Purpose: Exercise increases the production of reactive oxygen species (ROS) in skeletal muscle, and athletes often consume antioxidant supplements in the belief they will attenuate ROS-related muscle damage and fatigue during exercise. However, exercise-induced ROS may regulate beneficial skeletal muscle adaptations, such as increased mitochondrial biogenesis. We therefore investigated the effects of long-term antioxidant supplementation with vitamin E and α-lipoic acid on changes in markers of mitochondrial biogenesis in the skeletal muscle of exercise-trained and sedentary rats.
Methods: Male Wistar rats were divided into four groups: 1) sedentary control diet, 2) sedentary antioxidant diet, 3) exercise control diet, and 4) exercise antioxidant diet. Animals ran on a treadmill 4 d·wk−1 at ∼70%V˙O2max for up to 90 min·d−1 for 14 wk.
Results: Consistent with the augmentation of skeletal muscle mitochondrial biogenesis and antioxidant defenses, after training there were significant increases in peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) messenger RNA (mRNA) and protein, cytochrome C oxidase subunit IV (COX IV) and cytochrome C protein abundance, citrate synthase activity, Nfe2l2, and SOD2 protein (P < 0.05). Antioxidant supplementation reduced PGC-1α mRNA, PGC-1α and COX IV protein, and citrate synthase enzyme activity (P < 0.05) in both sedentary and exercise-trained rats.
Conclusions: Vitamin E and α-lipoic acid supplementation suppresses skeletal muscle mitochondrial biogenesis, regardless of training status.
1School of Human Movement Studies, The University of Queensland, St. Lucia, Queensland, AUSTRALIA; 2Program in Nutrition and Exercise Physiology, Washington State University, Spokane, WA; 3Department of Physiology, The University of Melbourne, Parkville, Victoria, AUSTRALIA; and 4Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, AUSTRALIA
Address for correspondence: Glenn D. Wadley, Ph.D., Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Hwy, Burwood, 3125, Australia; E-mail: email@example.com.
Submitted for publication August 2010.
Accepted for publication October 2010.