Pre-workout is more than just energy for the gym. Most all pre-workout supplements contain some kind proven muscle builder like creatine as we already discussed or Citrulline Malate which has been shown to increase muscle volume and strength. Another good muscle building ingredient you will find in pre-workouts is Beta-Alanine. Beta-Alanine is good for reducing muscle fatigue and studies have shown it to significantly increase lean muscle mass and decrease fat in wrestlers. They also contain ingredients like caffeine to give you more energy for your workouts as well as Betaine Anhydrouse which does many things including lowering fatigue, increasing strength and HGH and also lowering cortisol levels.