A pre-workout is a product used before exercise to increase performance and strength during exercise. The most advanced pre-workout supplements contain high doses of active ingredients that directly affect your workout performance.A pre-workout can be taken in liquid, capsule or powder form. The liquid form is the fastest absorbed by the body, giving you quick access to the energy you need for your workout. Capsules and tablets can take a little longer to absorb, and you need to take the whole pack with you when you can take just one shot.