研究课题：咖啡因，体液电解质平衡与运动效率
供稿：运动机能学，营养学，生理学和神经生物学系，康尼提格大学

    主要内容：休闲自娱者和运动员经常被要求远离含咖啡因的饮料（CB），这一观点的目的有两个：一是有关咖啡因对脱水和运动效率的影响，对照研究的结果是批评性的；二是不能确定如何戒断CB才是科学和生理学上合适的。文献提示饮用CB会产生中等利尿效果，类似于饮水。但是不会引发电解质紊乱，影响运动效率和身体健康。用咖啡因（100 – 680 mg）、水或安慰剂组进行对照实验，很难发现对尿量的影响有统计学差异。我们综述了10项研究结果，发现饮用CB引起0 - 84 %的尿潴留，而饮水也有0 – 81 %的尿潴留，而且随着咖啡因的耐受，发生伤害性电解质失衡的可能性进一步降低。

    结论：科研文献表明，无论是运动员还是休闲自娱者，只要含咖啡因饮品（CB）饮用量适中，就不会发生有害的体液电解质失衡。一般的脑力劳动者比运动员的风险就更低，因为出汗更少。

Caffeine, body background="../images_new/bg_hei.jpg" fluid-electrolyte balance, and exercise performance.
Armstrong, LE. Int J Sport Nutr Exerc Metab 2002, 12:189-206.
    Departments of Kinesiology, Nutritional Sciences, Physiology & Neurobiology, University of Connecticut, Storrs, CT.
Recreational enthusiasts and athletes often are advised to abstain from consuming caffeinated beverages (CB). The dual purposes of this review are to (a) critique controlled investigations regarding the effects of caffeine on dehydration and exercise performance, and (b) ascertain whether abstaining from CB is scientifically and physiologically justifiable. The literature indicates that caffeine consumption stimulates a mild diuresis similar to water, but there is no evidence of a fluid-electrolyte imbalance that is detrimental to exercise performance or health. Investigations comparing caffeine (100 – 680 mg) to water or placebo seldom found a statistical difference in urine volume. In the ten studies reviewed, consumption of a CB resulted in 0 - 84 % retention, whereas consumption of water resulted in 0 - 81 % retention, of the initial volume ingested. Further, tolerance to caffeine reduces the likelihood that a detrimental fluid-electrolyte imbalance will occur. The scientific literature suggests that athletes and recreational enthusiasts will not incur detrimental fluid-electrolyte imbalances if they consume CB in moderation and eat a typical U.S. diet. Sedentary members of the general public should be at less risk than athletes because their fluid losses via sweating are smaller.

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