The search for exercise factors in humans

Effects of Exercise-Induced Changes in Myokine Expression on the Tumor Microenvironment

In this narrative review, we summarize the direct and indirect effects that myokines have on the tumor microenvironment. We took studies of various cancer types and species into account. Systematic reviews and meta-analyses that matched the search terms were also considered. We searched databases for six months. As a narrative approach was chosen, no data was analyzed or reanalyzed. The goal of this narrative review is to create an overview on the topic to identify research gaps and answer the questions as to whether myokine expression may be relevant in cancer research in regard to the tumor microenvironment. Six commonly known myokines were chosen. We found strong links between the influence exercise has on interleukin-6, oncostatin M, secreted protein acidic and rich in cysteine, and irisin in the context of tumor progression and inhibition via interactions with the tumor microenvironment. It became clear that the effects of myokines on the tumor microenvironment can vary and contribute to disease progression or regression. Interactions among myokines and immune cells must also be considered and require further investigation. To date, no study has shown a clear connection, while multiple studies suggest further investigation of the topic, similar to the effects of exercise on myokine expression.

Interaction of the C2C12 myotube contractions and glucose availability on transcriptome and extracellular vesicle microRNAs

Exercise-like electrical pulse stimulation (EL-EPS) of myotubes mimics many key physiological changes induced by in vivo exercise. Besides enabling intracellular research, EL-EPS allows to study secreted factors, including muscle-specific microRNAs (myomiRs) carried in extracellular vesicles (EVs). These factors can participate in contraction-induced intercellular cross talk and may mediate the health benefits of exercise. However, the current knowledge of these responses, especially under variable nutritional conditions, is limited. We investigated the effects of EL-EPS on C2C12 myotube transcriptome in high- and low-glucose conditions by messenger RNA sequencing, while the expression of EV-carried miRNAs was analyzed by small RNA sequencing and RT-qPCR. We show that higher glucose availability augmented contraction-induced transcriptional changes and that the majority of the differentially expressed genes were upregulated. Furthermore, based on the pathway analyses, processes related to contractility and cytokine/inflammatory responses were upregulated. In addition, we report that EL-EPS increased packing of miR-1-3p into EVs independent of glucose availability. Together our findings suggest that in vitro EL-EPS is a usable tool not only to study contraction-induced intracellular mechanisms but also extracellular responses. The distinct transcriptional changes observed under variable nutritional conditions emphasize the importance of careful consideration of media composition in future exercise-mimicking studies.NEW & NOTEWORTHY The present study examined for the first time the effects of exercise-like electrical pulse stimulation administered under distinct nutritional conditions on 1) the transcriptome of the C2C12 myotubes and 2) their media containing extracellular vesicle-carried microRNAs. We report that higher glucose availability augmented transcriptional responses related especially to contractility and cytokine/inflammatory pathways. Agreeing with in vivo studies, we show that the packing of exercise-responsive miR-1-3p was increased in the extracellular vesicles in response to myotube contractions.

Molecular origin and biological effects of exercise mimetics

With the rapid development of sports science and molecular biology technology, academia refers to molecules or microorganisms that mimic or enhance the beneficial effects of exercise on the body, called "exercise mimetics." This review aims to clarify the concept and development history of exercise mimetics, and to define the concept of exercise mimetics by summarizing its characteristics and functions. Candidate molecules and drug targets for exercise mimetics are summarized, and the relationship between exercise mimetics and exercise is explained, as well as the targeting system and function of exercise mimetics. The main targeting systems for exercise mimetics are the exercise system, circulatory system, endocrine system, endocrine system, and nervous system, while the immune system is potential targeting systems. Finally, future research directions for exercise mimetics are discussed.

Effects of crossover point exercise and high-intensity interval training on vascular health in young overweight females

This study investigated the effects of 10 weeks of crossover point (COP) exercise training and high-intensity interval training (HIIT) on cardiovascular risk factors and vascular health in overweight young women. Overweight young women were randomized into HIIT and COP groups. Participants in the HIIT group (n = 10; age = 22 ± 2, body mass index (BMI) = 25.72 ± 0.90) and COP group (n = 10, age = 21 ± 2, BMI = 25.90 ± 1.90) took part in 10 weeks of HIIT and COP exercise training, respectively. Cardiorespiratory fitness, cardiovascular health, and oxidative stress indicators were measured before and after the intervention period. After 10 weeks of exercise intervention, both COP exercise and HIIT led to a significant increase in maximal oxygen uptake (p < 0.001). The systolic blood pressure (p = 0.006), diastolic blood pressure (p = 0.006), and brachial-ankle pulse wave velocity (p = 0.002) were significantly decreased in both COP group and HIIT group, while serum interleukin-6 levels were increased in HIIT and COP groups. The present study shows that a training program at COP could be an effective strategy to protect vascular health.

The Genetic Association with Athlete Status, Physical Performance, and Injury Risk in Soccer

The aim of this review was to critically appraise the literature concerning the genetic association with athlete status, physical performance, and injury risk in soccer. The objectives were to provide guidance on which genetic markers could potentially be used as part of future practice in soccer and to provide direction for future research in this area. The most compelling evidence identified six genetic polymorphisms to be associated with soccer athlete status (ACE I/D; ACTN3 rs1815739; AGT rs699; MCT1 rs1049434; NOS3 rs2070744; PPARA rs4253778), six with physical performance (ACTN3 rs1815739; AMPD1 rs17602729; BDNF rs6265; COL2A1 rs2070739; COL5A1 rs12722; NOS3 rs2070744), and seven with injury risk (ACTN3 rs1815739; CCL2 rs2857656; COL1A1 rs1800012; COL5A1 rs12722; EMILIN1 rs2289360; IL6 rs1800795; MMP3 rs679620). As well as replication by independent groups, large-scale genome-wide association studies are required to identify new genetic markers. Future research should also investigate the physiological mechanisms associating these polymorphisms with specific phenotypes. Further, researchers should investigate the above associations in female and non-Caucasian soccer players, as almost all published studies have recruited male participants of European ancestry. Only after robust, independently replicated genetic data have been generated, can genetic testing be considered an additional tool to potentially inform future practice in soccer.

Blood-Based Biomarkers for Managing Workload in Athletes: Perspectives for Research on Emerging Biomarkers

At present, various blood-based biomarkers have found their applications in the field of sports medicine. This current opinion addresses biomarkers that warrant consideration in future research for monitoring the athlete training load. In this regard, we identified a variety of emerging load-sensitive biomarkers, e.g., cytokines (such as IL-6), chaperones (such as heat shock proteins) or enzymes (such as myeloperoxidase) that could improve future athlete load monitoring as they have shown meaningful increases in acute and chronic exercise settings. In some cases, they have even been linked to training status or performance characteristics. However, many of these markers have not been extensively studied and the cost and effort of measuring these parameters are still high, making them inconvenient for practitioners so far. We therefore outline strategies to improve knowledge of acute and chronic biomarker responses, including ideas for standardized study settings. In addition, we emphasize the need for methodological advances such as the development of minimally invasive point-of-care devices as well as statistical aspects related to the evaluation of these monitoring tools to make biomarkers suitable for regular load monitoring.

Myokines as mediators of exercise-induced cognitive changes in older adults: protocol for a comprehensive living systematic review and meta-analysis

Background

The world's population is aging, but life expectancy has risen more than healthy life expectancy (HALE). With respect to brain and cognition, the prevalence of neurodegenerative disorders increases with age, affecting health and quality of life, and imposing significant healthcare costs. Although the effects of physical exercise on cognition in advanced age have been widely explored, in-depth fundamental knowledge of the underlying mechanisms of the exercise-induced cognitive improvements is lacking. Recent research suggests that myokines, factors released into the blood circulation by contracting skeletal muscle, may play a role in mediating the beneficial effect of exercise on cognition. Our goal in this ongoing (living) review is to continuously map the rapidly accumulating knowledge on pathways between acute or chronic exercise-induced myokines and cognitive domains enhanced by exercise.

Method

Randomized controlled studies will be systematically collected at baseline and every 6 months for at least 5 years. Literature search will be performed online in PubMed, EMBASE, PsycINFO, Web of Science, SportDiscus, LILACS, IBECS, CINAHL, SCOPUS, ICTRP, and ClinicalTrials.gov. Risk of bias will be assessed using the Revised Cochrane Risk of Bias tool (ROB 2). A random effects meta-analysis with mediation analysis using meta-analytic structural equation modeling (MASEM) will be performed. The primary research question is to what extent exercise-induced myokines serve as mediators of cognitive function. Secondarily, the pooled effect size of specific exercise characteristics (e.g., mode of exercise) or specific older adults' populations (e.g., cognitively impaired) on the relationship between exercise, myokines, and cognition will be assessed. The review protocol was registered in PROSPERO (CRD42023416996).

Discussion

Understanding the triad relationship between exercise, myokines and cognition will expand the knowledge on multiple integrated network systems communicating between skeletal muscles and other organs such as the brain, thus mediating the beneficial effects of exercise on health and performance. It may also have practical implications, e.g., if a certain myokine is found to be a mediator between exercise and cognition, the optimal exercise characteristics for inducing this myokine can be prescribed. The living review is expected to improve our state of knowledge and refine exercise regimes for enhancing cognitive functioning in diverse older adults' populations.

Registration

Systematic review and meta-analysis protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on the 24th of April 2023 (registration number CRD42023416996).

Ketogenic Diet Combined with Moderate Aerobic Exercise Training Ameliorates White Adipose Tissue Mass, Serum Biomarkers, and Hepatic Lipid Metabolism in High-Fat Diet-Induced Obese Mice

Obesity is a serious public health issue worldwide. Growing evidence demonstrates the efficacy of the ketogenic diet (KD) for weight loss, but there may be some adverse side effects such as dyslipidemia and hepatic steatosis. Aerobic exercise is a widely recognized approach for improving these metabolic markers. Here we explored the combined impacts of KD and moderate aerobic exercise for an 8-week intervention on body weight and fat loss, serum biomarkers, and hepatic lipid metabolism in a mouse model of high-fat diet-induced obesity. Both KD and KD combined with exercise significantly reduced body weight and fat mass. No significant adverse effects of KD were observed in serum biomarkers or hepatic lipid storage, except for an increase in circulating triglyceride level. However, aerobic exercise lowered serum triglyceride levels, and further ameliorated serum parameters, and hepatic steatosis in KD-fed mice. Moreover, gene and protein expression analysis indicated that KD combined with exercise was associated with increased expression of lipolysis-related genes and protein levels, and reduced expression of lipogenic genes relative to KD without exercise. Overall, our findings for mice indicate that further work on humans might reveal that KD combined with moderate aerobic exercise could be a promising therapeutic strategy for obesity.

Exercise Counters the Age-Related Accumulation of Senescent Cells

We propose the beneficial effects of exercise are in part mediated through the prevention and elimination of senescent cells. Exercise counters multiple forms of age-related molecular damage that initiate the senescence program and activates immune cells responsible for senescent cell clearance. Preclinical and clinical evidence for exercise as a senescence-targeting therapy and areas needing further investigation are discussed.

Aerobic exercise regulates FGF21 and NLRP3 inflammasome-mediated pyroptosis and inhibits atherosclerosis in mice

Fibroblast growth factor 21 (FGF21), a known risk factor for atherosclerosis, is readily regulated by exercise, and it can inhibit NOD-like receptor protein 3 (NLRP3)-mediated pyroptosis. However, it is not clear whether aerobic exercise inhibits atherosclerosis via these pathways. Eight-week-old apolipoprotein E-deficient (ApoE-/-) mice on a high-fat diet were randomly divided into 1-h post-exercise (EX-1h), 24-h post-exercise (EX-24h), and sedentary (SED) groups. C57BL/6J wild-type mice fed normal chow served as controls (WT group). Mice in the EX-1h and EX-24h groups were subjected to treadmill exercise training for 12 weeks. Aerobic exercise reduced body weight; blood glucose, lipid, and inflammation levels; and aortic plaque area proportion. Aerobic exercise increased the sensitivity of FGF21 by upregulating the expression of the downstream receptor adiponectin (ApN); the serum FGF21 level after exercise increased initially, and then decreased. Aerobic exercise downregulated the expression of NLRP3 inflammasome-mediated pyroptosis-related markers in the aorta, and FGF21 may participate in the above process. Meanwhile, the liver may be the tissue source of serum FGF21 during aerobic exercise. In conclusion, aerobic exercise may inhibit atherogenesis by regulating FGF21 and NLRP3 inflammasome-mediated pyroptosis. Our study provides new information on the atherosclerosis-preventing mechanism of aerobic exercise.

Cellular and Molecular Regulation of Exercise—A Neuronal Perspective

The beneficial effects of exercise on the proper functioning of the body have been firmly established. Multi-systemic metabolic regulation of exercise is the consequence of multitudinous changes that occur at the cellular level. The exercise responsome comprises all molecular entities including exerkines, miRNA species, growth factors, signaling proteins that are elevated and activated by physical exercise. Exerkines are secretory molecules released by organs such as skeletal muscle, adipose tissue, liver, and gut as a function of acute/chronic exercise. Exerkines such as FNDC5/irisin, Cathepsin B, Adiponectin, and IL-6 circulate through the bloodstream, cross the blood-brain barrier, and modulate the expression of important signaling molecules such as AMPK, SIRT1, PGC1α, BDNF, IGF-1, and VEGF which further contribute to improved energy metabolism, glucose homeostasis, insulin sensitivity, neurogenesis, synaptic plasticity, and overall well-being of the body and brain. These molecules are also responsible for neuroprotective adaptations that exercise confers on the brain and potentially ameliorate neurodegeneration. This review aims to detail important cellular and molecular species that directly or indirectly mediate exercise-induced benefits in the body, with an emphasis on the central nervous system.

Local and systemic transcriptomic responses from acute exercise induced muscle damage of the human knee extensors

Skeletal muscle is adaptable to a direct stimulus of exercise-induced muscle damage (EIMD). Local muscle gene networks and systemic circulatory factors respond to EIMD within days, mediating anti-inflammation and cellular proliferation. Here we show in humans that local EIMD of one muscle group is associated with a systemic response of gene networks that regulate muscle structure and cellular development in non-local homologous muscle not directly altered by EIMD. In the non-dominant knee-extensors of seven males, EIMD was induced through voluntary contractions against an electric motor that lengthened muscles. Neuromuscular assessments, vastus lateralis muscle biopsies and blood draws occurred at two days prior, and one and two days post the EIMD intervention. From the muscle and blood plasma samples, RNA-seq measured transcriptome changes of differential expression using bioinformatic analyses.Relative to the time of the EIMD intervention, local muscle that was mechanically damaged had 475 genes differentially expressed, as compared to 33 genes in the non-local homologous muscle. Gene and network analysis showed that activity of the local muscle was related to structural maintenance, repair, and energetic processes, whereas gene and network activity of the non-local muscle (that was not directly modified by the EIMD) were related to muscle cell development, stress response, and structural maintenance. Altered expression of two novel miRNAs related to the EIMD response supported that systemic factors were active. Together, these results indicate that the expression of genes and gene networks that control muscle contractile structure can be modified in response to non-local EIMD in humans.

Studies in Rats of Combined Muscle and Liver Perfusion and of Muscle Extract Indicate That Contractions Release a Muscle Hormone Directly Enhancing Hepatic Glycogenolysis

Background: Established neuroendocrine signals do not sufficiently account for the exercise-induced increase in glucose production. Using an innovative, yet classical cross-circulation procedure, we studied whether contracting muscle produces a factor that directly stimulates hepatic glycogenolysis. Methods: Isolated rat hindquarters were perfused in series with isolated livers. Results: Stimulation of the sciatic nerve of one or both legs resulted in an increase in force, which rapidly waned. During one-legged contractions, hepatic glucose production increased initially (from −0.9 ± 0.5 (mean ± SE) to 3.3 ± 0.7 µmol/min, p < 0.05). The peak did not differ significantly from that seen after 20 nM of epinephrine (5.1 ± 1.2 µmol/min, p > 0.05). In response to two-legged contractions, the increase in hepatic glucose production (to 5.4 ± 1.3 µmol/min) was higher (p < 0.05) and lasted longer than that seen during one-legged contractions. During contractions, peak hepatic glucose output exceeded concomitant hepatic lactate uptake (p < 0.05), and glucose output decreased to basal levels, while lactate uptake rose to a plateau. Furthermore, in separate experiments an increase in lactate supply to isolated perfused livers increased lactate uptake, but not glucose output. In intact rats, intra-arterial injection of extract made from mixed leg muscle elicited a prolonged increase (p < 0.05) in plasma glucose concentration (from 5.2 ± 0.1 mM to 8.3 ± 1.5 mM). In perfused livers, muscle extract increased glucose output dose dependently. Fractionation by chromatography of the extract showed that the active substance had a MW below 2000. Conclusion: This study provides evidence that contracting skeletal muscle may produce a hormone with a MW below 2000, which enhances hepatic glycogenolysis according to energy needs. Further chemical characterization is warranted.

Circadian rhythms and cancers: the intrinsic links and therapeutic potentials

The circadian rhythm is an evolutionarily conserved time-keeping system that comprises a wide variety of processes including sleep-wake cycles, eating-fasting cycles, and activity-rest cycles, coordinating the behavior and physiology of all organs for whole-body homeostasis. Acute disruption of circadian rhythm may lead to transient discomfort, whereas long-term irregular circadian rhythm will result in the dysfunction of the organism, therefore increasing the risks of numerous diseases especially cancers. Indeed, both epidemiological and experimental evidence has demonstrated the intrinsic link between dysregulated circadian rhythm and cancer. Accordingly, a rapidly increasing understanding of the molecular mechanisms of circadian rhythms is opening new options for cancer therapy, possibly by modulating the circadian clock. In this review, we first describe the general regulators of circadian rhythms and their functions on cancer. In addition, we provide insights into the mechanisms underlying how several types of disruption of the circadian rhythm (including sleep-wake, eating-fasting, and activity-rest) can drive cancer progression, which may expand our understanding of cancer development from the clock perspective. Moreover, we also summarize the potential applications of modulating circadian rhythms for cancer treatment, which may provide an optional therapeutic strategy for cancer patients.

Evaluation of Bone Mineral Density, Serum Osteocalcin, and Osteopontin Levels in Postmenopausal Women with Type 2 Diabetes Mellitus, with/without Osteoporosis

OBJECTIVE

Osteoporosis (OP) is a worldwide ailment; we aim to establish new biomarkers in diagnosis by determining the levels of serum osteocalcin and osteopontin along with bone mineral density (BMD) and lumbar T-score, in postmenopausal women with type 2 diabetes mellitus (T2DM) with or without OP.

METHODS

This observational study included 160 postmenopausal women who were an attendee at outpatient clinics in Al-Hussein Hospital, Thi-Qar province; subdivided into 3 groups based on their T-score testing: Group I (n = 40) comprised postmenopausal women without T2DM as controls, Group II (n = 60) comprised postmenopausal women with T2DM but without OP, and Group III (n = 60) comprised postmenopausal women with T2DM with OP. The dual-energy X-ray absorptiometry was used to measure the BMD (total body, lumbar spine, and femoral) and T-score for lumbar spine and femoral. Glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG), osteocalcin, and osteopontin levels were assessed in all three groups.

RESULTS

Compared with controls, Group III demonstrated significantly lower BMD (total body, lumbar spine, and femoral), T-score for lumbar spine and femoral, serum osteocalcin, and osteopontin levels than Group II and Group I (P < 0.001). FBG and HbA1c levels were significantly higher in Group III than in Groups I and II (P < 0.001). A negative correlation was proved between HbA1c levels with BMD, osteocalcin levels, and osteopontin levels in the three groups.

CONCLUSIONS

Iraqi postmenopausal women with T2DM had a significantly lower bone mineral density, serum osteocalcin, and osteopontin levels. These results may serve as adjuvants in screening for OP, particularly among diabetic patients.

Osteocalcin and the Physiology of Danger

Bone biology has long been driven by the question as to what molecules affect cell differentiation or the functions of bone. Exploring this issue has been an extraordinarily powerful way to improve our knowledge of bone development and physiology. More recently, a second question has emerged: does bone have other functions besides making bone? Addressing this conundrum revealed that the bone-derived hormone osteocalcin affects a surprisingly large number of organs and physiological processes, including acute stress response. This review will focus on this emerging aspect of bone biology taking osteocalcin as a case study and will show how classical and endocrine functions of bone help to define a new functional identity for this tissue.

Multiple Applications of Different Exercise Modalities with Rodents

A large proportion of chronic diseases can be derived from a sedentary lifestyle. Raising physical activity awareness is indispensable, as lack of exercise is the fourth most common cause of death worldwide. Animal models in different research fields serve as important tools in the study of acute or chronic noncommunicable disorders. With the help of animal-based exercise research, exercise-mediated complex antioxidant and inflammatory pathways can be explored, which knowledge can be transferred to human studies. Whereas sustained physical activity has an enormous number of beneficial effects on many organ systems, these animal models are easily applicable in several research areas. This review is aimed at providing an overall picture of scientific research studies using animal models with a focus on different training modalities. Without wishing to be exhaustive, the most commonly used forms of exercise are presented.

Exercise mimetics: harnessing the therapeutic effects of physical activity

Exercise mimetics are a proposed class of therapeutics that specifically mimic or enhance the therapeutic effects of exercise. Increased physical activity has demonstrated positive effects in preventing and ameliorating a wide range of diseases, including brain disorders such as Alzheimer disease and dementia, cancer, diabetes and cardiovascular disease. This article discusses the molecular mechanisms and signalling pathways associated with the beneficial effects of physical activity, focusing on effects on brain function and cognitive enhancement. Emerging therapeutic targets and strategies for the development of exercise mimetics, particularly in the field of central nervous system disorders, as well as the associated opportunities and challenges, are discussed.

Cytokine Drizzle-The Rationale for Abandoning "Cytokine Storm"

BACKGROUND

"Cytokine storm" has been used to implicate increased cytokine levels in the pathogenesis of serious clinical conditions. Similarities with Severe Acute Respiratory Syndrome Coronoavirus-2 (SARS CoV-2) and the 2012 Middle Eastern Respiratory Syndrome led early investigators to suspect a "cytokine storm" resulting in an unregulated inflammatory response associated with the significant morbidity and mortality induced by SARS CoV-2. The threshold of blood cytokines necessary to qualify as a "cytokine storm" has yet to be defined.

METHODS

A literature review was conducted to identify cytokine levels released during 11 assorted clinical conditions or diseases. Weighted averages for various cytokines were calculated by multiplying the number of patients in the paper by the average concentration of each cytokine. Correlation between cytokine levels for individual conditions or diseases were assessed using Pearson correlation coefficient.

RESULTS

The literature was reviewed to determine blood levels of cytokines in a wide variety of clinical conditions. These conditions ranged from exercise and autoimmune disease to septic shock and therapy with chimeric antigen receptor T cells. The most frequently measured cytokine was IL-6 which ranged from 24,123 pg/mL in septic shock to 11 pg/mL after exercise. In patients with severe SARS CoV-2 infections, blood levels of IL-6 were only 43 pg/mL, nearly three magnitudes lower than IL-6 levels in patients with septic shock. The clinical presentations of these different diseases do not correlate with blood levels of cytokines. Additionally, there is poor correlation between the concentrations of different cytokines among the different diseases. Specifically, blood levels of IL-6 did not correlate with levels of IL-8, IL-10, or TNF. Septic shock had the highest concentrations of cytokines, yet multiple cytokine inhibitors have failed to demonstrate improved outcomes in multiple clinical trials. Patients with autoimmune diseases have very low blood levels of cytokines (rheumatoid arthritis, IL-6 = 34 pg/mL; Crohn's disease, IL-6 = 5 pg/mL), yet respond dramatically to cytokine inhibitors.

CONCLUSION

The misleading term "cytokine storm" implies increased blood levels of cytokines are responsible for a grave clinical condition. Not all inflammatory conditions resulting in worsened disease states are correlated with significantly elevated cytokine levels, despite an association with the term "cytokine storm". "Cytokine storm" should be removed from the medical lexicon since it does not reflect the mediators driving the disease nor does it predict which diseases will respond to cytokine inhibitors.

Soluble Interleukin-6 Receptor Regulates Interleukin-6-Dependent Vascular Remodeling in Long-Distance Runners

Little is known about the effects of training load on exercise-induced plasma increase of interleukin-6 (IL-6) and soluble IL-6 receptor (sIL-6R) and their relationship with vascular remodeling. We sought to evaluate the role of sIL 6R as a regulator of IL-6-induced vascular remodeling. Forty-four male marathon runners were recruited and allocated into two groups: low-training (LT, <100 km/week) and high-training (HT, ≥100 km/week), 22 athletes per group. Twenty-one sedentary participants were used as reference. IL-6, sIL-6R and sgp130 levels were measured in plasma samples obtained before and immediately after finishing a marathon (42.2-km). Aortic diameter was measured by echocardiography. The inhibitory effect of sIL-6R on IL-6-induced VSMC migration was assessed using cultured A7r5 VSMCs. Basal plasma IL-6 and sIL-6R levels were similar among sedentary and athlete groups. Plasma IL-6 and sIL-6R levels were elevated after the marathon, and HT athletes had higher post-race plasma sIL-6R, but not IL-6, level than LT athletes. No changes in sgp130 plasma levels were found in LT and HT groups before and after running the marathon. Athletes had a more dilated ascending aorta and aortic root than sedentary participants with no differences between HT and LT athletes. However, a positive correlation between ascending aorta diameter and plasma IL-6 levels corrected by training load and years of training was observed. IL-6 could be responsible for aorta dilation because IL-6 stimulated VSMC migration in vitro, an effect that is inhibited by sIL-6R. However, IL-6 did not modify cell proliferation, collagen type I and contractile protein of VSMC. Our results suggest that exercise induces vascular remodeling. A possible association with IL-6 is proposed. Because sIL-6R inhibits IL-6-induced VSMC migration, a possible mechanism to regulate IL-6-dependent VSMC migration is also proposed.

Insulin Infusion Is Linked to Increased NPPC Expression in Muscle and Plasma C-type Natriuretic Peptide in Male Dogs

The purpose of this study was to assess insulin-stimulated gene expression in canine skeletal muscle with a particular focus on NPPC, the gene that encodes C-type natriuretic peptide, a key hormonal regulator of cardiometabolic function. Four conscious canines underwent hyperinsulinemic, euglycemic clamp studies. Skeletal muscle biopsy and arterial plasma samples were collected under basal and insulin-stimulated conditions. Bulk RNA sequencing of muscle tissue was performed to identify differentially expressed genes between these 2 steady-state conditions. Our results showed that NPPC was the most highly expressed gene in skeletal muscle in response to insulin infusion, rising 4-fold between basal and insulin-stimulated conditions. In support of our RNA sequencing data, we found that raising the plasma insulin concentration 15-fold above basal elicited a 2-fold (P = 0.0001) increase in arterial plasma concentrations of N-terminal prohormone C-type natriuretic peptide. Our data suggest that insulin may play a role in stimulating secretion of C-type natriuretic peptide by skeletal muscle. In this context, C-type natriuretic peptide may act in a paracrine manner to facilitate muscle–vascular bed crosstalk and potentiate insulin-mediated vasodilation. This could serve to enhance insulin and glucose delivery, particularly in the postprandial absorptive state.

Physical Exercise-Induced Myokines in Neurodegenerative Diseases

Neurodegenerative diseases (NDs), such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS), are disorders characterized by progressive degeneration of the nervous system. Currently, there is no disease-modifying treatments for most NDs. Meanwhile, numerous studies conducted on human and animal models over the past decades have showed that exercises had beneficial effects on NDs. Inter-tissue communication by myokine, a peptide produced and secreted by skeletal muscles during exercise, is thought to be an important underlying mechanism for the advantages. Here, we reviewed studies about the effects of myokines regulated by exercise on NDs and their mechanisms. Myokines could exert beneficial effects on NDs through a variety of regulatory mechanisms, including cell survival, neurogenesis, neuroinflammation, proteostasis, oxidative stress, and protein modification. Studies on exercise-induced myokines are expected to provide a novel strategy for treating NDs, for which there are no adequate treatments nowadays. To date, only a few myokines have been investigated for their effects on NDs and studies on mechanisms involved in them are in their infancy. Therefore, future studies are needed to discover more myokines and test their effects on NDs.

Novel methods for cold exposure of skeletal muscle in vivo and in vitro show temperature-dependent myokine production

Proteins secreted from skeletal muscle serving a signalling role have been termed myokines. Many of the myokines are exercise factors, produced and released in response to muscle activity. Cold exposures affecting muscle may occur in recreational, occupational and therapeutic settings. Whether muscle temperature independently affects myokine profile, is still to be elucidated. We hypothesized that manipulating muscle temperature by means of external cooling would change myokine production and release. In the present study we have established new models for cold exposure of muscle in vivo and in vitro where rat hind limb or cultured human myotubes were cooled to 18 °C. After a recovery period, muscle tissue, cells and culture media were harvested for further analysis by qPCR and immunoassays. Expression of several myokine genes were significantly increased after cold exposure in both models: in rat muscle, mRNA levels of CCL2 (p = 0.04), VEGFA (p = 0.02), CXCL1 (p = 0.02) and RBM3 (p = 0.02) increased while mRNA levels of IL-6 (p = 0.03) were decreased; in human myotubes, mRNA levels of IL6 (p = 0.01), CXCL8 (p = 0.04), VEGFA (p = 0.03) and CXCL1 (p < 0.01) were significantly increased, as well as intracellular protein levels of IL-8 (CXCL8 gene product; p < 0.01). The corresponding effect on myokine secretion was not observed, on the contrary, IL-8 (p = 0.02) and VEGF (VEGFA gene product) p < 0.01) concentrations in culture media were reduced after cold exposure in vitro. In conclusion, cold exposure of muscle in vivo and in vitro had an effect on the production and release of several known exercise-related myokines. Myokine expression at the level of mRNA and protein was increased by cold exposure, whereas secretion tended to be decreased.

Muscle-derived interleukin 6 increases exercise capacity by signaling in osteoblasts

Given the numerous health benefits of exercise, understanding how exercise capacity is regulated is a question of paramount importance. Circulating interleukin 6 (IL-6) levels surge during exercise and IL-6 favors exercise capacity. However, neither the cellular origin of circulating IL-6 during exercise nor the means by which this cytokine enhances exercise capacity has been formally established yet. Here we show through genetic means that the majority of circulating IL-6 detectable during exercise originates from muscle and that to increase exercise capacity, IL-6 must signal in osteoblasts to favor osteoclast differentiation and the release of bioactive osteocalcin in the general circulation. This explains why mice lacking the IL-6 receptor only in osteoblasts exhibit a deficit in exercise capacity of similar severity to the one seen in mice lacking muscle-derived IL-6 (mIL-6), and why this deficit is correctable by osteocalcin but not by IL-6. Furthermore, in agreement with the notion that IL-6 acts through osteocalcin, we demonstrate that mIL-6 promotes nutrient uptake and catabolism into myofibers during exercise in an osteocalcin-dependent manner. Finally, we show that the crosstalk between osteocalcin and IL-6 is conserved between rodents and humans. This study provides evidence that a muscle-bone-muscle endocrine axis is necessary to increase muscle function during exercise in rodents and humans.

Exercise intensity regulates cytokine and klotho responses in men

Background

Short-term exercise training programs that consist of moderate intensity endurance training or high intensity interval training have become popular choices for healthy lifestyle modifications, with as little as two weeks of training being shown to improve cardiorespiratory fitness and whole-body glucose metabolism. An emerging concept in exercise biology is that exercise stimulates the release of cytokines and other factors into the blood that contribute to the beneficial effects of exercise on metabolism, but whether these factors behave similarly in response to moderate and high intensity short term training is not known. Here, we determined the effects of two short-term exercise training programs on the concentrations of select secreted cytokines and Klotho, a protein involved in anti-aging.

Methods

Healthy, sedentary men (n = 22) were randomized to moderate intensity training (MIT) or sprint intensity training (SIT) treatment groups. SIT consisted of 6 sessions over 2 weeks of 6 × 30 s all out cycle ergometer sprints with 4 min of recovery between sprints. MIT consisted of 6 sessions over 2 weeks of cycle ergometer exercise at 60% VO_2peak, gradually increasing in duration from 40 to 60 min. Blood was taken before the intervention and 48 h after the last training session, and glucose uptake was measured using [¹⁸F]FDG‐PET/CT scanning. Cytokines were measured by multiplex and Klotho concentrations by ELISA.

Results

Both training protocols similarly increased VO_2peak and decreased fat percentage and visceral fat (P < 0.05). MIT and SIT training programs both reduced the concentrations of IL-6, Hepatocyte Growth Factor (HGF) and Leptin. Interestingly, MIT, but not SIT increased monocyte chemoattractant protein-1 (MCP-1) concentrations, an exercise-induced cytokine, as well as Klotho concentrations.

Conclusion

Short-term exercise training at markedly different intensities similarly improves cardiovascular fitness but results in intensity-specific changes in cytokine responses to exercise.

NAFLD and Physical Exercise: Ready, Steady, Go!

Along with the increase in obesity and type 2 diabetes, the non-alcoholic fatty liver disease (NAFLD) incidence is escalating, thus becoming a leading cause of liver cirrhosis and a significant burden of liver-related outcomes. Since there is no pharmacotherapy available to address the NAFLD, the most effective solutions seem to be lifestyle changes centered on physical activity. Exercise could mediate its beneficial effects directly on the liver and indirectly via extrahepatic pathways, forming a dose-response relationship with NAFLD in terms of prevalence and disease severity. Health-enhancing physical activity (HEPA) levels are mainly needed to exert beneficial effects in obese subjects, while even a small amount of exercise can be beneficial for lean individuals to prevent NAFLD. This mini-review addresses three major points regarding physical activity and NAFLD: prevention, treatment, and extrahepatic benefits, offering recommendations on type and intensity of exercise in liver disease.

Role of Interleukin-6 in Vascular Health and Disease

IL-6 is usually described as a pleiotropic cytokine produced in response to tissue injury or infection. As a pro-inflammatory cytokine, IL-6 activates innate and adaptative immune responses. IL-6 is released in the innate immune response by leukocytes as well as stromal cells upon pattern recognition receptor activation. IL-6 then recruits immune cells and triggers B and T cell response. Dysregulated IL-6 activity is associated with pathologies involving chronic inflammation and autoimmunity, including atherosclerosis. However, IL-6 is also produced and released under beneficial conditions, such as exercise, where IL-6 is associated with the anti-inflammatory and metabolic effects coupled with physical adaptation to intense training. Exercise-associated IL-6 acts on adipose tissue to induce lipogenesis and on arteries to induce adaptative vascular remodeling. These divergent actions could be explained by complex signaling networks. Classical IL-6 signaling involves a membrane-bound IL-6 receptor and glycoprotein 130 (gp130), while trans-signaling relies on a soluble version of IL-6R (sIL-6R) and membrane-bound gp130. Trans-signaling, but not the classical pathway, is regulated by soluble gp130. In this review, we discuss the similarities and differences in IL-6 cytokine and myokine signaling to explain the differential and opposite effects of this protein during inflammation and exercise, with a special focus on the vascular system.

Effects of Exercise on Inflammatory Cytokines in Patients with Type 2 Diabetes: A Meta-analysis of Randomized Controlled Trials

OBJECTIVE

Inflammation is involved in the pathogenesis of type 2 diabetes (T2DM) and the occurrence of insulin resistance. The purpose of this study was to investigate the effects of exercise on inflammatory factors in patients with T2DM.

METHODS

A systematic review was conducted on five databases, Cochrane, Embase, Pubmed, Web of Science, and EBSCO. All randomized controlled trials (RCTs) published between establishment of the database and November 2020 without restrictions on language were included. Studies evaluated the effects of exercise intervention on inflammatory cytokines in patients with T2DM were selected.

RESULTS

Twenty-three randomized controlled trials (1350 patients) were included in our meta-analysis. Exercise can significantly reduce the level of C-reactive protein (CRP) (MD: -0.79, 95% CI: -1.26 to -0.33, p = 0.0008), tumor necrosis factor-α (TNF-α) (MD: -2.33, 95% CI: -3.39 to -1.27, p < 0.0001), and interleukin-6 (IL-6) (MD: -0.42, 95% CI: -0.60 to -0.24, p < 0.0001) in T2DM patients.

CONCLUSION

The findings of this review suggest that exercise reduces inflammatory cytokines (CRP, TNF-α, and IL-6) in T2DM patients. More studies with high methodological qualities and large sample sizes need to be done to confirm which forms of exercise are most effective.

Bone Regulation of Insulin Secretion and Glucose Homeostasis

For centuries our image of the skeleton has been one of an inert structure playing a supporting role for muscles and a protective role for inner organs like the brain. Cell biology and physiology modified this view in the 20st century by defining the constant interplay between bone-forming and bone resorbing cells that take place during bone growth and remodeling, therefore demonstrating that bone is as alive as any other tissues in the body. During the past 40 years human and, most important, mouse genetics, have allowed not only the refinement of this notion by identifying the many genes and regulatory networks responsible for the crosstalk existing between bone cells, but have redefined the role of bone by showing that its influence goes way beyond its own physiology. Among its newly identified functions is the regulation of energy metabolism by 2 bone-derived hormones, osteocalcin and lipocalin-2. Their biology and respective roles in this process are the topic of this review.

Exercise and Muscle Atrophy

The incidence of muscle atrophy is increasing with each passing year, which imposes a huge burden on the quality of life of patients. It is a public health issue that causes a growing concern around the world. Exercise is one of the key strategies to prevent and treat various diseases. Appropriate exercise is conducive to compensatory muscle hypertrophy, to improve muscle strength and elasticity, and to train muscle coordination, which is also beneficial to the recovery of skeletal muscle function and the regeneration of muscle cells. Sequelae of paralysis of patients with limb dyskinesia caused by muscle atrophy will be significantly alleviated after regular exercise therapy. Furthermore, exercise therapy can slow down or even reverse muscle atrophy. This article aims to introduce the characteristics of muscle atrophy and summarize the role and mechanism of exercise in the treatment of muscle atrophy in the existing studies, in order to further explore the mechanism of exercise to protect muscle atrophy and provide protection for patients with muscular atrophy.

The Change of Interleukin-6 Level-Related Genes and Pathways Induced by Exercise in Sedentary Individuals

Sedentary behavior increases the risk of many chronic disorders, in addition, these chronic diseases are associated with elevated markers interleukin-6 (IL-6). Increasing evidence indicates that physical activity can prevent chronic inflammatory disease. However, the effect of exercise on sedentary individuals with disparate basal serum IL-6 level was not well elucidated. In this study, the gene expression profile of GES12384 was downloaded from the Gene Expression Omnibus (GEO) database. This data set contained 12 sedentary middle-aged men (6 high IL-6 and 6 low IL-6 level), and their blood samples were taken in the pre-exercise period and at the end of 24 weeks of exercise. The differentially expressed genes (DEGs) of 24 weeks group were identified, followed by functional enrichment analysis. Subsequently, protein-protein interaction (PPI) network and transcription factors (TFs)-DEGs network were constructed. A total of 193 DEGs were identified between high and low IL-6 level in the 24 weeks group. Functional enrichment analysis showed that DEGs were mainly involved in African trypanosomiasis pathway. PPI network revealed that the hub genes included C-C motif chemokine receptor 7 (CCR7), hemoglobin subunit delta (HBD), and interferon gamma (IFNG). Subnetworks analysis indicated that these genes were relevant to immune response, and participated in African trypanosomiasis pathway. The TF targets network found that myocyte enhancer factor 2A (MEF2A) was a key regulatory factor. In conclusion, the inflammation-related genes (CCR7, HBD, and IFNG) in sedentary individuals could be affected by exercise, and the identified DEGs and TFs in this study promoted our understanding of exercise inhibited the development of chronic disease. [Figure: see text].

Growth and differentiation factor 15 is secreted by skeletal muscle during exercise and promotes lipolysis in humans

We hypothesized that skeletal muscle contraction produces a cellular stress signal, triggering adipose tissue lipolysis to sustain fuel availability during exercise. The present study aimed at identifying exercise-regulated myokines, also known as exerkines, able to promote lipolysis. Human primary myotubes from lean healthy volunteers were submitted to electrical pulse stimulation (EPS) to mimic either acute intense or chronic moderate exercise. Conditioned media (CM) experiments with human adipocytes were performed. CM and human plasma samples were analyzed using unbiased proteomic screening and/or ELISA. Real-time qPCR was performed in cultured myotubes and muscle biopsy samples. CM from both acute intense and chronic moderate exercise increased basal lipolysis in human adipocytes. Growth and differentiation factor 15 (GDF15) gene expression and secretion increased rapidly upon skeletal muscle contraction. GDF15 protein was upregulated in CM from both acute and chronic exercise-stimulated myotubes. We further showed that physiological concentrations of recombinant GDF15 protein increased lipolysis in human adipose tissue, while blocking GDF15 with a neutralizing antibody abrogated EPS CM-mediated lipolysis. We herein provide the first evidence to our knowledge that GDF15 is a potentially novel exerkine produced by skeletal muscle contraction and able to target human adipose tissue to promote lipolysis.

Upregulation of IL-4 signaling contributes to aerobic exercise-induced insulin sensitivity

Insulin resistance (IR) is an important pathological basis of obesity, diabetes and cardiovascular diseases, and emerging evidence demonstrates aerobic exercise as an efficient therapeutical tool in the management of IR and IR-related metabolic disease. Interleukin-4 (IL-4), an important anti-inflammatory cytokine, was recently proved to be involved in regulation of IR, yet the effect of IL-4 on exercise-induced insulin sensitivity and underlying mechanism was less investigated. In this study, using a mouse model of swimming exercise training (60 min/day, 5 days/week for 8 weeks), we found that long-term swimming exercise promoted insulin sensitivity compared with sedentary groups as indexed by the homeostasis model assessment of insulin resistance (HOMA-IR), glucose and insulin tolerance test. Accompanying with increased insulin sensitivity, swimming exercise increased serum IL-4 levels as well as insulin receptor substrate 1 (IRS-1) and protein kinase B (Akt) phosphorylation. Mechanistically, IL-4 treatment increased insulin-stimulated glucose uptake and Akt phosphorylation in skeletal muscle C2C12 cells, and inhibition of IL-4 signaling via ruxolitinib, a Janus kinase (JAK) inhibitor, attenuated IL-4-induced insulin sensitivity. Taken together, our results demonstrated IL-4 as a novel exercise factor contributing to exercise-induced insulin sensitivity, providing a potential therapeutical target of IR and related metabolic disease.

Phenotypes of Sarcopenic Obesity: Exploring the Effects on Peri-Muscular Fat, the Obesity Paradox, Hormone-Related Responses and the Clinical Implications

Sarcopenic obesity combines the words sarcopenia and obesity. This definition of obesity should be better differentiated between visceral and subcutaneous fat phenotypes. For this reason, this review lays the foundation for defining the subcutaneous and the visceral fat into the context of sarcopenia. Thus, the review aims to explore the missing links on pathogenesis of visceral fat and its relationship on age: defining the peri-muscular fat as a new entity and the subcutaneous fat as a first factor that leads to the obesity paradox. Last but not least, this review underlines and motivates the mechanisms of the hormonal responses and anti-inflammatory adipokines responsible for the clinical implications of sarcopenic visceral obesity, describing factor by factor the multiple axis between the visceral fat-sarcopenia and all mortality outcomes linked to cancer, diabetes, cardiovascular diseases, cirrhosis, polycystic ovary, disability and postoperative complications.

Bone Control of Muscle Function

Bone and muscle represent a single functional system and are tightly connected to each other. Indeed, diseases characterized by alterations of muscle physiology have effects on bone remodeling and structure and vice versa. Muscle influence on bone has been deeply studied, and recent studies identified irisin as new molecule involved in this crosstalk. Muscle regulation by bone needs to be extensively investigated since in the last few years osteocalcin was recognized as a key molecule in the bone–muscle interaction. Osteocalcin can exist in two forms with different degrees of carboxylation. The undercarboxylated form of osteocalcin is a hormone released by the bone matrix during the osteoclast bone resorption and can bind its G-protein coupled receptor GPRC6A expressed in the muscle, thus regulating its function. Recently, this hormone was described as an antiaging molecule for its ability to regulate bone, muscle and cognitive functions. Indeed, the features of this bone-related hormone were used to test a new therapeutic approach for sarcopenia, since injection of osteocalcin in older mice induces the acquirement of physical abilities of younger animals. Even if this approach should be tested in humans, osteocalcin represents the most surprising molecule in endocrine regulation by the skeleton.

Extracellular transglutaminase 2 induces myotube hypertrophy through G protein-coupled receptor 56

Skeletal muscle secretes biologically active proteins that contribute to muscle hypertrophy in response to either exercise or dietary intake. The identification of skeletal muscle-secreted proteins that induces hypertrophy can provide critical information regarding skeletal muscle health. Dietary provitamin A, β-carotene, induces hypertrophy of the soleus muscle in mice. Here, we hypothesized that skeletal muscle produces hypertrophy-inducible secretory proteins via dietary β-carotene. Knockdown of retinoic acid receptor (RAR) γ inhibited the β-carotene-induced increase soleus muscle mass in mice. Using RNA sequencing, bioinformatic analyses, and literature searching, we predicted transglutaminase 2 (TG2) to be an all-trans retinoic acid (ATRA)-induced secretory protein in cultured C2C12 myotubes. Tg2 mRNA expression increased in ATRA- or β-carotene-stimulated myotubes and in the soleus muscle of β-carotene-treated mice. Knockdown of RARγ inhibited β-carotene-increased mRNA expression of Tg2 in the soleus muscle. ATRA increased endogenous TG2 levels in conditioned medium from myotubes. Extracellular TG2 promoted the phosphorylation of Akt, mechanistic target of rapamycin (mTOR), and ribosomal p70 S6 kinase (p70S6K), and inhibitors of mTOR, phosphatidylinositol 3-kinase, and Src (rapamycin, LY294002, and Src I1, respectively) inhibited TG2-increased phosphorylation of mTOR and p70S6K. Furthermore, extracellular TG2 promoted protein synthesis and hypertrophy in myotubes. TG2 mutant lacking transglutaminase activity exerted the same effects as wild-type TG2. Knockdown of G protein-coupled receptor 56 (GPR56) inhibited the effects of TG2 on mTOR signaling, protein synthesis, and hypertrophy. These results indicated that TG2 expression was upregulated through ATRA-mediated RARγ and that extracellular TG2 induced myotube hypertrophy by activating mTOR signaling-mediated protein synthesis through GPR56, independent of transglutaminase activity.

Exercise as an anti-inflammatory therapy for cancer cachexia: a focus on interleukin-6 regulation

Cancer cachexia is a complicated disorder of extreme, progressive skeletal muscle wasting. It is directed by metabolic alterations and systemic inflammation dysregulation. Numerous studies have demonstrated that increased systemic inflammation promotes this type of cachexia and have suggested that cytokines are implicated in the skeletal muscle loss. Exercise is firmly established as an anti-inflammatory therapy that can attenuate or even reverse the process of muscle wasting in cancer cachexia. The interleukin IL-6 is generally considered to be a key player in the development of the microenvironment of malignancy; it promotes tumor growth and metastasis by acting as a bridge between chronic inflammation and cancerous tissue and it also induces skeletal muscle atrophy and protein breakdown. Paradoxically, a beneficial role for IL-6 has also been identified recently, and that is its status as a “founding member” of the myokine class of proteins. Skeletal muscle is an important source of circulating IL-6 in people who participate in exercise training. IL-6 acts as an anti-inflammatory myokine by inhibiting TNFα and improving glucose uptake through the stimulation of AMPK signaling. This review discusses the action of IL-6 in skeletal muscle tissue dysfunction and the role of IL-6 as an “exercise factor” that modulates the immune system. This review also sheds light on the main considerations related to the treatment of muscle wasting in cancer cachexia.

Synergetic inhibition of daidzein and regular exercise on breast cancer in bearing-4T1 mice by regulating NK cells and apoptosis pathway

The aim of this study was to investigate the inhibition of daidzein or/and regular exercise on breast cancer and to reveal the potential biological mechanisms. BALB/c mice pretreated with regular exercise training for 20 days (15 m/min, 60 min/d) were orthotopically transplanted with mouse breast cancer cells (4T1), and then treated with daidzein (145 mg/kg) by gavage for another 22 days. Results showed that exercise or daidzein inhibited tumor growth in mice to a different degree. Particularly, co-treatment with exercise and daidzein showed an obviously synergistic inhibition on the tumor growth (P < 0.01), compared with the tumor control. Further researches indicated that the combination of exercise and daidzein synergistically mobilized and redistributed natural killer cells through upregulating the level of epinephrine and interleukin-6. Moreover, exercise combined with daidzein induces apoptosis in cancer cells via Fas/FasL-initiated mitochondrial apoptosis signaling pathway. These results suggested that regular exercise combined with daidzein may explore a candidate way to prevent and treat the breast cancer.

Exercise shapes redox signaling in cancer

In this paper of the special issue dedicated for the Olympics 2020, we put the light on an exciting facet of exercise-oncology, which may still be unknown to some audience. Accumulating convincing evidences show that exercise reduces cancer progression and recurrence mainly in colon and breast cancer patients. Interestingly, the positive effects of exercise on cancer outcomes were mainly observed when patients practiced vigorous exercise of 6 METs or more. At the molecular level, experimental studies highlighted that regular vigorous exercise could reduce tumor growth by driving changes in immune system, metabolism, hormones, systemic inflammation, angiogenesis and redox status. In the present review, we describe the main redox-sensitive mechanisms mediated by exercise. These redox mechanisms are of particular therapeutic interest as they may explain the emerging preclinical findings proving that the association of vigorous exercise with chemotherapy or radiotherapy improves the anti-cancer responses of both interventions. Clinical and preclinical studies converge to support the practice of exercise as an adjuvant therapy that improves cancer outcomes. The understanding of the underpinning molecular mechanisms of exercise in cancer can open new avenues to improve cancer care in patients.

Does exercise-induced apelin affect sarcopenia? A systematic review and meta-analysis

PURPOSE/OBJECTIVE

There have been a number of studies on the role of the novel protein apelin, identified in 1998, in improving muscular function and structure in various human organs, as well as on how it is involved in pathological processes. The aim of this systematic review and meta-analysis was to determine the effect of exercise on serum apelin levels to provide up-to-date data for the development of an exercise intervention for older adults.

METHODS

We searched for articles in PubMed, Ovid MEDLINE, and EMBASE from database inception to May 31, 2019. To conduct a meta-analysis of the primary outcome (serum apelin level), we analyzed intervention effect sizes of the differences between the exercise group and control groups for the primary outcome measure at post-treatment. The outcomes were analyzed using Hedge's statistic effect size (Zr) for weight mean difference (WMD) from various statistical results, including t, F, x², and r. A heterogeneity test was conducted using Higgin's I² statistic and Q statistics (p > 0.10) via a forest plot. A fixed-effect model was considered if Higgin's I² was less than 50%. If heterogeneity was high (I² > 50%), a random-effects model with a subgroup analysis or meta-regression was used. A meta-analysis using nine studies showed that exercise could increase serum apelin levels, which was beneficial for such metabolic diseases as diabetes.

RESULTS

In the subgroup analysis, the 50-60-year-old group showed significant effects of exercise. However, the BMI (normal, overweight, and obesity) categories failed to show any difference in exercise-induced effect.

CONCLUSION

Further studies are needed to clarify in greater detail the effect of resistance exercise on apelin levels, including data on frequency, type, intensity, and time of aerobic exercise, to compare their effects on sarcopenia and cognitive disorders.

Myokine levels after resistance exercise in young adults with Prader-Willi syndrome (PWS)

Individuals with PWS require marked caloric restriction and daily exercise to prevent morbid obesity. Lower energy expenditure, hypotonia, decreased muscle mass, and cognitive impairment make exercise challenging for this population. Exercise guidelines include resistance training as an important component. Myokine responses to resistance exercise may mediate beneficial metabolic effects. We aimed to determine if young PWS adults can perform a resistance exercise program and to measure myokine responses in PWS versus age- and BMI-matched controls. Each group included 11 participants (7M/4F). Ages and BMI for PWS and controls were 30.7 ± 4.6 versus 30.1 ± 4.3 years and 28.3 ± 4.3 versus 28.2 ± 4.2 kg/m² , respectively. Glucose, creatine kinase (CK), lactate, and myokines were measured before, after, 30, and 60 min after completing eight resistance exercises. Myokines were assayed using a multiplex myokine panel (Merck Millipore). CK was lower in PWS versus controls (62 ± 16 vs.322 ± 100 U/L, p < .04). Peak lactate was 3.7 ± 0.7 in PWS versus 7.3 ± 0.7 mmol/Lin controls (p < .001). The increase in interleukin-6 was similar in PWS and controls (41 ± 16% and 35 ± 10%, respectively). Pre- and post-exercise levels of the six myokines assayed showed no consistent differences between the PWS and control participants. PWS young adults are capable of performing resistance/strength-building exercise. The lower CK and peak lactate levels in PWS may reflect decreased muscle mass in this population. Further studies are needed to determine optimal exercise regimens and assess the role of myokines incontributing to the metabolic phenotype of PWS.

The Potential Mechanisms of Exercise-induced Cognitive Protection: A Literature Review

Dementia has become a major health concern for the aging population of the United States. Studies indicate that participation in moderate exercise, with training, has been shown to have a beneficial impact on cognition. Thus, exercise and its effects on cognitive function has become an important area of research. This review summarizes the current literature on the potential mechanisms of the benefits of exercise for cognitive function.

Influence of a Concurrent Exercise Training Intervention during Pregnancy on Maternal and Arterial and Venous Cord Serum Cytokines: The GESTAFIT Project

The aim of the present study was to analyze the influence of a supervised concurrent exercise-training program, from the 17th gestational week until delivery, on cytokines in maternal (at 17th and 35th gestational week, and at delivery) and arterial and venous cord serum. Fifty-eight Caucasian pregnant women (age: 33.5 ± 4.7 years old, body mass index: 23.6 ± 4.1kg/m²) from the GESTAFIT Project (exercise (n = 37) and control (n = 21) groups) participated in this quasi-experimental study (per-protocol basis). The exercise group followed a 60-min 3 days/week concurrent (aerobic-resistance) exercise-training from the 17th gestational week to delivery. Maternal and arterial and venous cord serum cytokines (fractalkine, interleukin (IL)-1β, IL-6, IL-8, IL-10, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α) were assessed using Luminex xMAP technology. In maternal serum (after adjusting for the baseline values of cytokines), the exercise group decreased TNF-α (from baseline to 35th week, p = 0.02), and increased less IL-1β (from baseline to delivery, p = 0.03) concentrations than controls. When adjusting for other potential confounders, these differences became non-significant. In cord blood, the exercise group showed reduced arterial IL-6 and venous TNF-α (p = 0.03 and p = 0.001, respectively) and higher concentrations of arterial IL-1β (p = 0.03) compared to controls. The application of concurrent exercise-training programs could be a strategy to modulate immune responses in pregnant women and their fetuses. However, future research is needed to better understand the origin and clearance of these cytokines, their role in the maternal-placental-fetus crosstalk, and the influence of exercise interventions on them.

Eccentric Muscle Contractions: Risks and Benefits

Eccentric contractions, characterized by the lengthening of the muscle-tendon complex, present several unique features compared with other types of contractions, which may lead to unique adaptations. Due to its specific physiological and mechanical properties, there is an increasing interest in employing eccentric muscle work for rehabilitation and clinical purposes. However, unaccustomed eccentric exercise is known to cause muscle damage and delayed pain, commonly defined as “Delayed-Onset Muscular Soreness” (DOMS). To date, the most useful preventive strategy to avoid these adverse effects consists of repeating sessions involving submaximal eccentric contractions whose intensity is progressively increased over the training. Despite an increased number of investigations focusing on the eccentric contraction, a significant gap still remains in our understanding of the cellular and molecular mechanisms underlying the initial damage response and subsequent adaptations to eccentric exercise. Yet, unraveling the molecular basis of exercise-related muscle damage and soreness might help uncover the mechanistic basis of pathological conditions as myalgia or neuromuscular diseases. In addition, a better insight into the mechanisms governing eccentric training adaptations should provide invaluable information for designing therapeutic interventions and identifying potential therapeutic targets.

Exercise-Induced Myokines With Therapeutic Potential for Muscle Wasting

Skeletal muscle is a highly vascularized tissue that can secrete proteins called myokines. These muscle-secreted factors exert biological functions in muscle itself (autocrine effect) or on short- or long-distant organs (paracrine/endocrine effects) and control processes such as metabolism, angiogenesis, or inflammation. Widely differing diseases ranging from genetic myopathies to cancers are emerging as causing dysregulated secretion of myokines from skeletal muscles. Myokines are also involved in the control of muscle size and may be important to be restored to normal levels to alleviate muscle wasting in various conditions, such as cancer, untreated diabetes, chronic obstructive pulmonary disease, aging, or heart failure. Interestingly, many myokines are induced by exercise (muscle-derived exerkines) and some even by specific types of physical activity, but more studies are needed on this issue. Most exercise-induced myokines travel throughout the body by means of extracellular vesicles. Restoring myokines by physical activity may be added to the list of mechanisms by which exercise exerts preventative or curative effects against a large number of diseases, including the deleterious muscle wasting they may cause. Extending our understanding about which myokines could be usefully restored in certain diseases might help in prescribing more tailored exercise or myokine-based drugs.

The effect of resistance exercise upon age-related systemic and local skeletal muscle inflammation

AIM

Chronic inflammation increases with age and is correlated positively to visceral fat mass, but inversely to muscle mass. We investigated the hypothesis that resistance training would increase muscle mass and strength together with a concomitant drop in local and systemic inflammation level independent of any changes in visceral fat tissue in elderly.

METHODS

25 subjects (mean 67, range 62-70 years) were randomized to 1 year of heavy resistance training (HRT) or control (CON), and tested at 0, 4 and 12 months for physical performance, body composition (DXA), vastus lateralis muscle area (MRI) local and systemic inflammation (blood and muscle). In addition, systemic and local muscle immunological responses to acute exercise was determined before and after the training period.

RESULTS

Increases in muscle mass (≈2%, p < 0.05), vastus lateralis area (≈9%. P < 0.05), isometric (≈15%) and dynamic (≈15%) muscle strength (p < 0.05) were found in the HRT group after 12 months training. HRT did not alter overall or visceral fat mass (p > 0.05). Blood C-Reactive Protein declined over time in both groups (p < 0.05), whereas muscle inflammation markers were unchanged to 1 year of HRT. Acute exercise increased plasma IL-6 and FGF-19 (p < 0.05), decreased FGF-21 (p < 0.05) and CCL-20 (p < 0.05), and increased GDNF in muscle (p < 0.001) similarly before and after 1 year in both groups.

CONCLUSION

Long term resistance training increased muscle strength and improved muscle mass, but did not alter visceral fat mass and did not show any specific effect upon resting or exercise induced markers of inflammation.

Angiopoietin-like proteins in multiple sclerosis

Angiopoietin-like proteins (ANGPTLs) are a group of proteins with functions in lipid metabolism, angiogenesis, and inflammation. Here, we investigated their involvement in multiple sclerosis (MS) progression and response to treatment in 100 MS patients and 77 healthy controls. ANGPTLs significantly associated with MS progression and response to therapy. High ANGPTL6 levels associated with slow disease progression and good response to fingolimod treatment and low ANGPTL4 associated with poor response to natalizumab treatment. Therefore, we propose high ANGPTL4 and 6 levels as markers for positive response to MS treatments either natalizumab or fingolimod respectively. Further investigations into their role in MS is warranted.

Habitual aerobic exercise and circulating proteomic patterns in healthy adults: relation to indicators of healthspan

Habitual aerobic exercise enhances physiological function and reduces risk of morbidity and mortality throughout life, but the underlying molecular mechanisms are largely unknown. The circulating proteome reflects the intricate network of physiological processes maintaining homeostasis and may provide insight into the molecular transducers of the health benefits of physical activity. In this exploratory study, we assessed the plasma proteome (SOMAscan proteomic assay; 1,129 proteins) of healthy sedentary or aerobic exercise-trained young women and young and older men ( n = 47). Using weighted correlation network analysis to identify clusters of highly co-expressed proteins, we characterized 10 distinct plasma proteomic modules (patterns). In healthy young (24 ± 1 yr) men and women, 4 modules were associated with aerobic exercise status and 1 with participant sex. In healthy young and older (64 ± 2 yr) men, 5 modules differed with age, but 2 of these were partially preserved at young adult levels in older men who exercised; among all men, 4 modules were associated with exercise status, including 3 of the 4 identified in young adults. Exercise-linked proteomic patterns were related to pathways involved in wound healing, regulation of apoptosis, glucose-insulin and cellular stress signaling, and inflammation/immune responses. Importantly, several of the exercise-related modules were associated with physiological and clinical indicators of healthspan, including diastolic blood pressure, insulin resistance, maximal aerobic capacity, and vascular endothelial function. Overall, these findings provide initial insight into circulating proteomic patterns modulated by habitual aerobic exercise in healthy young and older adults, the biological processes involved, and their relation to indicators of healthspan. NEW & NOTEWORTHY This is the first study to assess the relation between plasma proteomic patterns and aerobic exercise status in healthy adults. Weighted correlation network analysis identified 10 distinct proteomic modules, including 5 patterns specific for exercise status. Additionally, 5 modules differed with aging in men, two of which were preserved in older exercising men. Exercise-associated modules included proteins related to inflammation, stress pathways, and immune function and correlated with clinical and physiological indicators of healthspan.

Endocrine Crosstalk Between Skeletal Muscle and the Brain

Skeletal muscle is an essential regulator of energy homeostasis and a potent coordinator of exercise-induced adaptations in other organs including the liver, fat or the brain. Skeletal muscle-initiated crosstalk with other tissues is accomplished though the secretion of myokines, protein hormones which can exert autocrine, paracrine and long-distance endocrine effects. In addition, the enhanced release or uptake of metabolites from and into contracting muscle cells, respectively, likewise can act as a powerful mediator of tissue interactions, in particular in regard to the central nervous system. The present review will discuss the current stage of knowledge regarding how exercise and the muscle secretome improve a broad range of brain functions related to vascularization, neuroplasticity, memory, sleep and mood. Even though the molecular and cellular mechanisms underlying the communication between muscle and brain is still poorly understood, physical activity represents one of the most effective strategies to reduce the prevalence and incidence of depression, cognitive, metabolic or degenerative neuronal disorders, and thus warrants further study.