The dose-response relationship between pseudoephedrine ingestion and exercise performance

Objectives: The purpose of the present study was to examine a possible dose-response between pre-exercise pseudoephedrine intake and cycling time trial performance. Design: Randomised, double-blind, crossover trial. Methods: Ten trained male endurance cyclists (26.5 ± 6.2 years, 75.1 ± 5.9kg, 70.6 ± 6.8mLkg⁻¹ - 1min⁻¹) undertook three cycling time trials in which a fixed amount of work (7kJkg⁻¹ body mass) was completed in the shortest possible time. Sixty minutes before the start of exercise, subjects orally ingested either 2.3mgkg⁻¹ or 2.8mgkg⁻¹ body mass of pseudoephedrine or a placebo in a randomised and double-blind manner. Venous blood was sampled at baseline, pre- and post-warm up and post-exercise for the analysis of pH and lactate and glucose concentrations; plasma catecholamine and pseudoephedrine concentrations were measured at all times except post-warm up. Results: Cycling time trial performance (~30min) was not enhanced by pseudoephedrine ingestion. Plasma pseudoephedrine concentration increased from pre-warm up to post-exercise in both treatment conditions, with the 2.8mgkg⁻¹ body mass dose producing the highest concentration at both time points (2.8mgkg⁻¹ > 2.3mgkg⁻¹ > placebo; p