After familiarization , seven male endurance-trained volunteers , unacclimated to exercise in the heat , performed two experimental trials in @C ( @ % relative humidity ) in a crossover fashion separated by at least @ d. Subjects ingested @ mgkg ( -@ ) body mass tyrosine ( TYR ) or an isocaloric quantity of whey powder ( PLA ) in @ mL of sugar-free flavored water in a randomized , double-blind fashion .