title: Caffeine reduces myocardial blood flow during exercise.
abstract: Caffeine consumption has been receiving increased interest from both the medical and lay press, especially given the increased amounts now available in energy products. Acute ingestion of caffeine usually increases cardiac work; however, caffeine impairs the expected proportional increase in myocardial blood flow to match this increased work of the heart, most notably during exercise. This appears to be mainly due to caffeine's effect on blocking adenosine-induced vasodilatation in the coronary arteries in normal healthy subjects. This review summarizes the available medical literature specifically relating to pure caffeine tablet ingestion and reduced exercise coronary blood flow, and suggests possible mechanisms. Further studies are needed to evaluate this effect for other common caffeine-delivery systems, including coffee, energy beverages, and energy gels, which are often used for exercise performance enhancement, especially in teenagers and young athletes.
authors.affiliation: Memorial Hermann Ironman Sports Medicine Institute, The University of Texas Medical School at Houston, Houston, TX 77030-1501, USA. John.P.Higgins@uth.tmc.edu
authors.forename: John P
authors.initials: JP
authors.lastname: Higgins
authors.forename: Kavita M
authors.initials: KM
authors.lastname: Babu
mesh_terms: D002110:Caffeine / Q000009:adverse effects / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects*; D015444:Exercise / Q000502:physiology*; D006321:Heart / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000494:pharmacology*
chemical_list: D010726:Phosphodiesterase Inhibitors; D002110:Caffeine
keywords: Athletes; Caffeine; Cardiovascular effects; Endothelial function; Myocardial blood flow