Abstract: Purpose The purpose is to study the effect of endurance training and moderate caloric restriction on the molecular chaperone of endoplasmic reticulum in skeletal muscle and glucose metabolism. Methods 37 SD rats were divided into silent group(S), diet-silent group (DS), training group (T) and diet-training group (DT) to undertake swimming endurance training by increasing load, during which the D group's food intake was only 70% of the normal groups for four weeks. RT-PCR and western blotting were adopted respectively to detect skeletal muscle ER, stress protein GRP78 and the mRNA and protein expression of ORP150. Blood glucose(BG), fasting serum insulin(FINS), plasma glucagon(GLU), the glycogen(Gn) of quadriceps femoris, hexokinase (HK), and the activity of pyruvate kinase(PK) were also detected. Results (1) training and diet as well as training+diet mildly increased GRP78 and ORP150 mRNA (+ 24% to 43%, P > 0.05) and protein expression (15% - 15%, P > 0.05); (2) training and diet significantly reduced body weight and body fat while training + diet displayed more obvious effect; diet significantly reduced silence BG, training + diet significantly slowed BG's recovery; training and diet significantly reduced the level of FINS while training+diet reduced it more. Diet significantly increased insulin sensitivity (ISI); Training and training +diet largely increased HK's activity and training +diet obviously increased the Gn content; the expression of GRP78 and ORP150 mRNA exhibited significantly positive correlation and so did the protein expression of ORP150 and ISI followed by Gn and HK. Conclusion 4 weeks of increasing load swimming endurance training and moderate diet mildly increased the expression of skeletal muscle/ORP150 GRP78, the possible reason of which might be the reduction of BG and its low level of free sugar. Endurance training and moderate diet improves the sugar metabolism of skeletal muscle and endurance training combined with moderate diet could produce better effect.

Key words: endurance training, diet, ER stress, expression of GRP78 and ORP150, sugar metabolism