The primary purpose of this study was to examine the acute effects of a multi-ingredient pre-workout supplement versus an ergogenic dose of caffeine (6 mg/kg) on energy expenditure during low-intensity exercise. The effects of these substances on substrate utilization, gas exchange, and psychological factors were also investigated. Twelve males (mean ± SD: age = 22.8 ± 2.4 years) completed three bouts of 60-min of treadmill exercise at 4.8-6.4 km/hr on separate days after consuming a pre-workout supplement, 6 mg/kg of caffeine, or placebo in a randomized fashion. The pre-workout and caffeine supplements resulted in significantly greater energy expenditure (p < 0.001, p = 0.006, respectively), VO2 (p < 0.001, p = 0.007, respectively), VCO2 (p = 0.006, p = 0.049, respectively), and VE (p < 0.001, p = 0.007, respectively), but not rates of fat or carbohydrate oxidation or respiratory exchange ratio compared to placebo (collapsed across condition). In addition, the pre-workout supplement increased feelings of alertness (p = 0.015) and focus (p = 0.005) 30-minutes post-ingestion and decreased feelings of fatigue (p = 0.014) during exercise compared to placebo (collapsed across condition). Thus, the pre-workout supplement increased energy expenditure and measures of gas exchange to the same extent as 6 mg/kg of caffeine with concomitant increased feelings of alertness and focus and decreased feelings of fatigue.

Inclusion Criteria:

• Male

Exclusion Criteria:

• history of medical or surgical events, including cardiovascular disease, metabolic, renal, hepatic, or musculoskeletal disorders;
• use of any medications
• use of nutritional supplements
• habitual use of caffeine (≥1 caffeinated beverage per day)
• participation in another clinical trial or investigation of another investigational product within 30 days prior to screening/enrollment.

Identify as male.