On Friday, China’s ropy, swivel-hipped Zhen Wang sped past 73 competitors to take home the gold in the 20-kilometer race walk, the first men’s track and field event held at Rio de Janeiro’s Olympic Games. Most viewers didn’t notice Wang’s impeccable rigidity as he raced through the beaches of western Rio; in fact, most people didn’t notice the event at all. Race walking, a misnomer that wrongly suggests passivity, doesn’t get half the respect running gets, even though the two sports are arguably equally taxing on the body.

Just consider how damn fast these athletes are walking: Zhen completed the 20-kilometer race in one hour, 19 minutes, and 14 seconds. The world record for running that same distance is 55 minutes and 21 seconds. That’s a difference of roughly 24 minutes for two sports that, in the minds of most people, take place at very different speeds. In Friday’s race, the difference between silver and gold came down to only 12 seconds. A fifth of a minute does not a slow sport make.

China's Zhen Wang took home a gold medal in the 20 km race walk last Friday, finishing with a time of 1:19:14.

While the sport lacks the thrill of the 100-meter dash or the explosiveness of the long jump, it’s as rigorous a test of athletic ability — and physical discipline — as any of the other track and field events it’s lumped together with. What most casual viewers of the centuries-old sport (it got its start as “pedestrianism,” a popular activity among Victorian-era athletes) don’t often realize is that race walking has rules — strict ones that force the athlete to exert maximal physical effort within very narrow confines. That’s why the athletes look so robotic: They’re required to stay in contact with the ground at all times, and the leading leg has to be stick-straight when it first hits the ground. Any fouls caught by the sport’s vigilant judges can lead to disqualification.

These strict rules make the sport more physically taxing than you might assume, a point that a number of scientists have tried to drive home. In a study of eight competitive race walkers published in the International Journal of Sports medicine in 1984, researchers tried to determine the point at which race walking and running became equivalent in terms of how the body responds to exercise. They discovered that athletes competing in both sports hit the same level of oxygen consumption — a common measure of exertion during exercise — at a speed of roughly five miles per hour. The average speed of an Olympic race walker, according to a small study on Olympians published in the American Journal of Sports Medicine, is 7.7 miles per hour — the fastest marathon was run at an average speed of 12.43 miles per hour — suggesting that race walkers and runners in fact exert themselves to a similar degree.

Some race walkers, having perfected the technique of rotating the hip 20 degrees — the Elvis-like hips, according to RaceWalk.com, is the “body’s motor” — can actually reach speeds faster than runners, sometimes even beating them in marathons.

Reaching top speed within these confines is not easy on the body. Olympian race walkers reach peak speed not by making more strides but by taking longer ones, an action that requires a remarkable amount of power coming from the ankles and the hip joints, as one review in the European Journal of Sports Science outlined in 2014.

At speeds as fast as those reached by the likes of Zhen, Olympic race walkers manage to bend the official rules: At race speeds, one study found, athletes don’t stick to the “no flight time” rule, which states they must be in contact with the ground at all times. Since judges don’t use any tech to evaluate the competitors — they’re only allowed to assess visually — they can’t really tell that the race walkers are floating, for roughly 40 milliseconds at a time, off the ground. It’s a technique that, when executed correctly, some scientists think is crucial to winning Olympic gold.

Still think race walking isn’t worth the attention? Consider the effort it takes to keep track of its rules — and your body’s ability to adhere to them — over the course of 50 long kilometers, like some 81 male finalists will do in Rio on August 19. As the sport and its increasingly younger athletes attempt to make its comeback — Canadian Olympic race walkers have made a deliberate push to gain millennial cred with the hashtag #WorldDomination — now might be the time to swivel your hips and give it a second chance.

Photos via Getty Images / Ryan Pierse