The Effect of Green Tea Extract on Endurance Performance in Young Adults

Background: Green tea is rich in catechin, a polyphenolic antioxidant. Consumption of green tea or extract from green tea has been shown to result in weight loss, increased fat oxidation, and elevated energy expenditure in mice and humans. Green tea consumption has also been shown to result in increased exercise endurance in mice and improved maximal oxygen uptake (VO2max) in humans. It is not clearly known whether green tea consumption would increase exercise endurance in humans. Objective: The aim of this study was to determine if the daily consumption of decaffeinated green tea extract for 4-5 weeks, would improve exercise endurance in humans, as measured by running 2.5 miles on an indoor track. Subjects, Design, and Methods: This study was based on a randomized, double-blind design. Fourteen, normal, healthy individuals volunteered for participation and completed the study. They were divided into two groups (n= 7 for each group). All participants completed 2 endurance trials, 1 at the baseline and 1 at the conclusion of the study. Each trial consisted of a 2.5 mile run around the GSU Recreation Center indoor track. One group consumed green tea extract pill containing 900 mg catechins and the other group consumed a placebo for 4-5 weeks between run trials. Results: Green tea and placebo groups improved their running times, however, there was no significant difference between these two groups in mean end time (P = 0.74). Under one statistical analysis, the green tea group significantly improved their running time compared to baseline (P = 0.019), while the placebo group did not. However, under another statistical analysis (removing one participant due to possible skewing effect), both groups significantly improved their running time over baseline (P\u3c 0.05). Conclusions: This study was not able conclusively ascertain whether or not the daily consumption of green tea improved endurance performance as measured by 2.5 mile run times. Results of this study should be used with caution due to small sample size. Future studies are warranted on the impact of green tea consumption on exercise endurance, using a longer duration and a larger sample size than has been studied