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Effects of Combined Caffeine and Ephedrine Ingested with a Liquid Meal on Subsequent Exercise Performance

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Technical Report

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Defense and Civil Institute of Environmental Medicine North York Canada

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The ability to maintain or enhance our soldiers performance could be crucial to a mission in scenarios such as extended search and rescue and sustained operation. In this regard, DCIEM has been investigating the effects of ingesting various drugs to determine their effect on physical performance. Two such drugs, Caffeine C and ephedrine E ingested in combination have been shown to enhance physical performance. However, in some subjects, the combination has caused nausea and vomiting during high intensity exercise. These subjects had fasted for 10-12 hours. It was speculated that this fasting may have predisposed the subjects to developing nausea. Therefore, this study evaluated the effects of ingesting a standardized liquid meal, i.e., a can of ENSURE PLUS, after drug ingestion and one hour before exercise, to see if the incidence of nausea could be reduced. The results indicated that in those subjects that had ingested the meal, it did not alleviate the problem of nausea, and further it attenuated the effect of the drug on performance. This response may have been a result of a number of factors, i.e., unfamiliarity of meal, closeness of meal ingestion to time of exercise, and length of fasting. Before the Canadian Forces can use these drugs to enhance physical work more studies are needed to investigate whether or not a more familiar light meal, e.g., juice, toast, muffin, given 1.5 to 2 hours before exercise would be more effective in reducing the incidence of nausea associated with drug ingestion.

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