(21) EFFECTS OF A PRE-WORKOUT SUPPLEMENT ON REPETITIONS AND TOTAL WORKLOAD COMPLETED DURING A HIGH-INTENSITY FUNCTIONAL TRAINING WORKOUT

The individual ingredients of pre-workout formulations are often associated with enhancing blood flow to exercising muscle and provide energy, which might be useful for high-intensity functional training (HIFT) where trainees are often tasked with completing ‘as many repetitions as possible’ (AMRAP) within a time limit. Completing more repetitions and work within a set duration depends on, among other things, how well fatigue is managed during exercise. Currently, information on the effect of such formulations on HIFT performance is extremely limited.

Purpose: To examine the acute effects of a pre-workout supplement and exercise duration on AMRAP performance.

Methods: Men (n = 12) and women (n = 10) with HIFT experience (≥2 years; n=22: 29.3 ± 7.1 years, 171 ± 7 cm, 80.5 ± 15.6 kg) volunteered for this cross-over design, placebo-controlled study. Participants completed four consecutive weekly experimental visits at approximately the same time and day in randomized order. Upon arrival, they consumed either a pre-workout supplement (S) or a placebo (P) of similar caloric content, and then rested 40 minutes before completing either a 5- or 15-minute AMRAP of rowing (men: 9 kcal; women: 7 kcal), six barbell thrusters (men: 43.1 kg; women: 29.5 kg), and three box jumps (men: 0.6 m; women: 0.5 m). Performance was quantified by total rounds (men = 18 repetitions per round; women = 16 repetitions per round) and repetitions completed within the time limit, as well as total repetitions and volume load (kg) completed for each exercise. Volume load for rowing was calculated by converting average power reported by the ergometer microcomputer from watts to kilogram-meters per second, and then multiplying by average split duration and dividing by average meters covered per split. Workload for thrusters and box jumps were calculated by multiplying total repetitions and load, with load for box jumps being determined by having all jumps launch from an in-ground force plate and converting normalized (for body mass) force.

Results: Separate repeated measures analysis of variance revealed a significant sex x time interaction for rowing workload (p = 0.004), where men completed more work during 5S (44.1 ± 8.2 kg) compared to 5P (32.7 ± 6.6 kg). Significant (p < 0.05) sex x time interactions or main effects for sex and/or time were also noted in other variables, but none revealed differences between supplement conditions at the same workout duration.

Conclusion: The multi-ingredient pre-workout supplement did not affect total rounds or repetitions completed in neither the 5- nor 10-minute AMRAP but did lead to greater rowing force expression during the 5-minute bout in men. PRACTICAL APPLICATIONS: Although the multi-ingredient pre-workout supplement did not alter total repetitions completed nor total workload in this particular HIFT circuit, it did allow for a greater rowing workload (i.e., more powerful rowing strokes) to be completed during the 5-minute bout in men. The supplement may have greater value when shorter-duration HIFT-style workouts pair more aerobically-focused modalities (e.g., rowing) with low-repetition plyometric and resistance training exercises.

Acknowledgements: This study was funded by Shifted, LLC.