Pre-workout is a multi-ingredient supplement blending a combination of stimulants that can promote maximum energy, focus, strength and velocity during exercise. Most contain caffeine and a mix of other ingredients like vitamins, minerals and branched-chain amino acids (BCAAs), all designed to performance-enhance your workout, says Wendy Bazilian, doctor of public health, nutritionist and author of the Eat Clean, Stay Lean series.

Consumed 30 to 60 minutes prior to exercise (that’s how long it can take for a pre-workout to kick in), the supplement typically features caffeine of varying amounts (excluding the caffeine-free versions), which has long been hailed for its ability to improve a slew of exercise benefits, including muscular endurance and movement velocity.

What Does Pre-Workout Do?

Pre-workout is intended to help build muscle, increase focus and provide extra energy, according to the National Academy of Sports Medicine. The ingredients in pre-workout supplements, such as caffeine, beta-alanine, amino acids and creatine, work together to bring about these possible benefits.

When to Take Pre-Workout

Pre-workout supplements are usually taken about 15 to 30 minutes prior to exercise, but can also be consumed during your workout. Read the label instructions on the pre-workout you are considering to see what is recommended.