NutraBio PRE Stim-Free is a stimulant-free version intended for individuals sensitive to caffeine, those who visit the gym late at night, or those who otherwise desire a pre-workout with the performance-boosting components in PRE but without the stimulants. PRE Stim-Free is the most comprehensive, effective, and pure stimulant-free pre-workout on the market. Its blend of substances helps prepare your body physically and mentally by increasing muscular strength, power, and endurance, improving the mind-muscle connection, and combating exhaustion.