“For men who are sensitive to stimulants or who exercise in the late afternoon or evening and want to avoid caffeine, Transparent Labs offers a stim-free pre-workout,” says Boufounos. While it’s caffeine-free, the rest of the ingredients are clinically dosed, meaning key ingredients like citrulline malate, beta-alanine, and betaine anhydrous are added in amounts proven to be effective for exercise performance, adds Boufounos.

We also love that it includes BioPerine, a black pepper extract, to help your body better absorb the active ingredients in the supplement. This stimulant-free formula comes in 7 flavors, is gluten-free, and contains no artificial sweeteners or colors.