Did I say "carrying muscle will slow you down"? No, I said "a whole lot of extra muscle." But, since you're not vying to be a pro soccer player or anything, it's not a problem. Of course, top level sprinters have muscular upper bodies, but for example, have you ever seen a sprinter with 19 inch arms? Your goal is to play soccer while keeping muscle. The point I was trying to make is that it's not advantageous for a competitive pro soccer player who's goal is to be the best soccer player they can, to be carrying around a whole lot of extra weight.
Also keep in mind, these are sprint athletes, an extra 20 extra pounds of muscle is going to be more detrimental to an endurance athlete who has to run for 45 minutes continually, than one who has to run for 10 seconds.
pretty good stuff on this thread, looks like i´m going down the same road as Hater but it´s bball, summer is offseason so i only have like 1 practice a week, so i´m doing mostly weight training and shooting after that. so what i do to keep the muscle is to have a gatorade during and after practice/training. also have creatine+protein. any advice would be cool, sorry for hijacking your tread hater