You often notice in older films but it’s clearly on display here just how thin everybody was back then. And this was not in an era of poverty with insufficient caloric availability. A lot of the boys are pretty ripped so are obviously getting plenty of protein.
As you can see, this is an intense program. It’s also very oriented around calisthenics and functional movements. As a teacher says in the video, “We want our students to experience the pleasures of being in a great shape. And we want them to know how to stay that way.”
The program incorporated a number of features no one would every put in a school program today. Students were stratified by ability, not age. Because ability groups wore color coded shorts similar to martial arts belt colors, your rank in the hierarchy was clearly visible. And, as the film notes, “Advancement depends exclusively on performance, not on subjective judgment by a teacher.”
This sort of intense physical education approach fell out of style in the 1970s. By the time I took PE in high school, it was for only one year and was kind of a joke. I think it partially existed just to give the basketball coach something to teach, since in Indiana coaches were required to be teachers.
Someone made a documentary about this program called The Motivation Factor. I haven’t watched it but you can see the trailer here.