Beijing (NewsNation Now) — Trimetazidine, the drug that Kamila Valieva, 15, an Olympic figure skating favorite, allegedly tested positive for, is typically for preventing chest pains and treating vertigo— but it can also be used by athletes to up their endurance.

The drug, also known as “TMZ,” according to ESPN, is not approved in the United States, and sits on a prohibited list managed by the World Anti-Doping Agency as a “hormone and metabolic modulator.”

It increases blood flow to the heart and limits rapid swings in blood pressure.

The reason why Trimetazidine is banned is because it can increase blood flow efficiency and improve endurance, which are both crucial to high-end athletic performances like skating.

This was confirmed in a a 2014 study published in the National Library of Medicine that said the drug can be used by athletes to improve their physical efficiency.

Reports of Valieva testing positive, which were first in Russian outlets, didn’t indicate whether the teen athlete has any heart conditions.

Valieva has become a standout in the Beijing Winter Games as the first female skater to land a quad jump at the Olympics — a move she did twice to help Russia win gold in the team competition.

In that competition, the United States took second and Japan was third.

The International Olympic Committee paused Tuesday’s figure skating medal ceremony after the Russian team’s victory, citing a need for “legal consultation.”

While it is not confirmed why the IOC halted the ceremony, Russian media outlets and others have speculated it’s because an athlete used a banned drug.

Even amid these reports, Valieva was back on the rink Thursday, running through her program and skating with teammates while getting pointers from her coaches.

At the end of her roughly 30-minute session, Valieva flashed a smile to one of her coaches, but none of the skaters took questions from reporters.

Russian Figure Skating Federation spokeswoman Olga Ermolina said she is not suspended.

As a minor, Valieva does have extra protection from this incident, as public disclosure of cases is only mandatory for adults.

Trimetazidine has been a cause for concern before, most famously with Chinese swimmer Sun Yang.

Yang, a three-time Olympic champion, served a three-month ban in 2014 in a ruling that was initially not published by China’s anti-doping agency. Russian bobsledder Nadezhda Sergeeva tested positive for trimetazidine at the 2018 Pyeongchang Olympics.