This study is a randomized, double-blind, placebo-controlled crossover trial examining the effects of caffeinated and non-caffeinated pre-workout supplements on resistance exercise performance. Resistance-trained adults will be randomly assigned to complete three study conditions (caffeinated pre-workout, non-caffeinated pre-workout, and placebo) in one of the six possible condition orders. During each condition, participants will report to the laboratory for ingestion of the assigned beverage and subsequent muscular performance testing. Major performance outcomes will be force production variables from a mechanized squat device and maximal strength and muscular endurance on the bench press and leg press exercises.

Inclusion Criteria:

• Between the ages of 18 and 40;
• Body mass between 50 - 100 kg (110-220 lb)
• Generally healthy (defined as an absence of any disease or medical condition which could potentially be negatively affected by consumption of the commercially available dietary supplements or performance of exercise, including but not limited to musculoskeletal or cardiovascular diseases).
• Resistance-trained, defined as completing 2+ resistance training sessions per week for at least three months prior to screening.
• Participants must have reported regular training of the lower body through a multi-joint exercise such as the squat or leg press at least once weekly during the three-month period prior to screening.
• Participants must have reported regular training of the bench press or chest press variation at least once weekly during the three-month period prior to screening.
• Female participants will be required to bench press ≥ 0.5 x body mass and leg press ≥ 1.75 x body mass during initial 1RM assessments to be eligible for this study.
• Male participants will be required to bench press ≥ 1.0 x body mass and leg press ≥ 3.0 x body mass to be eligible.
• Regular caffeine consumption (due to the presence of caffeine in the commercially available dietary supplement). This will be defined as an average self-reported daily intake of 250+ mg of caffeine, which is equivalent to approximately 2.5 cups of coffee.

Exclusion Criteria:

• Failing to meet any of the aforementioned inclusion criteria.
• Pregnant or breastfeeding (for female participants)
• Taking prescription medication which could reasonably make participation unsafe for the participant or influence study outcomes
• An inability to complete resistance exercise due to injury or medical condition
• Self-reported caffeine sensitivity, as indicated by unwanted side effects when caffeine is consumed.
• Allergy to any of the ingredients in the test beverages or standardized breakfast.
• Current use of anabolic steroids
• Presence of a pacemaker or other implanted electrical device.
• Unwillingness to wear the provided surgical mask during all testing procedures.

All investigators will be blinded to the caffeinated vs. non-caffeinated supplement (i.e., these were provided by the manufacturer in a blinded manner). Select study investigators who will not be involved in assessing outcomes will formulate the placebo supplement and be responsible for dispensing all supplements to participants. Supplements will be provided to participants in opaque containers to maintain blinding. All investigators involved in assessing outcomes will also remain blinded and will not be involved in handling or dispensing the supplements.