A couple years ago I was playing adult tackle football. I want to play again but where I am at now the closest team is 3.5 hours away, and they play against teams that are 6-7 hours away. If I was to get the chance, I would shift my training the following ways:
(1) no "failure" training. Always leaving 3-4 RIR or more. Focus on going as fast and being as powerful as I can through the positive, using exercises that translate to the field
(2) exercises directed towards the field. leg day would be primarily pulling a weighted sled, and doing sprints uphill, high box jumps, things like that.. upper body would be push/pull movements, nothing that is trying to isolate any particular muscle, but more simulating shedding blockers, blocking, pulling people to the ground, throwing them to the side, would try to find a gym with a "jammers" machine
(3) diet would essentially be the same, maybe slightly less calories, more vegetables, but gear would shift completely, just a mild dose of testosterone, maybe a small bit of equipoise, nothing else