How many and exactly what ingredients are in pre-workout vary greatly depending on the brand. However, there are a few key ingredients most pre-workouts will have because they have been shown to aid in athletic performance. Here are the five most common ingredients and what they do.

Caffeine
Caffeine is a natural stimulant that comes in the form of beans or leaves that are most commonly found in coffee and tea. Its largest benefit for athletes is on the central nervous system to help reduce the perception of fatigue and/or pain.

Beta-Alanine
Beta-alanine is a non-essential amino acid, meaning your body produces it naturally. A favorite ingredient for Jason Kozma, winner of a Mr. America title, suggests beta-alanine “for the lactic acid buffering performance enhancement.” It supports the production of carnosine, which helps buffer acid levels in your muscles to delay muscle fatigue, ultimately allowing you to push harder and longer. Just a heads up on one common side effect — at higher doses you may feel tingling over your skin.

Creatine
Creatine is found naturally in our muscles. It aids in the production of adenosine triphosphate, or ATP, which supplies the muscles with short, intense bursts of energy. By supplementing with creatine you can potentially increase the production of ATP, thus improving short, powerful bursts of exercise. Creatine is also thought to increase muscle size and strength.

L-Citrulline & L-Arginine
Citrulline is a non-essential amino acid. Its primary benefit to athletes is that it triggers the production of arginine, another non-essential amino acid. Arginine is then converted into nitric oxide which allows muscles to acquire more oxygen and nutrients and aids in the removal of metabolic waste. More oxygen and nutrients flowing to your muscles allows them to work more efficiently, while the removal of metabolic waste helps you recover faster.

Branched Chain Amino Acids
Branched Chain Amino Acids or BCCAs are shown to stimulate muscle growth and decrease delayed muscle soreness. The three non-essential amino acids that make up BCCAs are leucine, isoleucine, and valine.