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Quercetin and endurance exercise capacity: a systematic review and meta-analysis

Kressler J, Millard-Stafford M, Warren GL

Medicine and science in sports and exercise, 2011

254 participants · 100 citations

Abstract

UNLABELLED: Quercetin is a dietary flavonoid purported to improve human endurance exercise capacity. However, published findings are mixed.

PURPOSE: The study's purpose was to perform a systematic review of the literature and meta-analysis to examine whether quercetin ingestion increases endurance exercise capacity.

METHODS: A search of the literature was conducted using the key words quercetin, performance, exercise, endurance, and aerobic capacity. Eleven studies were identified as meeting the inclusion criteria providing data on 254 human subjects. Across all studies, subject presupplementation VO(2max) ranged from 41 to 64 mL·kg(-1)·min(-1) (median = 46), and median treatment duration was 11 d with a median dosage of 1000 mg·d(-1). Effect sizes (ES) were calculated as the standardized mean difference, and meta-analyses were completed using a random-effects model.

RESULTS: The ES calculated for all studies combining VO(2max) and endurance performance measures indicates a significant effect favoring quercetin over placebo (ES = 0.15, P = 0.021, 95% confidence interval = 0.02-0.27), but the magnitude of effect is considered between trivial and small, equating to a ∼2% [corrected] improvement of quercetin over placebo. Using a subgroup meta-analysis comparing quercetin's effect on endurance exercise performance versus VO(2max), no significant difference was found (P = 0.69). Meta-regression of study ES relative to subjects' fitness level or plasma quercetin concentration…

How strong is the evidence?

Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 254 participants or records.

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