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Pseudo-ephedrine, the active ingredient in many cold remedies, improves some cyclists’ performance and has no effect on others. According to Kellie Pritchard-Pescheka, an Australian sports scientist at the University of Queensland, some athletes’ bodies absorb this stimulant surprisingly slowly. Even if this is taken into account, it’s still questionable whether pseudo-ephedrine actually works at all.

Pseudo-ephedrine, the active ingredient in many cold remedies, improves some cyclists’ performance and has no effect on others. According to Kellie Pritchard-Pescheka, an Australian sports scientist at the University of Queensland, some athletes’ bodies absorb this stimulant surprisingly slowly. Even if this is taken into account, it’s still questionable whether pseudo-ephedrine actually works at all.

Pseudo-ephedrine, the active ingredient in many cold remedies, improves some cyclists’ performance and has no effect on others. According to Kellie Pritchard-Pescheka, an Australian sports scientist at the University of Queensland, some athletes’ bodies absorb this stimulant surprisingly slowly. Even if this is taken into account, it’s still questionable whether pseudo-ephedrine actually works at all.

In 2010 Pritchard-Pescheka wrote in the International Journal of Sport Nutrition and Exercise Metabolism that trained cyclists were 5.1 percent faster on a time trial after taking 2-3 mg pseudo-ephedrine per kg bodyweight 60 minutes before starting. [Int J Sport Nutr Exerc Metab. 2010 Apr;20(2):132-8.] But in a new study that the same researcher is about to publish in the Journal of Science and Medicine in Sport, she concludes that pseudo-ephedrine does not improve cyclists’ endurance performance.

In the most recent study 10 experienced cyclists, average age 25, did a time trial on three occasions. On one occasion they were given a placebo 60 minutes before starting, on the other two occasions they were given 2.3 mg or 2.8 mg pseudo-ephedrine per kg bodyweight. The figure below shows that the cyclists’ average speed increased after they had taken the substance, which by the way is on the WADA doping list. The effect was not statistically significant, though.

1

The times of the individual cyclists are shown below. Clear as mud.

2

3

The researchers measured the amount of pseudo-ephedrine in the cyclists’ blood before and after they did the timed ride. The speed with which the cyclists absorbed the substance varied considerably. The figure above shows the concentration of pseudo-ephedrine after taking the higher dose.

When they looked more carefully at their data, the researchers discovered that the cyclists whose pseudo-ephedrine peak coincided with the timed ride didn’t automatically record better times.

“The considerable variation in plasma pseudoephedrine between individuals following ingestion was unexpected and may explain why some studies have shown improvements in performance while others have not”, the researchers conclude. “Moreover, peak plasma pseudoephedrine concentrations following pseudoephedrine administration in the present study did not appear to coincide with time trial performance.”

The dose-response relationship between pseudoephedrine ingestion and exercise performance.

Pritchard-Peschek KR, Jenkins DG, Osborne MA, Slater GJ, Taaffe DR.

Abstract

OBJECTIVES:

The purpose of the present study was to examine a possible dose-response between pre-exercise pseudoephedrine intake and cycling time trial performance.

METHODS:

Ten trained male endurance cyclists (26.5±6.2 years, 75.1±5.9kg, 70.6±6.8mLkg-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<0.001).

CONCLUSIONS:

There was large individual variation in plasma pseudoephedrine concentration between subjects following pseudoephedrine administration. A number of factors clearly influence the uptake and appearance of pseudoephedrine in the blood and these are not yet fully understood. Combined with subsequent differences in plasma pseudoephedrine between individuals, this may partially explain the present findings and also the inconsistencies in performance following pseudoephedrine administration in previous studies.

Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

PMID: 23988786 [PubMed - as supplied by publisher]

Source: http://www.ncbi.nlm.nih.gov/pubmed/23988786

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