title: Heart rate, blood pressure and repolarization effects of an energy drink as compared to coffee.
abstract: The goal of this study was to investigate the impact of energy drinks on haemodynamic and cardiac physiology. Comparisons were made to coffee as well as water consumption. In Protocol #1 the caffeine content was normalized to body weight to represent a controlled environment. Heart rate, blood pressure and cardiac QTc interval were assessed in 15 participants, on 4 days, prior to and for 6·5 h postconsumption of (i) energy drink (2 mg caffeine per kg body weight; low dose), (ii) energy drink (3 mg caffeine per kg body weight; medium dose), (iii) coffee (2 mg caffeine per kg body weight) and (iv) 250 ml water. In Protocol #2, the beverages were consumed in volumes that they are purchased to represent real-life conditions. The aforementioned measurements were repeated in 15 participants following (i) 1 16 oz can of energy drink (16 oz Monster), (ii) 1 24 oz can of energy drink (24 oz Monster), (iii) 1 packet of Keurig K-Cup Starbucks coffee (coffee) and (iv) 250 ml water. The order of the beverages was performed in a randomized double-blinded fashion. For both protocols, QTc interval, heart rate and systolic blood pressure were unchanged in any condition (P>0·05). Diastolic blood pressure and mean blood pressure were slightly elevated in Protocol #1 (P<0·05, main effect of time) with no difference between beverages (P<0·05, interaction of beverage × time); however, they were unaffected in Protocol #2 (P>0·05). These findings suggest that acute consumption of these commonly consumed beverages has no negative effect on cardiac QTc interval.
authors.affiliation: Environmental and Autonomic Physiology Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.|Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, USA.
authors.forename: R Matthew
authors.initials: RM
authors.lastname: Brothers
authors.affiliation: Environmental and Autonomic Physiology Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Christmas
authors.affiliation: Environmental and Autonomic Physiology Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.|Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, USA.
authors.forename: Jordan C
authors.initials: JC
authors.lastname: Patik
authors.affiliation: John Peter Smith Health Network, Fort Worth, TX, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Bhella
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects*; D002110:Caffeine / Q000008:administration & dosage* / Q000009:adverse effects; D003069:Coffee / Q000009:adverse effects; D004311:Double-Blind Method; D061215:Energy Drinks / Q000009:adverse effects; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D013781:Texas; D013997:Time Factors; D055815:Young Adult
chemical_list: D003069:Coffee; D002110:Caffeine
keywords: QT interval; arterial pressure; caffeine; cardiac function; physiology