At this point, age I think. Don't want to doxx myself, but I'm thoroughly middle aged and I think I've maxed out what I can do without gear given my age. I'm almost at a three plate one rep max for bench, 435 lbs squat, almost 500 lbs deadlift. Without juicing or at least testosterone supplementation, I think this is probably about the best I can do. Which is fine, I'm plenty strong for someone that just wants to be strong and isn't an athlete or something.