Should You Soak in Hot or Cold Water After a Marathon?

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After a long run, bike ride, or vigorous workout, many people will often do one of two things: take a hot bath to unwind or take a brisk shower to cool off. While both seem like respectable choices, one is far less therapeutic than you might imagine. Both hot and cold water therapies have their benefits, but they're actually quite different.

As forms of hydrotherapy, each has specific aims and purposes. On the surface, it may seem that each offers similar benefits. But how they do so differ enormously, and, depending on when you use them, they can sometimes cause more harm than good.

Hot Baths for Sore Muscles

Warm water (90 degrees to 100 degrees Fahrenheit) causes blood vessels to swell and increases circulation to muscles and joints. This form of therapy does wonders for people with joint stiffness, enhancing flexibility and easing the pain in as little as 10 minutes.

The best time to use hot water is immediately before a workout to heat sore areas that could benefit from a little extra blood flow. A hot bath can be useful for warming tight or painful muscles and joints.

Start by taking a hot water bath shortly before your workout, soaking for between 10 and 15 minutes in water between 100 and 105 degrees Fahrenheit.

Heat alone, however, is not necessarily enough to ward off pain. When combined with stretching, it can loosen stiff muscles, joints, and tendons and improve overall mobility. If you have a sore hamstring, for example, you might want to soak the area in hot water and follow up with some gentle stretches before you begin working out.

Hot water therapy is commonly used in people with fibromyalgia and can benefit anyone with pre-workout tightness or aches.

Skip Post-Workout Hot Baths

After a long run, the impact and stress on the muscles and joints will invariably cause inflammation. Inflammation is simply the body's response to physical stress, whether it be caused by extreme activity, injury, or infection.

When inflammation occurs, it triggers an immune response which causes blood vessels to swell and tissues to become porous. This allows immune cells closer to the site of the stress. While the effect is meant to repair damaged cells, it can also lead to swelling, redness, and pain.

After a run, the last thing you want to do is enhance this effect by soaking in warm water. Instead, you want to cool the affected area so that the vessels constrict, thereby relieving swelling and pain.

Post-Workout Cold and Ice

After an exercise session, whether cardiovascular or weight training, an ice bath will be your best source of relief and the fastest route to recovery. First, fill a bathtub with cold water and get in, allowing your body to adjust to the temperature. After a minute or so, dump one or two 5-pound bags of ice into the water and stay there 10 minutes at most.

If you can't handle the sensation of ice water on bare skin, you can wear clothing in the bath. A cold shower or applying ice packs to sore areas are alternatives.

Fortunately, you don't need to actually submerge yourself in a tub full of ice to get the benefits of cold therapy. The water should be cool, between 50 and 60 degrees Fahrenheit. But even if you are just soaking in cool water, keep the length of your bath to under 15 minutes to avoid muscle stiffness and skin damage. Adding Epsom salts to a cool bath is also soothing.

Cool Therapy Timing

There’s no need to rush right from your workout to dunking yourself in ice water. A 2018 study published in The International Journal of Research in Exercise Physiology found that bathing for 10 to 20 minutes in 55-degree water promoted exercise recovery immediately after a workout but was equally effective up to two hours later.

As long as you have a chilly soak within that two-hour window, you can reap the rewards. The study's authors suggest that you can likely derive some benefits as long as cold therapy is used up to two days after a high-intensity workout.

Ice baths might be helpful before exercise if you are working out in hot or humid weather. Research published in 2012 demonstrated that a cold bath could improve performance by reducing the effects of heat and humidity. If you plan to run a race in the sweltering heat, try soaking in an ice bath for about 10 to 15 minutes beforehand.

Contrast Therapy

One alternative known as contrast therapy involves switching between hot and cold water, starting with hot and ending with cold, or cycling between them. In a 2013 study, researchers compared contrast therapy with other recovery treatments (stretching, compression, cold water immersion, etc.) as well as no treatment.

While the study authors found that contrast therapy promoted faster recovery than no treatment, the results didn't reveal any significant benefits to contrast therapy over other recovery methods. To try contrast therapy at home, alternate between hot and cold water in the shower.

A Word From Verywell

Hot and cold water can be beneficial when they are used correctly to aid in exercise recovery. When it comes to post-workout recovery, you’ll get the greatest benefits from cold water therapy.

Stick to the hot water before, cold water after rule unless you have a specific reason to break it such as running in very hot or humid weather. Be aware of the potential risks. If you have a condition such as cardiovascular disease or high blood pressure, you should check with your doctor before you try either a hot soak or an ice bath.

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