Pre-workout Supplement, Arrhythmias and Exercise Stress Test

Pre-workout supplements are widely used by physically active individuals to enhance exercise performance. These products typically contain stimulant substances such as caffeine, beta-alanine, arginine, and tyrosine, which act on the cardiovascular and central nervous systems. Although their ergogenic effects are well established, their safety profile - particularly regarding cardiac arrhythmias during exercise - has not been thoroughly investigated. This study aimed to evaluate whether the acute ingestion of a commercially available multi-ingredient pre-workout supplement (V-FORT® ULTRA, Vitafor, Brazil) could trigger cardiac arrhythmias during a treadmill exercise stress test in young, physically active adults. A randomized, double-blind, placebo-controlled crossover design was used. Participants underwent two exercise stress tests separated by 3 to 10 days: a familiarization test (Day 1) and an intervention test (Day 2), in which they received either the pre-workout supplement or a placebo beverage. Neither the participants nor the research team conducting the test were aware of the allocated intervention until after test completion.