Your body uses more creatine when the muscles are active, so taking 10g's while you're working out isn't going to be as risky. Every time your muscles are active, more creatinine is produced, and your body has to get rid of it, so just make sure you urinate when you feel the need and you'll be just fine with the 10g's on workout days. But no more than 5g's on non-active days. You should also break it up so you get 5g pre-workout and 5g post-workout just to be on the safe side.