system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 what is pre-workout and how does it work?
gpt
Preworkouts are combinations of chemicals intended to do a few things (depending on what's in them). 

1. Make you feel more energetic. Thinks like caffeine or ephedrine are usually used for this.
2. Ensure you get the most out of your workout. Things like creatine and beta-alanine.
3. Ensure your body has the things it needs during a workout. Things like sugar and various amino acids are used for this.

In general, pre workouts DO help, but the effect is a lot smaller than people would like you to believe. In most cases you can get most of the effects with a proper diet and a cup of coffee.