The flavonoid quercetin is purported to have potent antioxidant and anti-inflammatory properties. This study examined if quercetin supplementation attenuates indicators of exercise-induced muscle damage in a doubleblind laboratory study. Thirty healthy subjects were randomized to quercetin (QU) or placebo (PL) supplementation and performed 2 separate sessions of 24 eccentric contractions of the elbow flexors. Muscle strength, soreness, resting arm angle, upper arm swelling, serum creatine kinase (CK) activity, plasma quercetin (PQ), interleukin-6 (IL-6), and C-reactive protein (CRP) were assessed before and for 5 d after exercise. Subjects then ingested nutrition bars containing 1,000 mg/d QU or PL for 7 d before and 5 d after the second exercise session, using the opposite arm. PQ reached 202 ± 52 ng/ml after 7 d of supplementation and remained elevated during the 5-d postexercise recovery period (p < .05). Subjects experienced strength loss (peak = 47%), muscle soreness (peak = 39 ± 6 mm), reduced arm angle (–7° ± 1°), CK elevations (peak = 3,307 ± 1,481 U/L), and arm swelling (peak = 11 ± 2 mm; p < .0001), indicating muscle damage and inflammation; however, differences between treatments were not detected. Eccentric exercise did not alter plasma IL-6 (peak = 1.9 pg/ml) or CRP (peak = 1.6 mg/L) relative to baseline or by treatment. QU supplementation had no effect on markers of muscle damage or inflammation after eccentric exercise of the elbow flexors.
O’Fallon and Clarkson are with the Dept. of Kinesiology, University of Massachusetts, Amherst, MA. Kaushik and Michniak-Kohn are with the Dept. of Pharmaceutics, Rutgers University, Piscataway, NJ. Dunne is with the Combat Feeding Directorate, U.S. Army Natick Soldier RDEC, Natick, MA. Zambraski is with the Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA.