Annie Behrend


September 2010

Document Type


Degree Name



Oregon Health & Science University


Background: Inherited disorders of long-chain fatty acid oxidation (FAO) inhibit the ability to oxidize long-chain fatty acids (LCFAs) for energy generation. As a result, bouts of exercise can lead to rhabdomyolysis, impaired cardiac function and, hence, exercise avoidance in these individuals. Medium-chain triglyceride (MCT) supplementation may bypass this defect and reduce the risk of adverse metabolic events. Objectives: To determine the influence of isocaloric MCT vs carbohydrate (CHO) supplementation prior to exercise on substrate oxidation and cardiac function during exercise in participants with long-chain FAO disorders. Design & Methods: Two 45-minute, moderate intensity treadmill exercise studies were completed by subjects (n=11) in a randomized crossover design. An isocaloric oral dose of CHO (1 g/kg LBM) or MCT-oil (0.5 g/kg LBM) was administered prior to exercise, hemodynamic and metabolic indices were assessed during exertion and a cardiac echocardiogram was performed following exercise. Energy metabolism and cardiac function during exercise were analyzed using paired T tests. Results: A statistically significant decrease in respiratory exchange ratio (RER), double product ejection fraction estimation, and steady state heart rate were observed following the exercise test pretreated with MCT. Conclusions: MCT supplementation prior to exercise in subjects with LCHAD, CPT2 or VLCAD deficiency increased the oxidation of medium chain fats and acutely improved cardiac ejection fraction for the same amount of work performed when compared to CHO supplementation. Results from this study may guide dietary therapies for individuals with long-chain FAO disorders.




Graduate Programs in Human Nutrition


School of Medicine



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