Green tea supplementation enhances exercise metabolism and athletic performance, a double-blinded, placebo-controlled study reports.

Published in the Journal of the International Society of Sports Nutrition, researchers from the University of Hertfordshire reported that four weeks of supplementation with green tea extract enhanced fat oxidation (fat burning) by 25 percent and decreased body fat compared to a placebo group (1). Moreover, subjects that received the green tea extract also saw an 11 percent improvement in athletic performance compared to the placebo group.

The study investigators used a decaffeinated green tea extract to eliminate the influence of caffeine on physiologic and athletic performance outcomes. The subjects consuming the green tea showed greater use of carbohydrate and fat for metabolism, along with a significant reduction in body fat compared to the placebo.

In this study, 14 male recreational athletes received either 571 milligrams of decaffeinated green tea extract or a placebo daily for four weeks. Subjects then cycled in a 40-minute performance trial at the beginning, midway, and at the end of the study period.

The general health benefits of polyphenolic compounds in green tea have been extensively investigated over the last fifteen years (2). Studies have shown excellent improvements in cardio-metabolic health, increased thermogenesis, fat burning and improved body composition (2-5). However, less is known about green tea extract in combination with exercise. One reason current research is conflicting is due to the presence of caffeine, with may skew the results.

These results of this study were similar to other studies looking at non-athletic populations (6-8). This new research is the first to demonstrate a significant impact of green tea extract on exercise performance. Performance markers specifically improved by 10.9 percent for distance covered, and 22.7 percent for average power output with green tea supplementation.

These results are promising for enhancing performance and add to earlier evidence that also shows high doses of green tea extract was able to reduce muscle soreness following strenuous exercise (9). Combined with the impact of green tea extract on performance improvements, this study supports the hypothesis that green tea extract may affect cellular pathways leading to better use of carbohydrates and fat for improved workouts.

Simply drinking green tea may not be enough, however. To get the same dosage used in this study, six to seven cups of green tea would have to be consumed per day. Supplementing with a concentrated form is not only convenient, but also reduces the total amount of caffeine consumed.

References

  1. Roberts JD, Roberts MG, Tarpey MD, Weekes JC, Thomas CH. The effect of a decaffeinated green tea extract formula on fat oxidation, body composition and exercise performance. J Int Soc Sports Nutr 2015;12:1.
  2. Dulloo AG, Duret C, Rohrer De et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr 1999;70:1040-5.
  3. Venables MC, Hulston CJ, Cox HR, Jeukendrup AE. Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans.  Am J Clin Nutr 2008;87:778-84.
  4. Ichinose T, Nomura S, Someya Y, Akimoto S, Tachiyashiki K, Imaizumi K. Effect of endurance training supplemented with green tea extract on substrate metabolism during exercise in humans. ScandJ Med & SciSports 2011;21:598-605.
  5. Rains TM, Agarwal S, Maki KC. Antiobesity effects of green tea catechins: a mechanistic review. J Nutr Biochem  2011;22:1-7.
  6. Nagao T, Hase T, Tokimitsu I. A green tea extract high in catechins reduces body fat and cardiovascular risks in humans. Obesity 2007;15:1473-83.
  7. Westerterp, GÇÉ, Plantenga MS, Lejeune MP, Kovacs EM. Body weight
    loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation. Obesity Res 2005;13:1195-204.
  8. Wang H, Wen Y, Du Y et al. Effects of catechin enriched green tea on body composition. Obesity 2010;18:773-9.
  9. Moradpourian MR, Ashkavand Z, Venkatesh C, Vishwanath BS. Effect of different doses of green tea on oxidative stress and muscle soreness in downhill treadmill running. Asian J Pharm Clin Res  2014;7.