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

Woman relaxing in bathtub
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After a long run or marathon, runners will often do one of two things: take a nice, hot bath to unwind or take a nice, brisk shower to cool off. While both seem like respectable choices, one is far less therapeutic than you might imagine.

Benefits of Hot and Cold Hydrotherapy

Both hot and cold water therapies have their benefits, but they're actually quite specific. As forms of hydrotherapy, each have different aims and purposes:

  • Warm water (90o to 100o F)causes blood vessels to swell and increases circulation to muscles and joints. This form of therapy does wonders or people with joint stiffness, enhancing flexibility and easing the pain in as little as 10 minutes.
  • Cold water does just the opposite. It causes the constriction (narrowing) of blood vessels which not only reduces inflammation but relieves pain by numbing the affected muscles and tissues.

On the surface, it may seem that each offers the same benefits. But how they do so differ enormously, and, depending on when you use them, they can sometimes cause more harm than good.

Why Hot Water Doesn't Help

When it comes to running, the rule is simple: use hot water before a run and cold water after.

Why? 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.

With regards to running, the last thing you would want to do is enhance this effect by soaking in warm water. Instead, you would want to cool the affected area so that the vessels are encouraged to constrict, thereby relieving swelling and pain.

A hot water bath is better suited for warming up stiff or painful muscles and joints. When combined with stretching, it can loosen stiff muscles, joints, and tendons and improve overall mobility. It is commonly used in people with fibromyalgia and can benefit runners-in-training who may have pre-run tightness or aches.

How to Take an Ice Bath

After a long run or marathon, an ice bath will be your best source of relief and the fastest road to recovery. To begin, you would need to 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 five-pound bags of ice into the water and stay there 10 minutes, no longer.

If you can't bear the sensation of ice water on bare skin, you can wear running shorts and a sweatshirt in the bath. A cold shower is also an acceptable alternative.

If all fails, you can apply an ice pack or a bag of frozen vegetables on the affected areas. However, you should avoid icing an area for more than 20 minutes or risk a possible frostbite injury.

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Article Sources
  • Mooventhan, A. and Nivethitha, L. "Scientific Evidence-Based Effects of Hydrotherapy on Various Systems of the Body." N Am J Med Sci. 2014 May; 6(5):199-209. DOI: 10.4103/1947-2714.132935.