Glucose Transporter protein-4 (GLUT-4) is considered the predominant glucose transporter in skeletal muscle. Exercise has been shown to increase glucose uptake and GLUT-4 protein content in skeletal muscle following muscle contraction. PURPOSE: To determine the acute effects of a single bout of moderate intensity endurance exercise on skeletal muscle GLUT-4 content. METHODS: 10 healthy male volunteers (age: 24.4 ± 1.3 years; BMI 23.16 ± 0.60 kg/m²) participated in a single bout of endurance exercise on a cycle ergometer at 65% maximal aerobic capacity (VO2max) for 1.5 – 2.0 hours (650kcal). Muscle biopsies were obtained from the vastus lateralis immediately before and after the exercise. Muscle glycogen content was measured using a Periodic acid-Schiff stain (PAS). GLUT-4 content was determined via immunohistochemistry techniques and quantified using ImageJ software. RESULTS: Blood glucose tended to decrease following aerobic exercise (Pre: 87.6 ± 1.78 mg/dl: Post: 84.5 ± 1.85 mg/dl; p=0.05). Glycogen content significantly decreased following exercise (Pre: 0.008 ± 0.0002 AU; Post: 0.007 ± 0.0002 AU; p=0.04). Total GLUT-4 content significantly increased after a single bout of exercise (Pre: 9.05±1.09 AU: Post 13.32±1.17 AU; p=0.01). CONCLUSION: A single bout of moderate intensity, long duration, aerobic exercise increase GLUT-4 protein content in healthy males.



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