To determine the influence of 2 wk of quercetin (Q; 1000 mg·d−1) compared with placebo (P) supplementation on exercise performance and skeletal muscle mitochondrial biogenesis in untrained, young adult males (N = 26, age = 20.2 ± 0.4 yr, V˙O2max = 46.3 ± 1.2 mL·kg−1·min−1).
Using a randomized, crossover design with a 2-wk washout period, subjects provided blood and muscle biopsy samples presupplementation and postsupplementation periods and were given 12-min time trials on 15% graded treadmills after 60 min of moderate exercise preloads at 60% V˙O2max.
Plasma Q levels rose significantly in Q versus P during the 2-wk supplementation period (interaction P value <0.001). During the 12-min trial, the net change in distance achieved was significantly greater during Q (2.9%) compared with P (−1.2%; 29.5 ± 11.5 vs −11.9 ± 16.0 m, respectively, P = 0.038). Skeletal muscle messenger RNA expression tended to increase (range = 16-25%) during Q versus P for sirtuin 1 (interaction effect, P = 0.152), peroxisome proliferator-activated receptor γ coactivator-1α (P = 0.192), cytochrome c oxidase (P = 0.081), and citrate synthase (P = 0.166). Muscle mitochondrial DNA (relative copy number per diploid nuclear genome) increased 140 ± 154 (4.1%) with Q compared with −225 ± 157 (6.0% decrease) with P (P = 0.098).
In summary, 1000 mg·d−1 Q versus P for 2 wk by untrained males was associated with a small but significant improvement in 12-min treadmill time trial performance and modest but insignificant increases in the relative copy number of mitochondrial DNA and messenger RNA levels of four genes related to mitochondrial biogenesis.
1Department of Health, Leisure, and Exercise Science, Appalachian State University, Boone, NC; 2Human Performance Laboratory, North Carolina Research Campus, Kannapolis, NC; and 3Department of Biology, Appalachian State University, Boone, NC
Address for correspondence: David C. Nieman, Dr.P.H., FACSM, Department of Health, Leisure, and Exercise Science, Appalachian State University, PO Box 32071, Boone, NC 28608; E-mail: email@example.com.
Submitted for publication February 2009.
Accepted for publication June 2009.