Date of Award


Degree Type


Degree Name




First Advisor

Milne, Kevin (Kinesiology)






Caffeine is a commonly used substance by athletes and has become more widespread since it's legalization by the World Anti Doping Association (WADA) and the International Olympic Committee (IOC). Extensive research has been done on the effect of caffeine on exercise performance, however, most studies were done at low intensity, and none compared differences in performance between men and women. Thus, 18 university aged (9 men and 9 women) individuals were recruited to perform three 20km cycling time trials including a familiarization trial (FAM), a carbohydrate plus placebo condition (CHO+P) and carbohydrate plus caffeine (5mg/kg) condition (CHO+C). Time to complete the 20km distance was significantly decreased in the CHO+C trial compared to the CHO+P trial in both men and women. This was concomitant with an increase in post-exercise blood glucose levels in the CHO+C trial but not in the CHO+P trial. However, ratings of perceived exertion (RER), respiratory exchange ratio (RER), tympanic temperature and a novel measure of arousal (long term excitement, LTE) were not different between trials. It is concluded that caffeine can improve performance when combined carbohydrate over carbohydrate alone. Moreover, these performance improvements are not different between sexes. Of the subjective (RPE), physiological (HR, RER) and excitement (LTE) variables that were measured, it is unclear why caffeine had this effect. Nonetheless, these findings are intriguing, especially for those athletes looking to gain an advantage in activity that requires intense work over the span of 20-35min, as well as WADA in their decisions to examine the use of caffeine during competition. Caffeine is currently a legal ergogenic aid and these data add to the significant body of literature indicating its powerful ergogenic properties in many activities.