Review of an article from the Journal of Applied Physiology"Effect of different caffeine consumption protocols on metabolism and endurance performance"IntroductionIn 2002, a group of Australian researchers published an article entitled "Effect of different caffeine consumption protocols on metabolism and endurance performance." Caffeine consumption during sporting events has become much more popular and has been the subject of numerous studies. The aim of the research was to examine the work-enhancing (ergogenic) effects of different caffeine regimens on metabolism and performance while simulating the typical nutritional preparation an athlete would do for a race. The study also aimed to examine the effect of timing of caffeine consumption, comparing results when caffeine was administered before an event (precaf) to results when caffeine was administered during an event (durcaf). Additionally, the researchers wanted to understand the practice of endurance athletes drinking defizzed Coca-Cola near the end of a race. It has been widely observed that many triathletes and marathoners feel they benefit from drinking Coca-Cola in the final stages of an event as a replacement for sports drinks. Participants and Overall Research Design Two similar, but separate, studies were carried out. The first study (A) involved 12 highly trained athletes, triathletes or cyclists. The second study (B) used a smaller sample of 8 athletes from similar backgrounds. Although training histories were similar, caffeine consumption histories varied from occasional to regular intake up to approximately 150 mg/day (2 mg/kg). Subjects first performed a maximum incremental power test to determine their peak VO2, a measure of the body's ability to take in O2 and transform it into work. A work pace of ...... middle of paper ...... e which cancels out all or part of the impact of caffeine. 5) Variation in testing method (for blood or urine tests) was not a factor. No data has been provided indicating the reproducibility of the testing methods used. One proposal to improve the design is to examine the results in relation to caffeine use before the trial. Would individuals who habitually consume caffeine experience the same improvement in performance as those who consume it occasionally, or would the effect be less? Another suggestion is to include a statement describing the test method variation and the impact (or lack of impact) on the test results. Finally, a larger sample size can help determine whether the borderline data is meaningful. Although cost is almost always a factor in research, the text considers changes in muscle metabolism not to be detectable. Additional data from more test subjects could produce statistically significant results.