Performance-enhancing drugs aren't just for regular sports anymore.

In the world of eSports, however, it's not about bulking up physically. In the world of eSports, performance is about mental acuity and concentration.

The drug of choice is Adderall, an amphetamine that requires a doctor's prescription. It's used to treat ADHD. Adderall is also common in colleges, where students use it as a study aid. It's a stimulant that enables long periods of concentration, or, as Business Insider science editor Kevin Loria put it: "It's basically speed."

And that's why it's been so easily adopted by the competitive eSports world.

"We were all on Adderall," Kory “SEMPHIS” Friesen, a professional eSports competitor, said in an interview with Launders on YouTube on July 12.

Here's the full interview (Friesen starts talking about using performance-enhancing drugs at around 7:30):

Friesen claimed that "everyone" used Adderall at one particular event – a $250,000 prize tournament in Poland – and that it's a commonly used drug among eSports players during competitive events. The event was hosted by ESL, the Electronic Sports League, which is one of the oldest and largest eSports leagues in operation. It boasts "more than 5,000,000 registered members."

As a result, ESL announced on Thursday that it's is implementing anti-doping measures.

We will be administering the first PED [performance-enhancing drug] skin tests at ESL One Cologne this August, with a view to performing these tests at every Intel Extreme Masters, ESL One and ESL ESEA Pro League event thereafter as soon as the official PED policy is established and tournament rules updated accordingly.

ESL is working with European regulators at the Nationale Anti Doping Agentur to establish rules and standards for it's anti-doping measures, and says it will begin implementing the regulations in August. Friesen, meanwhile, won't be punished. ESL representatives told Motherboard, "We can't punish someone if we are not 100 percent sure he is guilty. And as we have no way to test it anymore (we're four months after the event), we won't take action in this specific case."