I was in marching bands from the 7th grade through my sophomore year of college. When I was in high school, we could earn letter jackets for our band activities. The fact that we "band fags" could earn a letter didn't sit well with a lot of the high school athletes. They felt that our letters somehow trivialized theirs.
In graduate school, I got into a debate about this with a guy who had run track in high school. He was of the opinion that students should only earn letter jackets for sports activities. He further felt that competition and physical exertion were the defining qualities of sports.
"Well, in its primary capacity, is a group of people walking and playing musical instruments a sport? Most bands are not formed with the express purpose to compete," he argued.
In my experience as a band member in junior high and high school in Texas, most marching bands are organized with the express purpose to compete, at least at the big schools in that state.
Our whole marching band season was focused on preparing to compete in marching band competitions. Playing at the football games was seen as something we were expected to do for the school, but each halftime performance was mainly important as a run-through for the "real thing": regional marching competion, and if we did well, state competion.
In the competitions, the bands were judged in much the same way that skaters and synchronized swimmers are judged. Our musical performance was maybe 50% of our score -- the rest was based on how complex our routines were, how well we kept our body posture and how well we stayed in step. There were even people who avidly followed the band competitions in much the same way any high school sports fan does.
And it was a very physical activity. We would start daily practice several weeks before school began -- I think we started summer practice at about the same time the football team started meeting. We didn't even do much with our instruments -- the whole goal of the practice was to get into proper physical condition and learn the proper marching drills. And, like the football team, we had a coach (our band director) standing on top of an observation tower screaming "encouragements" at us if we screwed up.
We would practice for an hour and a half after school each day. We got a P.E. credit for each fall semester that we did marching band season, so even the administration recognized the physicality of what we were doing. I knew several kids who dropped out of marching band, not because they couldn't play their instruments, but because they weren't (or felt they weren't) up to the physical demands of the season. And some of the routines our drill majors, rifles and flag corps did were extremely difficult physically.
At no point during marching season was what we were doing viewed as an artistic endeavor -- art was for concert season which, while it was just as competitive, involved a whole different mindset. During marching season, we thought more like jocks (and, yes, some of the more serious musicians among us really resented that, but you weren't allowed in concert band unless you also participated in marching band). We went back to thinking like musicians during concert season.