On 4 occasions, the participants completed the workout, which involved completing an amount of rowing (until participants burned 9 calories for men and 7 calories for women), 6 barbell thrusters, and 3 box jumps.

The participants took either a supplement or a placebo 40 minutes before each workout, which lasted either 5 or 15 minutes.

The supplement contained 8 grams of citrulline, 5 grams of creatine monohydrate, 3 grams of taurine, 2.5 grams of beta-alanine, 2.5 grams of betaine, 1 gram of beetroot extract, 300 mg of alpha-GPC, and 300 milligrams of caffeine, among other ingredients.

The participants completed more total work (+4.4%) after taking the preworkout supplement — mainly, rowing performance improved, including a higher average power output (243 vs. 227 watts).

Taking a preworkout supplement improves high-intensity functional training performance Original paper