Gal016, actually the stimulation of muscle protein synthesis when essential amino acids is consumed before exercise is superior to that when EAC is consumed after exercise.
Taking a shake pre-workout is fine, but from personal experience working with people, eating real food (protein w/complex carb) 1-2 hrs. prew.o. helps fuel them through better.
Ingestion before has a proven greater anabolic effect and larger effect on the synthesis then it does when taken after.
If you can work out the best on an empty stomach, with a meal 1-2-3-4 hours before is individual and another matter.