The burpee is arguably one of the single greatest exercises a human could ever do.

It shreds fat, builds endurance, and works your entire body so hard that exhausted athletes have been known to stop mid-burpee workout and, huffing and puffing, use what little breath they can muster to curse profusely. Like pushups and jumping jacks, the humble bodyweight exercise can be done virtually anywhere, in any interval, with absolutely no equipment necessary except a functioning cardiovascular system and a strong stomach.

And while the burpee may have garnered a reputation lately as a CrossFit-centric exercise, people were doing them before anyone gathered in a box to do a WOD.

Long before then, as it turns out.

The original burpee was first created by Royal H. Burpee,

a man whose contributions to the art and science of human fitness should forever earn his (magificent) name a place in the pantheon of American awesomeness. Way back in 1939—years before Jack LaLanne bothered with jumping jacks, and decades before Arnold Schwarzenegger started pumping iron—Burpee was working double duty as the executive director of a YMCA in New York City and a Ph.D. candidate in applied physiology at Columbia University Teacher’s College. And as part of his doctoral research, Burpee was dedicated to figuring out a simple, fundamental concept: How to determine a person’s physical fitness.

Much of what we know about Royal H. Burpee comes from his granddaughter, Sheryl Burpee Dluginski—also a fitness expert—who has stewarded the story of her paternal grandfather and his work. (Royal’s middle name, she says, was Huddleston, his mother’s maiden name. His last name was likely the Americanization of the French-Canadian surname Beaupré.)

“He was an athletic guy his whole life, participating in gymnastics, wrestling, and weightlifting,” she tells Men’s Fitness. “He was also an intelligent, demanding perfectionist. A career in applied physiology probably appealed to the athlete and the scientist in him.”

Nowadays, as fitness crazes pop up left and right and Americans join gyms almost as fast as they can be built, it’s easy to imagine Mr. Burpee in his New York City office, devising methods to test how physically capable people were. But back in ’39, few people thought about fitness as an active pursuit. Lifting weights was for circus strongmen. Running around tracks was for Olympians. Regular folks played sports—wrestling, boxing, football, baseball—or worked on their feet. Nobody went to the gym. Nobody jogged.

“I remember him extolling the virtues of bodyweight exercises like gymnastics and wrestling as the most efficient and effective forms of exercise,” Burpee Dluginski says of her grandfather, whom she knew as “Goog.” “Bodybuilding/weightlifting was more of a vanity exercise for him, but he did take great pride in his health and appearance.”

But Royal Burpee wasn’t just ripped—he was also ahead of his time.

In his published thesis, Burpee created roughly 300 measures of fitness, listed alphabetically from Age to Wrestling, his granddaughter says. He also pioneered the notion of fitness that could be catered to a person’s skill and ability, which paved the way for the discipline of personal training: “Since interest is sustained not by repeated failure at unsuitable tasks, but by reasonable success following conscientious effort,” he wrote, “it is obvious that physical education programs should be adapted to individual ability.”

And so, as a fitness test, he devised a simple, four-step exercise:

1. Squat down and put both hands on the floor in front of you

2. Pop your feet backward into a plank position

3. Bring your feet back forward.

4. Stand back up.

The “burpee” was born.

Back then, it was slightly easier than its modern incarnation—no pushup in the middle, and no jump at the end. But Burpee recognized that it was still a supreme test of all-around fitness. The quick stand-plank-stand position change made it difficult for the heart to pump blood, Burpee Dluginski notes.

At first, Burpee used the exercise as part of the seven main “Tests of Physical Capacity” he created in his thesis. He’d measure an athlete’s standing heart rate, then have them do four burpees, and then test to see how long it took for their heart rate to return to normal. And there in his book the burpee likely would have stayed, except for one historical fluke: the U.S. entered World War II.

As hundreds of thousands of American men joined the armed forces,

military leaders realized they faced a difficult challenge: Figuring out exactly how physically fit those men were. Fortunately, Royal H. Burpee had just invented the solution. In late 1941 and 1942, Army experts settled on ten exercises to test which recruits were fit and which were flabby, according to Whitfield B. East’s huge, epic history [PDF] of physical training in the U.S. Army. One test was, simply, how many burpees a soldier could do in 20 seconds.

Even though Burpee hadn’t designed the exercise for such strenuous work, it stuck. “The military modified his original exercise into a more strenuous version, and in the second edition of his book, he recommended that the original version (time required to perform 4 standard exercises) be used for all those whose cardiovascular health is unknown,” Burpee Dluginski says. He was especially wary of unfit people trying to do it, since he feared they lacked the necessary core strength.

But by now, of course, the burpee is firmly entrenched in the modern fitness vernacular—even if everyone dreads it. One could, for example, do as many burpees as humanly possible in a short interval—a minute, say, or three minutes. Or you can do 100 burpees at once. Not tough enough? Do 100 burpees as fast as you can, but add seven kettlebell swings every minute. Hell, if you’re really feeling sadistic, you can do a Burpee Mile, in which you do a burpee and then a standing broad jump, over and over, for 5,280 feet. (It exists, it takes about two hours to complete, and it is more than a little insane.)

Our suggestion? The next time you get ready for a 100-burpee workout, say a quick note of thanks to Royal Burpee. He was a true pioneer of his time—and he wanted you to be as ripped, tough, and strong as you do.

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