Presentation Abstract

Presentation Number: 55
Title: Exercise-induced reduction in liver fat is accompanied by improvements in vascular function in non-alcoholic fatty liver disease
Presentation Time: Tuesday, Sep 21, 2010, 2:45 PM - 3:00 PM
Authors: C.J. Pugh1, H. Jones1, V.S. Sprung1, G.J. Kemp2, A. Irwin3, V.L. Adams2, W.E. Bimson2, N.T. Cable1, D.J. Green1, P. Richardson4, D.J. Cuthbertson3;
1Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom, 2Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom, 3Department of Diabetes and Endocrinology, University Hospital Aintree, Liverpool, United Kingdom, 4Departement of Haemotology, Royal Liverpool University Hospital, Liverpool, United Kingdom.
Keyword: 27 Exercise physiology
Abstract: Background and aims: Non-Alcoholic Fatty Liver Disease (NAFLD), the hepatic manifestation of the metabolic syndrome is characterised by the accumulation of triglycerides in the liver and is associated with liver-related morbidity and mortality as well as increased cardiovascular risk. Exercise training is recommended as a therapeutic technique to reduce hepatic fat in NAFLD patients, yet the efficacy of exercise training remains equivocal. Flow mediated dilation (FMD), the increase in conduit artery diameter in response to increases in flow, provides information regarding endothelial cell health and is an early barometer of cardiovascular disease. Endothelial function has been shown to improve with exercise training in young healthy, older sedentary and obese individuals but has not been investigated in the NAFLD population. Therefore, the aim of this study was to examine the effect of regular exercise on intrahepatocellular lipid (IHCL) content and endothelial function in NAFLD patients.
Materials and methods: 6 sedentary NAFLD patients aged 56±9 yrs underwent a 16-week supervised exercise training program (30-45mins, 3-5 times per week). Whole body magnetic resonance imaging with proton magnetic resonance spectroscopy was used to determine IHCL levels prior to and following training (n=5). Fasting glucose, lipids, AST and ALT, brachial artery FMD, responses to glyceryl trinitrate (GTN) and cardiorespiratory fitness (VO2peak) were also assessed before and after training. Differences between baseline and post-training data were analysed using paired t-tests. Data are described as mean±SD.
Results: IHCL significantly reduced by 28.7% following exercise training compared to baseline (21.4±13.7 vs 17.2±13.8%; P=0.01), this was accompanied by a significant improvement in FMD (7.3±3.8% vs 3.8±1.6%, P=0.02). Liver enzymes also significantly improved following exercise training; ALT was reduced to 28±6U/l from 39±9U/l at baseline (P=0.008). Fitness improved by 20.2% (23.50±4.56 vs 28.52±8.82ml/min/kg; P=0.06) and body mass (79.6±10.9 vs 77.2±12.0kg; P=0.04) and AST (P=0.01) were significantly reduced following exercise training. No significant changes in GTN or lipid profiles were evident after exercise training.
Conclusion: This is the first study to demonstrate that both IHCL and endothelial function significantly improve following exercise training in NAFLD patients. This indicates that regular exercise has concomitant therapeutic effects on both excess hepatic fat and cardiovascular disease in these high risk patients. The exercise-mediated improvement in IHCL and FMD was accompanied by clinically significant reductions in liver enzymes and body mass. These data strongly support the efficacy of exercise training as a non-pharmacological management strategy in NAFLD and suggest as well as improving liver function, exercise may decrease the risk of heart disease and stroke in these patients.
Supported By: an EFSD Clinical Research Grant