Pritchard-Peschek Kellie R, Jenkins David G, Osborne Mark A, Slater Gary J, Taaffe Dennis R
School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia.
School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia.
J Sci Med Sport. 2014 Sep;17(5):531-4. doi: 10.1016/j.jsams.2013.07.015. Epub 2013 Aug 8.
The purpose of the present study was to examine a possible dose-response between pre-exercise pseudoephedrine intake and cycling time trial performance.
Randomised, double-blind, crossover trial.
Ten trained male endurance cyclists (26.5 ± 6.2 years, 75.1 ± 5.9 kg, 70.6 ± 6.8 mL kg(-1)min(-1)) undertook three cycling time trials in which a fixed amount of work (7 kJ kg(-1) body mass) was completed in the shortest possible time. Sixty minutes before the start of exercise, subjects orally ingested either 2.3 mg kg(-1) or 2.8 mg kg(-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.
Cycling time trial performance (∼ 30 min) was not enhanced by pseudoephedrine ingestion. Plasma pseudoephedrine concentration increased from pre-warm up to post-exercise in both treatment conditions, with the 2.8 mg kg(-1) body mass dose producing the highest concentration at both time points (2.8 mg kg(-1)>2.3 mg kg(-1)>placebo; p<0.001).
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.
本研究旨在探讨运动前服用伪麻黄碱的剂量与自行车计时赛成绩之间可能存在的剂量反应关系。
随机、双盲、交叉试验。
10名训练有素的男性耐力自行车运动员（26.5±6.2岁，75.1±5.9千克，70.6±6.8毫升·千克⁻¹·分钟⁻¹）进行了三次自行车计时赛，要求在尽可能短的时间内完成固定量的功（7千焦·千克⁻¹体重）。在运动开始前60分钟，受试者以随机双盲方式口服2.3毫克·千克⁻¹或2.8毫克·千克⁻¹体重的伪麻黄碱或安慰剂。在基线、热身前后和运动后采集静脉血，分析pH值、乳酸和葡萄糖浓度；除热身后期外，随时测量血浆儿茶酚胺和伪麻黄碱浓度。
服用伪麻黄碱并未提高自行车计时赛成绩（约30分钟）。在两种治疗条件下，血浆伪麻黄碱浓度从热身前到运动后均升高，2.8毫克·千克⁻¹体重剂量在两个时间点的浓度最高（2.8毫克·千克⁻¹＞2.3毫克·千克⁻¹＞安慰剂；p＜0.001）。
服用伪麻黄碱后，受试者之间血浆伪麻黄碱浓度存在较大个体差异。许多因素显然会影响伪麻黄碱在血液中的摄取和出现情况，而这些因素尚未完全明确。结合个体间随后血浆伪麻黄碱的差异，这可能部分解释了本研究结果以及先前研究中服用伪麻黄碱后成绩不一致的情况。
