D-13 Thematic Poster - Attenuating Damage from Eccentric Exercise?: JUNE 2, 2011 1:00 PM - 3:00 PM: ROOM: 101
Quercetin, a plant-based flavonoid, is purported to have potent antioxidant/anti-inflammatory properties and may reduce the negative consequences of high force eccentric exercise.
PURPOSE: To determine if quercetin supplementation (via the First Strike™ bar, Natick Soldier RDEC, Natick MA) would attenuate eccentric exercise-induced muscle damage and associated functional decrements.
METHODS: 30 healthy men and women were assigned to a control (placebo, N=15) or experimental (quercetin, N=15) group and performed 24 maximal eccentric actions of the elbow flexors. Indices of muscle damage (strength loss, muscle soreness, relaxed arm angle, & plasma creatine kinase (CK) activity), inflammation (upper-arm swelling, plasma IL-6 & CRP levels), oxidative stress (plasma glutathione), profile of mood states (POMS), and plasma quercetin levels were assessed before, immediately after (relaxed arm angle and strength only), and 1-5 d post-exercise. Subjects then ingested either 1000 mg/d quercetin QU995 (Merck, SA Brazil) delivered via First Strike™ bars or placebo First Strike™ bars for 7 d prior to and 5 d following a 2nd bout of 24 eccentric actions with the opposite arm.
RESULTS: Subjects experienced significant strength loss (peak= -47±3%), muscle soreness (peak= 39±6 mm), muscle contracture (as assessed by reduce elbow angle 7±1 deg), CK elevations (peak=3,307±1,481 U/L), and upper-arm swelling (peak= 11±2 mm) (p<0.05). After 7 d of supplementation, plasma quercetin reached 202±47 ng/ml and remained elevated during the 5 d post-exercise recovery period. However, significant group differences (quercetin vs. placebo) were not observed among any study variables, nor were differences observed within quercetin and placebo groups pre- to post-supplementation (bout 1 vs. bout 2).
CONCLUSION: These findings confirm previous reports that 24 maximal eccentric contractions induced significant muscle damage and functional decrements for up to 5 d after each exercise bout. Quercetin supplementation had no effect on any post-exercise indices of muscle damage and functional decrements; thus, in this particular paradigm, quercetin does not reduce exercise-induced muscle damage or facilitate recovery.
This study was sponsored by U.S. Army, contract # W911QY-07-C-0001.