Supplements marketed to improve muscle size and strength are purported to do so through by enhancing resistance exercise performance (i.e., by enhancing force production or muscular endurance), by stimulating muscle protein synthesis, by increasing the availability of fuel sources (e.g., carbohydrate), and/or by supporting recovery.[1]
Some of the most effective options are creatine,[2] caffeine,[3] and protein.[4] Other popular options include citrulline, nitrate, beta-alanine, ashwagandha, betaine, alpha-GPC, and taurine.