The Effect of Caffeine Alone or as Part of a Multi-ingredient Pre- workout Supplement on Muscular Endurance in Recreationally Active College Males

Introduction: The purpose of this investigation was to examine the independent and combined effects of caffeine (CAF) alone or as a part of a multi-ingredient pre-workout supplement (PWS) on resistance exercise performance in recreationally active males. Methods: In a single-blind, randomized, placebo (PLA) controlled, crossover design; 10 recreationally active males (20.5 ± 0.9; 178.9 ± 7.7 cm; 81.8 ± 11.5 kg) completed three laboratory visits, after determination of one repetition-maximum (1-RM) on the bench press and leg press, where they performed bench press and leg press to failure at a load of 70% 1-RM. Subjects were randomly assigned to ingest either one serving of a commercially available PWS (C4 Original, Cellucor, Bryan, TX, United States), a dosage-matched anhydrous CAF beverage (150 mg), or a taste- matched PLA beverage. Heart rate (HR), affect, rating of perceived exertion (RPE), and mood state was assessed 20 minutes pre and post-substance ingestion, and immediately after exercise.Results: Participants completed significantly more repetitions to failure (p = 0.006) and lifted significantly greater weight (p = 0.009) during Leg Press in the PWS and CAF conditions compared to the PLA condition. There was not a significant difference found between CAF and PWS trials (p > 0.05).Conclusions: This data suggests that both CAF and PWS may have a positive effect on exercise performance in leg press but was not effective in increasing muscular endurance in bench press. The commercially available PWS offered no additional ergogenic effects when compared to the CAF.