Metabolic and perceived effort responses following acute multi-ingredient pre-workout supplementation prior to high-intensity functional training workouts.

Introduction: Multi-ingredient pre-workout supplements (MIPS) are formulated with ingredients thought to improve nutrient delivery, limit fatigue, and enhance focus. Since high-intensity functional training (HIFT) often challenges athletes to complete " Methods: Twelve men and ten women (29.3 ± 7.1 years, 171 ± 7 cm, 80.5 ± 15.6 kg) with at least 2 years of HIFT experience completed four weekly visits in a randomized, double-blind, crossover design. On each visit, pre-exercise heart rate, energy expenditure, subjective ratings of effort were measured, along with collecting ultrasound images of the rectus femoris (RF) and vastus lateralis (VL) to quantify muscle cross-sectional area (cm Results: MIPS led to a greater increase in RF CSA in both workout durations (+1.22 cm Conclusion: The multi-ingredient pre-workout supplement led to greater acute increases in quadriceps CSA, an indirect indicator of post-exercise muscle fluid shifts, without between-supplement differences in heart rate, energy expenditure, or metabolic byproducts. These findings help contextualize previously reported performance outcomes obtained using the same cohort and protocol.