Acute Caffeinated Coffee Consumption Does not Improve Time Trial Performance in an 800-m Run: A Randomized Double-Blind Crossover Placebo-Controlled Study

摘要

Introduction: Studies evaluating caffeinated coffee (CAF) can reveal ergogenic effects; however, studies on the effects of caffeinated coffee on running are scarce and controversial. Aim: To investigate the effects of CAF consumption compared to decaffeinated coffee (DEC) consumption on time trial performances in an 800-m run in overnight-fasting runners. Methods: A randomly counterbalanced, double-blind, crossover, placebo-controlled study was conducted with 12 healthy adult males with experience in amateur endurance running. Participants conducted two trials on two different occasions, one day with either CAF or DEC, with a one-week washout. After arriving at the data collection site, participants consumed the soluble CAF (5.5 mg/kg of caffeine) or DEC and after 60 min the run was started. Before and after the 800-m race, blood pressure and lactate and glucose concentrations were measured. At the end of the run, the ratings of perceived exertion (RPE) scale was applied. Results: The runners were light consumers of habitual caffeine, with an average ingestion of 91.3 mg (range 6–420 mg/day). Time trial performances did not change between trials (DEF: 2.38 + 0.10 vs. CAF: 2.39 + 0.09 min, p = 0.336), nor did the RPE (DEC: 16.5 + 2.68 vs. CAF: 17.0 + 2.66, p = 0.326). No difference between the trials was observed for glucose and lactate concentrations, or for systolic and diastolic blood pressure levels. Conclusion: CAF consumption failed to enhance the time trial performance of an 800-m run in overnight-fasting runners, when compared with DEC ingestion. In addition, no change was found in RPE, blood pressure levels, or blood glucose and lactate concentrations between the two trials.