Health Sciences Ultrasound-Derived Liver Composition and Metabolic Flexibility Under Exercise Stress Malak Ali; Rhodes Van Houten*; Jared M. Dickinson, PhD; Sarah Oppelt, PhD; Ana Paula Freire, PhD; Kelly Pritchett, PhD Project Mentor(s): Kelly Pritchett, PhD Introduction: Metabolic Associated Fatty Liver Disease (MAFLD) is characterized by abnormal liver fat accumulation in conjunction with metabolic syndromes. MAFLD affects 33% of individuals worldwide, though little is known about how increased liver fat impacts physiological responses to exercise. This study aimed to analyze the relationship between liver composition and metabolic flexibility during a graded exercise test. Methods: Body composition was analyzed via dual-energy X- ray absorptiometry. Liver ultrasound was evaluated for echogenicity, where elevated mean gray volume (MGV) indicates abnormal liver tissue. Rates of fat (FATox) and carbohydrate (CHOox) oxidation (g/min), respiratory exchange ratio (RER), and blood lactate concentrations ([LA-], mmol/L) were assessed during a graded exercise test on a cycle ergometer. Results: 24 healthy males ( n = 11) and females ( n = 13) completed this study. MGV was inversely associated with FATox and positively associated with RER at rest ( r = -0.43; r = 0.49), 50 W ( r = -0.40; r = 0.49), 70 W ( r = -0.35; r = 0.41), 90 W ( r = -0.41; r = 0.45), and 110 W ( r = -0.36; r = 0.44).MGV and [LA-] were positively correlated at 70 W ( r = 0.39), 90 W ( r = 0.39), and 110 W ( r = 0.39). Additionally, mean values of FATox and [LA-] presented an inverse linear relationship ( r = -0.99), and a nonlinear inverse relationship ( r = -0.54, β = ‑ 0.95) when data was grouped across time and participants. Discussion: In this study, elevated liver echogenicity was associated with reduced FATox and greater reliance on carbohydrates during exercise. Similar to previous literature, FATox and [LA-] were inversely correlated, thus validating [LA-] as a marker of metabolic flexibility. These results may help inform future exercise research design for MAFLD. Presentation Type: Poster Presentation (May 21, 9:30am–3:00pm) Keywords: Metabolic Flexibility, Metabolic Associated Fatty Liver Disease, Lipid Oxidation, Exercise SOURCE Form ID: 111
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