Muscle irisin response to aerobic vs HIIT in overweight female adolescents

Unlocking liver health: Can tackling myosteatosis spark remission in metabolic dysfunction-associated steatotic liver disease?

Myosteatosis is highly prevalent in metabolic dysfunction-associated steatotic liver disease (MASLD) and could reciprocally impact liver function. Decreasing muscle fat could be indirectly hepatoprotective in MASLD. We conducted a review to identify interventions reducing myosteatosis and their impact on liver function. Non-pharmacological interventions included diet (caloric restriction or lipid enrichment), bariatric surgery and physical activity. Caloric restriction in humans achieving a mean weight loss of 3% only reduces muscle fat. Lipid-enriched diet increases liver fat in human with no impact on muscle fat, except sphingomyelin-enriched diet which reduces both lipid contents exclusively in pre-clinical studies. Bariatric surgery, hybrid training (resistance exercise and electric stimulation) or whole-body vibration in human decrease both liver and muscle fat. Physical activity impacts both phenotypes by reducing local and systemic inflammation, enhancing insulin sensitivity and modulating the expression of key mediators of the muscle-liver-adipose tissue axis. The combination of diet and physical activity acts synergistically in liver, muscle and white adipose tissue, and further decrease muscle and liver fat. Several pharmacological interventions (patchouli alcohol, KBP-089, 2,4-dinitrophenol methyl ether, adipoRon and atglistatin) and food supplementation (vitamin D or resveratrol) improve liver and muscle phenotypes in pre-clinical studies by increasing fatty acid oxidation and anti-inflammatory properties. These interventions are effective in reducing myosteatosis in MASLD while addressing the liver disease itself. This review supports that disturbances in inter-organ crosstalk are key pathophysiological mechanisms involved in MASLD and myosteatosis pathogenesis. Focusing on the skeletal muscle might offer new therapeutic strategies to treat MASLD by modulating the interactions between liver and muscles.

Exploring the Effect of Acute and Regular Physical Exercise on Circulating Brain-Derived Neurotrophic Factor Levels in Individuals with Obesity: A Comprehensive Systematic Review and Meta-Analysis

Obesity is a major global health concern linked to cognitive impairment and neurological disorders. Circulating brain-derived neurotrophic factor (BDNF), a protein crucial for neuronal growth and survival, plays a vital role in brain function and plasticity. Notably, obese individuals tend to exhibit lower BDNF levels, potentially contributing to cognitive decline. Physical exercise offers health benefits, including improved circulating BDNF levels and cognitive function, but the specific impacts of acute versus regular exercise on circulating BDNF levels in obesity are unclear. Understanding this can guide interventions to enhance brain health and counter potential cognitive decline in obese individuals. Therefore, this study aimed to explore the impact of acute and regular physical exercise on circulating BDNF in individuals with obesity. The target population comprised individuals classified as overweight or obese, encompassing both acute and chronic protocols involving all training methods. A comprehensive search was conducted across computerized databases, including PubMed, Academic Search Complete, and Web of Science, in August 2022, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Initially, 98 studies were identified, from which 16 studies, comprising 23 trials, met the selection criteria. Substantial heterogeneity was observed for both acute (I2 = 80.4%) and long-term effects (I2 = 88.7%), but low risk of bias for the included studies. A single session of exercise increased circulating BDNF levels among obese patients compared to the control group (ES = 1.25, 95% CI = 0.19 to 2.30, p = 0.021). However, with extended periods of physical exercise, there was no significant increase in circulating BDNF levels when compared to the control group (ES = 0.49, 95% CI = -0.08 to 1.06, p = 0.089). These findings highlight the need to consider exercise duration and type when studying neurobiological responses in obesity and exercise research. The study's results have implications for exercise prescription in obesity management and highlight the need for tailored interventions to optimize neurotrophic responses. Future research should focus on elucidating the adaptive mechanisms and exploring novel strategies to enhance BDNF modulation through exercise in this population. However, further research is needed considering limitations such as the potential age-related confounding effects due to diverse participant ages, lack of sex-specific analyses, and insufficient exploration of how specific exercise parameters (e.g., duration, intensity, type) impact circulating BDNF.

Exploring exercise-driven exerkines: unraveling the regulation of metabolism and inflammation

Exercise has many beneficial effects that provide health and metabolic benefits. Signaling molecules are released from organs and tissues in response to exercise stimuli and are widely termed exerkines, which exert influence on a multitude of intricate multi-tissue processes, such as muscle, adipose tissue, pancreas, liver, cardiovascular tissue, kidney, and bone. For the metabolic effect, exerkines regulate the metabolic homeostasis of organisms by increasing glucose uptake and improving fat synthesis. For the anti-inflammatory effect, exerkines positively influence various chronic inflammation-related diseases, such as type 2 diabetes and atherosclerosis. This review highlights the prospective contribution of exerkines in regulating metabolism, augmenting the anti-inflammatory effects, and providing additional advantages associated with exercise. Moreover, a comprehensive overview and analysis of recent advancements are provided in this review, in addition to predicting future applications used as a potential biomarker or therapeutic target to benefit patients with chronic diseases.

Differences in the Impact of Various Types of Exercise on Irisin Levels: A Systematic Review and Meta-Analysis

Background

Irisin, a myokine that is responsive to exercise, induces significant changes in subcutaneous adipose tissue. By promoting the browning of white fat tissue, it enhances energy expenditure, thereby addressing overweight and obesity. This systematic review and meta-analysis aimed to compare the effects of different types of physical exercises on irisin levels in overweight and obese adults.

Methods

Specifically, the review focused on studies involving obese or overweight individuals who participated in exercise training for a minimum of 8 weeks, with measured and reported changes in serum irisin levels compared to a control group. Data were collected from four databases (Google Scholar, ISI Web of Science Core Collection, PubMed, and Scopus). The risk of bias was assessed using the Begg and Egger tests, and the results were synthesized.

Results

Initial searches identified 560 titles, out of which only seven met the criteria for inclusion in the systematic review. Statistical analysis demonstrated a significant increase in serum irisin concentration (SMD = 0.957, P = 0.005) among obese and overweight individuals who engaged in exercise, compared to the passive control group. High-intensity interval training (HIIT) (SMD = 1.229, P < 0.001) had a more pronounced effect on increasing serum irisin levels than other exercise protocols. Furthermore, the effectiveness of exercise varied based on the participants' weight status (significant changes for overweight individuals; P < 0.001 and insignificant changes for obese individuals; P = 0.1), age (significant changes for those under 40 years old; P < 0.001 and insignificant changes for those over 40 years old; P = 0.322), and gender (significant changes for men; P < 0.001 and insignificant changes for women; P = 0.285).

Conclusions

Consequently, exercise can elevate serum irisin levels, leading to alterations in adipose tissue phenotype and thermogenesis, ultimately contributing to weight reduction in obese and overweight individuals.

The effects of 12 weeks of high-intensity interval training and moderate-intensity continuous training on FGF21, irisin, and myostatin in men with type 2 diabetes mellitus

This study investigated the influence of a 12-week high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on irisin, fibroblast growth factor 21 (FGF21), and myostatin (MSTN) among men with type 2 diabetes mellitus (T2DM). Forty-five adult men with T2DM were randomly selected and assigned to receive and perform HIIT (4 × 4 min at 85-95% HRmax with three min of active rest at 50-60% HRmax in between) and MICT (walking/running continuously for 47 min at 60-70% HRmax) three sessions per week for 12 weeks, or to act as a non-exercise control (CON) group. The subjects' blood samples were collected at baseline and 48 hours after the last intervention session. Our research revealed that both interventions resulted in similar decreases in FGF21 and MSTN when compared to the CON (p < .01). However, only the HIIT group showed a significant increase in irisin (p < .01) compared to the CON. Further, improvements in insulin resistance, body composition, and VO2 peak were noted in both intervention groups compared with those of the CON group (p < .01). It seems that while either aerobic exercise strategy could be seen as a therapy for men with T2DM, HIIT had a more advantageous effect on the irisin response.

Effect of High-Intensity Resistance Training Versus Endurance Training on Irisin and Adipomyokine Levels in Healthy Individuals: An 8-Week Interventional Study

Background: Irisin and adipomyokine are proteins secreted by the body during exercise and exhibit potential therapeutic effects for chronic disorders. Gaining insights into how high-intensity resistance training and endurance training influence irisin and adipomyokine secretion could shed light on optimizing exercise regimens for potential therapeutic applications. Such knowledge could pave the way for personalized exercise prescriptions and contribute to the development of novel treatments for chronic conditions, enhancing overall health and well-being. Objectives: To investigate the effects of high-intensity resistance training (HIRT) and endurance training on irisin and adipomyokine levels in healthy individuals. Methods: An 8-week interventional comparative study was conducted at Nimra Institute of Medical Sciences, Andhra Pradesh, India. One hundred healthy male individuals aged 21 to 35 were divided into two groups: HIRT and endurance. The HIRT group performed high-intensity resistance training, while the endurance group performed endurance training. Ethical approval was obtained, and baseline and post-intervention values of the participants were recorded and analyzed using SPSS software. Results: After 8 weeks, irisin levels were significantly elevated in the HIRT group (167.39±11.27) compared to the endurance group (155.39±11.28). A positive correlation was observed between skeletal muscle and irisin levels in both the HIRT group (χ2-16.38; p=0.04) and the endurance group (χ2-18.36; p=0.01). Additionally, TNF-α (HIRT: 81.47±4.02 and Endurance: 61.19±4.00) and interleukin-6 (IL-6) (HIRT: 46.84±4.46 and Endurance: 36.15±3.89) levels significantly increased in the HIRT group. However, there was no significant change in leptin levels in either group (HIRT: 3.75±0.58 0.58 and 4.15±0.58). Conclusion: The findings of this study indicate that HIRT is more effective in increasing irisin levels compared to endurance training. However, the notable elevation of IL-6 and TNF-α in the HIRT group raises concerns about potential chronic inflammation. To optimize outcomes, a combined approach, coupling HIRT and endurance training, may be beneficial. Additionally, the results emphasize the significance of skeletal muscle as a primary source of irisin secretion, implying that increased muscle contraction contributes to higher irisin release even in healthy individuals. These insights can guide exercise prescriptions and potentially enhance therapeutic strategies for chronic disorders.

Chronic voluntary wheel running exercise ameliorates metabolic dysfunction via PGC-1α expression independently of FNDC5/irisin pathway in high fat diet-induced obese mice

Exercise is an effective intervention to ameliorate metabolic diseases including obesity and insulin resistance, but the mechanisms involved in the metabolic amelioration have not yet been fully elucidated. This study aimed to determine whether AMPK-SIRT1-PGC-1α-FNDC5/Irisin-UCP1 expression is activated and whether metabolic dysfunction is ameliorated by chronic voluntary wheel running (VWR) in high-fat diet (HFD) induced obese mice. C57BL6J mice were randomly assigned into three groups at the age of 7 weeks for 10 weeks: normal chow diet (CON) group, HFD group, and HFD + VWR group. Chronic VWR ameliorates metabolic parameters and leads to increases in the expression of PGC-1α in the gastrocnemius muscle in HFD-induced obese mice. In contrast, the expression of AMPKα, SIRT1, and FNDC5, or circulating irisin levels did not lead to alteration. Improvement of metabolic health was partly mediated via PGC-1α expression by chronic VWR, but not FNDC5/Irisin pathway in HFD-induced obese mice.

Effects of exercise on irisin in subjects with overweight or obesity. A systematic review of clinical studies

Introduction

Irisin is an adipomyokine involved in white adipose tissue browning, therefore, could be a key protein in metabolic health. However, exercise effects on irisin in subjects with overweight and/or obesity are conflicting. Therefore, this systematic review aims to search and analyse the literature available on this topic. From three databases: PubMed, ScienceDirect, and Medline, clinical studies published between 2010 and 2021 were considered. From 134 found, 14 studies were included. Only six reported plasma increases after exercise (~1.2 to 3-fold from pre-exercise levels). In addition, only 1 reported significant increases in skeletal muscle irisin mRNA levels (~2-fold). Also, irisin was measured from subcutaneous adipose tissue and saliva, where a ~2-fold increase in its protein levels was found in the latter. Exercise seems to increase the circulatory concentrations of irisin in subjects with overweight or obesity. However, this response is highly variable, therefore, a more integrative approach is urgently needed.

Fndc5/irisin is regulated by myogenesis stage, irisin, muscle type and training

OBJECTIVES

Irisin, a novel myokine that responds to exercise, was initially identified as a regulator of fat tissue metabolism. We aimed to investigate fibronectin type III domain-containing protein 5 (Fndc5)/irisin, auto/para-crine role in different muscle fibers, different activities, and muscle cell differentiation.

METHODS

Using in-vitro, ex-vivo, and in-vivo muscle models, Fndc5 was studied at the physiological and molecular levels.

RESULTS

Following training, C57BL/6 mice (n=10) were subject to fast and slow-twitch muscles dissection and molecular analysis. Isolated mice (C57BL/6, n=14) slow and fast-twitch muscles were subject to electrical aerobic and anaerobic pulses stimulation (EPS). L6 muscle cells differentiation was characterized by Fndc5 differentiation-depended expression pattern parallel with significant hypertrophy, Myogenin elevation, and overlapping Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (Pgc-1α) expression pattern. Exogenous irisin significantly altered Fndc5 expression; augmented at early differentiation (3-4-fold, P<0.05) and decreased (2-fold, P<0.05) at late differentiation. Training induced a significant elevation in Fndc5/irisin and Pgc-1α expression levels in all muscle types compared to the sedentary state, where soleus muscle (slow) Fndc5 expression levels were significantly higher compared to levels in all other fast muscles (3-140-fold, P<0.001). Similarly, following EPS, Fndc5 expression levels were significantly augmented in the soleus slow muscle following both aerobic and anaerobic activity (3-3.5-fold, P<0.05) compared to extensor digitorum longus (fast) muscle.

CONCLUSIONS

Muscle cell's Fndc5 expression has a differentiation-depended pattern paralleling Pgc-1α expression and hypertrophy. Irisin autocrinally and significantly regulate Fndc5 and Pgc-1α in a differentiation-depended manner. Muscle Fndc5 expression levels are dependent on fiber type and activity type.

Correlation of muscle mass and bone mineral density in the NHANES US general population, 2017-2018

The appendicular skeletal muscle mass index (ASMI) is commonly used to evaluate human skeletal muscle mass. Muscle, an adjacent tissue of bone, is closely related to bone growth and development. The purpose of this study was to explore the association between the ASMI and lumbar bone mineral density (BMD) to identify potential risk factors for osteoporosis. We analyzed the data collected by the NHANES from 2017 to 2018, and finally included 948 participants aged 40 to 59 years. We evaluated the correlation between the ASMI and lumbar spine BMD using univariate and multiple linear regression models. The ASMI was calculated from height and appendicular skeletal muscle mass obtained by dual energy X-ray absorptiometry. Lumbar spine BMD was obtained by dual energy X-ray absorptiometry and used as an observation in our study. In all the models, ASMI was significantly associated with lumbar spine BMD (model 1: β = 0.013, P < .001; model 2: β = 0.013, P < .001). In the subgroup analysis stratified by sex, this positive correlation was present in both sexes (male: β = 0.023, P < .001, β = 0.022, < 0.001; female: β = 0.030, P < .001, β = 0.031, P < .001). This study showed that the ASMI was positively associated with lumbar BMD, and that this correlation is present in both men and women.

The effects of exercise training induced calories expenditure on type 2 diabetes related cardio metabolic physiological parameters and adipocytokines

Background

Recently, many studies have examined the effects of various training on pro-inflammatory and anti-inflammatory adipocytes. The results of these studies are contradictory. Some have reported positive effects and others have reported negative effects. However, there is no research to study the effect of exercise on similar energy expenditures on adipocytes. Hence the purpose of this study was the effects exercise training induced calories expenditure on type 2 diabetes related cardio metabolic physiological parameters and adipocytokines.

Methods

Sixty-eight men patients with type 2 diabetes [12 weeks] were randomized to 4 groups according to training regimens. the groups are [1] HIIT [n = 17], [2] RT[n = 17], [3] AT[n = 18], and [4] AT + RT n = 16]. For 12 weeks [4 days/week, 20–30 min/season], participants performed training sessions with 300 kcal energy expenditure. Before and after 12 weeks interventions, Anthropometric and physiological variables and Glucose, insulin, FFA, LDL, HDL, TG, TC collected and analyses. Leptin, SFRP5, LGR4 and Irisin levels in Serum were assessment by ELISA.

Results

Serum irisin concentrations were significantly higher in AT [%20.4] compared to other groups. Leptin, SFRP5 and LGR4 were significantly higher in HIIT [%-21.7, %48.1 and %30.9 respectively] compared to other groups. Serum SFRP5 concentrations were significantly increased in 4 groups[P > 0.05]. However, leptin and LGR4 were significantly decreased and increased in 3 groups expect in RT group[P > 0.05]. And irisin concentrations were significantly increased in AT group only[P > 0.05]. And many variables indicated positive and negative relationship between together [P > 0.05].

Conclusions

The findings of the present study showed that if exercised with energy expenditure equal to HIIT training, it has the greatest effect on improving inflammatory and anti-inflammatory indicators in type 2 diabetic patients, as well as glycemic and lipid-chemical variables.

Irisin response to acute moderate intensity exercise and high intensity interval training in youth of different obesity statuses: A randomized crossover trial

Limited data exist regarding the impact of an acute bout of exercise with varying intensities on irisin levels in the youth of different obesity statuses. The objectives were to (1) compare an acute bout of moderate continuous intensity (MCI) exercise and an acute bout of high‐intensity interval training (HIIT) on irisin response in youth with different obesity statuses and, (2) investigate whether changes in irisin levels are correlated with exploratory outcomes. A randomized crossover design study was conducted on 25 youth aged 12–18 years old. Participants were classified as either healthy weight (BMI percentile <85; n = 14) or overweight/obese (BMI percentile ≥85; n = 11). Participants performed an MCI exercise session at 50% of heart rate reserve for 35 min and a HIIT exercise session for 35 min, with intervals every 5 min increasing from 50% heart rate reserve to 85–90% for 2 min. Irisin was measured using an enzyme‐linked immunoabsorbent assay from plasma sampling obtained throughout the exercise (at times 0, 7, 14, 21, 28, and 35 min). A time effect was observed throughout the HIIT session [F(1,5) = 6.478, p < 0.001]. Bonferonni post‐hoc analysis revealed significant differences in irisin levels post‐exercise (35 min) compared to times 7, 14, 21, and 28 min. Irisin increased during HIIT (81.0% ± 71.3; p = 0.012) in youth with a healthy weight. No differences were observed for youth living as overweight or with obesity. Overall, HIIT elicits a higher peak irisin response compared to MCI exercise training in youth.

The effect of exercise interventions on Irisin level: a systematic review and meta-analysis of randomized controlled trials

Irisin is a hormone that is offered to be a hopeful remedial target in obesity and type 2 diabetes. It has received striking attention recently, whereas, the interactions between exercise training and irisin are still unclear. Therefore, this systematic review and meta-analysis investigated the impacts of exercise interventions on circulating irisin in adults. A systematic search was conducted in PubMed, CINAHL, MEDLINE, Cochrane, Google Scholar, and Scopus up to July 15, 2021. Twenty-four studies, which assessed a total of 921 participants were included and analyzed using a random-effects model to estimate weighted mean differences (MD) with 95 % confidence intervals (CI). Overall, data revealed that exercise training significantly increased circulating irisin (MD: 0.01, 95 % CI: 0.00, 0.01, p = 0.005), and declined insulin (MD: -2.09, 95 % CI: -2.81, -1.37, p < 0.00001), glucose (MD: -12.89, 95 % CI: -16.52, -9.26, p < 0.00001), and insulin resistance (MD: -0.89, 95 % CI: -1.15, -0.62, p < 0.00001). Subgroup analysis revealed that irisin raised significantly when resistance training (p = 0.04) and combined training (p = 0.002) were applied, and for the type 2 diabetes and prediabetes (p = 0.002 for both) groups. Moreover, subgroup analysis by the type of intervention demonstrated that insulin reduced when aerobic training (p < 0.00001) and combined training (p = 0.0003) were employed, but glucose and HOMA-IR reduced after all three types of exercise training. These findings demonstrate that exercise interventions may produce ameliorations in circulating irisin. Further long-term studies are required to confirm these findings.

The exercise-instrumental music program and irisin levels in younger non-professional athletes

A passive lifestyle and lack of exercise are triggering factors in increasing metabolic syndrome, whereas metabolic syndrome is associated with increased morbidity and mortality. This study aimed to analyse an exercise-based non-pharmacological approach combined with instrumental music to the plasma levels of irisin. The study employed a randomised pretest-posttest-only group design recruiting 30 male participants. The individuals aged between 19-21 years, body mass index (BMI) 18.5-24.9 kg/m2, normal blood pressure, normal resting heart rate (RHR), VO2max 40-50 ml/kg bodyweight/min, normal haemoglobin (Hb). The subjects were randomly divided into three groups, MIE (n=10, moderate-intensity exercise), MIEM (n=10, moderate-intensity exercise + instrumental music), and HIE (n=10, high-intensity exercise). Blood sampling was collected from pre- and 5 min post-exercise treatment. ELISA method was used to measure the circulating irisin levels. The non-parametric Kruskal-Wallis test, Mann Whitney test and Spearman correlation were chosen to analyse the data. The results showed that there is no significant difference in pre-exercise irisin levels (ng/ml) in MIE (1.58±0.89), MIEM (1.77±3.12), and HIE (1.65±0.88) with a P-value of 0.098. Importantly, the alteration of irisin levels post-exercise program revealed that the level of this peptide (ng/ml) is higher in HIE (7.28±5.11) compared to MIE (1.95±1.85) and MIEM (4.16±3.40) with a P-value of 0.019. The plasma levels of irisin significantly correlate to energy expenditure (r=0.353, P≤0.01), plasma peroxisome proliferator-activated receptor gamma coactivator-1α (r=0.597, P≤0.001), and high-density lipoprotein (r=0.513, P≤0.01). In summary, increased irisin secretion may directly contribute to the gradual alteration of energy expenditure and correlate to physical exercise intensity-related musical treatment.

Effects of low and high intensity interval training exercises on VO2max and components of neuromuscular and vascular system in male volunteers

OBJECTIVES

To evaluate the effects of different intensity exercises on maximal oxygen consumption (VO_2max and levels of components, namely brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrKB), vascular endothelial growth factor (VEGF), peroxisome proliferator activated receptor-gamma coactivator (PGC-1α), and irisin.

METHODS

Thirty-six male participants were divided into control (CNT), low-intensity (LIIT), and high-intensity interval training (HIIT) groups. LIIT and HIIT groups consisted of 8 exercises (20 s work and rest in each repetition, respectively) conducted for 4 weeks. VO_2max and protein component levels were determined pre- and post-training. VO_2max capacity was also determined using the Yo Yo Intermittent Recovery Test-1 (Yo Yo IR-1). Statistical analysis was conducted to determine significance of the differences observed.

RESULTS

According to the YoYo IR-1, VO_2max, serum BDNF, VEGF, PGC1α, irisin, and TrkB data obtained in the study, a statistically significant difference between the groups was observed (p<0.05). While the interaction effect was found to be statistically significant in the study using PGC1α, VEGF, and TrkB data (p<0.05), it was not found to be statistically significant using YoYo IR-1, VO_2max, serum BDNF, or irisin data (p>0.05).

CONCLUSION

HIIT and LIIT improved all study parameters, while HIIT showed a greater effect than LIIT.

From Exercise to Cognitive Performance: Role of Irisin

The beneficial effects of exercise on the brain are well known. In general, exercise offers an effective way to improve cognitive function in all ages, particularly in the elderly, who are considered the most vulnerable to neurodegenerative disorders. In this regard, myokines, hormones secreted by muscle in response to exercise, have recently gained attention as beneficial mediators. Irisin is a novel exercise-induced myokine, that modulates several bodily processes, such as glucose homeostasis, and reduces systemic inflammation. Irisin is cleaved from fibronectin type III domain containing 5 (FNDC5), a transmembrane precursor protein expressed in muscle under the control of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). The FNDC5/irisin system is also expressed in the hippocampus, where it stimulates the expression of the neurotrophin brain-derived neurotrophic factor in this area that is associated with learning and memory. In this review, we aimed to discuss the role of irisin as a key mediator of the beneficial effects of exercise on synaptic plasticity and memory in the elderly, suggesting its roles within the main promoters of the beneficial effects of exercise on the brain.

Acute effects of high-intensity interval training and moderate-intensity continuous exercise on BDNF and irisin levels and neurocognitive performance in late middle-aged and older adults

The purposes of the present study were (1) to explore and compare the acute effects of high-intensity interval training (HIIT) and moderate-intensity continuous exercise (MICE) on neurocognitive performance and molecular biomarkers in late middle-aged and older adults, and (2) to examine the relationships of HIIT/MICE exercise-induced neurocognitive changes with changes in circulating irisin and BDNF levels elicited by different acute exercise modes. Using a within-subject design, twenty-one participants completed an acute bout of 30 min of HIIT, MICE, or a non-exercise-intervention (REST) session in a counterbalanced order. The neuropsychological [i.e., accuracy rate (AR) and reaction time (RT)] and neurophysiological [i.e., event-related potential (ERP) P3 latency and amplitude] indices were simultaneously measured when the participants performed a working memory task at baseline and after an intervention mode. Blood samples were also taken before and after the intervention mode. The results showed that, although ARs were significantly increased only via the MICE intervention mode, the acute HIIT and MICE interventions improved RT performance and increased ERP P3 amplitudes in the late middle-aged and older adults under consideration. Serum BDNF levels were significantly increased with the acute HIIT and MICE interventions, and significant irisin level increases were only observed following the HIIT intervention. However, changes in the levels of Irisin and BDNF pre- and post-intervention were not correlated with changes in neurocognitive performance, with the exception of the correlation between the changes in irisin levels and RTs with acute exercise in the MICE intervention mode. The present findings suggested similar beneficial effects on neurocognitive performance (i.e., RTs and ERP P3 amplitudes) and peripheral BDNF levels following MICE and HIIT interventions in the middle-aged and older adults. In terms of ARs and irisin, the two acute exercise modes appear to induce divergent effects. Irisin may play a potential facilitating role in the neuropsychological (e.g., RT) performance of working memory in such a group. However, the mechanisms remain to be determined.

Effect of high-intensity circuit training on obesity indices, physical fitness, and browning factors in inactive female college students

The recently discovered myokines, irisin and fibroblast growth factor-21, have emerged beneficial for metabolic health due to their role in regulating browning. This study examined the effects of high-intensity circuit training on obesity indices, physical fitness, and irisin and fibroblast growth factor-21 levels in inactive female college students. Ten female college students performed high-intensity circuit training (jogging, stretching, squat jumps, arm walking and push-ups, lunge jumps, burpee test, mountain climbers, side steps, and crunches and side crunches exercises). The exercise program consisted of 40 min of circuit training at 60%–80% hear rate reserve and was conducted 3 times per week for 4 weeks. The body composition, physical fitness, and concentration of plasma irisin and fibroblast growth factor-21 were analyzed before and after the exercise. The body weight (P=0.001), waist circumference (P=0.003), and body fat percentage (P=0.003) decreased, while the muscular strength (handgrip strength test, P=0.030; sit-ups test, P=0.024) and cardiorespiratory fitness (P=0.001) increased after the exercise program. However, there were no significant changes in the irisin and fibroblast growth factor-21 levels. These results suggest that high-intensity circuit training could be the ideal type of exercise in inactive female college students to induce a positive change in the obesity indices and physical fitness. Further studies are needed to determine the effects of exercise on the browning factors.

Exercise in the cold causes greater irisin release but may not be enough for adropin

When irisin and adropin were discovered, it was popularly hoped that they would become therapies for metabolic disorders that threaten global health. However, contradictory results have been reported in the subsequent period. Irisin, induced by exercise or cold exposure, is believed to be a myokine that causes the browning of adipose tissue thus increasing energy expenditure. Adropin is thought to be beneficial for health by regulating blood flow, capillary density, and playing an active role in glucose and insulin homeostasis. However, there were no experimental studies investigating the simultaneous effect of exercise and cold exposure in humans. The purpose of this study was to investigate irisin and adropin responses in young healthy individuals performing aerobic exercise in different environmental temperatures. Twenty-seven young, healthy individuals participated in this study. Participants performed 40 min of aerobic running exercise in environmental temperatures of 0°C, 12°C, and 24°C. Venous blood samples were taken pre- and post-exercise. Irisin and adropin levels were analyzed using an enzyme-linked immunosorbent assay. The principal findings showed that while serum irisin concentrations significantly increased after aerobic exercise was performed at an environmental temperature of 0°C, there was no significant difference between pre- and post-exercise recordings for physical activity performed at 12°C and 24°C. Adropin concentrations, however, remained unchanged between pre- and post-exercise at 0°C, 12°C, and 24°C. Interestingly, the exercise at 0°C caused an increase in adropin (12.5%), but this amount was not enough to be a statistically significant result. The findings of this study suggest that aerobic exercise in a cold environment causes greater irisin release. However, the combined effect of exercise and cold exposure may not be enough to statistically increase adropin level.

The Role of Irisin in Exercise-Mediated Bone Health

Exercise training promotes physical and bone health, and is the first choice of non-drug strategies that help to improve the prognosis and complications of many chronic diseases. Irisin is a newly discovered peptide hormone that modulates energy metabolism and skeletal muscle mass. Here, we discuss the role of irisin in bone metabolism via exercise-induced mechanical forces regulation. In addition, the role of irisin in pathological bone loss and other chronic diseases is also reviewed. Notably, irisin appears to be a key determinant of bone mineral status and thus may serve as a novel biomarker for bone metabolism. Interestingly, the secretion of irisin appears to be mediated by different forms of exercise and pathological conditions such as diabetes, obesity, and inflammation. Understanding the mechanism by which irisin is regulated and how it regulates skeletal metabolism via osteoclast and osteoblast activities will be an important step toward applying new knowledge of irisin to the treatment and prevention of bone diseases such as osteolysis and other chronic disorders.

A. A, Elsayed SH. Effect of focused ultrasound cavitation augmented with aerobic exercise on abdominal and intrahepatic fat in patients with non-alcoholic fatty liver disease: A randomized controlled trial

OBJECTIVES

The study aimed to examine the effect of focused ultrasound cavitation augmented with aerobic exercise on localized abdominal and intrahepatic fat in fatty liver patients.

METHODS

34 fatty liver patients aged 30-45 with a body mass index (BMI) of 30-40 kg/m2 were randomly assigned into two equally numbered groups. Group A received focused ultrasound cavitation and moderate aerobic exercise for three months, while Group B (control group) received moderate aerobic exercise only. Abdominal subcutaneous fat volume, visceral fat volume, liver-to-spleen ratio (L/S ratio), body weight, BMI, and waist circumference were measured both before and after the study period.

RESULTS

Both groups showed significant improvements in subcutaneous fat volume, visceral fat volume, body weight, BMI, and waist circumference relative to baseline where (P < 0.001), with a higher percentage in group A. L/S ratio only showed a significant improvement in group A. Between-group differences were noteworthy regarding L/S ratio and waist circumference where (P < 0.0001).

CONCLUSION

While substantial risky measures in non-alcoholic fatty liver disease have been modified by aerobic exercise, its combination with focused ultrasound cavitation causes more notable effects on the reduction of abdominal and intrahepatic fat, making it a superior option.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04161703.

Effects of high-intensity interval training and flaxseed oil supplement on learning, memory and immobility: relationship with BDNF and TrkB genes

This study examined the independent and combined effects of high-intensity interval training (HIIT) and flaxseed oil supplementation on cognitive/executive functions in middle-aged rats. Hippocampal neurotropic brain factor (BDNF) and tyrosine kinase receptor B (TrkB) gene expression were also measured. Animals were randomly divided into groups including no exercise control and saline (CS), no exercise control and flaxseed oil supplement (CF), exercise training-and saline (TS) and exercise training and flaxseed oil supplement (TF). The training groups undertook a program of HIIT (10 weeks, five sessions per week) and the supplement groups received flaxseed oil supplement (300 mg/kg). The results showed that HIIT and flaxseed oil supplementation independently had positive effects on memory and learning (P<0.05). HIIT and flaxseed oil independently decreased immobility behaviour and increased hippocampal BDNF and TrkB genes expression (P<0.05). HIIT and flaxseed oil combination had a greater effect on some variables (hippocampal TrkB gene expression, memory and immobility) compared to each intervention alone (P<0.05). In conclusion, HIIT and flaxseed oil can independently improve cognitive/executive functions. In addition, HIIT had a greater positive effect than flaxseed oil supplementation on memory and immobility. The combination of HIIT and flaxseed oil supplement had a more positive effect compared to each intervention alone on memory, and immobility. Hippocampal BDNF gene expression did not significantly differ in the combination or independent groups. Thus, future work is needed on several other genes in different segments of the brain to find the additive-mechanisms involved in memory and immobility regulation and younger and older species of rat should be examined.

Effects of a Combined Endurance/Strength Training Program on Circulating Irisin Levels in Overweight/Obese Men and Women with Type 2 Diabetes Mellitus

Irisin is a promising therapeutic target in patients with type 2 diabetes mellitus (T2DM), as studies have demonstrated that irisin can induce "browning" of adipocytes and mitigate pro-inflammatory conditions. Sex-specific changes in irisin levels have been reported in a study involving healthy men and women following physical training. The present study aims to analyze the effects of an 8-week training intervention on circulating irisin levels in patients with T2DM and to find out whether the training responses differ between T2DM men and women. Twenty-nine overweight/obese T2DM patients (19 men, 10 women; age: 46-74 years; body mass index >25 kg/m²) participated in a combined moderate-intensity endurance/strength training program (3 times a week). The irisin levels of men and women did not differ significantly. The post-training irisin levels did not differ significantly from the pre-training values, and there was no interaction effect of sex. This study shows no training-induced (sex-specific) changes in circulating irisin levels in T2DM patients. Large-scale studies using other forms of training are needed to fully clarify whether basal irisin levels can be changed in T2DM men and/or women to counteract T2DM.

Effect of HIIT with Tabata Protocol on Serum Irisin, Physical Performance, and Body Composition in Men

High-intensity interval training (HIIT) is frequently utilized as a method to reduce body mass. Its intensity of work results in a number of beneficial adaptive changes in a relatively short period of time. Irisin is a myokine and adipokine secreted to the blood during exercise and it takes part in the regulation of energy metabolism. It is a vital issue from the prophylaxis point of view as well as treatment through exercise of different diseases (e.g., obesity, type-2 diabetes). The aim of this study was to evaluate changes in irisin concentration, body composition, and aerobic and anaerobic performance in men after HIIT. Eight weeks of HIIT following the Tabata protocol was applied in the training group (HT) (n = 15), while a sedentary group (SED) (n = 10) did not participate in fitness activities within the same time period. Changes of irisin, body composition, and aerobic and anaerobic performance were evaluated after graded exercise test (GXT) and Wingate anaerobic test (WAnT) before and after eight weeks of training. Training resulted in an increased of blood irisin concentration (by 29.7%) p < 0.05), VO_2max increase (PRE: 44.86 ± 5.74 mL·kg⁻¹·min⁻¹; POST: 50.16 ± 5.80 mL kg⁻¹·min⁻¹; p < 0.05), reduction in percent body fat (PRE: 14.44 ± 3.33%; POST: 13.61 ± 3.16%; p < 0.05), and increase of WAnT parameters (p < 0.05) in the HT group. No changes were observed in the SED group. HIIT resulted in beneficial effects in the increase in blood irisin concentration, physical performance, and reduced fat content. The HIIT may indicate an acceleration of base metabolism. This effect can be utilized in the prevention or treatment of obesity.

The influence of concurrent training intensity on serum irisin and abdominal fat in postmenopausal women

Introduction

Menopause seems to be among the factors related to the development of prediabetes and central obesity. Conversely, physical activity may have a major role in reducing metabolic syndrome in women of postmenopausal age.

Material and methods

Forty-eight postmenopausal active and sedentary women within the ages of 45-65 years were randomized to four groups: 1) high-intensity concurrent interval exercise (HCI; n = 15), 2) moderate-intensity continuous concurrent exercise (MCC; n = 14), 3) control daily active (CDA; n = 10), and 4) control sedentary (COS; n = 9). The subjects in the preceding training groups exercised three times per week for 50-65 min/session with high/moderate concurrent exercise for 10 weeks. The levels of serum irisin, insulin sensitivity, abdominal fat distribution (visceral and subcutaneous), and total abdominal fat were measured at baseline and post-test.

Results

This study showed that the HCI group had a significantly increased serum irisin (p< 0.001), stimulated favorable alterations in insulin sensitivity status (p = 0.003), and significantly decreased subcutaneous, visceral and, total abdominal fat (p< 0.001). Also, the insulin sensitivity status was significantly increased (p = 0.01) and subcutaneous abdominal fat significantly decreased in the MCC group (p = 0.018). However, this study’s results did not find a considerable correlation between insulin sensitivity, irisin level, weight loss and abdominal fat distribution.

Conclusions

High-intensity concurrent exercise has a greater influence on improving most metabolic-related parameters than moderate-intensity concurrent exercise.

Two Weeks of High-Intensity Interval Training in Combination With a Non-thermal Diffuse Ultrasound Device Improves Lipid Profile and Reduces Body Fat Percentage in Overweight Women

This study evaluated the effectiveness of an innovative strategy which combined low-frequency ultra sound (LOFU) with high-intensity interval training (HIIT) to improve physical fitness and promote body fat loss in overweight sedentary women. A placebo controlled, parallel group randomized experimental design was used to investigate the efficacy of a 2-week combined LOFU and HIIT program (3 sessions per week). Participants were allocated into either the Experimental HIIT group (HIIT_EXP, n = 10) or Placebo HIIT group (HIIT_PLA, n = 10). Baseline exercise testing (maximal oxygen uptake, lower limb strength and substrate oxidation test), dietary assessment, anthropometric measures and blood sampling were completed in week 1 and repeated in week 4 to determine changes following the program (Post-HIIT). During each training session, the HIIT_EXP and HIIT_PLA groups wore a non-thermal diffuse ultrasound belt. However, the belt was only switched on for the HIIT_EXP group. Delta change scores were calculated for body weight, body fat percentage (Fat%), muscle mass, V.O_2max, hip and waist circumferences, and all lipid variables from Baseline to Post-HIIT. Statistical analysis was completed using a repeated-measures factorial analysis of variance by group (HIIT_PLA and HIIT_EXP) and time (Baseline and Post-HIIT). Results showed significant improvements in maximal oxygen uptake (HIIT_EXP; Baseline 24.7 ± 5.4 mL kg^–1 min^–1, Post-HIIT 28.1 ± 5.5 mL kg^–1 min^–1 and HIIT_PLA; Baseline 28.4 ± 5.9 mL kg^–1 min^–1, Post-HIIT 31.4 ± 5.5 mL kg^–1 min^–1) for both groups. Significant decreases in Fat% (HIIT_EXP; Baseline 32.7 ± 3.2%, Post-HIIT 28.9 ± 3.5% and HIIT_PLA; Baseline 28.9 ± 3.5%, Post-HIIT 28.9 ± 3.4% kg), waist circumference (HIIT_EXP; Baseline 95.8 ± 9.6 cm, Post-HIIT 89.3 ± 8.9 cm and HIIT_PLA; Baseline 104.3 ± 3.5 cm, Post-HIIT 103.6 ± 3.4 cm) and triglycerides (HIIT_EXP; −29.2%, HIIT_PLA; −6.7%) were observed in the HIIT_EXP group only. These results show that HIIT combined with LOFU was an effective intervention to improve body composition, lipid profile, and fitness. This combined strategy allowed overweight, sedentary women to achieve positive health outcomes in as little as 2 weeks.

Browning is activated in the subcutaneous white adipose tissue of mice metabolically challenged with a high-fructose diet submitted to high-intensity interval training

Fructose may induce an endocrine dysfunction in adipose tissue in rodents. Browning is identified by deposits of beige adipocytes in subcutaneous white adipose tissue (sWAT). We study the effects of the high-intensity interval training (HIIT) on the formation of beige adipocytes in the sWAT of mice fed a high-fructose diet. Sixty male mice (3 months old; C57BL/6) were fed two diets for 18 weeks (n=30 each): control diet (C) or high-fructose diet (F). At the 10th week, for an additional 8-week period, the groups were (n=15 each) nontrained (NT) or trained (HIIT): C-NT, C-HIIT, F-NT and F-HIIT. We evaluated body mass, energy expenditure and molecular analyses for browning and thermogenic markers in sWAT. The HIIT groups showed significantly lower body mass and increased energy expenditure. The consumption of fructose was linked with an increased sWAT mass. However, HIIT caused a reduction of sWAT mass compared to the NT groups. Energy intake was parallel in the groups, regardless of the diet type and HIIT. Fructose was related to higher glucose and insulin levels and hypertrophied sWAT adipocytes, but HIIT decreased both glucose and insulin levels and led to the appearance of brown fat-like adipocytes dispersed in sWAT with higher expression of browning markers. Also, fructose reduced the sWAT markers of mitochondrial biogenesis and beta-oxidation, which were enhanced by HIIT. In conclusion, HIIT might stimulate the sWAT browning in mice fed a high-fructose diet associated with beneficial changes in mitochondrial biogenesis and beta-oxidation markers, contributing to a whole-body metabolic improvement.

The effects of both age and sex on irisin levels in paired plasma and cerebrospinal fluid in healthy humans

BACKGROUND

Adipo-myokine irisin has important effects on the metabolism and functioning of multiple tissues and organs. However, the effects of aging and sex on irisin levels in cerebrospinal fluid (CSF) and on circulation have not been comprehensively studied.

OBJECTIVE

To investigate whether aging and sex can affect irisin levels in both CSF and plasma; to determine whether CSF irisin uptake involves a saturable transport mechanism.

DESIGN AND METHODS

In the present study, the irisin levels in paired CSF and plasma samples drawn from 71 healthy individuals were used to investigate effects by using commercial ELISA kits and mass spectrometry.

RESULTS

Multiple linear regression analysis results showed that CSF irisin levels are positively correlated with the CSF/plasma irisin ratio and age and that these levels present a reverse correlation with BMI. Age-related increases in CSF levels are validated by using ELISA and mass spectrometry. Higher plasma irisin levels are observed in men than women. CSF and plasma irisin levels are nonlinearly associated with the CSF/plasma irisin ratio, BMI, age and F scores. The CSF/plasma irisin ratio is U-shaped and associated with age.

CONCLUSIONS

There might be an age-related increase in irisin levels in the cerebrospinal fluid of healthy humans. Circulating irisin levels are higher in males than in females in the healthy population. A saturable mechanism might be involved in mediating the transport of circulating irisin across the blood-brain barrier. Factors shaping irisin levels for both circulation and the CSF of healthy humans must be further defined in future experiments.

Regular aerobic exercise correlates with reduced anxiety and incresed levels of irisin in brain and white adipose tissue

We have recently shown that regular voluntary aerobic exercised rats have low levels of anxiety. Irisin is an exercise-induced myokine that is produced by many tissues; and the role it plays in anxiolytic behavior is unknown. In this study we aimed to investigate the correlation between anxiety like behavior and irisin levels following regular voluntary aerobic exercise in male mice. We've have shown that anxiety levels decreased in exercised mice, while irisin levels increased in the brain, brown adipose tissue, white adipose tissue, kidney, and pancreas tissues. No significant difference of irisin levels in the liver, muscle and serum were detected in the exercise group, when compared to controls. In addition, there was a strong positive correlation between brain irisin levels and activity in middle area of open field test and in the open arms of elevated plus maze test; both which are indicators of low anxiety levels. Our results suggest that decrease in anxiolytic behavior due to regular voluntary exercise may be associated with locally produced brain irisin. White adipose tissue irisin levels also correlated very strongly with low anxiety. However, no serum irisin increase was detected, ruling out the possibility of increased peripheral irisin levels affecting the brain via the bloodstream. Further research is necessary to explain the mechanisms of which peripheral and central irisin effects anxiety and the brain region affected.