This study investigated the effects of eight weeks' intermittent hypoxia (14% O2) on glucose tolerance and skeletal muscle morphology. Twenty-one Sprague-Dawley rats were matched for weight and assigned into three different treatments: control, one-hour hypoxia/day, and eight-hour hypoxia/day. The fiber type of soleus muscle was determined using the mATPase (pH4.6) and SDH method, and the capillary density was visualized using the AP method. Visceral fat weight, fasting blood glucose, fasting and postprandial serum insulin concentration in Group E were significantly lower than Group C during the OGTT. Group E had a significantly increased percentage of Type Ⅱa fiber and capillary density in soleus muscle than Group C, whereas the fiber size of soleus muscle of the former group decreased. Furthermore, significant correlations were found among abdominal fat weight (r=0.50, p.05), the fiber size of soleus muscle (r=-0.43, p<.05), and postprandial serum insulin concentration. It was concluded that intermittent hypoxia improved insulin sensitivity and the degree of improvement was determined by the effect of hypoxia duration on visceral fat weight and muscle fiber size.
This study investigated the effects of eight weeks' intermittent hypoxia (14% O2) on glucose tolerance and skeletal muscle morphology. Twenty-one Sprague-Dawley rats were matched for weight and assigned into three different treatments: control, one-hour hypoxia/day, and eight-hour hypoxia/day. The fiber type of soleus muscle was determined using the mATPase (pH4.6) and SDH method, and the capillary density was visualized using the AP method. Visceral fat weight, fasting blood glucose, fasting and postprandial serum insulin concentration in Group E were significantly lower than Group C during the OGTT. Group E had a significantly increased percentage of Type Ⅱa fiber and capillary density in soleus muscle than Group C, whereas the fiber size of soleus muscle of the former group decreased. Furthermore, significant correlations were found among abdominal fat weight (r=0.50, p.05), the fiber size of soleus muscle (r=-0.43, p<.05), and postprandial serum insulin concentration. It was concluded that intermittent hypoxia improved insulin sensitivity and the degree of improvement was determined by the effect of hypoxia duration on visceral fat weight and muscle fiber size.