If you want to train often and reach your full potential, recovery is key. And while you can let your body heal on its own time with adequate rest, specific recovery techniques help speed up the process.
Foam rolling and light exercise are tried-and-true approaches, but contrast therapy—or alternating between hot and cold temperatures—is another effective method worth considering. To explain why, this guide offers an explanation of contrast therapy, how it boosts recovery, and what to keep in mind when you try it.
All About Contrast Therapy
Contrast therapy is a form of hydrotherapy (water-based) often used in physical therapy settings to treat injuries. Athletes, like cyclists and runners, might also turn to the technique to help their muscles recover from a tough workout.
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Traditionally, you soak an injured area or targeted muscles in water, alternating between hot and cold temperatures.
Repeatedly switching between hot and cold water causes your blood vessels to dilate (expand) and constrict (narrow), which creates a pumping effect. “The pumping effect initiated by contrast therapy may improve the flow of oxygenated blood, leading to tissue healing,” says Rami Hashish, D.P.T, Ph.D. in biomechanics, and adjunct clinical faculty in the University of Southern California’s Division of Biokinesiology and Physical Therapy. Oxygenated blood carries nutrients that your tissues need to repair.
According to a study published in the Journal of Athletic Training in 2018, the most common protocol for contrast therapy begins with a 10-minute rested soak in hot water that’s around 100.4 to 104 degrees Fahrenheit (38 to 40 degrees Celsius). After that, you alternate between one minute in cold water (46.4 to 50 degrees Fahrenheit or 8 to 10 degrees Celsius) and four minutes in hot water until you reach the 30-minute mark. This practice can alter, sometimes with three minutes in hot water and one in cold, but it can also change depending on where you go for the recovery method.
These days, there are also wearable devices on the market (like the Hyperice X and Therabody RecoveryTherm) that apply contrast therapy through infrared and cryotherapy technology, so you don’t have to use water. Not only are these devices more portable and convenient than using water, but one small study of 20 individuals published in Medical Science Monitor in 2020 reveals that this method may do a better job of improving blood flow.
The Benefits of Contrast Therapy
The primary perk of contrast therapy is that it promotes tissue repair, making it a go-to for injuries and postworkout recovery.
In one study published in the Journal of Athletic Training in 2018, 10 healthy men and women put their lower left leg through a 30-minute contrast therapy session. Compared to the lower right leg, which wasn’t immersed in water, the lower left leg had higher levels of oxygen-rich blood circulating through the muscles. Given how important oxygen and blood flow are for promoting tissue repair, the researchers believe these results support contrast therapy’s role in rehabilitation.
This type of therapy is best served for rehabilitation of minor injuries. “Contrast therapy is arguably most beneficial for sprains and strains, such as to the foot and ankle, knee, wrist, elbow, shoulder, or neck,” says Hashish, who points out that you should wait a day or two after the injury or onset of symptoms like swelling or redness, as the heat can actually exacerbate the swelling. (It’s also always a good idea to check with a doctor first before trying contrast therapy to help an injury.)
According to Jennifer McNamara, M.P.T., director of therapy services at Orthopedic Associates of Hartford, contrast therapy can also help lower inflammation and joint stiffness caused by an injury.
These benefits also make contrast therapy a helpful postworkout recovery tool—at least according to the findings of a systematic review and meta-analysis in PLoS One. After collecting data from 13 studies, researchers found that contrast therapy significantly improved exercise-induced muscle soreness compared to passive recovery (or rest days). Contrast therapy also lessened strength losses compared to passive recovery.
Boosting circulation and blood flow through contrast therapy may move more nutrients to sore and damaged muscles, which helps limit pain and improve function, Hashish says.
The Risks of Contrast Therapy
There are always risks to exposing your body to hot and cold. For example, Hashish says, you may damage or irritate your skin if the water is too hot or too cold.
The circulation changes that happen when you transition between the two temperatures can also make you feel dizzy, Hashish adds, especially if you immerse yourself in water.
For people with an irregular heartbeat (a heart arrhythmia) or nervous system dysfunction, the drastic temperature change may be too much of a shock to the system. It can affect your body’s sensory nerves and in extreme cases, potentially put you in a state of paralysis, warns Rochester Regional Health.
Contrast therapy may also be risky for people with nerve damage, such as diabetic neuropathy, as well as those with high blood pressure. Given the risks, McNamara recommends consulting your doctor before trying contrast therapy, especially if you have any of these conditions.
What to Keep in Mind if You Try Contrast Therapy
If you’ve been cleared by your doctor, you can use contrast therapy regularly to treat minor injuries and speed up exercise recovery, McNamara says. Try it after an especially intense training session or race when you want to feel better faster or if you have another workout on the docket soon after and want to perform your best.
Whether you use a wearable contrast therapy device or soak in a bath, stick to the recommended temperatures and durations. Pay attention to how you feel during the treatment; stop if it causes pain or dizziness.
Also, keep in mind that “there is minimal evidence to show the benefits of contrast therapy relative to other active recovery techniques,” Hashish says.
The aforementioned review and meta-analysis, for example, found that contrast therapy was an effective postexercise recovery method when compared to passive recovery (i.e. rest). But there was little difference between contrast therapy and recovery techniques, such as compression, stretching, and low-intensity exercise.
So, don’t expect contrast therapy to work better than other recovery methods. And don’t treat contrast therapy as a cure-all. However, “if implemented as part of a holistic recovery method, contrast therapy may prove to be quite beneficial,” Hashish says. “As contrast therapy can expedite postworkout recovery, it may allow for a quicker return to activity, which can lead to greater performance gains.”
Lauren Bedosky is a freelance health and fitness writer who specializes in covering running and strength training topics. She writes for a variety of national publications, including Runner’s World, Prevention, Experience Life and Women’s Running.
