The Polyphenol Epigallocatechin Gallate Lowers Circulating Catecholamine Concentrations and Alters Lipid Metabolism During Graded Exercise in Man.

Written informed consent was obtained from all subjects and all subjects completed the AHA/ACSM health screening questionnaire to ascertain their health status and to show their eligibility to partake in this study.

In a randomized, placebo-controlled, single blind, cross-over design study participants completed two trials after acute consumption of either EGCG or a placebo (PLAC) supplement after an overnight fast. After a two-hour monitoring period following ingestion participants performed a continuous graded cycle exercise test to volitional exhaustion. There was at least a 7-day washout period between trials.

Participants were randomly assigned to either the intervention or placebo trial. After an overnight fast participants arrived to the laboratory and were observed ingesting two capsules each of EGCG (minimum 94% EGCG <0.1% caffeine) from a commercially available brand (TEAVIGO™; TAIYO GmbH, 1450 mg) or a placebo (1450 mg Corn Flour). Capsules were weighed and sorted to within ±5%. The supplement was consumed in two size 00 vegetarian gelatin capsules alongside a standardized amount of distilled water (200ml).

Experimental Protocol Prior to participation in the experimental trials participants were familiarized with the laboratory equipment and the test procedures. On the morning of the test participants reported to the Exercise Physiology Laboratory following an 8-10 hour fast where standard measures of the participants' body mass, (weighting scales; Seca 770 Digital Scales, Seca Ltd, Birmingham, UK) height (stadiometer; Holtain Stadiometer, Holtain Ltd, Cymrych, Wales) and body fat percentage using bioelectrical impedance analysis (Bodystat Quadscan 4000, Bodystat Ltd, Isle of Man, UK) whilst wearing minimal clothing, were taken.

Participants were then seated for a 10-minute period while a cannula was inserted into an antecubital vein. This was connected to a three-way stopcock for the repeated collection of venous blood at rest and during the exercise test. Saline (2-3 ml) was infused regularly keep the cannula patent. After a 10-minute rest period a venous blood sample (7 ml) was collected into a lithium-heparinised vacutainer. In addition, baseline measures of heart rate (Polar RS800CX), and a 10-minute sample of respiratory gas (Jaeger Vyuntus CPX, Erich Jaeger GmbH,CareFusion Hoechbegh, Germany) were also taken at this time. Expired air was measured for the fractional concentration of oxygen (FEO2%) and carbon dioxide (FECO2%) and for the volume of air (SentrySuite Software, Erich Jaeger GmbH,CareFusion Hoechbegh, Germany) expired during the period to allow for determination of volumes of O2 utilization and CO2 production. These data were used for determination of oxidative energy expenditure using principles of indirect calorimetry (Frayn 1983; Jeukendrup & Wallis, 2005).