Walnut extract exhibits anti-fatigue action via improvement of exercise tolerance in mice

This study was conducted to investigate the anti-fatigue effect of walnut extract (WE) on forced swimming capacity in mice. Twenty-eight male ICR mice were randomly divided into four groups, a vehicle control (VC) or one of three WE administered groups (300, 600 and 900 mg/kg/day). WE was orally administered to mice once a day for 4 weeks, during which time a forced swimming test was conducted once a week. The vehicle control group was given a corresponding volume of sterile distilled water. After 4 weeks, the forced swimming capacity and levels of blood lactate, glucose, glutamine, ammonia and triacylglycerol, and liver glycogen were measured. In the WE administration group (600 and 900 mg/kg) the maximum swimming time increased significantly when compared with the vehicle control group. WE (600 and 900 mg/kg) significantly decreased the levels of lactate andammonia and increased the blood glutamine levels and liver glycogen content after forced swimming relative to the vehicle control group. The results of this study demonstrated the anti-fatigue effects of WE in a dose-dependent manner. The effects of WE at 600 and 900 mg/kg were similar. Overall, these results suggest that walnut has anti-fatigue activity and could elevate exercise tolerance.