TestoSup Xtreme Pre-exhaust weak muscle groups to ensure that you hit all the areas you want to target. A specific example of this happening is when your biceps conk out on you before your lats when you use the rowing machine. An exercise that isolates and works only your lats, performed before your workout, allows you to avoid this problem. That way when you are working your lats, you are not using the energy of your biceps, and they can get a more effective workout.