Skeletal muscle function largely depend on intact energy metabolism, stress response, and antioxidant defense mechanisms. In this study, we tested the effect of a combined supplementation of alpha-lipoic acid (LA) plus coenzyme Q10 (Q10) on PPARgamma-coactivator alpha (PGC1alpha) activity, expression of glutathione-related phase II enzymes and glutathione (GSH) levels in cultured C2C12 myotubes. Supplementation of myotubes with 250 mumol/L LA plus 100 mumol/L Q10 significantly increased nuclear levels of PGC1alpha, a master switch of energy metabolism and mitochondrial biogenesis. The increase of nuclear PGC1alpha was accompanied by an increase in PPARgamma transactivation, a downstream target of PGC1alpha, and an increase in mitochondrial transcription factor A mRNA centrally involved in mitochondrial replication and transcription. Furthermore, supplementation of myotubes with LA plus Q10 resulted in an increase of genes encoding proteins involved in stress response, GSH synthesis, and its recycling. In LA-plus-Q10-treated myotubes a significant 4-fold increase in GSH was evident. This increase in GSH was accompanied by increased nuclear Nrf2 protein levels, partly regulating gammaGCS and GST gene expression. Present data suggest that the combined supplementation of skeletal muscle cells with LA plus Q10 may improve energy homeostasis, stress response, and antioxidant defense mechanisms.