Goulet, E. D., Asselin, A., & Lacerte, G. (2011). A meta-analysis of the effect of Quercetin supplementation on endurance performance and maximal oxygen consumption. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 1783.

This study determined the magnitude of the effect of Quercetin supplementation on endurance performance and VO2max using a meta-analytic approach. Database searches and cross-referencing used to locate articles included the following criteria for selection: 1) data necessary to compute the effect estimates and variances; 2) protocols were placebo-controlled, double-blinded; 3) laboratory-based exercise protocols; 4) exercise protocol durations >5 minutes for endurance performance; and 5) studies published in English and in peer-reviewed journals. Exclusion criteria were: 1) Quercetin supplementation <5 days; and 2) research with animals. All endurance performance outcomes were adapted to the same scale and converted to mean changes in power output when necessary. A random-effects model was used to determine the mean weighted summary effects, along with a random-effects meta-regression (method- of-moments) to establish the relationship between fitness level and Quercetin supplementation-induced endurance performance changes. Magnitude-based inferential statistics were also used: the smallest worthwhile % change in VO2max was set at 2.5%, and for half-marathon and marathon-runners and long-distance cyclists the changes in power output were set at 2.15, 2.7, and 1.6%, respectively.

Ten research articles were located providing four (VO2max) and nine (endurance performance) effect estimates from four and six research articles meeting the inclusion criteria. Supplementation duration was 21±18 days (endurance performance) and 18±23 days (VO2max), with a daily amount of Quercetin of 1000 mg. For endurance performance, mean exercise duration was 82±87 min. Quercetin supplementation increased mean power output by ~0.73% and VO2max by ~2.06, compared with the placebo. The meta-regression established no relationship between the changes in endurance performance and VO2max. Under real-world conditions, the effect of Quercetin supplementation on VO2max half-marathon, marathon and long distance cycling performances is very likely to be trivial at best.

Implication. Quercetin supplementation (1000 mg/day) for 18-21 days does not provide an endurance performance advantage or incur a meaningful VO2max change in real-world conditions.

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