Training and diet are hypothesized to directly stimulate key molecular pathways that mediate animal performance, and flight-training, dietary fats, and dietary antioxidants are likely important in modulating molecular metabolism in migratory birds. This study experimentally investigated how long-distance flight-training as well as diet composition, affected the expression of key metabolic genes in the pectoralis muscle and the liver of European starlings (Sturnus vulgaris, N=95). Starlings were fed diets composed of either a high or low polyunsaturated fatty acid (PUFA; 18:2n-6) and supplemented with or without a water-soluble antioxidant, and half of these birds were flight-trained in a wind-tunnel while the rest were untrained. We measured the expression of 7 (liver) or 10 (pectoralis) key metabolic genes in flight-trained and untrained birds. Fifty percent of genes involved in mitochondrial metabolism and fat utilization were upregulated by flight-training in the pectoralis (P