The cardiovascular effects of caffeine and ephedrine during exercise.

摘要

The purpose of this study was to determine the effects of a caffeine/herbal ephedra supplement on cardiovascular measurements during exercise. Ten caffeine-naïve subjects (5 women and 5 men) were studied at rest, during exercise, and during recovery after the ingestion of either a placebo (PL) or 150mg of caffeine/20mg ephedrine (C+E). After the consumption of placebo or caffeine/ephedrine, subjects rested for 60 minutes. Measurements of heart rate, blood pressure, cardiac output and expired gas samples were made before and after 30 and 60 minute after supplementation. Subjects then began exercising at 60% VO₂max on a cycle ergometer. Measurements were obtained at 10, 30, and 60 minutes of exercise. Following exercise, measurements were obtained at 15, 45, 60 minutes of recovery. Findings indicate that C+E prior to exercise will alter the cardiovascular system by increase in heart rate prior, during, and after exercise and SBP before exercise. The higher rate pressure product prior to and after exercise indicates greater energy demands of the heart when individuals consume C+E. (Abstract shortened by UMI.)