The most accurate way to describe Katie Ledecky is unstoppable. The American distance swimmer and Rio Olympics favorite doesn't just beat her opponents by a couple hundredths of a second or an extra half stroke. Her winning margin in races is often measured in body lengths.
A 19-year-old phenom, Ledecky was dominant last summer at the 2015 FINA World Championships in Kazan, Russia. She won five gold medals and shattered three world records—twice breaking her 1,500-meter freestyle mark, which now stands at 15 minutes and 25.48 seconds.
Believe it or not, she won't have an opportunity to again break that record in Rio. The women's 1,500-meter freestyle—a race offered at numerous national and international competitions—is not part of the Olympic program.
Instead, the International Olympic Committee limits the maximum distance of women's Olympic swimming events in the pool to the 800-meter race, even though male swimmers compete in the 1,500, also known as the mile.
"It's definitely a sore subject," said Haley Anderson, who won the silver medal in the open-water 10,000-meter race at the London Olympics and will try for gold again in Rio. "I wish the women had the mile. I think that should be one of the next events they include because it's rough for us. It goes from the 800 to the 10K and nothing in between."
For as long as the modern Olympics have existed, they have featured inequality between men's and women's swimming, particularly in distance events. Women didn't swim in the inaugural 1896 Athens Games, and when they finally joined the Olympics program in 1912, they swam in only two events, the 100-meter freestyle and the 4×100-meter freestyle relay.
By 1904, men were swimming the 1,500 at the Olympics. Yet prior to the 1968 Mexico City Games, the longest race women could swim was the 400-meter freestyle. That year, the women's 200- and 800-meter freestyle races were added to the Games' lineup. However, the 1,500 was not. Why? According to Olympic medalist Debbie Meyer, women were considered "second-class" athletes who lacked the strength of their male counterparts and would be unable to handle longer distances.
Never mind, of course, that Meyer claimed the 1,500 world record the summer before the '68 Games at age 15, and held on to it—while continuing to break it—until 1971.
"I wanted the 1,500 in there," said Meyer, who won Olympic gold in the 200, 400, and 800 during the Mexico City Olympics as a 16-year-old, and loved the longer race precisely for its length. "I wanted to swim it."
Although equality for women in the Olympics has come a long way over the last several decades, Meyer believes the women's 1,500 should have been added to the lineup years ago. She speculated that the 1984 Summer Olympics were a major missed opportunity. Those Games were held in Los Angeles, and the United States dominated women's distance swimming, particularly with Eastern Bloc nations boycotting the event. That summer, Team USA won 34 swimming medals; 19 were in women's events and 12 of those were gold, as the American women swept the freestyle events.
Today, the women's 1,500 is offered at the U.S. national championships, the world championships, the Pan Pacific Swimming Championships, and the European Aquatics Championships, among many others. And Ledecky's 1,500 world record is well below the men's qualifying time for this year's U.S. Olympic Trials of 15 minutes and 49.99 seconds.
First-time Olympian Leah Smith, 21, is just one of many swimmers and coaches to call the event's continued exclusion at the Olympics outdated. Smith—who recently finished her third year at the University of Virginia and will compete alongside Ledecky in Rio in the 400- and 800-meter freestyle—said she would have raced in the 1,500 if it had been an option.
"Now that you can see Katie Ledecky going times that guys across the U.S. can't go, it's kind of ridiculous," Smith said prior to qualifying for the Olympics. "One of our hardest practices would be 8,000 or 9,000 yards, and we're swimming several miles in our practices. We even swim a straight mile in practice, (and) every single day I'm doing more than that. It's disheartening because I didn't ask to be good at distance swimming."
While female distance swimmers whose best event is the mile are denied the chance to compete in their favored race, they're not alone. Because men have the 1,500 in the Olympics, they don't have the 800. So if the 400 is just a little too short for them, the next option up is the mile.
With men's and women's events equal in so many international meets, it "doesn't really make a lot of sense" to have them swim different races at the Olympics, said Josh White, an associate head coach at the University of Michigan. White said he would welcome more events for men and women at the Olympics because he coaches several distance swimmers—most notably Connor Jaeger, who finished sixth in the 1,500 free at the 2012 London Games and will compete in the 400 and 1,500 in Rio.
"It's a big jump [from 400 meters to 1,500 meters]," White said, noting that not everyone is as versatile as Jaeger. At last year's world championships, Jaeger won the silver medal in the 1,500 and finished fourth in both the 400 and the 800.
After decades of indifference, FINA—the International Swimming Federation, the world governing body for aquatics—reportedly has pushed to add both the women's 1,500 and the men's 800 to the Olympics. The IOC hasn't budged from its position, citing a desire not to add additional events to a packed Games schedule.
Ledecky's coach, Bruce Gemmell, recently told NBC Sports that he believes there is a better chance of the IOC approving 50-meter backstroke, breaststroke, and butterfly races than adding the women's 1,500. The longer race, which lasts 30 laps, has a smaller field of world-class competitors, he said, and can make for less compelling television viewing.
White is unpersuaded by the IOC's argument.
"At world championships, they manage to fit both the  and the 1,500 into the order of events in the same eight days that they have for the Olympics," he said. "It definitely makes for a tough meet if you have eight days and you're swimming two 400s, two 800s, and two 1,500s. That's a lot of tough swimming, but people have done it really well."
For women, replacing the 800 with the 1,500 in order to have the same lineup as male swimmers would erase decades of Olympic history and create the same challenging gap the men currently face. White argues the best solution for equality and opportunity is to follow the lead of other international meets and allow men and women to swim both events.
"The women swimming the 800 and men swimming the [1,500] continues to communicate an erroneous bias that women aren't capable of the same feats of endurance as men," he said. "While the IOC's reluctance to add additional events to the Olympic program is in general understandable, in this case correcting the inequity should far outweigh any logistical concerns."
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