Chances are your high school gym class wasn’t anything to sweat over. Maybe you’d have to jog a mile every semester or waste time in a weight room while you made weekend plans or climb a rope once or twice a year. But if you were enrolled in La Sierra High School in Carmichael, California, in the ‘60s, “gym class” was just another way to say “boot camp.”

In this footage from the school’s 1960s fitness program, you can see high schoolers shredding through the monkey bars, walking on their hands across parallel bars, banging out some lightning-fast pushups, and climbing up and down a peg board. And their physiques reflect just how much was expected of them. The workouts were adopted by thousands of other schools and La Sierra was even acknowledged by President John F. Kennedy. 

According to an article over at Mental Floss, the program was devised by coach Stan LeProtti, and it was said to be more intense than military fitness tests both of the time and today. In an issue of Look magazine from 1962, it’s explained that the minimum pullups required for someone entering the U.S. Naval Academy was two. The minimum in this high school? You needed six.

The kids were even split up by rank, depending on their level of fitness. Starters had to wear white gym shorts to class, until they improved enough to move to other colors, like red, blue, and Navy-blue. To get the super-rare Navy one, a student had to “perform 34 pull-ups and carry someone on their back for five miles,” according to Mental Floss. In the program’s history, 19 kids managed to pull this feat off. 

You can check out some vintage footage of the class in the video below, courtesy of TheLeanBerets: