Abstract：Glycogen is an important fuel source in the skeletal muscle for endurance performance. Few studies demonstrated the influence of intermittent hypoxia training (IHT) on muscle glycogen levels. This study was designed to investigate whether IHT can enhance glycogen resynthesis in human skeletal muscle after a single bout exercise for 60 minutes with 70-75% VO2 peak. Seven healthy male subjects were recruited for this crossover study, and performed seven days exercise training under intermittent hypoxia (IHT trial) or normal oxygen (control trial) conditions. After seven days exercise training, on the 8th day morning, all subjects completed a 60-min cycling exercise at 70% VO2 peak, and ingested a high carbohydrate meal (2 g carbohydrate per body weight) immediately after exercise. Muscle samples from deep vastus lateralis, and blood samples were taken before exercise, immediately after exercise and 4-h after exercise. Biopsy muscle samples were taken for muscle glycogen assay, and blood samples were used to measure the glucose, insulin and cortisol concentrations. In control trail, muscle glycogen level was significantly decreased immediately after exercise compared to pre-exercise (p＜.05). However, no significant decrease in muscle glycogen was noticed in IHT trail immediately after exercise. During exercise recovery, IHT trial has no significant increase in muscle glycogen at 4-h after exercise compared to immediately after exercise. The glucose response was lower in IHT trial after same amount of carbohydrate meal. In this study, no significant differences in insulin and cortisol levels were shown in both trials. From our results, we conclude that the utilization of muscle glycogen was decrease in IHT trial after a single bout of 60 minutes exercise with 75% VO2 max. Therefore, the glycogen recovery was not significantly enhanced by IHT compared to control trial in exercised human skeletal muscle. (Full text)