摘要：International Journal of Exercise Science 10(3): 340-353, 2017. Dietary supplements are widely used to enhance sport performance and the combination of carbohydrate and caffeine (CHO+CAF) has yielded particularly high performance gains. Though the effects of a CHO+CAF supplement have been studied in a laboratory environment, little research exists on the effects of supplementation during competition. Therefore, the purpose of this study was to determine the effects of a CHO+CAF supplement on athletic performance in competition. Eight female collegiate volleyball players completed three testing sessions under three different conditions separated by approximately one week each: CHO+CAF supplement, placebo (PBO), and control (CTL) using a randomized, cross-over design. Blood glucose (BG) was assessed prior to supplementation and immediately after set three. The supplement and PBO were administered prior to play and between sets two and three. Following three sets of play, three performance tests were completed: vertical jump (VJ), agility (AGL), and repeated 30-m sprint ability (RSA). While CHO+CAF supplementation significantly increased BG, the performance tests were not different (p>.05) among the testing conditions. These findings suggest that the amount of the supplement used in this study is not beneficial to VJ, AGL, and RSA in female volleyball players. As these performance tests were largely anaerobic and non-glycolytic in nature, the ergogenicity of the supplement may have been underutilized. Additionally, coaches and athletes should not only be aware of what ingredients are in the supplements they choose, but the amount of those ingredients as they may modify the efficacy of the supplement to impact performance.
