I'm of an age where a mandatory shower after Phys Ed class was the rule, and sometimes find it hard to understand why the present generation of students is so uncomfortable with this.
In my home town, formal Phys Ed classes began in the seventh grade; you were expected to provide your own uniform -- not a standard print or color scheme, but the boys were expected to pack (and wear) an athletic supporter. Many of us had learned to swim at the local "Y", where nude swimming in all-male groups was still the practice, so the experience wasn't entirely new for a lot of us. The showers were of the "pull chain" type and not very warm, so a lot of us kept the experience as short as possible.
That changed when we graduated to a newer senor high school, by which time all of us had developed sexually to some degree, and where the shower facilities were a lot better -- they warmed up quickly and stayed that way. And there were a few of us who had only a tub (for a few, even a wash tub) at home. In one or two instances, some of the students would ask -- and get -- permission to use the locker room before or after the school day. Not so much an issue for the boys, most of whom played sports of one kind or another, but girls sports in that day were limited, and girls Phys Ed (in my district, anyway) didn't mandate showers.
I wasn't much of a "jock" but served as an athletic manager for football and basketball, and got to see the girls' (visitors) locker and shower facilities for a lot of the schools we played against; only a minority (perhaps one-third) expected the ladies to shower after Phys Ed.