Well, taking in consideration that they train almost daily and take their bodies to its limits on order to withstand long seasons of stress, they should.
No to mention that training everyday is their job. I would have my skin attached to my muscles witha job like that.
Because of that i despise players like Ronaldo,Cassano, ronaldinho and that sort of fat bastards who are irresponsible enought to not train and be fat, even when they play proffesional football.