Stimulant-free pre-workouts are relatively new to the supplement world. When brands say their products are free from stimulants, this almost always means they do not contain any caffeine. As a result, many of these supplements are also known as caffeine-free pre-workouts. The products in this category are designed to boost mental energy, raise endurance and induce muscle pumps without exciting the central nervous system. These stimulant-free pre-workouts are marketed to people who are sensitive to caffeine and who wish to avoid energy crashes or anxiety. They are also said to achieve this with blends of vitamins, minerals and amino acids – most of which are also common in stimulant-based products.