“The program, in sum, not only builds physical fitness, but good Americans.” That’s how Look magazine summarized the physical education program of La Sierra High School in January 1962 [PDF]. If you’re wondering how a gym class got a major spread in a national publication—as well as an endorsement from President John F. Kennedy—take a look at this.

That’s a bunch of teenagers looking like they could rip a phone book in half. The PE curriculum at La Sierra in Carmichael, California was not so much famous as it was notorious: It frequently asked more of the students than of prospects entering the Naval Academy. Calisthenics (push-ups, pull-ups, suspended sit-ups) were done on a circuit during both a 12-minute warm up and 5 minutes of punishing, high-intensity exercise through an obstacle course. Coach Stan LeProtti, who initiated the program in 1957, even had custom equipment like peg boards and monkey bars built.

“Kids today are not built like that,” Doug Orchard, a filmmaker working on a documentary about LeProtti’s efforts, tells mental_floss. “It was the last great physical education program in the country.”

Students moved through the program based on a color scale: white shorts were for rookies, while red, blue, purple, and gold signaled serious ability. White shorts had to do a minimum of six pull-ups. Today, a Marine can pass a physical doing only three. Most boys, Orchard says, got to at least red. Getting to blue was a big deal; gold athletes were “crazy impressive.” Those who wanted a rare Navy Blue rank had to do 34 pull-ups and carry someone on their back for five miles. Only 19 students in the history of the school ever earned one.

“There were no injuries we’ve found,” Orchard says. “If you got the flu and were out a month, you had to re-test. The intensity and volume were crazy, but there was a progression. Their entire freshman year, they spent a long time just learning how to breathe correctly.”

The media attention surrounding La Sierra was so intense that by 1962, a health-conscious President Kennedy made an open plea for other schools to get involved, and more than 4000 signed up for the program, which eventually grew to include females. America’s youth may have been at its fittest—until the 1960s began to chip away at their resolve.

“There was a lot of resistance when Vietnam lagged on,” Orchard says. “People started showing up not dressed for PE as a form of protest.” By the time La Sierra closed its doors in 1983, LeProtti’s efforts had been mostly forgotten. But a few years ago, clothing chain Abercrombie & Fitch phoned Ron Jones, a physical fitness historian, to ask about the workout footage he had uploaded.

It went viral. Now Jones and Orchard are hoping their film—due out in summer 2016—will help both lawmakers and educators to re-assess activity programs across the country. Currently, less than half of all high school students hit the gym for any reason, let alone exhibit the physical feats the kids of La Sierra were able to pull off.

“We have a shot of bringing back real physical education,” Orchard says. “These kids were doing things I’ve never seen anyone else do.”

All Images Courtesy of La Sierra High PE Film Project