That whole “gender fluidity” discussion has taken root in the professional running world, specifically the Boston Marathon and several other big races. Bowing to demands from transgender rights activists, ABC News reports that runners who “identify” as the opposite of their actual gender will be allowed to compete in the division of their choice. That means that men describing themselves as women will be able to compete against the actual women running in the races.

In 1967, a Boston Marathon official nearly dragged a woman off the course after she managed to enter the men’s-only race. Five decades later, race officials aren’t as concerned about gender boundaries: They’re now publicly acknowledging that transgender runners can compete using the gender they identify with.

“We take people at their word. We register people as they specify themselves to be,” said Tom Grilk, chief of the Boston Athletic Association, the group behind the race. “Members of the LGBT community have had a lot to deal with over the years, and we’d rather not add to that burden.”

At least five openly transgender women are signed up to run the storied 26.2-mile race through Boston and its suburbs April 16. And while they aren’t the first, their presence helped bring clarity to the race’s stance on transgender runners.

While some other sporting events, including the Olympics, have begun making such allowances, they also include restrictions which insist that men undergoing “transition” be on hormone therapy, lowering their testosterone levels significantly. How much that dampens the natural edge men have in physical sports competitions remains an open question, but it’s being ignored here. Officials are saying they are “taking the runners at their word” as to their gendert. The administrator of the Chicago Marathon is quoted as saying, “we don’t feel that we need to require legal or medical records or anything along those lines.”

That turns out to be great news for any guys who aren’t fast enough to win in the men’s division but don’t mind checking the “W” box under gender to give them a leg up. And there’s plenty on the line because winning one of these big marathons can carry a nice payday. The winners of each division in Boston receive $150K.

And how much of a difference could entering the wrong division make? Consider that the winning man in the 2017 Boston Marathon finished a full twelve minutes ahead of the fastest woman. That may not sound like much until you consider how far a professional runner can travel in 12 minutes. It’s a massive lead. If you put that winning woman into the Men’s division she wouldn’t have finished in the top forty. Conversely, a guy who was going to finish relatively far back in the pack of leaders among the men could actually be the winner in the woman’s division.

Keep in mind that this doesn’t mean a man will automatically win. Yes, the fastest man is considerably faster than the fastest woman. But the fastest woman is still far faster than the average man. For a comparison in the tennis world, the Williams sisters would be smoked off the court by Roger Federer, but they could beat any amateur male tennis buff reading this article. If a man who is significantly off the pace of the best in the world enters the Boston marathon “as a woman” there’s no assurance he’ll be able to beat the best women in the sport. But there remains that marginal, gray area if it turns out to be one of the guys who would normally finish in the top 20 or 30 in the men’s division.

If you want to let women compete against men, fine. Maybe the extra testosterone will give them a shot. But men shouldn’t compete against women. It’s just not fair. Even if the men are taking estrogen they still have advantages, and if they aren’t taking anything to lower their testosterone levels (as is allowed in these marathons) the lack of balance is ridiculous. Am I promoting a double standard here? Of course I am, but it’s one I’m willing to live with. Don’t make the women compete with men. That’s not how any of this is supposed to work.