Independent effects of diet and exercise training on fat oxidation in non-alcoholic fatty liver disease

AIM To investigate the independent effects of 6-mo of dietary energy restriction or exercise training on wholebody and hepatic fat oxidation of patients with nonalcoholic fatty liver disease(NAFLD).METHODS Participants were randomised into either circuit exercise training(EX;n = 13;3 h/wk without changes in dietary habits),or dietary energy restriction(ER) without changes in structured physical activity(ER;n = 8).Respiratory quotient(RQ) and whole-body fat oxidation rates(Fatox) were determined by indirect calorimetry under basal,insulin-stimulated and exercise conditions.Severity of disease and steatosis was determined by liver histology;hepatic Fatox was estimated from plasma β-hydroxybutyrate co.ncentrations;cardiorespiratory fitness was expressed as VO2 peak.Complete-case analysis was performed(EX:n = 10;ER:n = 6).RESULTS Hepatic steatosis and NAFLD activity score decreased with ER but not with EX.β-hydroxybutyrate concentrations increased significantly in response to ER(0.08 ± 0.02 mmol/L vs 0.12 ± 0.04 mmol/L,P = 0.03) but remained unchanged in response to EX(0.10 ± 0.03 mmol/L vs 0.11 ± 0.07 mmol/L,P = 0.39).Basal RQ decreased(P = 0.05) in response.to EX,while this change was not significant after ER(P = 0.38).VO_(2peak)(P < 0.001) and maximal Fa_(tox) during aerobic exercise(P = 0.03) improved with EX but not with ER(P > 0.05).The increase in β-hydroxybutyrate concentrations was correlated with the reduction in hepatic steatosis(r =-0.56,P = 0.04).CONCLUSION ER and EX lead to specific benefits on fat metabolism of patients with NAFLD.Increased hepatic Fat_(ox) in response to ER could be one mechanism through which the ER group achieved reduction in steatosis.

High-intensity Interval Training for the Management of Nonalcoholic Steatohepatitis: Participant Experiences and Perspectives

Background and Aims:High-intensity interval training(HIIT)is a therapeutic option for people with nonalcoholic steatohepatitis(NASH).However,the perspectives and experiences of HIIT for people with NASH are unknown,limiting translation of research.We explored the experiences and perspectives of both professionally supervised and self-directed HIIT in people with NASH and evaluated participant-reported knowledge,barriers,and enablers to commencing and sustaining HIIT.Methods:Twelve participants with NASH underwent 12 weeks of supervised HIIT(3 days/week,4×4 minutes at 85–95%maximal heart rate,interspersed with 3 minutes active recovery),followed by 12-weeks of selfdirected(unsupervised)HIIT.One-on-one,semistructured participant interviews were conducted by exercise staff prior to HIIT and following both supervised and self-directed HIIT to explore prior knowledge,barriers,enablers,and outcomes at each stage.Interviews were audio-recorded,transcribed,coded,and thematically analyzed by two independent researchers.Results:Four dominant themes were identified:(1)no awareness of/experience with HIIT and ambivalence about exercise capabilities;(2)multiple medical and social barriers to commencing and continuing HIIT;(3)exercise specialist support was a highly valued enabler,and(4)HIIT was enjoyed and provided holistic benefits.Conclusions:People with NASH may lack knowledge of and confidence for HIIT,and experience multiple complex barriers to commencing and continuing HIIT.Exercise specialist support is a key enabler to sustained engagement.These factors need to be addressed in future clinical programs to augment the uptake and long-term sustainability of HIIT by people with NASH so they can experience the range of related benefits.