Effects of different endurance training intensities on resting levels of skeletal muscle and liver glycogen concentrations in male rats

Liver and muscle glycogen are main energy sources, that playcrucial rolesin muscular functionand maintenance of blood glucose levels during short and vigorous exercise. Much data is available on the effects of different types of physical exercise training on liver and muscle glycogen contents, showing that endurance-trained humans and animals have higher liver and muscle glycogen contents, when compared with sedentary counterparts. The purpose of current study was to investigate the effects of treadmill running at different intensities on the glycogen contents of liver and skeletal muscle. Forty male wistar rats (14-16weeks old, weighing 250-260 g) were randomly assigned tocontrols (No. = 10), and the low (18 m/min)(No. = 10), moderate (26 m/min)(No. = 8)and high (34 m/min)(No. = 10) intensity groups.The three training groups ran for 60 min/d, 5d/wk at 18, 26, and 34 m/min and 0% grade for 12 weeks.Forty-eight hours after the last exercise session, rats were sacri, and liver and gastrocnemius muscle were collected and frozen in liquid nitrogen for glycogen measurements. One way ANVOA was, used and significance level was set at P ≤ 0.05. Data demonstrated that the trained groups had higher liver and lower muscle glycogen contents when compared to the control group, with the moderate exercise group having the highest levels. Moderate intensity exercise seems more suitable for maintaining and improving glycogen levels in liver and muscle