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

Short- and long-term effects of concurrent aerobic and resistance training on circulating irisin levels in overweight or obese individuals: a systematic review and meta-analysis of randomized controlled trials

Background

Concurrent training (CT) is emerging as a practical and effective approach to enhance body composition, cardiovascular function, and muscle mass, thereby elevating overall individual health. This study aims to systematically investigate the effects of short- and long-term concurrent aerobic and resistance training on circulating irisin levels in overweight or obese individuals.

Methodology

The electronic databases, including China National Knowledge Infrastructure, PubMed, Embase, Wan Fang Database, and Web of Science, were systematically searched for articles on "concurrent training" and "irisin" published from their inception to 30 November 2023. The pooled effect size was determined using standardized mean difference (SMD) and corresponding 95% confidence intervals (CIs). The study protocol received registration with the International Prospective Register of Systematic Reviews (CRD42023494163).

Results

All nine studies, encompassing a total of 264 participants, were randomized controlled trials and met the eligibility criteria. Results indicate that short- and long-term concurrent training moderately increased circulating irisin levels compared to the control group (SMD = 0.56, 95% CI [0.33-0.80], p = 0.00; I 2 = 36.6%, heterogeneity p = 0.106). Subgroup analyses revealed that both equal to or less than 10 weeks (SMD = 0.78, 95% CI [0.18-1.37], p = 0.01; I 2 = 62.3%, heterogeneity p = 0.03) and more than 10 weeks (SMD = 0.45, 95% CI [0.14-0.76], p = 0.00; I 2 = 0%, heterogeneity p = 0.54) of concurrent training significantly increased circulating irisin levels in overweight or obese individuals. There were no significant between-group differences (I 2 = 0%, p = 0.34). Additionally, concurrent training significantly increased irisin levels in overweight or obese participants (SMD = 1.06, 95% CI [0.34-1.78], p = 0.00; I 2 = 50.6%, heterogeneity p = 0.13) and in type 2 diabetes patients (SMD = 0.70, 95% CI [0.30-1.10], p = 0.00; I 2 = 0%, heterogeneity p = 0.99). However, no significant effect was observed in patients with metabolic syndrome (SMD = 0.21, 95% CI [-0.25-0.68], p = 0.37; I 2 = 38.7%, heterogeneity p = 0.18). There were significant between-group differences (I 2 = 53.9%, p = 0.11). Lastly, concurrent training significantly increased circulating irisin levels in overweight or obese individuals aged 45-60 years (SMD = 0.56, 95% CI [0.25-0.86], p = 0.00; I 2 = 6.5%, heterogeneity p = 0.38), and a significant increase in irisin levels was observed 12 h post-intervention (SMD = 0.70, 95% CI [0.35-1.05], p = 0.00; I 2 = 0%, heterogeneity p = 0.74). However, none of the above categorical variables showed significant between-group differences.

Conclusions

Short- and long-term concurrent training can effectively improve circulating irisin levels in overweight or obese individuals. However, the effects of short- and long-term concurrent training should consider the participants' health status, age, and the timing of post-exercise measurements to maximize health benefits.

The therapeutic potential of irisin to mitigate the risk of metabolic syndrome in postmenopausal women

Oestradiol withdrawal at menopause predisposes women to metabolic syndrome, a cluster of interrelated conditions including obesity, insulin resistance, dyslipidaemia and hypertension that together confer an increased risk of developing type 2 diabetes mellitus and cardiovascular disease. Hormone replacement therapies are commonly used to treat acute symptoms of the perimenopausal period, and whilst they have been associated with metabolic improvements in many studies, long-term use is considered unviable. Novel approaches are required to mitigate the risk of postmenopausal metabolic syndrome. In 2012, the exercise-inducible myokine irisin was isolated from the skeletal muscle of mice and identified to have anti-obesity and antidiabetic effects in vivo. Irisin is now recognised to exert pleiotropic action on cognitive, bone and metabolic health. There is accumulating evidence from in vitro and in vivo rodent studies that irisin can mitigate each component condition of metabolic syndrome. In postmenopausal women, independent associations have been observed between (a) exercise and plasma irisin concentration and (b) plasma irisin concentration and reduced incidence of metabolic syndrome. To date, however, no study has considered the mechanistic basis by which irisin, whether exercise-induced or exogenously administered, could reduce the incidence or severity of metabolic syndrome in postmenopausal women. This review aims to analyse the literature concerning the metabolic actions of irisin, with a focus on its therapeutic potential for metabolic syndrome driven by a state of oestradiol depletion. It evaluates the practicality of exercise as a therapy and discusses other irisin-based therapeutic strategies that may alleviate postmenopausal metabolic syndrome. Finally, it highlights areas where future research is required to advance knowledge of irisin's biological action such that it could be considered a viable candidate for clinical application.

Comparison of HIIT and MICT and further detraining on metabolic syndrome and asprosin signaling pathway in metabolic syndrome model of rats

Physical activity promotes various metabolic benefits by balancing pro and anti-inflammatory adipokines. Recent studies suggest that asprosin might be involved in progression of metabolic syndrome (MetS), however, the underlying mechanisms have not been understood yet. This study aimed to evaluate the effects of high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and further detraining on MetS indices, insulin resistance, serum and the liver levels of asprosin, and AMP-activated protein kinase (AMPK) pathway in menopause-induced MetS model of rats. A total of 64 Wistar rats were used in this study and divided into eight groups: Sham1, OVX1 (ovariectomized), Sham2, OVX2, OVX + HIIT, OVX + MICT, OVX + HIIT + Det (detraining), and OVX + MICT + Det. Animals performed the protocols, and then serum concentrations of asprosin, TNF-α, insulin, fasting blood glucose, and lipid profiles (TC, LDL, TG, and HDL) were assessed. Additionally, the liver expression of asprosin, AMPK, and P-AMPK was measured by western blotting. Both HIIT and MICT caused a significant decrease in weight, waist circumference, BMI (P = 0.001), and serum levels of glucose, insulin, asprosin (P = 0.001), triglyceride, total cholesterol, low-density lipoprotein (LDL), and TNF-α (P = 0.001), but an increase in the liver AMPK, P-AMPK, and P-AMPK/AMPK (P = 0.001), compared with OVX2 noexercised group. MICT was superior to HIIT in reducing serum asprosin, TNF-a, TG, LDL (P = 0.001), insulin, fasting blood glucose, HOMA-IR, and QUEKI index (P = 0.001), but an increase in the liver AMPK, and p-AMPK (P = 0.001). Although after two months of de-training almost all indices returned to the pre exercise values (P < 0.05). The findings suggest that MICT effectively alleviates MetS induced by menopause, at least partly through the activation of liver signaling of P-AMPK and the reduction of asprosin and TNF-α. These results have practical implications for the development of exercise interventions targeting MetS in menopausal individuals, emphasizing the potential benefits of MICT in mitigating MetS-related complications.

Cardioprotective Effects of Exercise: The Role of Irisin and Exosome

Exercise is an effective measure for preventing and treating cardiovascular diseases, although the exact molecular mechanism remains unknown. Previous studies have shown that both irisin and exosomes can improve the course of cardiovascular disease independently. Therefore, it is speculated that the cardiovascular protective effect of exercise is also related to its ability to regulate the concentrations of irisin and exosomes in the circulatory system. In this review, the potential synergistic interactions between irisin and exosomes are examined, as well as the underlying mechanisms including the AMPK/PI3K/AKT pathway, the TGFβ1/Smad2/3 pathway, the PI3K/AKT/VEGF pathway, and the PTEN/PINK1/Parkin pathway are examined. This paper provides evidence to propose that exercise promotes the release of exosomes enriched with irisin, miR-486-5p and miR-342-5p from skeletal muscles, which results in the activation protective networks in the cardiovascular system. Moreover, the potential synergistic effect in exosomal cargo can provide new ideas for clinical research of exercise mimics.

The effect of two concurrent exercise modalities on serum concentrations of FGF21, irisin, follistatin, and myostatin in men with type 2 diabetes mellitus

This study investigated the effect of concurrent training (CT) sequences on fibroblast growth factor 21 (FGF21), irisin, myostatin (MSTN), and follistatin (FST) among adults with type 2 diabetes mellitus (T2DM). Fifty-one diabetic men were randomly selected and assigned to concurrent aerobic-resistance (A-R) training and concurrent resistance-aerobic (R-A) training, and non-exercise control (CON) groups. The training protocols consisted of three sessions per week for 12 weeks. The A-R and R-A groups received the same CT protocols and performed with different sequences. The subjects' blood samples were obtained at baseline and 48 hours after the last session of the intervention. The results showed that the concentration of FGF21 did not change significantly after the 12 weeks of CT with different sequences (p > .05, η² = 0.123), but the serum concentration of irisin (A-R = 2.93 μg.L^-1 (95% CI = 1.45-4.42, d = -0.57) and R-A = 3.31 μg.L^-1 (95% CI = 1.13-5.49, d = -0.68)) and FST (A-R = 4.96 ng.mL^-1 (95% CI = 3.41-6.5, d = -0.39) and R-A = 4.19 ng.mL^-1 (95% CI = 2.82-5.56, d = -0.55)) significantly increased while the serum MSTN concentration (A-R = 152.32 ng.L^-1 (95% CI = 61.83-242.82, d = 1.31) and R-A = 173 ng.L^-1 (95% CI = 35.89-227.5, d = 0.83)) of both A-R and R-A groups mainly decreased (p < .01). There was no significant difference between A-R and R-A groups' irisin, FST, and MSTN concentration (p > .05), though the CT improved the body compositions, strength, and peak oxygen uptake in both groups (p < .01). Regardless of the CT sequences, it was found that CT acted as a therapeutic modality of training for T2DM patients by increasing their irisin and FST and decreasing their MSTN concentrations.

Serum Irisin level is associated with fall risk, muscle strength, and cortical porosity in postmenopausal women

BACKGROUND

Irisin plays a role in bone-muscle crosstalk, but the relationship between the serum irisin level and bone microarchitecture remains unknown.

OBJECTIVE

This study aimed to investigate the relationships between serum irisin level and fall risk, muscle strength, bone mineral density (BMD), and bone microarchitecture among Chinese postmenopausal women.

METHODS

In all 138 postmenopausal women, handgrip strength, short physical performance battery (SPPB), and the timed up-and-go test were performed to evaluate muscle strength, physical performance, and fall risk, respectively. The serum irisin was measured. High-resolution peripheral quantitative computed tomography (HR-pQCT) was performed to acquire volumetric BMD and bone microarchitecture. Bivariate analysis was used to explore relationships between serum irisin level and muscle strength and HR-pQCT parameters. Univariate and multivariate linear regression analyses were performed to determine associations between serum irisin level and vBMD and cortical porosity (Ct.Po).

RESULTS

All participants had a median serum irisin level of 3.91 μg/ml. Participants with high fall risk had significantly lower serum irisin levels than those with low fall risk (2.22 μg/ml vs. 4.16 μg/ml, p=0.024). Irisin level was positively related to handgrip strength (rs=0.185, p=0.030) and SPPB performance. In univariate linear regression, serum irisin level was positively associated with cortical volumetric BMD (Ct.vBMD, radius: standardized β=0.184, p=0.031; tibia: standardized β=0.242, p=0.004), but it had no significant associations with Ct.vBMD after multivariate adjustment. After adjusting by age, height, serum sclerostin level, and body fat ratio, only Ct.Po at the distal radius had a significantly negative association with serum irisin level (standardized β=-0.276, p=0.003).

CONCLUSION

Postmenopausal women with lower serum irisin levels have a higher fall risk, weaker muscle strength, and higher cortical porosity. Moreover, serum irisin level has a positive association with Ct.vBMD, but it is affected by factors such as age.

Concurrent Exercise Training: Long-Term Changes in Body Composition and Motives for Continued Participation in Women with Obesity

The purpose of this project was to examine the effect of a concurrent exercise program (sprint interval training and resistance exercise) on body composition in women with obesity and factors associated with continued exercise participation following the program. Twenty women (37.1 ± 7.4 y, height = 1.63 ± 0.09 m, weight = 98.22 ± 0.22 kg, BMI = 34.2 ± 2.50 kg/m2) participated in a 10-week exercise intervention consisting of a sprint interval treadmill protocol and resistance training three times a week totaling 30 sessions. Body composition was measured by dual-energy X-ray absorptiometry (iDXA) at pretest, 12 weeks, and six months post-intervention. Semi-structured interviews assessed participants’ perception of the program at both 12 weeks and six months. Participants significantly reduced fat mass (p < 0.001), gynoid fat mass (p < 0.010), android fat mass (p = 0.003), and visceral fat mass (p = 0.003) at 12 weeks post-test. At six months, participants maintained their reductions in fat mass (p = 0.015), visceral fat (p = 0.040) and gynoid fat mass (p = 0.032). There were no significant main time effects in lean mass (p = 0.099) or caloric intake (p = 0.053) at 12 weeks or six months. Themes that emerged from the semi-structured interviews at 12 weeks reflected enjoyment in the training, increases in competence and knowledge, as well as apprehension of continuing training on their own. At six months, themes that emerged reflected overcoming barriers, competence regarding high-intensity training, and a lack of competence to engage in resistance training. Sprint interval training coupled with resistance training is a feasible exercise protocol for women with obesity and results in reduced fat mass over six months. Improving women’s competence for training is imperative for continued participation.

The effects of different types of exercise on circulating irisin levels in healthy individuals and in people with overweight, metabolic syndrome and type 2 diabetes

Irisin is a myokine secreted during exercise. It has drawn the attention of researchers as it regulates several effects of exercise that are considered beneficial. It has also been proposed as a therapeutic tool to treat metabolic disorders. In recent years, the effect of different types of training on circulating irisin has been studied in large populations. An overall beneficial result has been shown, however, the outcome of the investigations has raised some controversy. Herein we evaluated the existing literature on the effects of different types of training on the circulating irisin levels in healthy subjects and in those displaying different metabolic condition. We conducted queries in the PubMed and Web of Science databases for literature published between January 2010 and January 2021. Thirty-seven original articles were retrieved and they were included in this review. Any letter to the editor, meta-analyses, reviews, and systematic review articles were excluded. From these 37 articles, 19 of them reported increased levels of circulating irisin. The interventions encompassed aerobic, resistance, combined, circuit, and interval training types. Such increase of circulating irisin was reported for healthy subjects and for those displaying different metabolic condition. A training that is steadily kept with a moderate to high intensity, including that characterized by brief highly intense intervals, were distinguishable from the rest. Nevertheless, the training effectiveness as evaluated by the increased circulating irisin levels depends on the subject’s metabolic condition and age.

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.

Long-Term Effect of Exercise on Irisin Blood Levels-Systematic Review and Meta-Analysis

Physical exercise may activate a number of important biochemical processes in the human body. The aim of this systematic review and meta-analysis was to identify the long-term effect of physical activity on irisin blood levels. We searched PubMed, Scopus, and Web of Science for articles addressing the long-term effect of physical exercise on irisin blood levels. Fifty-nine articles were included in the final qualitative and quantitative syntheses. A statistically significant within-group effect of exercise on irisin blood levels was in 33 studies; out of them, the irisin level increased 23× and decreased 10×. The significant positive between-groups effect was found 11×. Furthermore, the meta-analysis indicated that physical exercise had a significant positive effect on irisin blood levels (SMD = 0.39 (95% CI 0.27–0.52)). Nevertheless, considerably high heterogeneity was found in all the analyses. This systematic review and meta-analysis indicate that physical exercise might increase irisin blood levels; however, the results of individual studies were considerably inconsistent, which questions the methodological detection of irisin by ELISA kits.

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.

Wand Stretching Exercise Decreases Abdominal Obesity Among Adults With High Body Mass Index Without Altering Fat Oxidation

Rationale

We designed a wand-based muscle stretching (WE) exercise program, which has become increasingly popular in physical therapy and has been used for elderly patients with adhesive capsulitis. However, studies regarding the effects of WE training on abdominal obesity and measures of cardiovascular risk factors among overweight/obese adults aged ≥55 years are rare.

Purpose

The objective of this study is to evaluate the effects of a 15-week wand stretching exercise program on waist circumference and cardiovascular risk factors in sedentary adults aged 55–70 years.

Methods

A total of 124 participants were randomly assigned to either participate in wand stretching exercise (WE) over a 15-week period or a control group (n = 62 each). Sixty participants in the WE group (26 overweight and 34 obese) and 51 in the control group (29 overweight and 22 obese) completed the study. The WE program included wand-assisted muscle stretching exercise on both the upper body and lower body for 40 min per day, 5 days per week, whereas the control group maintained their sedentary lifestyle.

Results

No significant improvements were observed in plasma glucose, insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR) after exercise training. Compared with the control group, the WE group had more significant reductions in waist circumference among participants with a body mass index (BMI) < 25 kg/m² (−2.6 cm, 95% CI: −4.19 to −0.97 cm, d = 0.48) and BMI > 25 kg/m² (−2.5 cm, 95% CI: −4.1 to −0.9 cm, d = 0.59) (both P < 0.01). Furthermore, within groups, a significant increase in % fat free mass was observed after WE training. The basal metabolic rate was slightly increased, but the fat oxidation rate remained unaltered in the WE group. Improvements in low-density lipoprotein cholesterol to high-density lipoprotein cholesterol were minimal after WE. Significant reductions in high-sensitivity C-reactive protein were observed after WE only for participants with a BMI <25 kg/m².

Conclusion

The results suggest redistribution of a carbon source from the abdominal region to challenged skeletal muscle, following prolonged WE training. This abdominal fat reducing outcome of the WE is unlikely to be associated with fatty acid oxidation.