Energy-matched moderate and high intensity exercise training improves nonalcoholic fatty liver disease risk independent of changes in body mass or abdominal adiposity - A randomized trial

Impact of exercise training on the sarcopenia criteria in non-alcoholic fatty liver disease: a systematic review and meta-analysis

Sarcopenia is a highly prevalent complication of non-alcoholic fatty liver disease (NAFLD). We aimed to conduct a systematic review and meta-analyses to elucidate the exercise training (ET)'s efficacy on NAFLD adult patients' sarcopenia criteria. We identified relevant randomized controlled trials (RCT) in electronic databases PubMed, CINAHL, and Scopus. We selected seven RCT from 66 screened studies. The ET programs included endurance or combined (endurance and resistance) training. No study performed resistance training alone. The physical function improved with endurance or combined training (mean differences [MD] 8.26 mL/Kg*min [95% CI 5.27 to 11.24 mL/Kg*min], p < 0.0001); Muscle mass showed no evidence of the beneficial effects of endurance or combined training (MD 1.01 Kg [95% CI -1.78 to 3.80 Kg], p = 0.48). None of the selected studies evaluated muscle strength. Endurance and combined training increase physical function criteria but do not improve muscle mass criteria on sarcopenia in NAFLD patients. These results must be interpreted with caution for the small number of patients included in the RCTs analyzed, the different characteristics of the ET carried out, the non-use of resistance training, which prevents assess its effect on sarcopenia despite the evidence that recommends it and does not assessment muscle strength criteria in RCT include. Future research should include muscle strength assessments and resistance training to evaluate the effects in this condition. Exercise training is beneficial for sarcopenia in NAFLD but is necessary more experimental evidence to define the best type of training that positively affects the three criteria of sarcopenia. PROSPERO reference number CRD42020191471.

Effect of exercise on hepatic steatosis: Are benefits seen without dietary intervention? A systematic review and meta-analysis

BACKGROUND

Interventions involving both exercise and dietary modification are effective in reducing steatosis in nonalcoholic fatty liver disease (NAFLD). However, exercise alone may reduce liver fat and is known to have other positive effects on health. The primary aim of this study was to systematically review the effect of exercise alone without dietary intervention on NAFLD and to examine correlations across changes in liver fat and metabolic markers during exercise.

METHODS

Relevant online databases were searched from earliest records to May 2020 by two researchers. Studies were included where the trial was a randomized controlled trial, participants were adults, exercise intervention was longer than 4 weeks, no dietary intervention occurred, and the effect of the intervention on liver fat was quantified via magnetic resonance imaging/proton magnetic resonance spectroscopy.

RESULTS

Of 21 597 studies retrieved, 16 were included involving 706 participants. Exercise was found to have a beneficial effect on liver fat without dietary modification (-2.4%, -3.13 to -1.66) (mean, 95% CI). Pearson correlation showed significant relationships between change in liver fat and change in weight (r = 0.67, P = .007), liver enzymes aspartate aminotransferase (r = 0.76, P = .002) and alanine aminotransferase (r = 0.91, P < .001), and cardiorespiratory fitness VO₂ peak (peak volume oxygen consumption) (r = -0.88, P = .004). By multivariate regression, change in weight and change in VO₂ peak significantly contributed to change in liver fat (R² = 0.84, P = .01).

CONCLUSIONS

This systematic review found that exercise without dietary intervention improves liver fat and that clinical markers may be useful proxies for quantifying liver fat changes.

Aerobic Exercise in the Management of Metabolic Dysfunction Associated Fatty Liver Disease

Sedentarism is the pandemic of modern times. It is associated with several medical conditions including obesity, type 2 diabetes mellitus, cardiovascular diseases and also liver disease, particularly metabolic dysfunction associated fatty liver disease (MAFLD). In an era when MAFLD is the most prevalent chronic liver disease worldwide, whilst no pharmacological therapy has been approved for it, exercise has proved to be effective in improving liver steatosis. Interestingly, exercise decreases liver fat even in the absence of weight loss. The challenge for the clinician is to motivate the obese patient with MAFLD, and associated co-morbidities, who has crystallized a sedentary behavior, at times when every need is at the distance of a click on the Internet, and the entire world can be visited behind a screen. In this review, the aggregate evidence on the mechanisms and effects of exercise in the management of MAFLD is summarized, with simple recommendations for everyday clinical practice.

Fetuin-A as a Potential Biomarker of Metabolic Variability Following 60 Days of Bed Rest

Background: Fetuin-A is a hepatokine linked to the development of insulin resistance. The purpose of this study was to determine if 60 days head-down-tilt (HDT) bed rest increased circulating fetuin-A and if it was linked to whole body insulin sensitivity (IS). Additionally, we examined whether reactive jump training (RJT) could alleviate the metabolic changes associated with bed rest. Methods: 23 young men (29 ± 6 years, 181 ± 6 cm, 77 ± 7 kg) were randomized to a control (CTRL, n = 11) or RJT group (JUMP, n = 12) and exposed to 60 days of bed rest. Before and after bed rest, body composition and V . O 2 ⁢ p ⁢ e ⁢ a ⁢ k were measured and an oral glucose tolerance test was performed to estimate IS. Circulating lipids and fetuin-A were measured in fasting serum. Results: Body weight, lean mass, and V . O 2 ⁢ p ⁢ e ⁢ a ⁢ k decreased in both groups following bed rest, with greater reductions in CTRL (p < 0.05). There was a main effect of time, but not the RJT intervention, for the increase in fetuin-A, triglycerides (TG), area under the curve for glucose (AUCG) and insulin (AUCI), and the decrease in Matsuda and tissue-specific IS (p < 0.05). Fetuin-A increased in participants who became less insulin sensitive (p = 0.019). In this subgroup, liver IS and adipose IS decreased (p < 0.05), while muscle IS was unchanged. In a subgroup, where IS did not decrease, fetuin-A did not change. Liver IS increased (p = 0.012), while muscle and adipose tissue IS remained unchanged. Conclusions: In this study, we report an increase in circulating fetuin-A following 60 days of bed rest, concomitant with reduced IS, which could not be mitigated by RJT. The amount of fetuin-A released from the liver may be an important determinant of changes in whole body IS. In this regard, it may also be a useful biomarker of individual variation due to inactivity or lifestyle interventions.

Lifestyle interventions affecting hepatic fatty acid metabolism

PURPOSE OF REVIEW

Prevalence of metabolic-associated fatty liver disease (MAFLD) is increasing, and as pharmacological treatment does not exist, lifestyle interventions (i.e. diet and exercise) represent the cornerstone management and treatment strategy. Although the available data clearly demonstrate that changes in lifestyle influence intrahepatic triglyceride (IHTG) content, the mechanisms through which this is achieved are seldom investigated. Here, we review recent evidence demonstrating the influence of lifestyle interventions on hepatic fatty acid metabolism and IHTG content.

RECENT FINDINGS

Diet and exercise influence IHTG content through various, and often interrelated factors. These include alterations in whole-body and tissue-specific insulin sensitivity, which may influence the flux of fatty acid and lipogenic substrates to the liver, and changes in intrahepatic fatty acid synthesis and partitioning. Notably, there are only a few studies that have investigated intrahepatic fatty acid metabolism in vivo in humans before and after an intervention.

SUMMARY

Lifestyle interventions represent an effective means of influencing hepatic fatty acid metabolism. IHTG content is decreased without weight-loss either through exercise or by changing the macronutrient composition of the diet, although what the optimal macronutrient composition is to achieve this has yet to be defined.

A Fad too Far? Dietary Strategies for the Prevention and Treatment of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is a major health problem, and its prevalence has increased in recent years, concurrent with rising rates of obesity and other metabolic diseases. Currently, there are no FDA-approved pharmacological therapies for NAFLD, and lifestyle interventions, including weight loss and exercise, remain the cornerstones for treatment. Manipulating diet composition and eating patterns may be a sustainable approach to NAFLD treatment. Dietary strategies including Paleolithic, ketogenic, Mediterranean, high-protein, plant-based, low-carbohydrate, and intermittent fasting diets have become increasingly popular because of their purported benefits on metabolic disease. This review highlights what is currently known about these popular dietary approaches in the management of NAFLD in clinical populations with mechanistic insight from animal studies. It also identifies key knowledge gaps to better inform future preclinical and clinical studies aimed at the treatment of NAFLD.

The role of the gut microbiome and exercise in non-alcoholic fatty liver disease

In recent years, the human gut microbiome has been found to influence a multitude of non-communicable diseases such as cardiovascular disease and metabolic syndrome, with its components type 2 diabetes mellitus and obesity. It is recognized to be mainly influenced by environmental factors, such as lifestyle, but also genetics may play a role. The interaction of gut microbiota and obesity has been widely studied, but in regard to non-alcoholic fatty liver disease (NAFLD) as a manifestation of obesity and insulin resistance, the causal role of the gut microbiome has not been fully established. The mechanisms by which the gut microbiome influences lipid accumulation, inflammatory responses, and occurrence of fibrosis in the liver are a topic of active research. In addition, the influence of exercise on gut microbiome composition is also being investigated. In clinical trials, exercise reduced hepatic steatosis independently of weight reduction. Other studies indicate that exercise may modulate the gut microbiome. This puts forward the question whether exercise could mediate its beneficial effects on NAFLD via changes in gut microbiome. Yet, the specific mechanisms underlying this potential connection are largely unknown. Thus, associative evidence from clinical trials, as well as mechanistic studies in vivo are called for to elucidate the relationship between exercise and the gut microbiome in NAFLD. Here, we review the current literature on exercise and the gut microbiome in NAFLD.

Understanding the Role of Exercise in Nonalcoholic Fatty Liver Disease: ERS-Linked Molecular Pathways

Nonalcoholic fatty liver disease (NAFLD) is globally prevalent and characterized by abnormal lipid accumulation in the liver, frequently accompanied by insulin resistance (IR), enhanced hepatic inflammation, and apoptosis. Recent studies showed that endoplasmic reticulum stress (ERS) at the subcellular level underlies these featured pathologies in the development of NAFLD. As an effective treatment, exercise significantly reduces hepatic lipid accumulation and thus alleviates NAFLD. Confusingly, these benefits of exercise are associated with increased or decreased ERS in the liver. Further, the interaction between diet, medication, exercise types, and intensity in ERS regulation is more confusing, though most studies have confirmed the benefits of exercise. In this review, we focus on understanding the role of exercise-modulated ERS in NAFLD and ERS-linked molecular pathways. Moderate ERS is an essential signaling for hepatic lipid homeostasis. Higher ERS may lead to increased inflammation and apoptosis in the liver, while lower ERS may lead to the accumulation of misfolded proteins. Therefore, exercise acts like an igniter or extinguisher to keep ERS at an appropriate level by turning it up or down, which depends on diet, medications, exercise intensity, etc. Exercise not only enhances hepatic tolerance to ERS but also prevents the malignant development of steatosis due to excessive ERS.

Treatment of Obesity in Mitigating Metabolic Risk

Through diverse mechanisms, obesity contributes to worsened cardiometabolic health and increases rates of cardiovascular events. Effective treatment of obesity is necessary to reduce the associated burdens of diabetes mellitus, cardiovascular disease, and death. Despite increasing cardiovascular outcome data on obesity interventions, only a small fraction of the population with obesity are optimally treated. This is a primary impetus for this article in which we describe the typical weight loss, as well as the associated impact on both traditional and novel cardiovascular disease risk factors, provided by the 4 primary modalities for obtaining weight loss in obesity-dietary modification, increasing physical activity, pharmacotherapy, and surgery. We also attempt to highlight instances where changes in metabolic risk are relatively specific to particular interventions and appear at least somewhat independent of weight loss. Finally, we suggest important areas for further research to reduce and prevent adverse cardiovascular consequences due to obesity.

Exercise Combats Hepatic Steatosis: Potential Mechanisms and Clinical Implications

Hepatic steatosis, the excess storage of intrahepatic lipids, is a rampant clinical problem associated with the obesity epidemic. Hepatic steatosis is linked to increased risk for insulin resistance, type 2 diabetes, and cardiovascular and advanced liver disease. Accumulating evidence shows that physical activity, exercise, and aerobic capacity have profound effects on regulating intrahepatic lipids and mediating susceptibility for hepatic steatosis. Moreover, exercise can effectively reduce hepatic steatosis independent of changes in body mass. In this perspective, we highlight 1) the relationship between obesity and metabolic pathways putatively driving hepatic steatosis compared with changes induced by exercise; 2) the impact of physical activity, exercise, and aerobic capacity compared with caloric restriction on regulating intrahepatic lipids and steatosis risk; 3) the effects of exercise training (modalities, volume, intensity) for treatment of hepatic steatosis, and 4) evidence for a sustained protection against steatosis induced by exercise. Overall, evidence clearly indicates that exercise powerfully regulates intrahepatic storage of fat and risk for steatosis.

The molecular basis for current targets of NASH therapies

Introduction: Nonalcoholic steatohepatitis (NASH) is a leading cause of liver disease in children and adults, a major contributor to health-care expenditures, and now a leading reason for liver transplantation. Adopting lifestyle modifications with regular exercise and a focus on healthy eating habits is the primary recommendation. However, patients are often unable to achieve and sustain such changes for a variety of social, physical, psychological and genetic reasons. Thus, treatments that can prevent and reverse NASH and its associated fibrosis are a major focus of current drug development.Areas covered: This review covers the current understanding of lipotoxic liver injury in the pathogenesis of NASH and how lifestyle modification and the spectrum of drugs currently in clinical trials address the many pathways leading to the phenotype of NASH.Expert opinion: Contrary to the frequently expressed nihilistic view of our understanding of NASH and disappointment with clinical trial results, much is known about the pathogenesis of NASH and there is much reason to be optimistic that effective therapies will be identified in the next 5-10 years. Achieving this will require continued refinement of clinical trial endpoints, continued engagement of trial sponsors and regulatory authorities, and continued participation of dedicated patients in clinical trials.

HIIT is not superior to MICT in altering blood lipids: a systematic review and meta-analysis

Objective

To compare the effects of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on adult lipid profiles; to identify training or participant characteristics that may determine exercise-induced change in total cholesterol (TC), triglycerides (TRG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C).

Design

Systematic review and meta-analysis.

Data sources

English language searches of several databases were conducted from inception until September 2019.

Eligibility criteria for excluding studies

Inclusion: (1) published randomised controlled human trials with group population n≥5; (2) intervention duration ≥4 weeks; (3) comparing HIIT with MICT; and (4) reporting pre–post intervention lipid measurements. Exclusion: subjects with chronic disease, <18 years, pregnant/lactating, in elite athletic training; and studies with a dietary or pharmaceutical intervention component.

Results

Twenty-nine data sets (mmol/L) of 823 participants were pooled and analysed. Neither HIIT nor MICT was better in decreasing TC (0.10 (−0.06 to 0.19), p=0.12, I²=0%), TRG (−0.05 (−0.11 to 0.01), p=0.10, I²=0%), LDL-C (0.05 (−0.06 to 0.17), p=0.37, I²=0%), or TC/HDL-C (−0.03 (−0.36 to 0.29), p=0.85, I²=0%). HIIT significantly raised HDL-C (0.07 (0.04 to 0.11), p<0.0001, I²=0%) compared with MICT.

Conclusion

Neither HIIT nor MICT is superior for altering TC, TRG, or LDL-C, or TC-HDL-C ratio. Compared with MICT, HIIT appeared to significantly improve HDL-C. Clinicians may prescribe either protocol to encourage participation in exercise and reduce cardiovascular risk. To raise HDL-C, HIIT may result in a larger effect size compared with MICT.

PROSPERO registration number

CRD42019136722.

Metabolic Implications of Diet and Energy Intake during Physical Inactivity

PURPOSE

Physical inactivity is associated with disruptions in glucose metabolism and energy balance, whereas energy restriction may blunt these adverse manifestations. During hypocaloric feeding, higher-protein intake maintains lean mass which is an important component of metabolic health. This study determined whether mild energy restriction preserves glycemic control during physical inactivity and whether this preservation is more effectively achieved with a higher-protein diet.

METHODS

Ten adults (24 ± 1 yr) consumed a control (64% carbohydrate, 20% fat, 16% protein) and higher-protein diet (50% carbohydrate, 20% fat, 30% protein) during two 10-d inactivity periods (>10,000 → ~5000 steps per day) in a randomized crossover design. Energy intake was decreased by ~400 kcal·d to account for reduced energy expenditure associated with inactivity. A subset of subjects (n = 5) completed 10 d of inactivity while consuming 35% excess of their basal energy requirements, which served as a positive control condition (overfeeding+inactivity).

RESULTS

Daily steps were decreased from 12,154 ± 308 to 4275 ± 269 steps per day (P < 0.05) which was accompanied by reduced V˙O2max (-1.8 ± 0.7 mL·kg·min, P < 0.05), independent of diet conditions. No disruptions in fasting or postprandial glucose, insulin, and nonesterified fatty acids in response to 75 g of oral glucose were observed after inactivity for both diet conditions (P > 0.05). Overfeeding+inactivity increased body weight, body fat, homeostasis model assessment of insulin resistance, and 2-h postprandial glucose and insulin concentrations (P < 0.05), despite no changes in lipid concentrations.

CONCLUSIONS

We show that independent of diet (normal vs higher-protein), mild energy restriction preserves metabolic function during short-term inactivity in healthy subjects. That is, metabolic deterioration with inactivity only manifests in the setting of energy surplus.

Are Lifestyle Therapies Effective for NAFLD Treatment?

Nonalcoholic fatty liver disease (NAFLD) is becoming the most common liver disorder worldwide. Specifically, nonalcoholic steatohepatitis (NASH) and fibrosis pose an enormous burden for patients and health-care systems. In the absence of approved pharmacological therapies, effective lifestyle interventions for NAFLD, such as dietary strategies and exercise training, are currently the therapeutic strategies of choice. This review covers the influence of macronutrient quality and quantity (i.e., low-carbohydrate and high-protein diets), for successful reduction of intrahepatocellular lipids (IHL). Moreover, we discuss the effectiveness of different modalities of physical exercising with and without weight loss. These lifestyle modifications not only provide strategies to reduce IHL but may also hold a still underestimated potential to induce improvement and/or even remission of NAFLD.

Exercise as a prescription for patients with various diseases

A growing understanding of the benefits of exercise over the past few decades has prompted researchers to take an interest in the possibilities of exercise therapy. Because each sport has its own set of characteristics and physiological complications that tend to occur during exercise training, the effects and underlying mechanisms of exercise remain unclear. Thus, the first step in probing the effects of exercise on different diseases is the selection of an optimal exercise protocol. This review summarizes the latest exercise prescription treatments for 26 different diseases: musculoskeletal system diseases (low back pain, tendon injury, osteoporosis, osteoarthritis, and hip fracture), metabolic system diseases (obesity, type 2 diabetes, type 1 diabetes, and nonalcoholic fatty liver disease), cardio-cerebral vascular system diseases (coronary artery disease, stroke, and chronic heart failure), nervous system diseases (Parkinson's disease, Huntington's disease, Alzheimer's disease, depression, and anxiety disorders), respiratory system diseases (chronic obstructive pulmonary disease, interstitial lung disease, and after lung transplantation), urinary system diseases (chronic kidney disease and after kidney transplantation), and cancers (breast cancer, colon cancer, prostate cancer, and lung cancer). Each exercise prescription is displayed in a corresponding table. The recommended type, intensity, and frequency of exercise prescriptions are summarized, and the effects of exercise therapy on the prevention and rehabilitation of different diseases are discussed.

Perspectives on Interval Exercise Interventions for Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is associated with an increased risk of type 2 diabetes, cardiovascular disease, cirrhosis, and liver cancer. Exercise therapy is the most effective treatment for patients with NAFLD. High-intensity interval training (HIIT) is attracting attention as a time-efficient and an effective exercise modality for treating patients with NAFLD. Previous studies have shown that HIIT can reduce fat mass, visceral adipose tissue, and intrahepatic lipid levels and improve hepatic stiffness. HIIT may be an optimal exercise therapy to improve NAFLD in patients with a lack of time.

Dietary and Pharmacological Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the developed world. Simple hepatic steatosis is mild, but the coexistence of steatohepatitis (NASH) and fibrosis increases the risk of hepatocellular carcinoma. Proper dietary and pharmacological treatment is essential for preventing NAFLD progression. The first-line treatment should include dietary intervention and increased physical activity. The diet should be based on the food pyramid, with a choice of products with low glycemic index, complex carbohydrates in the form of low-processed cereal products, vegetables, and protein-rich products. Usage of insulin-sensitizing substances, pro- and prebiotics, and vitamins should also be considered. Such a therapeutic process is intended to support both liver disease and obesity-related pathologies, including insulin resistance, diabetes, dyslipidemia, and blood hypertension. In the pharmacological treatment of NAFLD, apart from pioglitazone, there are new classes of antidiabetic drugs that are of value, such as glucagon-like peptide 1 analogs and sodium/glucose cotransporter 2 antagonists, while several other compounds that target different pathogenic pathways are currently being tested in clinical trials. Liver biopsies should only be considered when there is a lack of decline in liver enzymes after 6 months of the abovementioned treatment. Dietary intervention is recommended in all patients with NAFLD, while pharmacological treatment is recommended especially for those with NASH and showing significant fibrosis in a biopsy.

Constant-Moderate and High-Intensity Interval Training Have Differential Benefits on Insulin Sensitive Tissues in High-Fat Fed Mice

In a mouse model of diet-induced obesity, this study determined if two exercise prescriptions with equivalent time and distance covered, [constant-moderate endurance (END) and high intensity interval training (HIIT)], exert differential metabolic benefits on insulin sensitive tissues. Male 10 week old C57BL/6 mice were fed a high fat diet (HFD; 45% kcal fat) ad libitum for 10 weeks and for a further 10 weeks they underwent END or HIIT training (3 × 40 min sessions/wk). Untrained HFD and chow-fed mice acted as controls. At 30 weeks of age, mice were sacrificed and quadriceps muscle, subcutaneous adipose tissue (SAT) and liver were excised. Neither END nor HIIT altered body weight or composition in HFD mice. In quadriceps, HFD decreased high-molecular weight adiponectin protein, which was normalized by END and HIIT. In contrast, HIIT but not END reversed the HFD-driven decrease in the adiponectin receptor 1 (AdipoR1). In SAT, both programs tended to decrease collagen VI protein (p = 0.07–0.08) in HFD, whereas only HIIT induced an increase in the mRNA (3-fold vs. HFD untrained) and protein (2-fold vs. HFD untrained) of UCP1. In liver, only END reversed collagen I accumulation seen in HFD untrained mice. Our results suggest that HIIT may promote better systemic metabolic changes, compared to END, which may be the result of the normalization of muscle AdipoR1 and increased UCP1 seen in SAT. However, END was more effective in normalizing liver changes, suggesting differential metabolic effects of END and HIIT in different tissues during obesity.

Effects of short-term sprint interval and moderate-intensity continuous training on liver fat content, lipoprotein profile, and substrate uptake: a randomized trial

Type 2 diabetes (T2D) and increased liver fat content (LFC) alter lipoprotein profile and composition and impair liver substrate uptake. Exercise training mitigates T2D and reduces LFC, but the benefits of different training intensities in terms of lipoprotein classes and liver substrate uptake are unclear. The aim of this study was to evaluate the effects of moderate-intensity continuous training (MICT) or sprint interval training (SIT) on LFC, liver substrate uptake, and lipoprotein profile in subjects with normoglycemia or prediabetes/T2D. We randomized 54 subjects (normoglycemic group, n = 28; group with prediabetes/T2D, n = 26; age = 40-55 yr) to perform either MICT or SIT for 2 wk and measured LFC with magnetic resonance spectroscopy, lipoprotein composition with NMR, and liver glucose uptake (GU) and fatty acid uptake (FAU) using PET. At baseline, the group with prediabetes/T2D had higher LFC, impaired lipoprotein profile, and lower whole body insulin sensitivity and aerobic capacity compared with the normoglycemic group. Both training modes improved aerobic capacity (P < 0.001) and lipoprotein profile (reduced LDL and increased large HDL subclasses; all P < 0.05) with no training regimen (SIT vs. MICT) or group effect (normoglycemia vs. prediabetes/T2D). LFC tended to be reduced in the group with prediabetes/T2D compared with the normoglycemic group posttraining (P = 0.051). When subjects were divided according to LFC (high LFC, >5.6%; low LFC, <5.6%), training reduced LFC in subjects with high LFC (P = 0.009), and only MICT increased insulin-stimulated liver GU (P = 0.03). Short-term SIT and MICT are effective in reducing LFC in subjects with fatty liver and in improving lipoprotein profile regardless of baseline glucose tolerance. Short-term MICT is more efficient in improving liver insulin sensitivity compared with SIT. NEW & NOTEWORTHY In the short term, both sprint interval training and moderate-intensity continuous training (MICT) reduce liver fat content and improve lipoprotein profile; however, MICT seems to be preferable in improving liver insulin sensitivity.

Dose-response association between physical activity and non-alcoholic fatty liver disease: a case-control study in a Chinese population

AIM

Physical activity plays an important role in the development of non-alcoholic fatty liver disease (NAFLD).However, the optimal intensity and dose of physical activity for the treatment of NAFLD have yet to be found. In the present study, we aimed to provide a dose-response association between physical activity and NAFLD in a Chinese population.

METHODS

We recruited 543 patients with NAFLD diagnosed by abdominal ultrasonography, and 543 age-matched and sex-matched controls. The amount of physical activity, sedentary time and energy intake was collected through a structured questionnaire. Logistic regression analyses were performed to investigate the association between physical activity and NAFLD.

RESULTS

After adjusting for hypertension, diabetes, body mass index, fasting blood glucose, energy intake and sedentary time, the total amount of physical activity was found to be inversely associated with NAFLD in a dose-dependent manner in men (>3180 metabolic equivalent of energy [MET]-min/week vs ≤1440 MET-min/week: OR 0.60, 95% CI 0.40 to 0.91, p for trend=0.01). In addition, both moderate-intensity and vigorous-intensity physical activity were effective in reducing the risk of NAFLD, independent of confounding variables in men (moderate-intensity physical activity: >684 MET-min/week vs none: OR 0.58, 95% CI 0.40 to 0.86, p for trend=0.01; vigorous-intensity physical activity: >960 MET-min/week vs none: OR 0.63, 95% CI 0.41 to 0.95, p for trend=0.02).

CONCLUSIONS

Physical activity was inversely associated with risk of NAFLD in a dose-dependent manner in men. Vigorous-intensity and moderate-intensity physical activity were both beneficial to NAFLD, independent of sedentary time and energy intake.

Voluntary exercise in mice fed an obesogenic diet alters the hepatic immune phenotype and improves metabolic parameters - an animal model of life style intervention in NAFLD

Reproducible animal models to recapitulate the pathophysiology of non-alcoholic fatty liver disease (NAFLD) are urgently required to improve the understanding of the mechanisms of liver injury and to explore novel therapeutic options. Current guidelines recommend life-style interventions as first-line therapy for NAFLD and these types of intervention are considered standard-of-care. The current study establishes a reproducible mouse model of a life-style intervention in NAFLD using voluntary wheel running (VWR). Male C57BL/6J mice were fed a high-fat, high-carbohydrate diet (HFD) to induce NAFLD or a corresponding control diet for 12 weeks. Starting at week 9 of the obesogenic NAFLD diet, mice were randomized to either free access to a running wheel or being single caged resembling a sedentary (SED) life-style. VWR induced a transient weight reduction in HFD-fed mice up until week 10. In contrast to the SED mice, VWR mice exhibited normal ALT at the end of the intervention, while the metabolic alterations including elevated fasting glucose, insulin, triglyceride, and total cholesterol levels remained almost unchanged. Additionally, VWR prevented HFD-induced hepatic steatosis by alterations in key liver metabolic processes including the induction of fatty acid β-oxidation and lipogenesis inhibition following increased AMP-activated protein kinase (AMPK)-α activity. Phosphorylation of the serine kinase Akt in hepatic tissue was enhanced following VWR. Furthermore, VWR mice were protected from HFD-induced expression of pro-inflammatory cytokines, chemokines and liver macrophage infiltration. The SED/HFD group exhibited increasing activity of hepatic nuclear factor (NF)-κB p65, which was absent following exercise in the VWR/HFD group. In summary, in an obesogenic mouse model of NAFLD physical exercise improves fatty acid and glucose homeostasis and protects from macrophage-associated hepatic inflammation.

Effects of exercise training on Fetuin-a in obese, type 2 diabetes and cardiovascular disease in adults and elderly: a systematic review and Meta-analysis

Background

Elevated levels of fetuin-A are associated with increased risks of metabolic syndrome, type 2 diabetes and nonalcoholic fatty liver disease. This meta-analysis investigated whether exercise interventions can reduce fetuin-A in adults.

Methods

We searched clinical trials that objectively assessed fetuin-A and included study arms with exercise intervention. The pre-intervention and post-intervention data were used for meta-analysis. The effect sizes were calculated as standardized mean differences or changes in fetuin-A and expressed as Hedges’ g using random-effects models.

Results

The overall Hedges’ g for fetuin-A in all included interventions was − 0.640 (95%CI − 1.129 to − 0.151; n = 9), but this effect was not observed in obese (g = − 0.096; 95%CI, − 0.328 to 0.135) and type 2 diabetes/dysglycemia (g = − 0.56; 95%CI, − 1.348 to 0.236) individuals. Additionally, the random-effects meta-regression analysis showed that there was not a greater decrease in fetuin-A in individuals who achieved greater body mass index reductions (regression coefficient = 0.065; 95%CI, − 0.185 to 0.315).

Conclusion

Supervised exercise is associated with reductions in fetuin-A levels in adults and elderly. However, the results of the present meta-analysis should be interpreted with caution because of the variety of type of exercises and individual obesity related-disorders involve. Therefore, additional high-quality randomized controlled trials describing the effect of supervised exercise interventions on fetuin-A in adults are still needed. 

Electronic supplementary material

The online version of this article (10.1186/s12944-019-0962-2) contains supplementary material, which is available to authorized users.

The Mexican consensus on nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) affects nearly one third of the population worldwide. Mexico is one of the countries whose population has several risk factors for the disease and its prevalence could surpass 50%. If immediate action is not taken to counteract what is now considered a national health problem, the medium-term panorama will be very bleak. This serious situation prompted the Asociación Mexicana de Gastroenterología and the Asociación Mexicana de Hepatología to produce the Mexican Consensus on Fatty Liver Disease. It is an up-to-date and detailed review of the epidemiology, pathophysiology, clinical forms, diagnosis, and treatment of the disease, whose aim is to provide the Mexican physician with a useful tool for the prevention and management of nonalcoholic fatty liver disease.

VO2max is associated with measures of energy expenditure in sedentary condition but does not predict weight change

BACKGROUND/OBJECTIVES

Energy expenditure measured under sedentary conditions predicts weight change but evidence that directly measured VO₂max is associated with weight change is lacking. The aim of this study was to determine the associations of VO₂max with measures of predominantly sedentary 24-h thermogenesis, and subsequent weight change.

SUBJECTS/METHODS

Three hundred fifty-seven individuals (162 females; 27 Blacks, 72 Caucasians, and 258 American Indians) had measures of body composition, resting metabolic rate (RMR), and intermittent treadmill run test for assessment of VO₂max. On a separate day, 24-h energy expenditure (EE), diet-induced thermogenesis (DIT) expressed as "awake and fed" thermogenesis (AFT), sleeping metabolic rate (SMR), and spontaneous physical activity (SPA) were measured in a whole-room indirect calorimeter. Follow-up weight for 217 individuals was available (median follow-up time, 9.5 y; mean weight change, 12.4 ± 14.9 kg).

RESULTS

After adjustment for fat free mass, fat mass, age, sex, and race, a higher VO₂max was associated with a higher RMR (β = 68.2 kcal/day per L/min, P < 0.01) and 24-h EE (β = 62.2 kcal/day per L/min, P < 0.05) and including additional adjustment for energy intake higher AFT (β = 66.1 kcal/day per L/min, P = 0.01). Neither SMR (P > 0.2) nor SPA (P > 0.8) were associated with VO₂max. VO₂max at baseline did not predict follow-up weight after adjustment for baseline weight, follow-up time, sex, and race (P > 0.4).

CONCLUSION

VO₂max is associated with measures of EE including 24-h EE, RMR and DIT implying a common mechanism regulating the energetics of skeletal muscle during exercise and thermogenesis. However, this did not translate to VO₂max as a predictor of weight change.

Lifestyle interventions for patients with nonalcoholic fatty liver disease: a network meta-analysis

Lifestyle interventions remain the first-line therapy for nonalcoholic fatty liver disease (NAFLD). This study aims to evaluate the individual impact of exercise and/or dietary interventions on the level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), homeostasis model of assessment for insulin resistance index (HOMA-IR), and BMI. Randomized-controlled trials from patients diagnosed with NAFLD were included in the meta-analysis if they reported the associations between changes in ALT, AST, HOMA-IR, or BMI and types of lifestyle interventions. Nineteen eligible articles were included. Compared with observation, aerobic exercise training (AEx) plus diet [weighted mean difference (WMD)=-25.85; 95% confidence interval (CI): -43.90 to -7.80], AEx (WMD=-8.81; 95% CI: -20.22-2.60) and diet (WMD=-11.85; 95% CI: -47.65-24.95) showed significant efficacy in the improvement of ALT levels. Also AST, AEx plus diet showed a significant tendency to reduce AST levels. In addition, progressive resistance training (WMD=-1.70; 95% CI: -5.61-2.21) led to the most obvious reduction in HOMA-IR compared with observation, but appeared to show no significant effect in BMI (WMD=0.27; 95% CI: -0.48 to -0.07), whereas AEx plus diet (WMD=-0.96; 95% CI: -1.54 to -0.38 and WMD=-1.96; 95% CI: -2.79 to -1.12) showed great efficacy both in the improvement of HOMA-IR and BMI. AEx plus diet is the most effective intervention in the management of patients with NAFLD. Dietary intervention may be more effective in the improvements of aminotransferases, whereas exercise shows superiority in improving insulin sensitivity and reduction of BMI.

Nonalcoholic Fatty Liver Disease in University Rugby Football Players

Physical activity improves various metabolic disturbances. The effect of physical activity on non-alcoholic fatty liver disease (NAFLD) has not been defined, particularly in athletes who are able to consume a diet to increase body mass. The aim of this study was to evaluate the prevalence of NAFLD and associated factors of NAFLD among male university rugby football players [n = 69, 37 forwards (FW) and 32 backs (BK)], relative to age-matched controls (CON; n = 29). For FW players exercise consists of physical contact play, such as ruck, mall, scrum, and tackle. For BK players exercise consists of sprints and endurance running. Liver function tests and bioimpedance analysis to assess body composition were performed. Subjects consuming ≤ 20 g/day of ethanol and exhibiting an aspartate transaminase (AST) level ≥ 33 U/L, and/or alanine transaminase (ALT) level ≥ 43 U/L, were considered to have NAFLD. The PNPLA3 and MTP genotypes were determined using real-time polymerase chain reaction (PCR). The body mass index, body fat mass, and lean body mass were significantly higher in the FW group than in the BK and CON groups (P < 0.05). The total cholesterol, low-density lipoprotein cholesterol, triglyceride, AST, ALT, and alkaline phosphatase levels were significantly higher in the FW group than in the CON group (P < 0.05). The prevalence of NAFLD was significantly higher in the FW group than in the BK group and CON group (18.9, 8.6, and 0.0%, respectively), whereas there were non-significant between-group differences in the frequency of the PNPLA3 and MTP genotypes. These findings indicate that rugby football players, especially those in the FW position, are at higher risk of developing NAFLD, which emphasizes the role of diet and exercise in the development of NAFLD.

High-Intensity Interval Training Is Equivalent to Moderate-Intensity Continuous Training for Short- and Medium-Term Outcomes of Glucose Control, Cardiometabolic Risk, and Microvascular Complication Markers in Men With Type 2 Diabetes

We sought to determine the efficacy of 12 weeks high-intensity interval training (HIIT), compared to moderate-intensity continuous training (MICT) on glucose control, cardiometabolic risk and microvascular complication markers in men living with type 2 diabetes (T2D). Both modalities were combined with resistance training (RT). Additionally, the study aimed to determine the medium-term durability of effects. After a 12-week, thrice weekly, training intervention incorporating either MICT+RT (n = 11) or HIIT+RT (n = 12), the study concluded with a 6-month follow-up analysis. The middle-aged study participants were obese, had moderate duration T2D and were taking multiple medications including insulin, statins and beta-blockers. Participants, randomized via the method of minimization, performed MICT (progressing to 26-min at 55% maximum estimated workload [eWLmax]) or HIIT (progressing to two variations in which twelve 1-min bouts at 95% eWLmax interspersed with 1-min recovery bouts, alternated with eight 30-s bouts at 120% eWLmax interspersed with 2:15 min recovery bouts) under supervision at an exercise physiology facility. To account for fixed and random effects within the study sample, mixed-effect models were used to determine the significance of change following the intervention and follow-up phases and to evaluate group^*time interactions. Beyond improvements in aerobic capacity (P < 0.001) for both groups, both training modalities elicited similar group^*time interactions (P > 0.05) while experiencing benefits for glycated hemoglobin (HbA1c; P = 0.01), subcutaneous adiposity (P < 0.001), and heart rate variability (P = 0.02) during the 12-week intervention. Adiposity (P < 0.001) and aerobic capacity (P < 0.001) were significantly maintained in both groups at the 6-month follow-up. In addition, during the intervention, participants in both MICT+RT and HIIT+RT experienced favorable reductions in their medication usage. The study reported the inter-individual variability of change within both groups, the exaggerated acute physiological responses (using exercise termination indicators) that occurred during the interventions as well as the incidence of precautionary respite afforded in such a study sample. To reduce hyperglycaemia, and prevent further deterioration of cardiometabolic risk and microvascular complication markers (in both the short- and medium-term), future strategies that integrate the adoption and maintenance of physical activity as a cornerstone in the treatment of T2M for men should (cognisant of appropriate supervision) include either structured MICT+RT, or HIIT+RT. Clinical Trials Registration Number: ACTRN12617000582358 http://www.anzctr.org.au/default.aspx.

Therapeutic Approaches to Nonalcoholic Fatty Liver Disease: Exercise Intervention and Related Mechanisms

Exercise training ameliorates nonalcoholic fatty liver disease (NAFLD) as well as obesity and metabolic syndrome. Although it is difficult to eliminate the effects of body weight reduction and increased energy expenditure-some pleiotropic effects of exercise training-a number of studies involving either aerobic exercise training or resistance training programs showed ameliorations in NAFLD that are independent of the improvements in obesity and insulin resistance. In vivo studies have identified effects of exercise training on the liver, which may help to explain the "direct" or "independent" effect of exercise training on NAFLD. Exercise training increases peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) expression, improves mitochondrial function and leads to reduced hepatic steatosis, inflammation, fibrosis, and tumor genesis. Crosstalk between the liver and adipose tissue, skeletal muscle and the microbiome is also a possible mechanism for the effect of exercise training on NAFLD. Although numerous studies have reported benefits of exercise training on NAFLD, the optimal duration and intensity of exercise for the prevention or treatment of NAFLD have not been established. Maintaining adherence of patients with NAFLD to exercise training regimes is another issue to be resolved. The use of comprehensive analytical approaches to identify biomarkers such as hepatokines that specifically reflect the effect of exercise training on liver functions might help to monitor the effect of exercise on NAFLD, and thereby improve adherence of these patients to exercise training. Exercise training is a robust approach for alleviating the pathogenesis of NAFLD, although further clinical and experimental studies are required.

Comparison of the Prevalence of Metabolic Disease Between Two Types of Urbanization in China

Objective: China is experiencing the world's largest urbanization. There are two primary types of urbanization in China: rural-to-urban migration and in situ urbanization, represented by Zhejiang Shangyu (SY) and Jiangsu Nanjing (NJ), respectively. Our aim is to compare changes in the prevalence of metabolic disease between these two types of urbanization in China. Methods: This is a cross-sectional study derived from the SPECT-China 2014 study. This study includes subjects and metabolic parameters from SY and NJ. Furthermore, biochemical and anthropometric indexes were taken into consideration and compared between the areas of interest. Results: The prevalence rates of diabetes, prediabetes and healthy subjects were 6.5, 17.9, and 75.7% in SY and 16.0, 31.0, and 53.0% in NJ, respectively. Industrial and agricultural jobs accounted for 77.9% and 32.0% of employment in SY and NJ, respectively. Fasting plasma glucose (FPG) was higher in SY than in NJ; however, HbA1c was lower in SY than in NJ. There was a significant difference in nonalcoholic fatty liver disease (NAFLD) and healthy subjects between SY and NJ (P < 0.05). Significant differences were also found with respect to body mass index (BMI), waist circumference (WC) and hip circumference (HC) between these two locations (P < 0.001). Logistic regression analysis revealed that the prevalence of prediabetes, diabetes, overweight, obesity and dyslipidemia was higher in NJ than in SY. Conclusions: In situ urbanization has notably changed occupational distribution. The prevalence rates of diabetes, obesity, and NAFLD were increased in rapidly urbanized areas. Thus, more attention should be paid to rapidly urbanizing areas to reduce the prevalence of metabolic disease.