Article Title



Melitza Ramirez1, Jesse Stein1, and Katie Heinrich1

1Kansas State University, Manhattan, KS

Caffeine demonstrates an ergogenic effect on endurance exercise performance, however, limited information exists establishing its efficacy during high-intensity functional training (HIFT). HIFT is an exercise program that incorporates a variety of multi-joint movements performed at a relatively high-intensity and designed to improve parameters of general physical fitness and performance. PURPOSE: Our study aimed to determine the effects of caffeine on HIFT performance. METHODS: 13 HIFT-trained men (age = 28.5 ± 6.6 years, HIFT experience = 4.1 ± 3.0 years, body weight= 84.3 ± 9.9 kg) were randomized in a double-blind, crossover design. After consent, participants completed two HIFT sessions separated by a 7-day washout period, 60-minutes after consuming 5mg/kg of caffeine or a placebo. During HIFT sessions, participants completed as-many-rounds-as-possible in 20 minutes of 5 pull-ups, 10 push-ups, and 15 air squats, with performance measured as the number of rounds completed (30 repetitions = 1 round). Paired-samples t-tests were used to compare HIFT performance between the caffeine and placebo conditions and to test for a potential learning effect between the first and second sessions. RESULTS: Participants significantly improved HIFT performance during the caffeine trial (15.3 ± 3.6 rounds) as compared to placebo (14.3 ± 3.0 rounds), t(12) = -2.783, p < 0.05. The eta squared statistic (0.39) indicated a large effect size. Moreover, no significant learning effect was identified between the first and second sessions (14.9 ± 3.2 vs. 14.7 ± 3.5 rounds, p = 0.73). CONCLUSION: Caffeine elicited an ergogenic response during HIFT in HIFT-trained men, with no identifiable learning effect, which is useful for competitive HIFT athletes aiming to optimize performance. However, future investigations should establish the efficacy of caffeine during varying-duration HIFT sessions and among female HIFT athletes.

ACKNOWLEDGEMENTS: This study was funded by the College of Human Ecology from Kansas State University.

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