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Abstract

Caffeine-containing multi-ingredient pre-workout supplements (MIPS), marketed as improving physical performance acutely, are a particularly popular category within sports nutrition and yet finished products are rarely clinically evaluated. PURPOSE: The purpose of this randomized, controlled, crossover study was to examine the acute effects of an investigational MIPS formula when used by experienced resistance trained consumers of high-stimulant MIPS. METHODS: Eighteen (n=18) US military veteran, adult males (40.6 ± 1.7 yrs; 90.2 ± 2.2 kg; 28.7 ± 0.6 BMI; mean ± SEM) completed familiarization and 2 randomly assigned and counter-balanced lab visits, separated by 5±1 days between visits. Resting heartrate (HR), blood pressure (SBP & DBP), rate pressure product (RPP = HR x SBP), and Profile of Mood States 2nd Ed. Adult Short Form (POMS) was assessed prior to (PreTRX) and 50-min after (PostTRX) consuming 16 fl ozs H2O (positive control; CTL) or H20+MIPS (C4A; Nutrabolt; Austin, TX). Hemodynamic safety response was also assessed immediately post-exercise testing (PostEX; ~130 mins after consuming treatment). Adverse events (AEs) questionnaire was completed at the end of each lab visit. Exercise performance presented separately. RESULTS: There were no within or between treatment differences (p>0.05) for POMS “Total Mood Disturbance”. C4A reduced fatigue (FA; “Fatigue-Inertia”) and increased “Tension-Anxiety” (TA) from PreTRx to PostTRx [FA: -6.2% (p=0.0119); TA: +14.3% (p=0.0052)] and when compared to CTL at PostTRx [FA: -13.6% (p=0.0190); TA: +16.7% (p=0.0118)]. PreTRx to PostTRx HR was unchanged (p>0.05) by C4A, and there were no differences (p>0.05) in HR between C4A vs CTL at PostTRx and PostEX. C4A increased PreTRx to PostTRx SBP and DBP by 8.3 ± 1.7 mmHg and 4.2 ± 1.7 mmHg, respectively, and these effects by time were significant (ppp>0.05) for PostTRx to PostEX SBP for either condition. PostTRx to PostEX DBP was unchanged by CTL, whereas C4A promoted a PostTRx to PostEX decrease in DBP (-4.8%; pp>0.05) were observed for RPP between C4A and CTL. Beta-alanine induced paresthesia was observed in 61% of subjects in response to C4A vs CTL (p=0.001). No other significant differences (p≥0.25) were observed for AEs between conditions. CONCLUSION: This pre-market proof of concept study suggests that acute use of C4A poses no undue cardiovascular or safety risk when used by experienced resistance trainers that regularly consume caffeine-containing MIPS.

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