(24) A MULTI-INGREDIENT PRE-WORKOUT SUPPLEMENT AND EXERCISE DURATION AFFECT ENERGY METABOLISM FOLLOWING HIGH-INTENSITY FUNCITONAL TRAINING AMRAPS

Fatigue management seems to become increasingly important to performance during high-intensity functional training (HIFT) workouts as exercise duration increases. Multi-ingredient pre-workout supplements (S) contain a variety of ingredients known to affect metabolism during exercise. However, little is known about the acute effects of S on metabolism following HIFT.

Purpose: To examine the acute effects of a multi-ingredient pre-workout supplement and exercise duration on metabolism and perceived exertion following a HIFT-style workout.

Methods: Men (n = 12) and women (n = 10) with at least 2 years of HIFT experience (29.3 ± 7.1 years, 171 ± 7 cm, 80.5 ± 15.6 kg) volunteered to complete four weekly visits in randomized, cross-over fashion. Upon arrival, participants completed pre-exercise (PRE) ratings of perceived exertion and subjective feelings of focus, energy, and fatigue. They were then affixed with a heart rate monitor and laid quietly beneath a ventilated canopy connected to a metabolic cart for 10 minutes while gas exchange was monitored to determine oxygen consumption (VO₂), metabolic equivalent of task (MET), and respiratory quotient (RQ). This was followed by a blood sample donation to quantify lactate concentrations. After PRE-assessments, participants consumed either S or a non-caloric placebo (P), rested 40 minutes, and then completed a 5- or 15-minute circuit of rowing (men: 9kcal; women: 7kcal), six barbell thrusters (men: 43.1 kg; women: 29.5 kg), and three box jumps (men: 0.6 m; women: 0.5 m) for ‘as many reps as possible’ (AMRAP). All PRE-assessments were repeated post-exercise (POST) with heart rate and lactate measures being repeated immediately (IP) and 5-minutes (5M) post-exercise.

Results: Analysis of variance with repeated measures did not reveal any supplement-condition differences in any measure collected at PRE nor with repetitions completed during the workouts. Significant condition x time (p = 0.049) and condition x sex (p = 0.021) interactions for blood lactate concentrations, where concentrations were approximately 22.4% higher following exercise with S compared to P both S-workouts compared to both P-workouts and only in women. Regardless of sex, differences were seen between 15-minute workouts at IP (+8.2%) and 5M (+15.5%), whereas differences between 5-minute workouts were not seen until 5M (+10.8%). Condition x time interactions were also seen with VO₂ (p = 0.034) and MET (p < 0.001), where higher values (+12.2 – 12.4%) were seen during 5S compared to both P-workouts at POST, and 15S at POST was greater than 15P (+7.4 – 7.6%). Although a condition x time interaction (p < 0.001) was also observed for RQ, specific differences at POST were limited to workout durations (higher values were seen after the 5-minute workouts). No other supplement-condition differences were found.

Conclusion: Consuming the mulit-ingredient pre-workout supplement led to greater post-exercise oxygen consumption and higher lactate concentrations compared to placebo but had no effect on repetitions completed. PRACTICAL APPLICATIONS: Although the pre-workout supplement did not affect repetitions completed in these specific HIFT workouts, the greater availability of oxygen and completing the same amount of work with higher concentrations of lactate and the same perceived effort suggest an enhanced ability to sustain effort if it were necessary.

Acknowledgements: "This study was funded by Shifted, LLC"