Human pharmacology of a performance-enhancing dietary supplement under resting and exercise conditions.

What Was Tested

Researchers studied Caffeine and Synephrine in this controlled clinical trial publication.

Supplement-induced effects on blood pressure and glucose levels are not ameliorated by exercise.

Exercise does not affect the kinetics of stimulant ingredients, caffeine and synephrine.

Who Took Part

The age groups tagged for this paper are adults, both men and women.

In clinical trials performed under resting conditions, performance-enhancing supplements raise blood pressure and affect glucose homeostasis.

Ten healthy adults (three women) aged 20-31 years participated in a three-arm, double-blind, placebo-controlled, crossover study.

How the Study Was Run

In design terms this was a double-blind, placebo-controlled and crossover study.

Neither the participants nor the staff measuring them knew who was on Caffeine, so expectations could not easily colour the readings.

A placebo (an inactive look-alike) gave the Caffeine group a baseline to be compared against.

In the crossover set-up each of the participants took both Caffeine and the comparison in turn, acting as their own control.

Plasma synephrine and caffeine concentrations were measured over 12 h, and vital signs, serum electrolytes, oxygen consumption and perceived exercise exertion were monitored.

What Was Measured

Supplement-induced effects on blood pressure and glucose levels are not ameliorated by exercise.

The subject headings attached to it are Blood Glucose, Caffeine, Central Nervous System Stimulants, Dietary Supplements, Energy Metabolism, Exercise and Synephrine.

What This Means in Plain Language

The paper is a double-blind, placebo-controlled and crossover study of Caffeine and Synephrine.

The abstract goes on to report its results in about 9 sentences; this page does not restate them, so read the paper for the findings and their limits.

The publication is from 2008 (British journal of clinical pharmacology), a journal based in England.

More context: all human trials.