Abstract: Objective: To explore the effect and molecular mechanism of high F-value corn peptide on improving exercise capacity, so as to provide theoretical support for its development as a sports nutritional supplement. Methods: Eighty SD rats were randomly divided into four groups: a control group and high F-value corn peptide with low-dose, medium-dose and high-dose groups. Each morning, the rats in low-dose, medium-dose and high-dose groups were orally administered with 0.1, 0.2 and 0.4 g/kg mb of high F-value corn peptide respectively, and the rats in the control group were administered with the same volume of normal saline. All rats received one-hour swimming training without weight loading every day over a period of 8 weeks and also performed exercise in the first five days every week with two-day intervals. After the last treatment, weight-bearing exercise was carried out and the time to exhaustion was recorded. Blood lactate levels were determined as well. After being at rest for three days, the rats were sacrificed to harvest peripheral blood and skeletal muscle tissue. Subsequently, commercial test kits were used to measure malondialdehyde (MDA) concentration, and the activities of superoxide dismutase (SOD) activity and adenosine triphosphate (ATP) synthase and hydrolase in muscle. Meanwhile, the expression of the antioxidative stress regulator nuclear factor erythroid-2 related factor 2 (Nrf2), Kelch-like?ECH-associated protein?1 (Keap1), the mitochondrial fusion protein mitofusin 2 (Mfn2) and the mitochondrial fission protein dynamin-related protein 1 (Drp1) were detected by Western blot analysis. Results: Compared with the control group, high F-value corn peptide significantly prolonged the exhaustive exercise time of mice (P < 0.05) in a dose-dependent manner, and dramatically reduced the level of blood lactic acid at 5 and 15 min after exhaustive exercise (P < 0.05). The level of blood lactic acid in the high-dose group was significantly lower than that in the low-dose group (P < 0.05). In addition, high F-value corn peptide dose-dependently significantly elevated the activities of ATP synthase and hydrolase in skeletal muscle of rats compared to the control group (P < 0.05). We also found that oral administration of high F-value corn peptide could increase SOD activity and reduce MDA production in skeletal muscle of experimental rats, increase the expression of Nrf2 in the nucleus and of Keap1 protein in the cytoplasm, significantly increase the expression of Mfn2, and significantly reduce the expression of Drp1. Conclusion: High F-value corn peptide improves exercise capacity in experimental rats by improving the mitochondrial function of skeletal muscle.

Key words: corn peptide; exercise fatigue; mitochondria; superoxide dismutase; mitofusin 2