Athletic Performance

In a series of studies, Bell et al. assessed the effects of ephedrine mixtures on performance, and found measurable improvement. One and one-half hours after ingesting a placebo (P), caffeine (C) (4 mg/kg), ephedrine (E) (0.8 mg/kg), or caffeine and ephedrine, 12 subjects performed a 10-km run while wearing a helmet and backpack weighing 11 kg. The trials were performed in a climatic suite at 12-13°C, on a treadmill where the speed was regulated by the subject. VO2, VCO2, V(E), HR, and rating of perceived exer tion were measured during the run at 15 and 30 minutes, and again when the individual reached 9 km. Blood was sampled at 15 and 30 minutes and again at the end of the run and assayed for lactate, glucose, and catecholamines. Run times (mean ± SD), in minutes, were for C (46.0 ± 2.8), E (45.5 ± 2.9), C + E (45.7 ± 3.3), and P (46.8 ± 3.2). The run times for the E trials (E and C + E) were significantly reduced compared with the non-E trials (C and P). Pace was increased for the E trials compared with the non-E trials over the last 5 km of the run. VO2 was not affected by drug ingestion. HR was elevated for the ephedrine trials (E and C + E), but the respiratory exchange ratio (a measure of maximal exertion) remained similar for all trails. Caffeine increased the epinephrine and norepinephrine response associated with exercise and also increased blood lactate, glucose, and glycerol levels. Ephedrine reduced the epinephrine response but increased dopamine and free fatty acid levels. Bell concluded previously that the effects of caffeine, when taken with ephedrine, were not additive, and that all of the observed improvement could be accounted for by the presence of ephedrine (19).

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