SARAH MCCAMMON, HOST:

You may have heard the news this week about American track-and-field athlete Sha'Carri Richardson. The U.S. Anti-Doping Agency announced yesterday that Richardson had accepted a one-month suspension from competition after testing positive for marijuana at the U.S. track and field trials last month. The suspension means Richardson may not be able to represent the U.S. at the upcoming Tokyo Olympics, despite her dominating the 100-meter race at trials and earning a spot on Team USA with that performance. She had been considered a favorite for a gold medal in Tokyo in the 100 meters. Now, it's not clear if she'll even take part in the games at all.

The rules are clear. Marijuana is on the World Anti-Doping Agency's list of prohibited substances for athletes. But we wanted to know more about why pot is considered a performance-enhancing drug in the first place, so we called Dr. Michael Joyner. He's a physician and researcher on exercise physiology at the Mayo Clinic in Minnesota. And he joins us now. Welcome.

MICHAEL JOYNER: Sarah, it's great to be with you.

MCCAMMON: So the reaction I heard from a lot of people this week was, who knew that marijuana could actually enhance performance? So tell us about that. I mean, do you have any insight into how and why marijuana made its way onto the World Anti-Doping Agency list of banned substances?

JOYNER: You know, it's very interesting because I think, Sarah, there's a couple of answers here. First, in some sports like shooting, archery and sports where you have to be relaxed and so forth, sedatives and things like alcohol are, in fact, banned substances. But those certainly aren't going to help people sprint fast or, you know, throw the shot put farther, ride a bike fast or whatever it is. So I think that there is a rationale for some substances that have sedative qualities like marijuana to be on the list for some sports.

But the list is a blanket list. So if it's banned in one sport, it's banned in everything. And then I think when the list emerged - as the list emerged in the '60s, '70s, '80s and later on, people wanted to, you know, ban what they saw at the time as drugs of abuse. So I think this is a legacy of just kind of poor regulation in terms of not specifically saying what drug is banned for which event and also this sort of reefer madness sort of holdover.

MCCAMMON: I want to talk more about that in a moment. But what is the history of marijuana's use in sports, and when did the agency start paying attention to it?

JOYNER: Well, again, I think it's really tied up in the whole, you know, should marijuana be legal, illegal, drug of abuse, drug of use, recreational drug? And all of these sorts of discussions have been going on in our country, you know, really for a long time, but especially the last 30, 40 years. And I think if you actually look at the data - and I did that yesterday - I went on PubMed, the National Medical Library, which is online, and looked at the data. And really, there's almost no information about how it influences athletic performance and certainly very little information about how it might influence performance in things like shooting, archery and so forth, things that would require relaxation. So really, the evidence is either non-existent, very thin, and again, wouldn't apply to any of the events that Richardson is in.

MCCAMMON: You mentioned that marijuana is a sedative and in some sports, it might actually help you if you need to be relaxed and others not so much. Does it make sense to have blanket bans on substances?

JOYNER: No. No. And really, you know, what you want to ban is you want to ban drugs or compounds that make people stronger like steroids, make people able to transport more oxygen like erythropoietin or blood doping or, you know, central nervous system stimulants like amphetamines. And once you get beyond those three big classes, you know, you just wonder how granular things should be and how often things should be revisited and what the evidence base is for some of this. And really, as I looked, I didn't think the evidence base for marijuana would be particularly strong. But as I looked at the papers yesterday, I was surprised at how weak it is.

MCCAMMON: The World Anti-Doping Agency says in its own code that some substances are prohibited, quote, "because they are frequently abused in society outside of the context of sport." That seems to suggest that substances might be banned because they're viewed as as morally wrong or damaging to society. Do you think that's an appropriate consideration for what's banned in sports and what's not?

JOYNER: The first short answer to that is no. I think the longer answer is that our thoughts about, you know, what are drugs of use and drugs of abuse vary, they change, they're different in one society than the next and so forth. And so I think it's a bit of a slippery slope. And certainly the code is behind where we are legally. There's a hodgepodge of laws all over the country. And things have really changed in the last 10 or 20 years. So I think these rules and the list certainly needs to be revamped. And I think what's happened to Sha'Carri is just really, really unfortunate because she's a terrific athlete, remarkable performances, and really would have been a, you know, bright, shining star in the upcoming Olympics. There is some thought, Sarah, that she might be able to get on the relays, and I don't know where that is now, but hopefully that will happen.

MCCAMMON: Is that because of the timing of the events?

JOYNER: Yeah, the timing of the events and the selection criteria. So her 30-day ban would be up by the 4x100 relay event. But again, I'm not sure exactly what the selection criteria are. And if the coaches in Team USA has the flexibility to pick her, I hope they can.

MCCAMMON: The last thing I want to ask you, Dr. Joyner, is about the treatment of Sha'Carri Richardson. How does it compare to other athletes who've tested positive for substances like marijuana?

JOYNER: You know, this is so high-profile, and it came at such an inopportune time, you just don't know how much is out there. And I don't know how many people have been banned because typically these bans are very short, you know, 30 days, a couple of months. And so I don't know how many people have have been, you know, subtly or quietly, you know, sent to treatment and banned. But I do think that things need to be looked at again and looked at more comprehensively so that'll at least be one positive outcome of this very, very unfortunate situation.

MCCAMMON: Dr. Michael Joyner is a physician and researcher on exercise physiology at the Mayo Clinic in Rochester, Minnesota. Dr. Joyner, thanks so much for speaking with us.

JOYNER: It's my pleasure. Transcript provided by NPR, Copyright NPR.