Effects and Mechanism of High Intensity Interval Training on Skeletal Muscle Glycogen Content

Objective:To observe the effects of 8-week high intensity interval training(HIIT)on skeletal muscle glycogen content and investigate the possible mechanism to provide evidence for athletic training and mass fitness exercise prescription scientifically.Methods:Twenty SD rats were randomly divided into control group(CG,n=10)and HIIT group(TG,n=10).Animals in TG conducted high intensity interval treadmill running(5times/week,60 min/time)and those in CG were housed individually in plastic cages.Fourty-eight hours after last test,animals were sacrificed and exhaust duration,blood glucose,serum insulin,glycogen content,glucose uptake rate,activity of glycogen phosphorylase(GP)and glycogen synthase(GS),protein expression of glucose transporter type 4(GLUT4),GP,phospho-GP(p-GP),GS,phospho-GS(p-GS)were measured.Results:Compare with rats in CG,exhaust duration,glycogen content,insulin-induced glucose uptake rate,activity of total GS,protein level of total GLUT4,sarcolemma GLUT4,GS and p-GS increased(P<0.05),activity GS ratio decreased(P<0.05),blood glucose,serum insulin,basal glucose uptake rate,activity and protein of GP had no significantly different(P>0.05)in those of TG.Conclusion:1)Long-term may upregulate glycogen content of skeletal muscle and enhance exercise capacity;2)HIIT-induced increases in glycogen content of skeletal muscle were attributable to an increase in glycogen synthesis,rather than a decrease in glycogen breakdown,which was related to increase in muscle glucose uptake due to upregulation and translocation of GLUT4,protein expression upregulation of GS and glucose-6-phosphate allosteric activation of GS.