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Why Do Swimmers Have Dark Circles On Their Backs? (Explained)

Updated: Aug 15

As the swimming competition at the Tokyo Olympic Games began, several of the athletes can be seen wandering about the pool and lining up on the starting blocks covered with strange-looking dark circles on their skin.

What exactly are they and what do they do?

The dark circles you see on some athletes skin is caused by a recovery technique called cupping, it causes blood to be pulled close to the skin's surface, similar to how a bruise occurs. It's not unhealthy, and it may even help with muscle recovery.

In this article, I'll also explain what cupping is, what it does, and why it's used in sports.

What Is Cupping?

Cupping is an old alternative medicine with origins in Middle Eastern and Asian traditions.

It entails employing cups to create suction on the skin. This increases blood flow to the suctioned region, which is supposed to help improve recovery for the muscles and connective tissue.

The cups are only on the skin for a few minutes, but that is enough time for capillaries just under the skin's surface to burst, resulting in the strange-looking circles.

These dark circles are essentially bruises.

olympic swimmer with dark circles on skin from cupping

Cupping In Sports

Dwayne Johnson and Conor McGregor have been proponents of the method in recent years, and during the Rio 2016 Olympics, Michael Phelps, among other athletes, was spotted coated in brown circles.

Many athletes take it to help them recover from hard exercise, but despite its claims to have a slew of advantages, the research behind it is slim.

Does It Help?

According to the US National Center for Complementary and Integrative Health, "not enough high quality research" has been done to determine if it has any advantages.

Meanwhile, one 2019 study revealed that the injury to the skin caused by cupping may trigger a pain-inhibiting mechanism in the body. (1)

cupping effects theory diagram

Although some theory does exist for the benefits of cupping like found on Olympic athletes skin, more study is required to conclude anything.

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