depends on dose and what your shooting plus personal preference, and also like rickson already said better absorption through bigger muscles, its pretty easy the bigger the muscles more than likely the greater the blood flow, thus the better the absorption, but as far as shooting it lets say into your shoulders (upper body) and having it stay there, that doens't make too much sense, its not like your body has a preference of where blood flow goes, the blood is going to circulate 'throughout' your body, and whatever is absorbed (the steroid compound) is going to as well...