Is a preworkout supplement better than caffeine alone for improving resistance exercise performance? Original paper

In this crossover trial, a preworkout supplement was no better than caffeine for improving resistance exercise performance, and neither of them was better than a placebo in women with resistance training experience who were habituated to caffeine.

The effect of a multi-ingredient preworkout supplement (MIPS), compared to caffeine and a placebo, on resistance-exercise performance in women.

The outcomes assessed were the number of repetitions completed for the bench press and leg press.

10 women (average age of 22) with resistance training experience and who were habituated to caffeine.

Potential participants who consumed less than 250 mg of caffeine per day were excluded.

In this crossover trial, the participants completed as many repetitions as possible on one set of leg press (using 80%–85% of 1-repetition maximum) and one set of bench press (using 75% of 1-repetition maximum).

Thirty minutes before each workout, the participants ingested either a full scoop of the MIPS, a half scoop of the MIPS, caffeine (6 milligrams per kilogram of body weight), or a placebo. The workouts were separated by a washout period of at least 72 hours.

Each full scoop of the MIPS contained citrulline malate (8,000 mg), beta-alanine (4,000 mg), betaine (2,500 mg), taurine (1,300 mg), L-tyrosine (1,000 mg), alpha-GPC (300 mg), caffeine (200 mg), and L-theanine (200 mg), among other ingredients.

There were no differences between the supplements.

The potential usefulness of citrulline malate, beta-alanine, and betaine is related to their ability to help buffer metabolites produced during high-intensity exercise.^[1][2][3] A workout involving 2 sets, 1 for the upper body and 1 for the lower body, is unlikely to generate enough metabolic stress for the MIPS to provide an ergogenic effect. As such, the results are not necessarily generalizable to higher-volume workouts.