldest water you can get from your tap. This will most likely fill your tub within the range of 50 to 60 degrees F, Biehl says. Double-check by dipping a thermometer in the water. If your water isn't cold enough to reach 60 degrees, that's okay; you can add ice after your tolerance to cold exposure has increased.

Once you're ready for a dip, step carefully into the water and slowly lower yourself until you're submerged from the neck down. You can also target a specific region of the body. For example, only sit in water high enough to cover the legs to boost recovery following an intense lower-body strength routine or cycling session, Biehl says. “Try to sit for 2 or 5 minutes and work your way up to 10 minutes.”

Get out once you start to shake or shiver, recommends Jonathan Leary, DC, a chiropractor and CEO and founder of Remedy Place, a wellness facility in New York City and California that offers ice bath classes. “That's your body telling you that you've reached your max time for the day,” he says.

Before

If you're doing cold water therapy at home, you may choose to go without clothes. In public places, you can wear a swimsuit or shorts and a light top or sports bra. Before stepping in, gather essentials like a towel and dry clothes for afterward. “It's also important to mentally prepare by engaging in deep breathing or mindfulness to help manage the initial shock of the cold,” Gallucci says.

During

Entering cold water may take your breath away at first, “and you can feel your heart race,” Biehl says. Gallucci recommends staying calm and focusing on slow, controlled breathing to overcome the initial shock.

In the beginning, you might spend only a few minutes in the cold water. You'll have to gauge how your body responds and tailor your practice accordingly. “There's a very fine line between what each person can tolerate,” says Matthew Welch, CSCS, an exercise physiologist at the Hospital for Special Surgery in New York City. Just because your friend can sit for five minutes doesn't mean you can.

“Numbness, dizziness, or uncontrollable shivering are signs that it's time to exit,” Gallucci says. “For those using localized cold therapy (such as for an ankle or knee), the same principles apply on a smaller scale.”

After

Once you get out of the water, drying off and changing into warm, dry clothes is essential, Gallucci says. “Many people follow up with light movement, a warm drink, or contrast therapy (alternating hot and cold) to help stabilize circulation and promote recovery,” he says. You may feel an initial energy boost or endorphin rush, followed by a period of relaxation, Gallucci continues. Take note of your body's response and adjust your next session accordingly, Gallucci suggests. Once you're warmed up, you may notice that you have greater mobility and less pain. But if you experience adverse effects, it may signal that you did more than your body can handle.

• Cold water therapy is an age-old practice known for its ability to accelerate post-workout recovery, though it may have additional mental and physical health benefits.
• Cold immersion therapy is generally safe for most people, but it can pose risks, especially to those with underlying health conditions, including heart disease, high blood pressure, diabetes, and nerve issues.
• Research on cold water therapy's benefits has yielded mixed results, and it isn't a good fit for everyone, so it's best to talk with your healthcare provider before giving it a try.