Seifert John G, Connor David A
Movement Science Laboratory, Montana State University, Bozeman, MT 59717 USA.
J Int Soc Sports Nutr. 2014 Dec 10;11(1):56. doi: 10.1186/s12970-014-0056-5. eCollection 2014.
Caffeine based energy shot products accounted for $1.3 billion in sales in 2011. Caffeine has been shown to confer numerous benefits during exercise and is oftentimes combined with ingredients such as carbohydrates and taurine in the hope of further performance improvement. The purpose of this project was to compare auditory response time, power output, and physiological responses between the ingestion of a CHO, PRO, caffeine supplement (CPC), a caffeine-taurine-niacin based supplement (CTN), and a placebo (PL) in commercially formulated products that make claims as to improving performance.
Fourteen subjects cycled an interval exercise of 70% VO2max for 13 minutes and 90% of VO2max for two minutes for a total of 120 minutes which was then followed by a six-minute power output (PO) task. Subjects ingested a total of 45 g CHO, 7.5 g PRO, and 375 mg caffeine for CPC while 512 mg caffeine and 1200 mg taurine were ingested for CTN throughout the exercise. The treatments were administered in a double blind, randomly assigned protocol. Response time was assessed by auditory response. Significance was set at p < 0.05.
Average PO was significantly greater for CPC: 309 ± 60 W than CTN: 290 ± 57 W and PL: 282 ± 63 W. Response time was significantly faster for the CPC: 0.219 ± .049 s than CTN: 0.232 ± .060 s and PL: 0.228 ± .047 s. HR was significantly greater for CTN: 143 ± 16 bpm than CPC: 139 ± 16 bpm. RPE was significantly lower for CPC: 13.0 ± 1.7 than CTN: 13.5 ± 1.2 and PL: 13.8 ± 1.9. Blood glucose was greater for CPC: 5.5 ± 0.8 mM/L than CTN: 4.9 ± 0.7 mM/L and PL: 4.6 ± 1.1 mM/L. No significant differences were observed for RER.
The co-ingestion of CPC improved both cycling power output and auditory response time following 2 hours of moderate and high intensity interval cycling compared to CTN and PL. It is possible that the CPC treatment conferred not only a positive peripheral effect, but also a central effect. Even with a large caffeine dose, the combination of caffeine, taurine, niacin led to an inhibitory pattern which did not improve power output or response time performances over a PL.
2011年，含咖啡因的能量饮料产品销售额达13亿美元。咖啡因已被证明在运动过程中能带来诸多益处，并且常与碳水化合物和牛磺酸等成分混合，以期进一步提高运动表现。本项目的目的是比较商业配方产品中，摄入碳水化合物（CHO）、蛋白质（PRO）、咖啡因补充剂（CPC）、基于咖啡因 - 牛磺酸 - 烟酸的补充剂（CTN）和安慰剂（PL）后，听觉反应时间、功率输出和生理反应，这些产品均宣称可提高运动表现。
14名受试者进行间歇运动，先以70%的最大摄氧量（VO2max）骑行13分钟，再以90%的VO2max骑行2分钟，共120分钟，随后进行6分钟的功率输出（PO）任务。整个运动过程中，受试者摄入CPC时，共摄入45克CHO、7.5克PRO和375毫克咖啡因；摄入CTN时，共摄入512毫克咖啡因和1200毫克牛磺酸。治疗采用双盲、随机分配方案。通过听觉反应评估反应时间。显著性设定为p < 0.05。
CPC组的平均PO显著高于CTN组：309 ± 60瓦和PL组：282 ± 63瓦。CPC组的反应时间显著快于CTN组：0.219 ± 0.049秒和PL组：0.228 ± 0.047秒。CTN组的心率显著高于CPC组：143 ± 16次/分钟。CPC组的主观用力程度（RPE）显著低于CTN组：13.5 ± 1.2和PL组：13.8 ± 1.9。CPC组的血糖高于CTN组：4.9 ± 0.7毫摩尔/升和PL组：4.6 ± 1.1毫摩尔/升。呼吸交换率（RER）未观察到显著差异。
与CTN和PL相比，在进行2小时的中高强度间歇骑行后，同时摄入CPC可提高骑行功率输出和听觉反应时间。CPC治疗可能不仅产生了积极的外周效应，还产生了中枢效应。即使使用大剂量咖啡因，咖啡因、牛磺酸、烟酸的组合导致了一种抑制模式，在功率输出或反应时间表现上并未优于PL。
