Olympics Live Updates: A Bumper Year for Australia’s Winter Sports

When news broke that Kamila Valieva, the 15-year-old figure skater who helped propel Russia to gold in the team competition and is a favorite in the women’s individual competition, had tested positive for a banned substance before the Olympics, the episode raised questions that have come up many times before in doping scandals.

Did the banned drug trimetazidine, known as TMZ, make a difference? Could it have helped Valieva?

The heart expert Dr. Benjamin J. Levine, a professor of exercise science at the University of Texas Southwestern Medical School, said no.

“The chance that trimetazidine would improve her performance, in my opinion, is zero,” Dr. Levine said.

“The only chance would be for it to hurt her,” he added.

Antidoping experts disagree on whether trimetazidine could enhance Valieva’s performance, which is why its use is prohibited. It can be difficult to perform controlled studies on banned substances. But antidoping experts said analyses of the use of the drug, predominantly by Eastern European athletes, indicate that it can increase stamina and endurance, provide benefits to training and perhaps aid recovery from strenuous workouts. Thus, they say, it could provide an unfair advantage in increasing oxygen-carrying capacity.

Trimetazidine is listed by the World Anti-Doping Agency in the category of hormone and metabolic modulators, a class of drugs that athletes have been known to use for performance enhancement. It was added to the list of substances prohibited for use during competition in 2014 and banned for use out of competition in 2015. It is not approved for sale in the United States.

The intended medical use of trimetazidine is to increase blood flow to the heart in patients who have chest pain because their cardiac arteries are blocked. But blood flow to the heart is not a problem in events like figure skating, Dr. Levine said, nor is the type of fuel the heart uses.

“The heart has plenty of blood,” Dr. Levine said. “And the heart is so good at using different fuels.”

But figure-skating routines can last up to four minutes — far longer than the average 45-second hockey shift — and are extremely taxing. A drug like trimetazidine, antidoping experts say, could illicitly increase stamina. That could be particularly valuable in the second half of routines, when skaters get bonus points for jumps.

This is not the first time trimetazidine has been used by Olympians. In 2014, the star Chinese swimmer Sun Yang tested positive for it and was suspended for three months. The Russian bobsledder Nadezhda Sergeeva was disqualified and banned for eight months after testing positive for trimetazidine at the 2018 Games.

Trimetazidine is a metabolic cousin of meldonium, whose use resulted in a wave of positive drug screens in 2016 in sports like tennis, speedskating, wresting and track and field. Among those suspended was the Russian tennis star Maria Sharapova, who received a 15-month ban. At the 2018 Olympics, the Russian curler Aleksandr Krushelnitckii was stripped of his bronze medal in the mixed-doubles event after testing positive for meldonium.

Because Valieva is younger than 16, she is considered a “protected person” by the World Anti-Doping Agency. If she can show that her use of trimetazidine was unintentional, she could receive a warning instead of a maximum two-year suspension and not face the potential loss of two gold medals. It is even possible that her reprimand would not be announced publicly. But because the authorities did not resolve her case before the Olympics began, her reputation has been left to twist in the wind.