I've NC for this as my ex has been stalking me all over the Internet and this will really out me so I don't want it linked to my previous posting history.
So, I was the first female American Football player in the UK to play kitted football. The rules used to be that boys and girls were on the same teams for Juniors which was non contact up to the age of 15. After that it became Youth which was kitted. A lot of girls dropped out at that point, some carried on playing but moved to a female only team and league (which had about 4 teams nationally, so was shit).
I played for my local team on the Juniors and the year I was due to turn 15, the head of my club was also on the league committee. He asked me if I wanted to carry on and if so, could I write a letter to the league as there was an actual rule prohibiting girls playing. Most of the committee wanted it changing, but they needed an application from someone to make it happen.
So I wrote in, it was rubber stamped and I played a season of kitted football. I spent that season being a curiosity to other teams, the mythical girl they had heard rumours about. It got to the stage that so many other teams were waiting for us to arrive and get off the coach to see if the rumours were true and my team had gasp a girl playing, that we used to travel down in themed clothes just to make the most of our audience. The Reservoir Dogs day will stay with me forever. Turning up for a game, the coach doors opened and then the film's theme music was played as 20 odd youngsters in suits and shades filed down the steps.
Anyway, I digress. None of the teams I ever played had changing facilities for me. They were all either purpose built AF club houses or soccer clubs that also hosted the AF. No female changing in any of them, so I spent a season trying to negotiate putting on shoulder pads in the toilets in a rush, because there was a line of lads outside who needed a pre game pee. I never once got tackled in a match. If I'd been any good at all, this would have been brilliant for my team, but alas I now know I am Dyspraxic 
. No one wanted to hit a girl. I wasn't a player who signed up for a contact sport, I was a delicate flower who needed protecting.
I'm sure everyone thought they were being nice and chivalrous and stuff, and I never once heard a bad word about my being there, but it was still made very clear I was 'other'. I wasn't a player like everyone else, because I wasn't male and it was a male sport.
I think it became a self fulfilling prophecy in that there were no girls wanting to play, so no facilities were created for them, then no girls wanted to start because there were no facilities for them so it seemed they weren't wanted.
The thing is, I don't think that is an American football specific issue. As I said, many of the away games I went to were at soccer club houses and they didn't have female changing either, just home and away. I think it is a general sport issue.
Male sport is seen as more worthy of attention, funding, worship and big pay cheques. Female sport is something cute the wifey does to keep trim for her hubby and is treated as such. Mixed sports are severely limited, strictly non contact and fall somewhere between male and female in terms of coverage and how seriously they are taken.
As long as male sport is lauded above female sport (in terms of segregating sports by gender like football for boys, netball for girls and of coverage of those sports) then sportsmen will be disproportionately idolised for their achievements, and excused from expectations of civilised behaviour in their private lives "because they can kick a ball really well" and that is more important than being a decent human being.