High intensity interval training improves liver and adipose tissue insulin sensitivity

Evaluating the RESET care program: Advancing towards scalable and effective healthcare solutions for metabolic dysfunction-associated liver disease

In this article, we discuss the recently published article by Soni et al. This study explores the effectiveness of a comprehensive digital health program, RESET care, which integrates personalized dietary plans, structured exercise, and cognitive behavioral therapy delivered through a mobile app equipped with Internet of Things devices such as body composition analyzers and smartwatches. Metabolic dysfunction-associated liver disease (MASLD), a global health burden affecting approximately 25% of the population, demands sustainable lifestyle modifications as its primary management strategy. The study reports that 100% of participants in the comprehensive intervention group (diet + exercise + cognitive behavioral therapy) achieved a weight reduction ≥ 7% (6.99 ± 2.98 kg, 7.00% ± 3.39%; P = 0.002), a clinically significant threshold for MASLD improvement. In addition, participants showed a mean weight reduction of 6.99 kg (101.10 ± 17.85 vs 94.11 ± 17.38, P < 0.001) and a body mass index reduction of 2.18 kg/m² (32.90 ± 3.02 vs 30.72 ± 3.41, P < 0.001). These results underscore the potential of digital health platforms to provide scalable, evidence-based solutions for the treatment of MASLD. While these results highlight the potential of digital platforms in the scalable and personalized management of MASLD, the small study sample size and short duration of follow-up limit the generalizability of the results. Future large-scale, long-term trials are needed to confirm sustained benefits, cost-effectiveness, and broader applicability. This letter contextualizes the study within the evolving landscape of MASLD management and emphasizes the clinical implications of integrating digital technologies into standard care.

The combined effects of high-intensity interval training and time-restricted feeding on the AKT/FOXO1/PEPCK pathway in diabetic rats

High-intensity interval training (HIIT) and time-restricted feeding (TRF) have shown promise for improving glucose regulation by increasing insulin sensitivity, enhancing glucose uptake, reducing glucose production. Therefore, this study investigates the combined effects of HIIT and TRF on the AKT/FOXO1/PEPCK signaling pathway in the liver tissue of type 2 diabetic rats. 42 male Wistar rats (4-5 weeks of age) were included in the study. The animals were randomly divided into two groups: (1) Standard diet (SD, non-Diabetic (Non-D, n = 7) (2) High-fat diet (HFD, n = 35) for 4 weeks. To induce diabetes, 35 mg/kg of streptozotocin (STZ) was injected intraperitoneally (IP). Animals with blood glucose levels of > 250 mg/dL were considered as diabetic. Diabetic rats were randomly divided into 5 groups (n = 7): (1) Diabetes-exercise (D-EX), (2) Diabetes-TRF (D-TRF), (3) Diabetes-combined TRF and exercise (D-TRF&EX), (4) Diabetes no treatment (D-NT), (5) Diabetes with metformin (D-MET). Interventions (HIIT and TRF) were performed for 10 weeks. Rats in the Non-D group did not exercise and did not receive metformin or TRF. Periodic Acid-Schiff (PAS) staining was used to histologically analyze the liver tissue. Levels of blood glucose, insulin resistance (IR), FOXO1 protein, PEPCK, and area under the curve (AUC) following the IPGTT test, were significantly decreased in treatment groups compared to the D-NT group (p < 0.05). The AKT protein levels (p < 0.01), glycogen content (p < 0.05), and insulin sensitivity (p < 0.001) increased in the treatment groups as compared with the D-NT group. Microscopic examination of the liver tissue in general showed a better tissue arrangement in both treatment groups than in the D-NT group. Combining HIIT and TRF may be effective for improving blood glucose regulation, insulin sensitivity, in type 2 diabetes, as compared to TRF or HIIT interventions alone.

Physiological change of striatum and ventral midbrain's glia cell in response to different exercise modalities

Exercise not only regulates neurotransmitters and synapse formation but also enhances the function of multiple brain regions, beyond cortical activation. Prolonged aerobic or resistance exercise modality has been widely applied to reveal the beneficial effects on the brain, but few studies have investigated the direct effects of different exercise modalities and variations in exercise intensity on the neuroinflammatory response in the brain and overall health. Therefore, in this study, we investigated changes in brain cells and the immune environment of the brain according to exercise modalities. This study was conducted to confirm whether different exercise modalities affect the location and function of dopaminergic neurons, which are responsible for regulating voluntary movement, before utilizing animal models of disease. The results showed that high-intensity interval exercise (HIE) increased the activity of A2-reactive astrocytes in the striatum (STR), which is directly involved in movement control, resulting in neuroprotective effects. Both HIE and combined exercises (CE) increased the expression of dopamine transporter (DAT) in the STR without damaging dopamine neurons in the ventral midbrain (VM). This means that exercise training can help improve and maintain exercise capacity. In conclusion, specific exercise modalities or intensity of exercise may contribute to preventing neurodegenerative diseases such as Parkinson's disease or enhancing therapeutic effects when combined with medication for patients with neurodegenerative diseases.

High-Intensity Interval Training for Individuals With Isolated Impaired Fasting Glucose: Protocol for a Proof-of-Concept Randomized Controlled Trial

BACKGROUND

Standard lifestyle interventions have shown limited efficacy in preventing type 2 diabetes among individuals with isolated impaired fasting glucose (i-IFG). Hence, tailored intervention approaches are necessary for this high-risk group.

OBJECTIVE

This study aims to (1) assess the feasibility of conducting a high-intensity interval training (HIIT) study and the intervention acceptability among individuals with i-IFG, and (2) investigate the preliminary efficacy of HIIT in reducing fasting plasma glucose levels and addressing the underlying pathophysiology of i-IFG.

METHODS

This study is a 1:1 proof-of-concept randomized controlled trial involving 34 physically inactive individuals (aged 35-65 years) who are overweight or obese and have i-IFG. Individuals will undergo a 3-step screening procedure to determine their eligibility: step 1 involves obtaining clinical information from electronic health records, step 2 consists of completing questionnaires, and step 3 includes blood tests. All participants will be fitted with continuous glucose monitoring devices for approximately 80 days, including 10 days prior to the intervention, the 8-week intervention period, and 10 days following the intervention. Intervention participants will engage in supervised HIIT sessions using stationary "spin" cycle ergometers in groups of 5 or fewer. The intervention will take place 3 times a week for 8 weeks at the Aerobic Exercise Laboratory in the Rehabilitation Hospital at Emory University. Control participants will be instructed to refrain from engaging in intense physical activities during the study period. All participants will receive instructions to maintain a eucaloric diet throughout the study. Baseline and 8-week assessments will include measurements of weight, blood pressure, body composition, waist and hip circumferences, as well as levels of fasting plasma glucose, 2-hour plasma glucose, and fasting insulin. Primary outcomes include feasibility parameters, intervention acceptability, and participants' experiences, perceptions, and satisfaction with the HIIT intervention, as well as facilitators and barriers to participation. Secondary outcomes comprise between-group differences in changes in clinical measures and continuous glucose monitoring metrics from baseline to 8 weeks. Quantitative data analysis will include descriptive statistics, correlation, and regression analyses. Qualitative data will be analyzed using framework-driven and thematic analyses.

RESULTS

Recruitment for the study is scheduled to begin in February 2025, with follow-up expected to be completed by the end of September 2025. We plan to publish the study findings by the end of 2025.

CONCLUSIONS

The study findings are expected to guide the design and execution of an adequately powered randomized controlled trial for evaluating HIIT efficacy in preventing type 2 diabetes among individuals with i-IFG.

TRIAL REGISTRATION

Clinicaltrials.gov NCT06143345; https://clinicaltrials.gov/study/NCT06143345.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/59842.

Gut Microbiota at the Crossroad of Hepatic Oxidative Stress and MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent chronic liver condition marked by excessive lipid accumulation in hepatic tissue. This disorder can lead to a range of pathological outcomes, including metabolic dysfunction-associated steatohepatitis (MASH) and cirrhosis. Despite extensive research, the molecular mechanisms driving MASLD initiation and progression remain incompletely understood. Oxidative stress and lipid peroxidation are pivotal in the "multiple parallel hit model", contributing to hepatic cell death and tissue damage. Gut microbiota plays a substantial role in modulating hepatic oxidative stress through multiple pathways: impairing the intestinal barrier, which results in bacterial translocation and chronic hepatic inflammation; modifying bile acid structure, which impacts signaling cascades involved in lipidic metabolism; influencing hepatocytes' ferroptosis, a form of programmed cell death; regulating trimethylamine N-oxide (TMAO) metabolism; and activating platelet function, both recently identified as pathogenetic factors in MASH progression. Moreover, various exogenous factors impact gut microbiota and its involvement in MASLD-related oxidative stress, such as air pollution, physical activity, cigarette smoke, alcohol, and dietary patterns. This manuscript aims to provide a state-of-the-art overview focused on the intricate interplay between gut microbiota, lipid peroxidation, and MASLD pathogenesis, offering insights into potential strategies to prevent disease progression and its associated complications.

Amelioration of fructose-induced hepatic lipid accumulation by vitamin D3 supplementation and high-intensity interval training in male Sprague‒Dawley rats

BACKGROUND

Intrahepatic lipid accumulation (IHL), a hallmark of metabolic disorders, is closely associated with de novo lipogenesis (DNL). Notably, fructose feeding increased the DNL. Lifestyle modifications resulting from dietary changes and increased physical activity/exercise can decrease the IHL content. We examined the effects of vitamin D3 supplementation (VDS), high-intensity interval training (HIIT), and their combination on the transcription factors and enzymes of the DNL pathway in male Sprague‒Dawley rats fed a high-fructose diet (HFrD).

METHODS

Forty male rats were assigned to 5 groups (n = 8): CS (the control group had a standard diet); CF (the control group had HFrD (10% (w/v) fructose solution in tap water)); and FT (HFrD + HIIT: 10 bouts of 4 min of high-intensity running, corresponding to 85-90% of the maximal speed with 2 min active rest periods of 50% maximal speed, 5 days per week); FD (HFrD + intervention of intraperitoneal injection of 10000 IU/kg/week VDS); FTD (HFrD + HIIT + VDS) that were maintained for 12 weeks. ELISA, the GOD-POD assay, folch, western blotting, and oil red O staining were used to determine insulin, fasting blood glucose (FBG), hepatic triglyceride (TG) and cholesterol levels; SREBP1c, ChREBP-β, ACC1, FASN, p-ACC1, AMPK, p-AMPK, and PKA protein expression; and IHL content, respectively.

RESULTS

Both HIIT and VDS led to significant increases in the levels of PKA, AMPK, p-AMPK, and p-ACC1, as well as significant decreases in the levels of SREBP1c, ChREBP-β, ACC1, FASN, insulin, FBG, liver TG, liver cholesterol, and IHL. HIIT exhibited superior efficacy over VDS in reducing ChREBP-β, ACC1, insulin, FBG, liver TG and cholesterol, as well as increasing p-ACC1 and PKA. Notably, the combined intervention of HIIT and VDS yielded the most substantial improvements across all the parameters.

CONCLUSIONS

HFrD causes IHL accumulation and the onset of diabetes, whereas VDS and HIIT, along with their combined effects, prevent the consequences of HFrD.

Comparing the effect of high-intensity interval exercise and voluntary exercise training on cognitive functions in rats

It is known that exercise increases brain-derived neurotrophic factor (BDNF) levels in the hippocampus, the brain region responsible for learning and memory, resulting in improved cognitive functions and learning processes. However, it is claimed that different types of exercise cause different responses in the brain. It is thought that lactate and osteocalcin secreted in response to exercise are associated with an increase in BDNF levels. However, there are not enough studies on this subject. This study aimed to compare the effects of high-intensity interval training (HIIT) and voluntary exercise training on cognitive performance and molecular connections. Male rats were randomly divided into control, voluntary exercise training and HIIT groups. The voluntary exercise group had free access to the voluntary wheel for 8 weeks. The HIIT group performed HIIT on the treadmill 3 days a week for 8 weeks. The rats underwent open field (OF), elevated plus maze (EPM) and Morris water maze (MWM) tests 24 h after the last exercise training. Then, after blood was drawn under anesthesia, the rats were sacrificed and their hippocampus tissues were separated. Glucocorticoid and BDNF levels in the blood were evaluated by enzyme-linked immunosorbent assay (ELISA), and osteocalcin and BDNF expressions in the hippocampus were evaluated by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). Neither voluntary exercise training nor HIIT had any significant effect on behavioral parameters assessed by OF, EPM and MWM tests. However, BDNF expression in hippocampus tissue was higher in the HIIT group than in the control group. In addition, osteocalcin expression in hippocampus tissue was higher in the HIIT and voluntary exercise groups than in the control group. In conclusion, according to the findings we obtained from this study, although it does not have a significant effect on cognitive functions, the effect of HIIT on brain functions seems to be more effective than voluntary exercise.

Effects of different training models and subsequent exercise cessation on adipose tissue and associated variables

BACKGROUND

The General Adaptation Syndrome and the supercompensation Model are concepts widely applied in exercise science. Considering that fat is essential for tissue and the main energy source during continuous moderate-intensity exercise (MICE), the hypothesis arises that this type of effort may pay off after a detraining period.

OBJECTIVE

This study aimed to investigate how different exercise models, followed by a period of detraining, affected adipose tissue cellularity in adult rats. Two specific models were examined: moderate-intensity continuous exercise (MICE) and high-intensity intermittent exercise (HIIT).

MATERIALS AND METHODS

This is an experimental study in which rats were allocated into three groups: i) Continuous moderate-intensity exercise (MICE); ii) High-intensity intermittent exercise (HIIT); and iii) Control group (GC). Data were collected in three moments, namely: baseline values (T1), after which the animals exercised on a treadmill for eight weeks (T2) and then were followed up for four weeks after interruption of physical exercise (T3). For statistical analysis, a two-way analysis of variance (ANOVA) was performed, with Tukey's post-hoc for the group (GC, MICE, or HIIT) and Bonferroni's for the moment (T1, T2 and T3).

RESULTS

Regarding the periepididymal mass, GC showed an increase of 45% in T3 compared to T2. The HIIT and MICE groups had lower T3 values when compared to the CG. Comparing groups relative to the delta variation between T2 and T3 showed a difference in periepididymal mass (p = 0.012), with HIIT showing lower values than CG (p = 0.009). Analysis of the number of periepididymal adipocytes showed that HIIT (p < 0.001) and GC (p = 0.003) captured smaller numbers of cells than MICE.

CONCLUSION

In conclusion, our findings demonstrated positive effects of both interventions (HIIT and MICE) in the control of periepididymal adipose tissue mass of adult rats after 4 weeks of exercise interruption, with less mass gain in HIIT. More adipocytes were observed in MICE compared to HIIT and GC. These results suggest that both exercise models helped control fat accumulation, even after detraining.

Comparative effects of lifelong moderate-intensity continuous training and high-intensity interval training on blood lipid levels and mental well-being in naturally ageing mice

OBJECTIVE

This study aimed to investigate the impact of lifelong exercise, including both moderate-intensity continuous training and high-intensity interval training, on blood lipid levels and mental behaviour in naturally ageing mice to identify effective exercise strategies for ageing-related health issues.

METHODS

Six-week-old male BALB/c mice were randomly assigned to one of four groups: young control (YC), natural ageing control (OC), lifelong moderate-intensity continuous exercise (EM), and lifelong high-intensity interval exercise (EH) groups. The EM group was trained at a speed corresponding to 70 % of the maximum running speed, while the EH group was trained at a running speed alternating between 50 % of the maximum running speed, 70 % of the maximum running speed, and 90 % of the maximum running speed. All exercise sessions were conducted three times per week, with each session lasting 50 min. Behavioural tests and blood sample collection were conducted at 72 weeks of age.

RESULTS

Ageing in mice led to changes in muscle and fat mass. Both the EM and EH groups showed greater muscle mass and lower fat mass than did the OC group. Ageing was associated with elevated anxiety (fewer open arm entries, time spent in the central region) and depression (lower sucrose preference) indicators. However, these changes were reversed in both exercise groups, with no differences between the two exercise groups. Blood lipid levels, including total cholesterol (TC), total triglycerides (TGs), low-density lipoprotein (LDL), and free fatty acid (FFA) levels, were greater in the OC group than in the YC group. Additionally, the OC group exhibited lower high-density lipoprotein (HDL) levels. However, both the EM and EH groups exhibited improved lipid profiles compared to those of the YC group.

CONCLUSION

Lifelong exercise, whether moderate-intensity continuous or high-intensity interval training, can preserve body health during ageing, prevent anxiety and depression, and maintain stable blood lipid levels. Both exercise types are equally effective, suggesting that exercise intensity may not be the critical factor underlying these beneficial adaptations.

Emerging Therapies for Non-Alcoholic Steatohepatitis (NASH): A Comprehensive Review of Pharmacological and Non-Pharmacological Approaches

Non-alcoholic steatohepatitis (NASH) has emerged as a significant global health concern, closely linked to the obesity epidemic and metabolic syndrome. This review explores emerging therapies for NASH that go beyond traditional lifestyle modifications. The complex pathophysiology of NASH, involving insulin resistance, lipotoxicity, oxidative stress, and chronic inflammation, offers multiple targets for therapeutic intervention. While lifestyle changes remain fundamental, their limitations in achieving sustained improvements highlight the need for effective pharmacological and interventional therapies. This review discusses novel pharmacological approaches, including farnesoid X receptor (FXR) agonists, peroxisome proliferator-activated receptor (PPAR) agonists, and agents addressing metabolic dysfunction, inflammation, and fibrosis. Promising candidates such as obeticholic acid, lanifibranor, and semaglutide are highlighted, along with combination therapies targeting multiple pathways simultaneously. Non-pharmacological interventions, including bariatric surgery, endoscopic bariatric and metabolic therapies, and innovative exercise regimens, are also examined for their potential in NASH management. Despite significant advancements, NASH drug development faces challenges due to the disease's complexity, patient heterogeneity, and stringent regulatory requirements. This review also addresses these limitations and explores future directions, including personalized medicine approaches, non-invasive diagnostic tools, and the potential of microbiome modulation and regenerative therapies. The evolving landscape of NASH research emphasizes the need for multidisciplinary approaches integrating advances in diagnostics, therapeutics, and digital health technologies. As the field progresses, the focus remains on developing more effective, personalized, and accessible strategies for preventing, diagnosing, and treating NASH, with the ultimate goal of improving outcomes for patients affected by this increasingly prevalent liver disease.

High-intensity interval training and medium-intensity continuous training may affect cognitive function through regulation of intestinal microbial composition and its metabolite LPS by the gut-brain axis

AIMS

The gut-brain axis is the communication mechanism between the gut and the central nervous system, and the intestinal flora and lipopolysaccharide (LPS) play a crucial role in this mechanism. Exercise regulates the gut microbiota composition and metabolite production (i.e., LPS). We aimed to investigate the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cognitive function in C57BL/6 J mice through gut-brain axis regulation of gut microbiota composition and LPS displacement.

MAIN METHODS

C57BL/6 J male mice were randomly divided into sedentary, HIIT, and MICT groups. After 12 weeks of exercise intervention, the cognitive function of the brain and mRNA levels of related inflammatory factors were measured. RNA sequencing, Golgi staining, intestinal microbial 16 s rDNA sequencing, and ELISA were performed.

KEY FINDINGS

HIIT and MICT affect brain cognitive function by regulating the gut microbiota composition and its metabolite, LPS, through the gut microbiota-gut-brain axis. HIIT is suspected to have a risk: it can induce "intestinal leakage" by regulating intestinal permeability-related microbiota, resulting in excessive LPS in the blood and brain and activating M1 microglia in the brain, leading to reduced dendritic spine density and affecting cognitive function.

SIGNIFICANCE

This study revealed a potential link between changes in the gut microbiota and cognitive function. It highlighted the possible risk of HIIT in reducing dendritic spine density and affecting cognitive function.

Depletion of TBC1D4 Improves the Metabolic Exercise Response by Overcoming Genetically Induced Peripheral Insulin Resistance

The Rab-GTPase-activating protein (RabGAP) TBC1D4 (AS160) represents a key component in the regulation of glucose transport into skeletal muscle and white adipose tissue (WAT) and is therefore crucial during the development of insulin resistance and type 2 diabetes. Increased daily activity has been shown to be associated with improved postprandial hyperglycemia in allele carriers of a loss-of-function variant in the human TBC1D4 gene. Using conventional Tbc1d4-deficient mice (D4KO) fed a high-fat diet, we show that moderate endurance exercise training leads to substantially improved glucose and insulin tolerance and enhanced expression levels of markers for mitochondrial activity and browning in WAT from D4KO animals. Importantly, in vivo and ex vivo analyses of glucose uptake revealed increased glucose clearance in interscapular brown adipose tissue and WAT from trained D4KO mice. Thus, chronic exercise is able to overcome the genetically induced insulin resistance caused by Tbc1d4 depletion. Gene variants in TBC1D4 may be relevant in future precision medicine as determinants of exercise response.

ARTICLE HIGHLIGHTS

Beneficial Effects of High-Intensity Interval Training and Dietary Changes Intervention on Hepatic Fat Accumulation in HFD-Induced Obese Rats

Lifestyle intervention encompassing nutrition and physical activity are effective strategies to prevent progressive lipid deposition in the liver. This study aimed to explore the effect of dietary change, and/or high-intensity interval training (HIIT) on hepatic lipid accumulation in high fat diet (HFD)-induced obese rats. We divided lean rats into lean control (LC) or HIIT groups (LH), and obese rats into obese normal chow diet (ND) control (ONC) or HIIT groups (ONH) and obese HFD control (OHC) or HIIT groups (OHH). We found that dietary or HIIT intervention significantly decreased body weight and the risk of dyslipidemia, prevented hepatic lipid accumulation. HIIT significantly improved mitochondrial fatty acid oxidation through upregulating mitochondrial enzyme activities, mitochondrial function and AMPK/PPARalpha/CPT1alpha pathway, as well as inhibiting hepatic de novo lipogenesis in obese HFD rats. These findings indicate that dietary alone or HIIT intervention powerfully improve intrahepatic storage of fat in diet induced obese rats. Keywords: Obesity, Exercise, Diet, Mitochondrial function, Lipid deposition.

Mitochondria-associated membranes contribution to exercise-mediated alleviation of hepatic insulin resistance: Contrasting high-intensity interval training with moderate-intensity continuous training in a high-fat diet mouse model

OBJECTIVE

Mitochondria-associated membranes (MAMs) serve pivotal functions in hepatic insulin resistance (IR). Our aim was to explore the potential role of MAMs in mitigating hepatic IR through exercise and to compare the effects of different intensities of exercise on hepatic MAMs formation in high-fat diet (HFD) mice.

METHODS

Male C57BL/6J mice were fed an HFD and randomly assigned to undergo supervised high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT). IR was evaluated using the serum triglyceride/high-density lipoprotein cholesterol ratio (TG/HDL-C), glucose tolerance test (GTT), and insulin tolerance test (ITT). Hepatic steatosis was observed using hematoxylin-eosin (H&E) and oil red O staining. The phosphatidylinositol 3-kinase/protein kinase B/glycogen synthase kinase 3 beta (PI3K-AKT-GSK3β) signaling pathway was assessed to determine hepatic IR. MAMs were evaluated through immunofluorescence (colocalization of voltage-dependent anion-selective channel 1 [VDAC1] and inositol 1,4,5-triphosphate receptor [IP3R]).

RESULTS

After 8 weeks on an HFD, there was notable inhibition of the hepatic PI3K/Akt/GSK3β signaling pathway, accompanied by a marked reduction in hepatic IP3R-VDAC1 colocalization levels. Both 8-week HIIT and MICT significantly enhanced the hepatic PI3K/Akt/GSK3β signaling and colocalization levels of IP3R-VDAC1 in HFD mice, with MICT exhibiting a stronger effect on hepatic MAMs formation. Furthermore, the colocalization of hepatic IP3R-VDAC1 positively correlated with the expression levels of phosphorylation of protein kinase B (p-AKT) and phosphorylation of glycogen synthase kinase 3 beta (p-GSK3β), while displaying a negative correlation with serum triglyceride/high-density lipoprotein cholesterol levels.

CONCLUSION

The reduction in hepatic MAMs formation induced by HFD correlates with the development of hepatic IR. Both HIIT and MICT effectively bolster hepatic MAMs formation in HFD mice, with MICT demonstrating superior efficacy. Thus, MAMs might wield a pivotal role in exercise-induced alleviation of hepatic IR.

Mitofusin-2 induced by exercise modifies lipid droplet-mitochondria communication, promoting fatty acid oxidation in male mice with NAFLD

BACKGROUND AND AIM

The excessive accumulation of lipid droplets (LDs) is a defining characteristic of nonalcoholic fatty liver disease (NAFLD). The interaction between LDs and mitochondria is functionally important for lipid metabolism homeostasis. Exercise improves NAFLD, but it is not known if it has an effect on hepatic LD-mitochondria interactions. Here, we investigated the influence of exercise on LD-mitochondria interactions and its significance in the context of NAFLD.

APPROACH AND RESULTS

Mice were fed high-fat diet (HFD) or HFD-0.1 % methionine and choline-deficient diet (MCD) to emulate simple hepatic steatosis or non-alcoholic steatohepatitis, respectively. In both models, aerobic exercise decreased the size of LDs bound to mitochondria and the number of LD-mitochondria contacts. Analysis showed that the effects of exercise on HOMA-IR and liver triglyceride levels were independent of changes in body weight, and a positive correlation was observed between the number of LD-mitochondria contacts and NAFLD severity and with the lipid droplet size bound to mitochondria. Cellular fractionation studies revealed that ATP-coupled respiration and fatty acid oxidation (FAO) were greater in hepatic peridroplet mitochondria (PDM) from HFD-fed exercised mice than from equivalent sedentary mice. Finally, exercise increased FAO and mitofusin-2 abundance exclusively in PDM through a mechanism involving the curvature of mitochondrial membranes and the abundance of saturated lipids. Accordingly, hepatic mitofusin-2 ablation prevented exercise-induced FAO in PDM.

CONCLUSIONS

This study demonstrates that aerobic exercise has beneficial effects in murine NAFLD models by lessening the interactions between hepatic LDs and mitochondria, and by decreasing LD size, correlating with a reduced severity of NAFLD. Additionally, aerobic exercise increases FAO in PDM and this process is reliant on Mfn-2 enrichment, which modifies LD-mitochondria communication.

Exercise training adaptations in liver glycogen and glycerolipids require hepatic AMP-activated protein kinase in mice

Regular exercise elicits adaptations in glucose and lipid metabolism that allow the body to meet energy demands of subsequent exercise bouts more effectively and mitigate metabolic diseases including fatty liver. Energy discharged during the acute exercise bouts that comprise exercise training may be a catalyst for liver adaptations. During acute exercise, liver glycogenolysis and gluconeogenesis are accelerated to supply glucose to working muscle. Lower liver energy state imposed by gluconeogenesis and related pathways activates AMP-activated protein kinase (AMPK), which conserves ATP partly by promoting lipid oxidation. This study tested the hypothesis that AMPK is necessary for liver glucose and lipid adaptations to training. Liver-specific AMPKα1α2 knockout (AMPKα1α2fl/fl+AlbCre) mice and littermate controls (AMPKα1α2fl/fl) completed sedentary and exercise training protocols. Liver nutrient fluxes were quantified at rest or during acute exercise following training. Liver metabolites and molecular regulators of metabolism were assessed. Training increased liver glycogen in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. The inability to increase glycogen led to lower glycogenolysis, glucose production, and circulating glucose during acute exercise in trained AMPKα1α2fl/fl+AlbCre mice. Deletion of AMPKα1α2 attenuated training-induced declines in liver diacylglycerides. In particular, training lowered the concentration of unsaturated and elongated fatty acids comprising diacylglycerides in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. Training increased liver triacylglycerides and the desaturation and elongation of fatty acids in triacylglycerides of AMPKα1α2fl/fl+AlbCre mice. These lipid responses were independent of differences in tricarboxylic acid cycle fluxes. In conclusion, AMPK is required for liver training adaptations that are critical to glucose and lipid metabolism.NEW & NOTEWORTHY This study shows that the energy sensor and transducer, AMP-activated protein kinase (AMPK), is necessary for an exercise training-induced: 1) increase in liver glycogen that is necessary for accelerated glycogenolysis during exercise, 2) decrease in liver glycerolipids independent of tricarboxylic acid (TCA) cycle flux, and 3) decline in the desaturation and elongation of fatty acids comprising liver diacylglycerides. The mechanisms defined in these studies have implications for use of regular exercise or AMPK-activators in patients with fatty liver.

Physical Exercise Methods and Their Effects on Glycemic Control and Body Composition in Adults with Type 2 Diabetes Mellitus (T2DM): A Systematic Review

The prevalence of T2DM represents a challenge for health agencies due to its high risk of morbidity and mortality. Physical Activity (PA) is one of the fundamental pillars for the treatment of T2DM, so Physical Exercise (PE) programs have been applied to research their effectiveness. The objective of the study was to analyze the effects of PE methods on glycemic control and body composition of adults with T2DM. A systematic review without meta-analysis was performed, using the PubMed database. Quasi-experimental and pure experimental clinical trials were included, which were available free of charge and were published during 2010-2020. In the results, 589 articles were found and 25 passed the inclusion criteria. These were classified and analyzed according to the methods identified (AE, IE, RE, COM, and others), duration and variable(s) studied. It is concluded that PE is effective for glycemic control and body composition in adults with T2DM using different methods (AE, IE, RE, COM, and others), both in the short and long term. Adequate organization of PE components such as frequency, duration, volume, and intensity, is essential.

High-intensity interval training induces lactylation of fatty acid synthase to inhibit lipid synthesis

BACKGROUND

The aim of study was to observe the effect of increased lactate levels during high-intensity interval training (HIIT) on protein lactylation, identify the target protein, and investigate the regulatory effect of lactylation on the function of the protein.

METHODS

C57B/L6 mice were divided into 3 groups: the control group, HIIT group, and dichloroacetate injection + HIIT group (DCA + HIIT). The HIIT and DCA + HIIT groups underwent 8 weeks of HIIT treatment, and the DCA + HIIT group was injected DCA before HIIT treatment. The expression of lipid metabolism-related genes was determined. Protein lactylation in subcutaneous adipose tissue was identified and analyzed using 4D label-free lactylation quantitative proteomics and bioinformatics analyses. The fatty acid synthase (FASN) lactylation and activity was determined.

RESULTS

HIIT had a significant effect on fat loss; this effect was weakened when lactate production was inhibited. HIIT significantly upregulated the protein lactylation while lactate inhibition downregulated in iWAT. FASN had the most modification sites. Lactate treatment increased FASN lactylation levels, inhibited FASN activity, and reduced palmitate and triglyceride synthesis in 3T3-L1 cells.

CONCLUSIONS

This investigation revealed that lactate produced by HIIT increased protein pan-lactylation levels in iWAT. FASN lactylation inhibited de novo lipogenesis, which may be an important mechanism in HIIT-induced fat loss.

High-Intensity Interval Training Ameliorates High-Fat Diet-Induced Metabolic Disorders via the Cyclic GMP-AMP Synthase-Stimulator of Interferon Gene Signaling Pathway

Metabolic diseases are growing in prevalence worldwide. Although the pathogenesis of metabolic diseases remains ambiguous, the correlation between cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) and metabolic diseases has been identified recently. Exercise is an effective intervention protecting against metabolic diseases, however, the role of the cGAS-STING signaling pathway in this process is unclear, and the effect and mechanism of different exercise intensities on metabolic disorders are still unknown. Thus, we explored the association between exercise to ameliorate HFD-induced metabolic disorders and the cGAS-STING signaling pathway and compared the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). Male C57BL/6 mice (6-8 weeks old) were fed HFD for 8 weeks to establish a metabolic disease model and were subjected to 8-week MICT or HIIT training. Glucose tolerance tests (GTT) and insulin tolerance tests (ITT) were used to assess glucose metabolism. Serum triglyceride (TG) and total cholesterol (TC) were measured to evaluate lipid metabolism. Oil red staining was used to observe the lipid droplets in the gastrocnemius muscle. An enzyme-linked immunosorbent assay was used to detect the serum inflammatory factors IL-6 and IFN-β. The protein expression of the cGAS-STING signaling pathway was detected by the WesTM automatic protein expression analysis system. We reported that HFD induced metabolic disorders with obesity, abnormal glucolipid metabolism, and significant inflammatory responses. Both HIIT and MICT ameliorated the above adverse reactions, but MICT was superior to HIIT in improving glucolipid disorders. Additionally, HIIT significantly increased the expression of STING protein, as well as the phosphorylation of TBKI and the ratio of p-IRF3/IRF3. MICT only increased the expression of STING protein. Our findings suggest that HIIT may alleviate HFD-induced metabolic disorder phenotype through the cGAS-STING signaling pathway. However, the improvement of MICT on metabolic disorder phenotype is less associated with the cGAS-STING pathway, which needs to be further explored.

High-Intensity Interval Training Improves Glycemic Control, Cellular Apoptosis, and Oxidative Stress of Type 2 Diabetic Patients

Background and Objectives: Physical exercise is an important therapeutic modality for treating and managing diabetes. High-intensity interval training (HIIT) is considered one of the best non-drug strategies for preventing and treating type 2 diabetes mellitus (T2DM) by improving mitochondrial biogenesis and function. This study aimed to determine the effects of 12 weeks of HIIT training on the expression of tumor suppressor protein-p53, mitochondrial cytochrome c oxidase (COX), and oxidative stress in patients with T2DM. Methods: A total of thirty male sedentary patients aged (45-60 years) were diagnosed with established T2DM for more than five years. Twenty healthy volunteers, age- and sex-matched, were included in this study. Both patients and control subjects participated in the HIIT program for 12 weeks. Glycemic control variables including p53 (U/mL), COX (ng/mL), total antioxidant capacity (TAC, nmole/µL), 8-hydroxy-2'-deoxyguanosine (8-OHdG, ng/mL), as well as genomic and mitochondrial DNA content were measured in both the serum and muscle tissues of control and patient groups following exercise training. Results: There were significant improvements in fasting glucose levels. HbA1c (%), HOMA-IR (mUmmol/L2), fasting insulin (µU/mL), and C-peptide (ng/mL) were reported in T2DM and healthy controls. A significant decrease was also observed in p53 protein levels. COX, 8-OhdG, and an increase in the level of TAC were reported in T2DM following 12 weeks of HIIT exercise. Before and after exercise, p53; COX, mt-DNA content, TAC, and 8-OhdG showed an association with diabetic control parameters such as fasting glucose (FG), glycated hemoglobin (HbA1C, %), C-peptide, fasting insulin (FI), and homeostatic model assessment for insulin resistance (HOMA-IR) in patients with T2DM. These findings support the positive impact of HIIT exercise in improving regulation of mitochondrial biogenesis and subsequent control of diabetes through anti-apoptotic and anti-oxidative pathways. Conclusions: A 12-week HIIT program significantly improves diabetes by reducing insulin resistance; regulating mitochondrial biogenesis; and decreasing oxidative stress capacity among patients and healthy controls. Also; p53 protein expression; COX; 8-OhdG; and TAC and mt-DNA content were shown to be associated with T2DM before and after exercise training.

Effects of an aerobic training program on liver functions in male athletes: a randomized controlled trial

The optimal functioning of the liver is essential for athletic performance. It is necessary to maintain the liver's enzymes at an optimal level so that liver cells can be protected from inflammation or damage. This study investigated the effects of a 12-week aerobic exercise program on the liver function of adult athletes. A pretest-posttest experimental design was used. A total of thirty healthy male athletes (football players) aged 21 to 24 years were recruited for this study and randomly and equally divided into the experimental group (EG) and control group (CG). The CG did not participate in any special activities. The EG performed an aerobic training program consisting of several exercises for 12 weeks. Evaluation of all participants in both groups was carried out before and after the intervention by measuring the blood levels of Alkaline phosphate, AST/SGOT, ALT/SGPT, Bilirubin Total/indirect/direct, Albumin, Globulin, and Total protein using the standard methods by collecting blood samples. There was a significant decrease (p < 0.05) in Bilirubin and globulin levels in the EG after 12 weeks of aerobic training sessions. However, there was no significant difference in alkaline phosphate, AST/SGOT, ALT/SGPT Total protein, and Albumin (p > 0.05) between both groups post-treatment. The 12 weeks of aerobic training used in the study can potentially improve the liver function of adult athletes.

Effects of Exercise Intensity on Cardiometabolic Parameters of Ovariectomized Obese Mice

The aim of this study was to compare the effects of continuous-moderate vs. high-intensity interval aerobic training on cardiovascular and metabolic parameters in ovariectomized high-fat-fed mice. C57BL/6 female ovariectomized were divided into four groups (n=8): low-fat-fed sedentary (SLF); high-fat-fed sedentary (SHF); high-fat-fed moderate-intensity continuous trained (MICT-HF); and high-fat-fed high-intensity interval aerobic trained (HIIT-HF). The high-fat diet lasted 10 weeks. Ovariectomy was performed in the fourth week. The exercise training was carried out in the last four weeks of protocol. Fasting glycemia, oral glucose tolerance, arterial pressure, baroreflex sensitivity, and cardiovascular autonomic modulation were evaluated. Moderate-intensity continuous training prevented the increase in arterial pressure and promoted a reduction in HR at rest, associated with an improvement in the sympathovagal balance in MICT-HF vs. SHF. The high-intensity interval training reduced blood glucose and glucose intolerance in HIIT-HF vs. SHF and MICT-HF. In addition, it improved sympathovagal balance in HIIT-HF vs. SHF. Moderate-intensity continuous training was more effective in promoting cardiovascular benefits, while high-intensity interval training was more effective in promoting metabolic benefits.

Treatment with EV-miRNAs Alleviates Obesity-Associated Metabolic Dysfunction in Mice

Most cells release extracellular vesicles (EVs) that can be detected circulating in blood. We and others have shown that the microRNA contents of these vesicles induce transcriptomic changes in acceptor cells, contributing to the adjustment of metabolic homeostasis in response to environmental demands. Here, we explore the potential for modulating obesity- and exercise-derived EV-microRNAs to treat the metabolic dysfunction associated with obesity in mice. Treatment with EV-miRNAs alleviated glucose intolerance and insulin resistance in obese mice to an extent similar to that of high-intensity interval training, although only exercise improved cardiorespiratory fitness and decreased body weight. Mechanistically, EV-miRNAs decreased fatty acid and cholesterol biosynthesis pathways in the liver, reducing hepatic steatosis and increasing insulin sensitivity, resulting in decreased glycemia and triglyceridemia. Our data suggest that manipulation of EV-miRNAs may be a viable strategy to alleviate metabolic dysfunction in obese and diabetic patients who are unable to exercise, although actual physical activity is needed to improve cardiorespiratory fitness.

FOXO1 is downregulated in obese mice subjected to short-term strength training

Obesity is a worldwide health problem and is directly associated with insulin resistance and type 2 diabetes. The liver is an important organ for the control of healthy glycemic levels, since insulin resistance in this organ reduces phosphorylation of forkhead box protein 1 (FOXO1) protein, leading to higher hepatic glucose production (HGP) and fasting hyperglycemia. Aerobic physical training is known as an important strategy in increasing the insulin action in the liver by increasing FOXO1 phosphorylation and reducing gluconeogenesis. However, little is known about the effects of strength training in this context. This study aimed to investigate the effects of short-term strength training on hepatic insulin sensitivity and glycogen synthase kinase-3β (GSK3β) and FOXO1 phosphorylation in obese (OB) mice. To achieve this goal, OB Swiss mice performed the strength training protocol (one daily session for 15 days). Short-term strength training increased the phosphorylation of protein kinase B and GSK3β in the liver after insulin stimulus and improved the control of HGP during the pyruvate tolerance test. On the other hand, sedentary OB animals reduced FOXO1 phosphorylation and increased the levels of nuclear FOXO1 in the liver, increasing the phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) content. The bioinformatics analysis also showed positive correlations between hepatic FOXO1 levels and gluconeogenic genes, reinforcing our findings. However, strength-trained animals reverted to this scenario, regardless of body adiposity changes. In conclusion, short-term strength training is an efficient strategy to enhance the insulin action in the liver of OB mice, contributing to glycemic control by reducing the activity of hepatic FOXO1 and lowering PEPCK and G6Pase contents.

The effectiveness of high-intensity interval training on body composition of rodent models of obesity: A systematic review and meta-analysis

The present systematic review was compiled to analyze the effectiveness of High-intensity interval training (HIIT) protocols on the body composition of rodents with obesity. Databases were searched until February 2021 for experimental trials in rodents with a minimum duration of four weeks of HIIT and endpoints associated with obesity. The data were analyzed by meta-analysis performed for comparisons of body composition. Sensitivity analysis was performed to investigate the consistency of individual researches. Of all of the 524 studies found, only 14 were included. The analysis showed a significant reduction in body weight ([CI 95%: -8.35; -1.98] P ≤ 0.01), adiposity index ([IC 95%: -1.04; -0.80] P ≤ 0.01), and fat pads ([IC 95%: -0.59; -0.06] P ≤ 0.01). HIIT performed on treadmill or water was effective to reduce body weight (P < 0.05). In conclusion, HIIT attenuated both body weight and adiposity induced either by HFD (high-fat diet) or by GOM (genetic obese model), thereby inducing positive changes in body composition.

Isolated and combined impact of dietary olive oil and exercise on markers of health and energy metabolism in female mice

An olive oil (OO) rich diet or high-intensity interval training (HIIT) independently improve markers of health and energy metabolism, but it is unknown if combining OO and HIIT synergize to improve these markers. This study characterized the isolated and combined impact of OO and HIIT on markers of health and energy metabolism in various tissues in C57BL/6J female mice. Nine-week-old mice were divided into four groups for a 12-week diet and/or exercise intervention including: (1) Control Diet without HIIT (CD), (2) Control Diet with HIIT (CD+HIIT), (3) OO diet (10% kcal from olive oil) without HIIT, and (4) OO diet with HIIT (OO+HIIT). Neither dietary OO or HIIT altered body weight, glucose tolerance, or serum lipids. HIIT, regardless of diet, increased aerobic capacity and HDL cholesterol levels. In liver and heart tissue, OO resulted in similar adaptations as HIIT including increased mitochondrial content and fatty acid oxidation but combining OO with HIIT did not augment these effects. In skeletal muscle, HIIT increased mitochondrial content in type II fibers similarly between diets. An RNA sequencing analysis on type I fibers revealed OO reduced muscle regeneration and lipid metabolism gene abundance, whereas HIIT increased the abundance of these genes, independent of diet. HIIT training, independent of diet, induced subcutaneous white adipose tissue (sWAT) hypertrophy, whereas OO induced gonadal white adipose tissue (gWAT) hypertrophy, an effect that was augmented with HIIT. These data highlight the pleiotropic effects of OO and HIIT, although their combination does not synergize to further improve most markers of health and energy metabolism.

Balanced Free Essential Amino Acids and Resistance Exercise Training Synergistically Improve Dexamethasone-Induced Impairments in Muscle Strength, Endurance, and Insulin Sensitivity in Mice

Our previous study shows that an essential amino acid (EAA)-enriched diet attenuates dexamethasone (DEX)-induced declines in muscle mass and strength, as well as insulin sensitivity, but does not affect endurance. In the present study, we hypothesized that the beneficial effects will be synergized by adding resistance exercise training (RET) to EAA, and diet-free EAA would improve endurance. To test hypotheses, mice were randomized into the following four groups: control, EAA, RET, and EAA+RET. All mice except the control were subjected to DEX treatment. We evaluated the cumulative rate of myofibrillar protein synthesis (MPS) using ²H₂O labeling and mass spectrometry. Neuromuscular junction (NMJ) stability, mitochondrial contents, and molecular signaling were demonstrated in skeletal muscle. Insulin sensitivity and glucose metabolism using ¹³C₆-glucose tracing during oral glucose tolerance tests were analyzed. We found that EAA and RET synergistically improve muscle mass and/or strength, and endurance capacity, as well as insulin sensitivity, and glucose metabolism in DEX-treated muscle. These improvements are accomplished, in part, through improvements in myofibrillar protein synthesis, NMJ, fiber type preservation, and/or mitochondrial biogenesis. In conclusion, free EAA supplementation, particularly when combined with RET, can serve as an effective means that counteracts the adverse effects on muscle of DEX that are found frequently in clinical settings.

Paternal obesity induces placental hypoxia and sex-specific impairments in placental vascularization and offspring metabolism

Paternal obesity predisposes offspring to metabolic dysfunction, but the underlying mechanisms remain unclear. We investigated whether this metabolic dysfunction is associated with changes in placental vascular development and is fueled by endoplasmic reticulum (ER) stress-mediated changes in fetal hepatic development. We also determined whether paternal obesity indirectly affects the in utero environment by disrupting maternal metabolic adaptations to pregnancy. Male mice fed a standard chow or high fat diet (60%kcal fat) for 8–10 weeks were time-mated with female mice to generate pregnancies and offspring. Glucose tolerance was evaluated in dams at mid-gestation (embryonic day (E) 14.5) and late gestation (E18.5). Hypoxia, angiogenesis, endocrine function, macronutrient transport, and ER stress markers were evaluated in E14.5 and E18.5 placentae and/or fetal livers. Maternal glucose tolerance was assessed at E14.5 and E18.5. Metabolic parameters were assessed in offspring at ~60 days of age. Paternal obesity did not alter maternal glucose tolerance but induced placental hypoxia and altered placental angiogenic markers, with the most pronounced effects in female placentae. Paternal obesity increased ER stress-related protein levels (ATF6 and PERK) in the fetal liver and altered hepatic expression of gluconeogenic factors at E18.5. Offspring of obese fathers were glucose intolerant and had impaired whole-body energy metabolism, with more pronounced effects in female offspring. Metabolic deficits in offspring due to paternal obesity may be mediated by sex-specific changes in placental vessel structure and integrity that contribute to placental hypoxia and may lead to poor fetal oxygenation and impairments in fetal metabolic signaling pathways in the liver.

The impact of high-intensity interval training on postprandial glucose and insulin: A systematic review and meta-analysis

AIMS

We performed a systematic review and meta-analysis to investigate the effects of high-intensity interval training (HIIT) on postprandial glucose (PPG) and insulin (PPI) versus non-exercise control and moderate-intensity continuous training (MICT) in participants with both normal and impaired glucose.

METHODS

The PubMed, Scopus, and Web of Science electronic databases were searched up to October 2021 for randomized trials evaluating HIIT versus control and/or versus MICT on glucose and insulin AUC using oral glucose tolerance testing. Subgroup analyses based on intervention duration (short-duration < 8 weeks, moderate-duration ≥ 8 weeks), baseline glucose levels (normal glucose and impaired glucose) and type of HIIT (L-HIIT and SIT) were also conducted across included studies.

RESULTS

A total of 25 studies involving 870 participants were included in the current meta-analysis. HIIT effectively reduced glucose [-0.37 (95% CI -0.60 to -0.13), p = 0.002] and insulin [-0.36 (95% CI -0.68 to -0.04), p = 0.02] AUC when compared with a CON group. Reductions in glucose AUC were significant for those with impaired glucose at baseline (p = 0.03), but not for those with normal glucose levels (p = 0.11) and following moderate-duration (p = 0.01), but not short-duration interventions (p = 0.18). However, there were no differences in glucose (p = 0.76) or insulin (p = 0.43) AUC between HIIT and MICT intervention arms.

CONCLUSIONS

Our results demonstrated that both HIIT and MICT are effective for reducing postprandial glycemia and insulinemia, particularly by moderate-duration interventions, and in those with impaired glucose.

Exercise regulation of hepatic lipid droplet metabolism

Lipid droplets (LD) are not just lipid stores. They are now recognized as highly dynamic organelles, having a life cycle that includes biogenesis, growth, steady-state, transport, and catabolism. Importantly, LD exhibit different features in terms of size, number, lipid composition, proteins, and interaction with other organelles, and all these features exert an impact on cellular homeostasis. The imbalance of LD function causes non-alcoholic fatty liver disease (NAFLD). Studies show that exercise attenuates NAFLD by decreasing LD content; however, reports show metabolic benefits without changes in LD amount (intrahepatic triglyceride levels) in NAFLD. Due to the multiple effects of exercise in LD features, we think that these metabolic benefits occur through changes in LD features in NAFLD, rather than only the reduction in content. Exercise increases energy mobilization and utilization from storages such as LD, and is one of the non-pharmacological treatments against NAFLD. Therefore, exercise modification of LD could be a target for NAFLD treatment. Here, we review the most up-to-date literature on this topic, and focus on recent findings showing that LD features could play an important role in the severity of NAFLD.

Molecular Mechanisms of Exercise and Healthspan

Healthspan is the period of our life without major debilitating diseases. In the modern world where unhealthy lifestyle choices and chronic diseases taper the healthspan, which lead to an enormous economic burden, finding ways to promote healthspan becomes a pressing goal of the scientific community. Exercise, one of humanity's most ancient and effective lifestyle interventions, appears to be at the center of the solution since it can both treat and prevent the occurrence of many chronic diseases. Here, we will review the current evidence and opinions about regular exercise promoting healthspan through enhancing the functionality of our organ systems and preventing diseases.

AMPK and the Adaptation to Exercise

Noncommunicable diseases are chronic diseases that contribute to death worldwide, but these diseases can be prevented and mitigated with regular exercise. Exercise activates signaling molecules and the transcriptional network to promote physiological adaptations, such as fiber type transformation, angiogenesis, and mitochondrial biogenesis. AMP-activated protein kinase (AMPK) is a master regulator that senses the energy state, promotes metabolism for glucose and fatty acid utilization, and mediates beneficial cellular adaptations in many vital tissues and organs. This review focuses on the current, integrative understanding of the role of exercise-induced activation of AMPK in the regulation of system metabolism and promotion of health benefits.

Physical activity ameliorates the function of organs via adipose tissue in metabolic diseases

Adipose tissue is a dynamic organ in the endocrine system that can connect organs by secreting molecules and bioactive. Hence, adipose tissue really plays a pivotal role in regulating metabolism, inflammation, energy homeostasis, and thermogenesis. Disruption of hub bioactive molecules secretion such as adipokines leads to dysregulate metabolic communication between adipose tissue and other organs in non-communicable disorders. Moreover, a sedentary lifestyle may be a risk factor for adipose tissue function. Physical inactivity leads to fat tissue accumulation and promotes obesity, Type 2 diabetes, cardiovascular disease, neurodegenerative disease, fatty liver, osteoporosis, and inflammatory bowel disease. On the other hand, physical activity may ameliorate and protect the body against metabolic disorders, triggering thermogenesis, metabolism, mitochondrial biogenesis, β-oxidation, and glucose uptake. Furthermore, physical activity provides an inter-organ association and cross-talk between different tissues by improving adipose tissue function, reprogramming gene expression, modulating molecules and bioactive factors. Also, physical activity decreases chronic inflammation, oxidative stress and improves metabolic features in adipose tissue. The current review focuses on the beneficial effect of physical activity on the cardiovascular, locomotor, digestive, and nervous systems. In addition, we visualize protein-protein interactions networks between hub proteins involved in dysregulating metabolic induced by adipose tissue.

High-Intensity Interval Training Improves Physical Function, Prevents Muscle Loss, and Modulates Macrophage-Mediated Inflammation in Skeletal Muscle of Cerebral Ischemic Mice

Although skeletal muscle is the main effector organ largely accounting for disability after stroke, considerably less attention is paid to the secondary abnormalities of stroke-related skeletal muscle loss. It is necessary to explore the mechanism of muscle atrophy after stroke and further develop effective rehabilitation strategy. Here, we evaluated the effects of high-intensity interval (HIIT) versus moderate-intensity aerobic training (MOD) on physical function, muscle mass, and stroke-related gene expression profile of skeletal muscle. After the model of middle cerebral artery occlusion (MCAO) was successfully made, the blood lactate threshold corresponding speed (S_LT) and maximum speed (S_max) were measured. Different intensity training protocols (MOD < S_LT; S_LT < HIIT < S_max) were carried out for 3 weeks beginning at 7 days after MCAO in the MOD and HIIT groups, respectively. We found that both HIIT and MOD prevented stroke-related gastrocnemius muscle mass loss in MCAO mice. HIIT was more beneficial than MOD for improvements in muscle strength, motor coordination, walking competency, and cardiorespiratory fitness. Furthermore, HIIT was superior to MOD in terms of reducing lipid accumulation, levels of IL-1β and IL-6 in paretic gastrocnemius, and improving peripheral blood CD4+/CD8+ T cell ratio, level of IL-10. Additionally, RNA-seq analysis revealed that the differentially expressed genes among HIIT, MOD, and MCAO groups were highly associated with signaling pathways involved in inflammatory response, more specifically the I-kappaB kinase/NF-kappaB signaling. Following the outcome, we further investigated the infiltrating immune cells abundant in paretic muscles. The results showed that HIIT modulated macrophage activation by downregulating CD86+ (M1 type) macrophages and upregulating CD163+ (M2 type) macrophages via inhibiting the TLR4/MyD88/NFκB signaling pathway and exerting an anti-inflammatory effect in paretic skeletal muscle. It is expected that these data will provide novel insights into the mechanisms and potential targets underlying muscle wasting in stroke.

Short-term combined training reduces hepatic steatosis and improves hepatic insulin signaling

Hepatic steatosis is directly associated with hepatic inflammation and insulin resistance, which is correlated with hyperglycemia and type 2 diabetes mellitus (T2DM). Aerobic and strength training have been pointed out as efficient strategies against hepatic steatosis. However, little is known about the effects of the combination of those two protocols on hepatic steatosis. Therefore, this study aimed to evaluate the impact of short-term combined training (STCT) on glucose homeostasis and in the synthesis and oxidation of fat in the liver of obesity-induced mice with hepatic steatosis. Swiss mice were distributed into three groups: control lean (CTL), sedentary obese (OB), and combined training obese (CTO). The CTO group performed the STCT protocol, which consisted of strength and aerobic exercises in the same session. The protocol lasted seven days. The CTO group reduced the glucose levels and fatty liver when compared to the OB group. Interestingly, these results were observed even without reductions in body adiposity. CTO group also showed increased hepatic insulin sensitivity, with lower hepatic glucose production (HGP). STCT reduced the expression of the lipogenic genes Fasn and Scd1 and hepatic inflammation, as well as increased the ACC phosphorylation and the oxidative genes Cpt1a and Ppara, reverting the complications caused by obesity. Since this protocol increased lipid oxidation and reduced hepatic lipogenesis, regardless of body fat mass decrease, it can be considered an effective non-pharmacological strategy for the treatment of hepatic steatosis.

Physical Activity, Dietary Patterns, and Glycemic Management in Active Individuals with Type 1 Diabetes: An Online Survey

Individuals with type 1 diabetes (T1D) are able to balance their blood glucose levels while engaging in a wide variety of physical activities and sports. However, insulin use forces them to contend with many daily training and performance challenges involved with fine-tuning medication dosing, physical activity levels, and dietary patterns to optimize their participation and performance. The aim of this study was to ascertain which variables related to the diabetes management of physically active individuals with T1D have the greatest impact on overall blood glucose levels (reported as A1C) in a real-world setting. A total of 220 individuals with T1D completed an online survey to self-report information about their glycemic management, physical activity patterns, carbohydrate and dietary intake, use of diabetes technologies, and other variables that impact diabetes management and health. In analyzing many variables affecting glycemic management, the primary significant finding was that A1C values in lower, recommended ranges (<7%) were significantly predicted by a very-low carbohydrate intake dietary pattern, whereas the use of continuous glucose monitoring (CGM) devices had the greatest predictive ability when A1C was above recommended (≥7%). Various aspects of physical activity participation (including type, weekly time, frequency, and intensity) were not significantly associated with A1C for participants in this survey. In conclusion, when individuals with T1D are already physically active, dietary changes and more frequent monitoring of glucose may be most capable of further enhancing glycemic management.

Evaluation of the effect of high-intensity interval training on macular microcirculation via swept-source optical coherence tomography angiography in young football players

Purpose:

This study was conducted to evaluate the effect of high intensity interval training (HIIT) on macular microcirculation, measured by swept source optical coherence tomography angiography (ss OCTA) in young football players.

Methods:

Football players between 18–20 years old were included. After a detailed ophthalmological examination, physiological parameters, including height, body weight, body fat, systemic blood pressure, hematocrit values, oxygen saturation, and heart rate, were recorded. Intraocular pressure and ss OCTA parameters were measured one day before and the day after the high intensity interval training program using DRI OCT Triton (Topcon, Tokyo, Japan) between 11:00 am and 1:00 pm.

Results:

Fifteen participants completed the study. All were males with a mean age of 18.1 ± 0.4 years. Systolic and diastolic blood pressure and oxygen saturation did not change significantly (P > 0.05), while hematocrit levels increased remarkably (P = 0.049) after the HIIT program. Heart rates and intraocular pressure decreased (P = 0.003, P = 0.017, respectively). There was a significant increase in the central vessel density in deep capillary plexus (before: 18.7 ± 3.8%, after: 21.1 ± 4.5%) and central vessel density in choriocapillaris (before: 54.5 ± 2.8%, after 56.9 ± 2.2%) (P = 0.02, P = 0.02, respectively), although no changes were observed in other ss OCTA or in the central macular thickness and subfoveal choroidal thickness.

Conclusion:

A 6 week, high intensity interval training program with three exercise sessions per week seems not to alter mean superficial vascular densities, deep foveal avascular zone, and superficial foveal avascular zones, central macular thickness, or subfoveal choroidal thickness, while the central deep vascular density and central choriocapillaris vascular density increased remarkably among ss OCTA parameters.

Exercise induces favorable metabolic changes in white adipose tissue preventing high-fat diet obesity

Diet and/or exercise are cost effective interventions to treat obesity. However, it is unclear if the type of exercise undertaken can prevent the onset of obesity and if it can act through different effects on fat depots. In this study we did not allow obesity to develop so we commenced the high-fat diet (HFD) and exercise programs concurrently and investigated the effect of endurance exercise (END) and high-intensity interval training (HIIT) on changes in cellular adipogenesis, thermogenesis, fibrosis, and inflammatory markers in three different fat depots, on a HFD and a chow diet. This was to assess the effectiveness of exercise to prevent the onset of obesity-induced changes. Mice fed with chow or HFD (45% kcal fat) were trained and performed either END or HIIT for 10 weeks (3 x 40 min sessions/week). In HFD mice, both exercise programs significantly prevented the increase in body weight (END: 17%, HIIT: 20%), total body fat mass (END: 46%, HIIT: 50%), increased lean mass as a proportion of body weight (Lean mass/BW) by 14%, and improved insulin sensitivity by 22%. Further evidence of the preventative effect of exercise was seen significantly decreased markers for adipogenesis, inflammation, and extracellular matrix accumulation in both subcutaneous adipose tissue (SAT) and epididymal adipose tissue (EPI). In chow, no such marked effects were seen with both the exercise programs on all the three fat depots. This study establishes the beneficial effect of both HIIT and END exercise in preventing metabolic deterioration, collagen deposition, and inflammatory responses in fat depots, resulting in an improved whole body insulin resistance in HFD mice.

Effect of high-intensity interval training on cardiometabolic risk factors in childhood obesity: a meta-analysis

INTRODUCTION

This systematic review with meta-analysis aimed to quantify the effectiveness of high-intensity interval training (HIIT) on the cardiometabolic health of obese children and adolescents.

EVIDENCE ACQUISITION

Relevant articles were sourced from PubMed, Embase, the Web of Science, EBSCO, the Cochrane Library and China National Knowledge Infrastructure (CNKI). Randomized controlled trials were included if they employed participants aged 7-19 years. Outcomes included fasting glucose (FG), fasting insulin (FI), homeostasis model assessment-insulin resistance (HOMA-IR), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), triacylglycerol (TG), total cholesterol (TC), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured at baseline and postintervention and compared with those in the control group. Data analysis and synthesis were completed by Revman 5.3 software and Stata 12.0 software (StataCorp LLC., College Station, TX, USA).

EVIDENCE SYNTHESIS

Eight trials involving 379 participants were identified. HIIT significantly decreased the FI, HOMA-IR, TC, TG, LDL-c and SBP in participants with obesity. With regard to changes in blood glucose and lipids, participants who underwent HIIT showed great improvement in FI (mean difference: -3.09 µU/mL, 95% confidence interval [CI] -3.71 to -2.46, P<0.0001), HOMA-IR (mean difference: -0.64, 95% CI -0.82 to -0.46, P<0.0001), TG (mean difference: -0.21 mmol/L, 95% CI -0.31 to -0.10, P<0.0001) and LDL-c (mean difference: -0.35 mmol/L, 95% CI -0.48 to -0.22, P<0.001) than the control group. Similar results were found for SBP (mean difference: -3.61 mmHg, 95% CI -5.85 to -1.37, P=0.002). However, no significant differences in changes in FG, HDL-c and DBP were observed between HIIT and control groups.

CONCLUSIONS

HIIT can produce a positive effect on cardiometabolic risk factors in obese children and adolescents. HIIT may be an alternative and effective training method for managing childhood obesity.

The impact of high intensity interval training on liver fat content in overweight or obese adults: A meta-analysis

Liver fat is a marker of the metabolic derangements associated with obesity for which exercise training is a potential therapy. We therefore performed a systematic meta-analysis to investigate the effect of high intensity interval training (HIIT) on liver fat content in overweight or obese adults with metabolic disorders. PubMed, Scopus, Web of Science and the Cochrane were searched up to October 2020 for HIIT vs. Control (CON) or HIIT vs. moderate intensity interval training (MICT) studies on liver fat content in overweight and obese individuals with metabolic disorders. Standardized mean differences (SMD) and 95% confidence intervals (95% CIs) were calculated. Ten studies involving 333 participants were included in the meta-analysis. Based on studies that directly compared HIIT and CON (6 studies), HIIT was beneficial for promoting a reduction in liver fat [-0.51 (95% CI: -0.85 to -0.17), p = 0.003]. However, there were no significant evidence for an effect of HIIT on liver fat [-0.07 (95% CI: -0.33 to 0.19), p = 0.59], when compared with MICT (7 studies). These results suggest that a HIIT could induce improvements in liver fat of overweight and obese adults with metabolic disorders despite no weight loss.

High-Intensity Interval Training and α-Linolenic Acid Supplementation Improve DHA Conversion and Increase the Abundance of Gut Mucosa-Associated Oscillospira Bacteria

Obesity, a major public health problem, is the consequence of an excess of body fat and biological alterations in the adipose tissue. Our aim was to determine whether high-intensity interval training (HIIT) and/or α-linolenic acid supplementation (to equilibrate the n-6/n-3 polyunsaturated fatty acids (PUFA) ratio) might prevent obesity disorders, particularly by modulating the mucosa-associated microbiota. Wistar rats received a low fat diet (LFD; control) or high fat diet (HFD) for 16 weeks to induce obesity. Then, animals in the HFD group were divided in four groups: HFD (control), HFD + linseed oil (LO), HFD + HIIT, HFD + HIIT + LO. In the HIIT groups, rats ran on a treadmill, 4 days.week^-1. Erythrocyte n-3 PUFA content, body composition, inflammation, and intestinal mucosa-associated microbiota composition were assessed after 12 weeks. LO supplementation enhanced α-linolenic acid (ALA) to docosahexaenoic acid (DHA) conversion in erythrocytes, and HIIT potentiated this conversion. Compared with HFD, HIIT limited weight gain, fat mass accumulation, and adipocyte size, whereas LO reduced systemic inflammation. HIIT had the main effect on gut microbiota β-diversity, but the HIIT + LO association significantly increased Oscillospira relative abundance. In our conditions, HIIT had a major effect on body fat mass, whereas HIIT + LO improved ALA conversion to DHA and increased the abundance of Oscillospira bacteria in the microbiota.

Influences of Recreational Tennis-Playing Exercise Time on Cardiometabolic Health Parameters in Healthy Elderly: The ExAMIN AGE Study

BACKGROUND

Aging and chronic degeneration are the primary threats to cardiometabolic health in elderly populations. Regular appropriate exercise would benefit the advanced aging population.

PURPOSE

This study investigates whether the degree of weekly tennis participation exhibits differences in primary cardiometabolic parameters, including arterial stiffness, inflammation, and metabolic biomarkers in elderly tennis players.

METHODS

One hundred thirty-five long-term participants in elder tennis (>50 years old) were initially screened. Twenty-six eligible and voluntary subjects were divided into high tennis time group (HT) (14 ± 1.3 h/week) and low tennis time group (LT) (4.5 ± 0.7 h/week) by stratification analysis based on the amount of tennis playing activity time. The brachial-ankle pulse wave velocity (baPWV), blood pressure, ankle-brachial index (ABI), blood metabolic biomarkers, and insulin resistance were measured to compare the difference between HT and LT groups.

RESULTS

The baPWV was significantly lower in the HT group than that in the LT group (1283.92 ± 37.01 vs. 1403.69 ± 53.71 cm/s, p < 0.05). We also found that the HT insulin-resistant homeostasis model assessment (HOMA-IR) was significantly lower than that of LT (1.41 ± 0.11 vs. 2.27 ± 0.48 μIU/mL, p < 0.05). However, the blood lipid biomarkers (glucose, cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride) were not statistical different between HT and LT groups (p > 0.05).

CONCLUSION

We demonstrated that under the condition of similar daily physical activity level, elderly with a higher time of tennis-playing (HT group) exhibited relatively lower arterial stiffness (lower PWV) and lower insulin resistance compared to those with lower time tennis-playing (LT).

Continuous and interval training attenuate encephalomyelitis by separate immunomodulatory mechanisms

BACKGROUND

Studies have reported beneficial effects of exercise training on autoimmunity, and specifically on multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). However, it is unknown whether different training paradigms affect disease course via shared or separate mechanisms.

OBJECTIVE

To compare the effects and mechanism of immune modulation of high intensity continuous training (HICT) versus high intensity interval training (HIIT) on systemic autoimmunity in EAE.

METHODS

We used the proteolipid protein (PLP)-induced transfer EAE model to examine training effects on the systemic autoimmune response. Healthy mice performed HICT or HIIT by running on a treadmill. Lymph-node (LN)-T cells from PLP-immunized trained- versus sedentary donor mice were transferred to naïve recipients and EAE clinical and pathological severity were assessed. LN cells derived from donor trained and sedentary PLP-immunized mice were analyzed in vitro for T-cell activation and proliferation, immune cell profiling, and cytokine mRNA levels and cytokine secretion measurements.

RESULTS

Both HICT and HIIT attenuated the encephalitogenicity of PLP-reactive T cells, as indicated by reduced EAE clinical severity and inflammation and tissue pathology in the central nervous system, following their transfer into recipient mice. HICT caused a marked inhibition of PLP-induced T-cell proliferation without affecting the T-cell profile. In contrast, HIIT did not alter T-cell proliferation, but rather inhibited polarization of T cells into T-helper 1 and T-helper 17 autoreactive populations.

INTERPRETATION

HICT and HIIT attenuate systemic autoimmunity and T cell encephalitogenicity by distinct immunomodulatory mechanisms.

Four weeks exercise training enhanced the hepatic insulin sensitivity in high fat- and high carbohydrate-diet fed hyperinsulinemic rats

Aim

Hyperinsulinemia is considered the primary defect underlying the development of type 2 diabetes. The liver is essential for the regular glucose homeostasis. In this study, we examined the effect of physical training on the insulin signaling, oxidative stress enzymes and Glucose-6-phosphatase(G6Pase) activity in the liver of Wistar rats.

Methods

Adult male Wistar rats were divided into Control diet group(C), High carbohydrate diet(HCD), High fat diet(HFD), HCD and HFD with training(HCD Ex & HFD Ex). HFD Ex and HCD Ex were trained on a small animal treadmill running at 20 m/min for 30 min, 5 days/wk. The present work investigated the effect of training on hepatic insulin receptor(InsR) signaling events, oxidative stress marker expressions and G6Pase activity in hyperinsulinemic rats.

Results

High carbohydrate and fat feeding led to hyperinsulinemic status with increased hepatic G6Pase activity and impaired phosphorylation of insulin receptor substrate 1(IRS1) and reduced expression of antioxidant enzymes.Training significantly reduced hepatic G6Pase activity, upregulated phosphoinositide 3 kinase(PI3K) docking site phosphorylation and downregulated the negative IRS1 phosphorylations thereby increasing the glucose transporter(GLUT) expressions (aa(P < 0.001) when compared to HFD, b(P < 0.01),bb (P < 0.001 when compared to HCD). Anti oxidant enzymes like CAT, SOD, eNOS expression were increased with reduction in the expression of inflammatory enzymes like TNF-α and COX-2 (*(P < 0.05),**(P < 0.01),***(P < 0.001) when compared to control, †(P < 0.05),††(P < 0.01),†††(P < 0.001) when compared to HFD and HCD).

Conclusion

Thus, our study shows that four weeks training enhanced the hepatic insulin sensitivity in high fat and high carbohydrate-diet fed hyperinsulinemic rats.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-020-00694-y.

Delivery of muscle-derived exosomal miRNAs induced by HIIT improves insulin sensitivity through down-regulation of hepatic FoxO1 in mice

Implementation of regular physical activity helps in the maintenance of a healthy metabolic profile both in humans and mice through molecular mechanisms not yet completely defined. Here, we show that high-intensity interval training (HIIT) modifies the microRNA (miRNA) profile of circulating exosomes in mice, including significant increases in miR-133a and miR-133b Importantly, treatment of sedentary mice with exosomes isolated from the plasma of trained mice improves glucose tolerance, insulin sensitivity, and decreases plasma levels of triglycerides. Moreover, exosomes isolated from the muscle of trained mice display similar changes in miRNA content, and their administration to sedentary mice reproduces the improvement of glucose tolerance. Exosomal miRNAs up-regulated by HIIT target insulin-regulated transcription factor forkhead box O1 (FoxO1) and, accordingly, expression of FoxO1 is decreased in the liver of trained and exosome-treated mice. Treatment with exosomes transfected with a miR-133b mimic or with a specific siRNA targeting FoxO1 recapitulates the metabolic effects observed in trained mice. Overall, our data suggest that circulating exosomes released by the muscle carry a specific miRNA signature that is modified by exercise and induce expression changes in the liver that impact whole-body metabolic profile.

Exercise Attenuates Ribosomal Protein Six Phosphorylation in Fatty Liver Disease

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of liver disease worldwide. Nonalcoholic steatohepatitis (NASH), is a more severe type of NAFLD. Exercise improves NASH, by reversing steatosis, and may arrest fibrosis. However, the mechanisms underlying these interactions are unknown. AMP-activated protein kinase (AMPK) is a fuel-sensing enzyme that is activated by energy stress. Mammalian target of rapamycin in complex 1 (mTORC1) is a nutrient sensor that regulates protein synthesis. In NASH, AMPK activity is low and mTORC1 is high. In healthy persons, exercise activates AMPK and suppresses mTORC1. We examined the effects of exercise on hepatic ribosomal protein S6 phosphorylation, a downstream target of AMPK and mTORC1 in patients with NASH.

METHODS

Three subjects with biopsy-proven NASH underwent a structured, 20-week aerobic exercise intervention, five-days a week for 30-min at a moderate intensity (40-55% of VO2max). Immunofluorescence staining for rpS6 phosphorylation in hepatic tissue was quantified by ImageJ software.

RESULTS

Following 20-weeks of aerobic exercise, rpS6 levels were significantly attenuated (3.9 ± 1.9 pre-exercise vs. 1.4 +/0.4 post-exercise, p = 0.04).

CONCLUSIONS

These findings suggest exercise modulates the AMPK/mTORC1 pathway in patients with NASH and may guide the design of future studies into the mechanism of how exercise improves NASH and possibly reverses fibrosis.

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.