Exercise and mitochondrial health

Mitochondria: An overview of their origin, genome, architecture, and dynamics

Mitochondria are traditionally viewed as the powerhouses of eukaryotic cells, i.e., the main providers of the metabolic energy required to maintain their viability and function. However, the role of these ubiquitous intracellular organelles far extends energy generation, encompassing a large suite of functions, which they can adjust to changing physiological conditions. These functions rely on a sophisticated membrane system and complex molecular machineries, most of which imported from the cytosol through intricate transport systems. In turn, mitochondrial plasticity is rooted on mitochondrial biogenesis, mitophagy, fusion, fission, and movement. Dealing with all these aspects and terminology can be daunting for newcomers to the field of mitochondria, even for those with a background in biological sciences. The aim of the present educational article, which is part of a special issue entitled "Mitochondria in aging, cancer and cell death", is to present these organelles in a simple and concise way. Complex molecular mechanisms are deliberately omitted, as their inclusion would defeat the stated purpose of the article. Also, considering the wide scope of the article, coverage of each topic is necessarily limited, with the reader directed to excellent reviews, in which the different topics are discussed in greater depth than is possible here. In addition, the multiple cell type-specific genotypic and phenotypic differences between mitochondria are largely ignored, focusing instead on the characteristics shared by most of them, with an emphasis on mitochondria from higher eukaryotes. Also ignored are highly degenerate mitochondrion-related organelles, found in various anaerobic microbial eukaryotes lacking canonical mitochondria.

Aerobic exercise improves astrocyte mitochondrial quality and transfer to neurons in a mouse model of Alzheimer's disease

Mitochondrial dysfunction is a well-established hallmark of Alzheimer's disease (AD). Despite recent documentation of transcellular mitochondrial transfer, its role in the pathogenesis of AD remains unclear. In this study, we report an impairment of mitochondrial quality within the astrocytes and neurons of adult 5 × FAD mice. Following treatment with mitochondria isolated from aged astrocytes induced by exposure to amyloid protein or extended cultivation, cultured neurons exhibited an excessive generation of reactive oxygen species and underwent neurite atrophy. Notably, aerobic exercise enhanced mitochondrial quality by upregulating CD38 within hippocampal astrocytes of 5 × FAD mice. Conversely, the knockdown of CD38 diminished astrocytic-neuronal mitochondrial transfer, thereby abolishing the ameliorative effects of aerobic exercise on neuronal oxidative stress, β-amyloid plaque deposition, and cognitive dysfunction in 5 × FAD mice. These findings unveil an unexpected mechanism through which aerobic exercise facilitates the transference of healthy mitochondria from astrocytes to neurons, thus countering the AD-like progression.

Mitochondria in focus: From structure and function to their role in human diseases. A review

Mitochondria, double-membraned organelles within all eukaryotic cells, are essential for the proper functioning of the human organism. The frequently used phrase "powerhouses of the cell" fails to adequately capture their multifaceted roles. In addition to producing energy in the form of adenosine triphosphate through oxidative phosphorylation, mitochondria are also involved in apoptosis (programmed cell death), calcium regulation, and signaling through reactive oxygen species. Recent research suggests that they can communicate with one another and influence cellular processes. Impaired mitochondrial function on the one hand, can have widespread and profound effects on cellular and organismal health, contributing to various diseases and age-related conditions. Regular exercise on the other hand, promotes mitochondrial health by enhancing their volume, density, and functionality. Although research has made significant progress in the last few decades, mainly through the use of modern technologies, there is still a need to intensify research efforts in this field. Exploring new approaches to enhance mitochondrial health could potentially impact longevity. In this review, we focus on mitochondrial research and discoveries, examine the structure and diverse roles of mitochondria in the human body, explore their influence on energy metabolism and cellular signaling and emphasize their importance in maintaining overall health.

Effect of acute performance fatigue on tibial bone strain during basketball maneuvers

The tibia is one of the most common sites for bone stress injury (BSI) in active individuals. BSIs are thought to occur in response to damage accumulation from repetitive loading below the tissue's yield limit. The effect of fatigue on musculoskeletal biomechanics and tibial bone strain during athletic movements remains unclear. In this study, participant-specific finite element (FE) and musculoskeletal models in 10 collegiate-basketball players were used to analyze the effect of acute performance fatigue on joint kinematics and torques, ground reaction forces (GRFs), and the magnitude and distribution of tibial bone strains during select basketball maneuvers. Participants were fatigued by performing repeated exercises wearing a weighted vest until their vertical jump height decreased by 20 %. Fatigue reduced the vertical GRF during midstance of a jump task, and lowered hip and knee peak extension torques and ankle plantarflexion. However, fatigue had limited impact on tibial bone strain magnitude and distribution during jumping. In contrast, there was a shift in peak strain timing following fatigue during a lateral cut task and reduced strain at various times of stance during sprinting. The results suggest that fatigue was induced and, if anything, reduced tibial bone strain. As increased bone strain is thought to be associated with increased BSI risk, the reduced strain observed in the current study suggests that fatigue may actually be partly protective, possibly as a result of reduced muscle activation and force production.

Absolute substrate oxidation rates are lower in older adults with amnestic mild cognitive impairment

Previous studies in individuals with mild cognitive impairment suggest that they may have altered systemic metabolic function at rest; however, metabolic function during aerobic exercise is not fully understood in this population. This study sought to determine whether individuals with amnestic mild cognitive impairment (aMCI) have lower rates of baseline and peak fat oxidation (FatOx) during a graded exercise test (GXT) compared with cognitively unimpaired control participants (CU). Twenty-two (22) older adults with aMCI and 21 age- and sex-matched adults completed a GXT to assess rates of substrate oxidation and peak oxygen consumption (VO2 peak). Rates of FatOx and carbohydrate oxidation (CHOOx) were assessed using VO2 and VCO2. Resting absolute (0.10 ± 0.03 vs. 0.09 ± 0.02 g/min, p = 0.126) and relative (1.5 ± 0.43 vs. 1.4 ± 0.44 mg/kg/min, p = 0.492) rates of FatOx, as well as resting absolute (0.51 ± 0.11 vs. 0.59 ± 0.15 g/min, p = 0.093) and relative (8.0 ± 2.3 vs. 7.5 ± 2.7 mg/kg/min, p = 0.126) rates of CHOOx were similar between groups. However, peak absolute rates of FatOx (0.33 ± 0.13 vs. 0.39 ± 0.10 g/min, p = 0.033) and CHOOx (1.9 ± 0.41 vs. 2.2 ± 0.49 g/min, p = 0.046) were significantly lower in the aMCI group. Time to fatigue (7.2 ± 2.0 vs. 8.7 ± 2.3 min, p = 0.033) and absolute VO2 peak (1.3 ± 0.34 vs. 1.6 ± 0.47 L/min, p = 0.024) were also significantly lower in the aMCI group. These findings suggest that absolute peak rates of whole-body FatOx and CHOOx are reduced during aerobic exercise in older adults with aMCI.

Improving effect of physical exercise on heart failure: Reducing oxidative stress-induced inflammation by restoring Ca2+ homeostasis

Heart failure (HF) is associated with the occurrence of mitochondrial dysfunction. ATP produced by mitochondria through the tricarboxylic acid cycle is the main source of energy for the heart. Excessive release of Ca2+ from myocardial sarcoplasmic reticulum (SR) in HF leads to excessive Ca2+ entering mitochondria, which leads to mitochondrial dysfunction and REDOX imbalance. Excessive accumulation of ROS leads to mitochondrial structure damage, which cannot produce and provide energy. In addition, the accumulation of a large number of ROS can activate NF-κB, leading to myocardial inflammation. Energy deficit in the myocardium has long been considered to be the main mechanism connecting mitochondrial dysfunction and systolic failure. However, exercise can improve the Ca2+ imbalance in HF and restore the Ca2+ disorder in mitochondria. Similarly, exercise activates mitochondrial dynamics to improve mitochondrial function and reshape intact mitochondrial structure, rebalance mitochondrial REDOX, reduce excessive release of ROS, and rescue cardiomyocyte energy failure in HF. In this review, we summarize recent evidence that exercise can improve Ca2+ homeostasis in the SR and activate mitochondrial dynamics, improve mitochondrial function, and reduce oxidative stress levels in HF patients, thereby reducing chronic inflammation in HF patients. The improvement of mitochondrial dynamics is beneficial for ameliorating metabolic flow bottlenecks, REDOX imbalance, ROS balance, impaired mitochondrial Ca2+ homeostasis, and inflammation. Interpretation of these findings will lead to new approaches to disease mechanisms and treatment.

Bridging the gap: Integrating exercise mimicry into chronic disease management through suppressing chronic inflammation

BACKGROUND

Chronic inflammation is a common hallmark of many chronic diseases. Although exercise holds paramount importance in preventing and managing chronic diseases, adherence to exercise programs can be challenging for some patients. Consequently, there is a pressing need to explore alternative strategies to emulate the anti-inflammatory effects of exercise for chronic diseases.

AIM OF REVIEW

This review explores the emerging role of green tea bioactive components as potential mitigators of chronic inflammation, offering insights into their capacity to mimic the beneficial effects of exercise. We propose that bioactive components in green tea are promising agents for suppressing chronic inflammation, suggesting their unique capability to replicate the health benefits of exercise.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review focuses on several key concepts, including chronic inflammation and its role in chronic diseases, the anti-inflammatory effects of regular exercise, and bioactive components in green tea responsible for its health benefits. It elaborates on scientific evidence supporting the anti-inflammatory properties of green tea bioactive components, such as epigallocatechin gallate (EGCG), and theorizes how these bioactive components might replicate the effects of exercise at a molecular level. Through a comprehensive analysis of current research, this review proposes a novel perspective on the application of green tea as a potential intervention strategy to suppress chronic inflammation, thereby extending the benefits akin to those achieved through exercise.

Acute treadmill exercise induces mitochondrial unfolded protein response in skeletal muscle of male rats

Mitochondria are often referred to as the energy centers of the cell and are recognized as key players in signal transduction, sensing, and responding to internal and external stimuli. Under stress conditions, the mitochondrial unfolded protein response (UPRmt), a conserved mitochondrial quality control mechanism, is activated to maintain mitochondrial and cellular homeostasis. As a physiological stimulus, exercise-induced mitochondrial perturbations trigger UPRmt, coordinating mitochondria-to-nucleus communication and initiating a transcriptional program to restore mitochondrial function. The aim of this study was to evaluate the UPRmt signaling response to acute exercise in skeletal muscle. Male rats were subjected to acute treadmill exercise at 25 m/min for 60 min on a 0 % grade. Plantaris muscles were collected from both sedentary and exercise groups at various times: immediately (0), and at 1, 3, 6, 12, and 24 h post-exercise. Reactive oxygen species (ROS) production was assessed using hydrogen peroxide assay and dihydroethidium staining. Additionally, the mRNA and protein expression of UPRmt markers were measured using ELISA and real-time PCR. Mitochondrial activity was assessed using succinate dehydrogenase (SDH) and cytochrome c oxidase (COX) staining. Our results demonstrated that acute exercise increased ROS production and upregulated UPRmt markers at both gene and protein levels. Moreover, skeletal muscle exhibited an increase in mitochondrial activity in response to exercise, as indicated by SDH and COX staining. These findings suggest that acute treadmill exercise is sufficient to induce ROS production, activate UPRmt signaling, and enhance mitochondrial activity in skeletal muscle, expanding our understanding of mitochondrial adaptations to exercise.

In Vivo Reprogramming of Tissue-Derived Extracellular Vesicles for Treating Chronic Tissue Injury Through Metabolic Engineering

Extracellular vesicles (EVs) have emerged as promising therapeutics for regenerative medicine, but the efficacy of current exogenous EV-based therapies for treating chronic tissue injury is still unsatisfactory. Exercise can affect skeletal muscle EV secretion and that this process regulates the systemic health-promoting role of exercise, suggesting that fine-tuning of endogenous tissue EV secretion may provide a new therapeutic avenue. Here, this work reports that in vivo reprogramming of EV secretion via metabolic engineering is a promising strategy for treating chronic diseases. Briefly, exercise enhanced mitochondrial metabolism and EV production in healthy skeletal muscles, and EVs from healthy skeletal muscles subjected to exercise or metabolic engineering (boosting mitochondrial biogenesis via AAV-mediated muscle-specific TFAM overexpression) exerted cellular protective effects in vitro. In injured skeletal muscles, in vivo metabolic engineering therapy could reprogram EV secretion patterns (reducing pathological EV compositions while increasing beneficial EV compositions) by regulating multiple EV biogenesis and cargo sorting pathways. Reprogrammed muscle-derived EVs could reach major organs and tissues via the circulation and then simultaneously attenuated multiple-tissue (e.g., muscle and kidney) injury in chronic kidney disease. This study highlights that in vivo reprogramming of tissue-derived EVs via a metabolic engineering approach is a potential strategy for treating diverse chronic diseases.

Short-term structured dietary and exercise interventions delay diabetes onset in prediabetic patients: a prospective quasi-experimental study

Hypothesis

Prediabetes indicates an increased risk of developing diabetes mellitus. We hypothesized that structured anti-inflammatory and antioxidant dietary and exercise interventions (SAIDEs) can reduce the onset of diabetes in prediabetic patients.

Methods

This study included 542 prediabetic patients who met at least one of the three common criteria for prediabetes: fasting blood glucose (FBG), 2-h oral glucose tolerance (2h OGTT), or hemoglobin A1c (HbA1C). Patients were randomly assigned to one of four groups using the block randomization method: routine community intervention, dietary intervention, exercise intervention, or SAIDEs for 6 months. Follow-up assessments were conducted at 6 months and 7.5 years, monitoring diabetes-related outcomes, inflammatory markers, and diabetes progression.

Results

At baseline, most tested variables, including age, gender, body weight, blood lipids, blood sugar, β-cell function, blood inflammatory and immunological markers, and energy intake, did not differ among the groups. After 6 months of short-term interventions (diet, exercise, and SAIDEs) and 6 months of follow-up, all intervention groups exhibited reduced total energy intake, body weight, blood pressure, blood cholesterol, and glucose levels, along with improved β-cell functions (all p < 0.001). Regardless of time considerations, intervention consistently increased total physical activity (p < 0.001). Short-term interventions also reduced blood IgE, high-sensitivity C-reactive protein, IL-6, and TNF-α, while increasing blood IL-4 and IL-10 (all p < 0.001). The prevalence of abnormal blood glucose markers-FBG, 2h OGTT, and HbA1C-significantly decreased within each intervention group after short-term intervention and 6 months of follow-up. The time-dependent Cox regression test did not indicate a significant effect of dietary or exercise intervention on diabetes incidence over the 8-year follow-up period. However, the log-rank test revealed significant differences in "survival" distribution among the four intervention groups (χ 2 = 15.63, p = 0.001). The mean survival time before diabetes onset was significantly longer in prediabetic patients who received SAIDEs than in those in other groups.

Conclusions

Short-term intervention with SAIDEs exhibited significant anti-inflammatory activity and reduced the prevalence of abnormal blood glucose markers. These benefits persisted even after 6 months of follow-up. However, over the 8-year follow-up period, intensive SAIDEs did not reduce diabetes incidence among prediabetic patients but did delay its onset.

Clinical trial registration

https://www.chictr.org.cn/searchproj.html, identifier ChiCTR-IOR-16008445.

Mitochondrial targeted therapies in MAFLD

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a clinical-pathological syndrome primarily characterized by excessive accumulation of fat in hepatocytes, independent of alcohol consumption and other well-established hepatotoxic agents. Mitochondrial dysfunction is widely acknowledged as a pivotal factor in the pathogenesis of various diseases, including cardiovascular diseases, cancer, neurodegenerative disorders, and metabolic diseases such as obesity and obesity-associated MAFLD. Mitochondria are dynamic cellular organelles capable of modifying their functions and structures to accommodate the metabolic demands of cells. In the context of MAFLD, the excess production of reactive oxygen species induces oxidative stress, leading to mitochondrial dysfunction, which subsequently promotes metabolic disorders, fat accumulation, and the infiltration of inflammatory cells in liver and adipose tissue. This review aims to systematically analyze the role of mitochondria-targeted therapies in MAFLD, evaluate current therapeutic strategies, and explore future directions in this rapidly evolving field. We specifically focus on the molecular mechanisms underlying mitochondrial dysfunction, emerging therapeutic approaches, and their clinical implications. This is of significant importance for the development of new therapeutic approaches for these metabolic disorders.

Efficacy and Safety of Photobiomodulation in MELAS: Protocol for a Series of N-of-1 Trials

Background: There is no cure for mitochondrial diseases which manifest in numerous ways including fatigue, muscle weakness, and exercise intolerance. Medical treatment varies and focuses on managing symptoms. Photobiomodulation (PBM) can decrease mitochondrial damage thereby increasing energy production and decreasing cell death. This pilot study will apply PBM to people with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) to examine the safety of application, and if changes occur in symptoms and signs after cross-over application/withdrawal of a sham or active PBM treatment including a two-week period of washout. Methods: This study is an exploratory, prospective series N-of-1 (single patient) studies. The protocol is guided by the CONSORT extension for reporting N-of-1 trials (CENT 2015), chosen due to the rarity of mitochondrial diseases, the fluctuating symptomology, and heterogeneity of the clinical presentation. The primary outcome is patient-reported fatigue assessed using the Checklist of Individual Strength and with concomitant evaluation of safety. Secondary measures are of depression, anxiety and stress, sleepiness, physical activity, blood lactate and creatine kinase, physical measures of sit-to-stand, and heel raise capability. Mitochondrial function will be evaluated using hydrogen magnetic resonance spectroscopy for lactate. PBM will be a participant-administered, home-based therapy using a multiple diode flexible array (BeniLight iLED-Pro Multi-Wave Multi-Pulse belt; 465 nm, 660 nm, 850 nm; average irradiance 5.23 mW/cm2; total joules: 770.1 J/treatment, all sites; 5 KHz; 20% duty ratio) over the anterior thigh muscles, posterior calf muscles and abdomen for 10 min to each site, three times/week. The safety of the intervention will be assessed. Descriptive statistics, causal analyses of time series data and dynamic modelling will be applied as relevant to the variables collected. Hydrogen magnetic resonance spectra will be acquired and averaged to obtain the content of the targeted hydrogen levels. Discussion: The study will provide guidance on whether and how to progress to a larger, randomised cohort study with sham control.

Unveiling the link: exploring muscle oxygen saturation in fibromyalgia and its implications for symptomatology and therapeutic strategies

Fibromyalgia, characterized as a complex chronic pain syndrome, presents with symptoms of pervasive musculoskeletal pain, significant fatigue, and pronounced sensitivity at specific anatomical sites. Despite extensive research efforts, the origins of fibromyalgia remain enigmatic. This narrative review explores the intricate relationship between muscle oxygen saturation and fibromyalgia, positing that disruptions in the oxygenation processes within muscle tissues markedly influence the symptom profile of this disorder. Muscle oxygen saturation, crucial for muscle function, has been meticulously investigated in fibromyalgia patients through non-invasive techniques such as near-infrared spectroscopy and magnetic resonance imaging. The body of evidence consistently indicates substantial alterations in oxygen utilization within muscle fibers, manifesting as reduced efficiency in oxygen uptake during both rest and physical activity. These anomalies play a significant role in fibromyalgia's symptomatology, especially in terms of chronic pain and severe fatigue, potentially creating conditions that heighten pain sensitivity and accumulate metabolic byproducts. Hypothesized mechanisms for these findings encompass dysfunctions in microcirculation, mitochondrial irregularities, and autonomic nervous system disturbances, all meriting further research. Understanding the dynamics of muscle oxygen saturation in fibromyalgia is of paramount clinical importance, offering the potential for tailored therapeutic approaches to alleviate symptoms and improve the quality of life for sufferers. This investigation not only opens new avenues for innovative research but also fosters hope for more effective treatment strategies and improved outcomes for individuals with fibromyalgia.

Pioneering the future: incorporating lifestyle medicine tools in osteopathic medical education

The role of lifestyle has taken a renewed importance in disease prevention and chronic disease management. Osteopathic medicine has long focused on comprehensive, holistic care for our patients, and the tenets support the role of lifestyle medicine (LM) in osteopathic clinical care. In this commentary, the authors make the argument for incorporating LM more formally into the clinical curriculum at colleges of osteopathic medicine and will draw parallels with these two programs.

Effects of Sulforaphane Treatment on Skeletal Muscle from Exhaustive Exercise-Induced Inflammation and Oxidative Stress Through the Nrf2/HO-1 Signaling Pathway

Skeletal muscle is primarily involved in exercise performance and health promotion. Sulforaphane (SFN) is a naturally occurring isothiocyanate that indirectly activates the transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), thus inducing the expression of Nrf2 target genes, including antioxidant enzymes. This study aimed to identify the effects of a single dose of SFN administration on exhaustive exercise-induced inflammation and oxidative stress in skeletal muscle tissue and elucidate the underlying mechanisms. Thirty-six mice were divided into four groups: control, SFN, exercise (Ex), and SFN + Ex. The SFN group and SFN + Ex group received SFN orally (50 mg/kg body weight) 2 h before the running test. Exercise significantly reduced plasma glucose levels, while the SFN-treated group exhibited a smaller reduction. Acute exhaustive exercise increased the expression of pro-inflammatory cytokines in muscle tissue, while the SFN + Ex group exhibited significantly reduced expression of pro-inflammatory cytokines. The gene expression of Nrf2 and its target enzymes, including heme oxygenase (HO)-1, superoxide dismutase (SOD)-1, catalase (CAT), and glutathione peroxidase (GPx)-1, was measured in the gastrocnemius and soleus muscle tissue. Compared with the Ex group, the SFN + Ex group showed upregulated expression of all these parameters, including Nrf2. SFN treatment reduced acute exhaustive exercise-induced oxidative stress and inflammation via activation of the Nrf2/HO-1 signaling pathway.

Low-Magnitude High-Frequency Vibration Attenuates Sarcopenia by Modulating Mitochondrial Quality Control via Inhibiting miR-378

BACKGROUND

Sarcopenia, the age-related decline in muscle mass and muscle strength, significantly contributes to falls, diminished quality of life, and mortality. Although mitochondrial dysfunction is increasingly implicated in sarcopenia, the underlying mechanisms are not fully discovered. Low-magnitude high-frequency vibration (LMHFV), a recommended treatment by the Centers for Disease Control and Prevention (CDC) to reduce fall risk, remains poorly understood of the mechanism on improving skeletal muscle quality. This study aims to investigate whether mitochondrial dysfunction contributes to sarcopenia and evaluate whether LMHFV mitigates sarcopenia by improving mitochondrial homeostasis.

METHODS

The relationship between mitochondria dysfunction and sarcopenia using senescence accelerated mice prone 8 (SAMP8) model was investigated, assessing muscle and mitochondria. The effects of LMHFV on muscle and mitochondria were evaluated in SAMP8 mice during sarcopenia progression. The role of miR-378 in muscle and mitochondrial homeostasis were evaluated in SAMP8 mice and transgenic over-expressing miR-378 mice (TG mice). The target gene of miR-378 was investigated by dual-luciferase reporter assay in C2C12 cells. Subsequently, we evaluated the effect of LMHFV on miR-378 using both mouse models.

RESULTS

Reduction in muscle strength was observed from the ages of month 8 to 10 in SAMP8 mice (grip strength decreased 27.1%, p = 0.0263; twitch force decreased 29.1%, p = 0.0178; tetanic force decreased 29.9%, p = 0.011), as well as muscle atrophy (cross-section area: 38.3%, p = 0.0121). Mitochondrial morphological deterioration was noticed from month 6 to 10. Mitochondrial homeostasis, including biogenesis, fusion, fission, mitophagy, and ATP production declined from month 6 to 10. Compared to control group at month 10, knocking down miR-378 in SAMP8 mice mitigated sarcopenia (twitch force increased 44.3%, p = 0.0023; tetanic force increased 51.9%, p = 0.0005), improved mitochondrial morphologies (mitochondrial number increased 1.65-fold, p = 0.0023; mitochondrial density increased 1.65-fold, p = 0.0023; mitochondrial relative area increased 9.05-fold, p = 0.0019) along with improved mitochondrial homeostasis. Over-expressing miR-378 in transgenic mice exacerbated muscle atrophy and mitochondrial deterioration significantly. The dual-luciferase reporter assay in C2C12 cells revealed that miR-378 inhibited PGC-1α directivity. LMHFV was found to mitigate sarcopenia by modulating mitochondrial homeostasis, such as attenuating mitochondrial morphological deterioration and improving mitochondrial biogenesis through increasing PGC-1α via inhibiting miR-378 in skeletal muscle.

CONCLUSIONS

Our findings indicate that mitochondrial biogenesis, fusion, fission, and mitophagy were compromised during progression of sarcopenia, with mitochondrial deterioration preceding the onset of sarcopenia symptoms. The study also demonstrated that LMHFV could attenuate sarcopenia by modulating mitochondrial quality control through inhibiting miR-378, highlighting its therapeutic potential in the management of age-related muscular degeneration.

The Effects of Glucagon-Like Peptide-1 Receptor Agonists on Mitochondrial Function Within Skeletal Muscle: A Systematic Review

BACKGROUND

Obesity is a chronic disease associated with increased risk of multiple metabolic and mental health-related comorbidities. Recent advances in obesity pharmacotherapy, particularly with glucagon-like peptide-1 (GLP-1) receptor agonists (RAs), have the potential to transform obesity and type 2 diabetes mellitus (T2DM) care by promoting marked weight loss, improving glycaemic control and addressing multiple obesity-related comorbidities, with added cardio-renal benefits. Dual agonists combining GLP-1 with other enteropancreatic hormones such as glucose-dependent insulinotropic polypeptide (GIP) have also been developed in recent years, leading to greater weight loss than using GLP-1 RAs alone. However, up to 40% of the weight lost with GLP-1 RAs comes from lean body mass, raising concerns about potential adverse effects on skeletal muscle function. Mitochondrial dysfunction, characterized by reduced mitochondrial size and activity, is prevalent in individuals with obesity and T2DM and is a known contributor to muscle wasting in ageing and some chronic diseases. This systematic review investigates the impact of GLP-1-based therapies on skeletal muscle mitochondrial function in individuals with obesity and T2DM or in related animal and cell models.

METHODS

A comprehensive search of MEDLINE, Scopus, CINAHL and clinicaltrials.gov was conducted. Inclusion criteria included randomized controlled trials, randomized crossover trials, cluster randomized control trials and basic science studies involving any GLP-1 RA or GLP-1/GIP dual agonist. Outcomes of interest were skeletal muscle respiratory function either in the form of measurements of mass, number, content, oxidative capacity/respiratory function, mitochondrial dynamics, mitochondrial biogenesis and mitophagy.

RESULTS

Eight studies were eligible for analysis; no human studies were identified. All of the included studies used GLP-1 RAs (single agonists) as intervention. The emerging evidence suggests that GLP-1 RAs increase mitochondrial area, number and morphology (i.e., reduces swelling). Data are conflicting on the effect of GLP-1 RAs upon mitochondrial mass, respiration and the expression of uncoupling proteins and PGC-1α. Data also demonstrate muscle specific (i.e., soleus vs. extensor digitorum longus) responses to GLP-1 RAs.

CONCLUSION

GLP-1 RAs appear to have a positive effect upon mitochondria area, number and morphology, but effects upon other aspects of mitochondrial health remain inconclusive. Data are very limited and solely presented in animal and in vitro models. Future studies should be conducted in human populations in order to begin to understand the effect of GLP-1 RAs and GLP-1-based therapies on human skeletal muscle mitochondria.

Sulforaphane treatment mimics contractile activity-induced mitochondrial adaptations in muscle myotubes

Mitochondria are metabolic hubs that govern skeletal muscle health. Although exercise has been established as a powerful inducer of quality control processes that ultimately enhance mitochondrial function, there are currently limited pharmaceutical interventions available that emulate exercise-induced mitochondrial adaptations. To investigate a novel candidate for this role, we examined sulforaphane (SFN), a naturally occurring compound found in cruciferous vegetables. SFN has been documented as a potent antioxidant inducer through its activation of the nuclear factor erythroid 2-related factor 2 (Nrf-2) antioxidant response pathway. However, its effects on muscle health have been underexplored. To investigate the interplay between chronic exercise and SFN, C2C12 myotubes were electrically stimulated to model chronic contractile activity (CCA) in the presence or absence of SFN. SFN promoted Nrf-2 nuclear translocation, enhanced mitochondrial respiration, and upregulated key antioxidant proteins including catalase and glutathione reductase. These adaptations were accompanied by reductions in cellular and mitochondrial reactive oxygen species (ROS) emission. Signaling toward biogenesis was enhanced, demonstrated by increases in mitochondrial transcription factor A (TFAM), peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1α nuclear translocation, PGC-1α promoter activity, mitochondrial content, and organelle branching, suggestive of a larger, more interconnected mitochondrial pool. These mitochondrial adaptations were accompanied by an increase in lysosomal proteins, suggesting coordinated regulation. There was no difference in mitochondrial and antioxidant-related proteins between CCA and non-CCA SFN-treated cells. Our data suggest that SFN activates signaling cascades that are common to those produced by contractile activity, indicating that SFN-centered therapeutic strategies may improve the mitochondrial phenotype in skeletal muscle.NEW & NOTEWORTHY Nrf-2 is a transcription factor that has been implicated in mitigating oxidative stress and regulating mitochondrial homeostasis. However, limited research has demonstrated how Nrf-2-mediated adaptations compare with those produced by exercise. To investigate this, we treated myotubes with Sulforaphane, a well-established Nrf-2 activator, and combined this with stimulation-induced chronic contractile activity to model exercise training. Our work is the first to establish that sulforaphane mimics training-induced mitochondrial adaptations, including enhancements in respiration, biogenesis, and dynamics.

Skeletal Muscle mRNA Splicing Variants Association With Four Different Fitness and Energetic Measures in the GESTALT Study

BACKGROUND

Physical activity is essential for maintaining muscle mitochondrial function and aerobic capacity. The molecular mechanisms underlying such protective effects are incompletely understood, in part because it is difficult to separate the effects of disease status and physical activity. We explored the association of human skeletal muscle transcriptomic with four measures of energetics and mitochondria oxidative capacity in healthy individuals.

METHODS

Using RNA sequencing of vastus lateralis muscle biopsies from 82 GESTALT participants (52 males, aged 22-89 years), we explored gene and splicing variant expression profiles associated with self-reported physical activity, peak oxygen consumption (VO2 peak), muscle oxidative capacity (kPCr) and mitochondrial respiration (Mit-O2 flux). The effect of aging on gene expression was examined in participants with low and high VO2 peak.

RESULTS

The four measures of energetics were negative correlated with age and generally intercorrelated. We identified protein-coding genes associated with four energetic measures adjusting for age, muscle fiber-ratio, sex and batch effect. Mitochondrial pathways were overrepresented across all energetic variables, albeit with little overlap at the gene level. Alternative spliced transcript isoforms associated with energetics were primarily enriched for cytoplasmic ribonucleoprotein granules. The splicing pathway was up-regulated with aging in low but not in high fitness participants, and transcript isoforms detected in the low fitness group pertain to processes such as cell cycle regulation, RNA/protein localization, nuclear transport and catabolism.

CONCLUSIONS

A consistent mitochondrial signature emerged across all energetic measures. Alternative splicing was enhanced in older, low fitness participants supporting the energy-splicing axis hypothesis. The identified splicing variants were enriched in pathways involving the accumulation of ribonucleoproteins in cytoplasmic granules, whose function remains unclear. Further research is needed to understand the function of these proteoforms in promoting adaptation to low energy availability.

The acute and chronic influence of exercise on mitochondrial dynamics in skeletal muscle

Exercise and nutritional modulation are potent stimuli for eliciting increases in mitochondrial mass and function. Collectively, these beneficial adaptations are increasingly recognized to coincide with improvements in skeletal muscle health. Mitochondrial dynamics of fission and fusion are increasingly implicated as having a central role in mediating aspects of key organelle adaptations that are seen with exercise. Exercise-induced mitochondrial adaptation dynamics that have been implicated are 1) increases to mitochondrial turnover, resulting from elevated rates of mitochondrial synthesis (biogenesis) and degradative (mitophagy) processes and 2) morphological changes to the three-dimensional (3-D) tubular network, known as the mitochondrial reticulum, that mitochondria form in skeletal muscle. Notably, mitochondrial fission has also been implicated in coordinating increases in mitophagy, following acute exercise. Furthermore, increased fusion following exercise training promotes increased connectivity of the mitochondrial reticulum and is associated with improved metabolism and mitochondrial function. However, the molecular basis and fashion in which exercise infers beneficial mitochondrial adaptations through mitochondrial dynamics remains to be fully elucidated. This review attempts to highlight recent developments investigating the effects of exercise on mitochondrial dynamics, while attempting to offer a perspective of the methodological refinements and potential variables, such as substrate/glycogen availability, which should be considered going forward.

Physical activity, cathepsin B, and cognitive health

Regular physical activity (PA) is beneficial for cognitive health, and cathepsin B (CTSB) - a protease released by skeletal muscle during PA - acts as a potential molecular mediator of this association. PA-induced metabolic and mechanical stress appears to increase plasma/serum CTSB levels. CTSB facilitates neurogenesis and synaptic plasticity in brain regions (e.g., hippocampus and prefrontal cortex) that support performance in specific cognitive domains including memory, learning, and executive function. However, the evidence regarding the role of PA-induced changes in CTSB as a mediator of PA-induced cognitive health in humans is mixed. To guide future research, this article identifies key factors that may explain the observed heterogeneity in the findings from human studies and proposes a PA-CTSB-cognition model.

Exerkines and Sarcopenia: Unveiling the Mechanism Behind Exercise-Induced Mitochondrial Homeostasis

Background/Objectives: Sarcopenia, characterized by the progressive loss of muscle mass and strength, is linked to physical disability, metabolic dysfunction, and an increased risk of mortality. Exercise therapy is currently acknowledged as a viable approach for addressing sarcopenia. Nevertheless, the molecular mechanisms behind exercise training or physical activity remain poorly understood. The disruption of mitochondrial homeostasis is implicated in the pathogenesis of sarcopenia. Exercise training effectively delays the onset of sarcopenia by significantly maintaining mitochondrial homeostasis, including promoting mitophagy, improving mitochondrial biogenesis, balancing mitochondrial dynamics, and maintaining mitochondrial redox. Exerkines (e.g., adipokines, myokines, hepatokines, and osteokines), signaling molecules released in response to exercise training, may potentially contribute to skeletal muscle metabolism through ameliorating mitochondrial homeostasis, reducing inflammation, and regulating protein synthesis as a defense against sarcopenia. Methods: In this review, we provide a detailed summary of exercise-induced exerkines and confer their benefit, with particular focus on their impact on mitochondrial homeostasis in the context of sarcopenia. Results: Exercise induces substantial adaptations in skeletal muscle, including increased muscle mass, improved muscle regeneration and hypertrophy, elevated hormone release, and enhanced mitochondrial function. An expanding body of research highlights that exerkines have the potential to regulate processes such as mitophagy, mitochondrial biogenesis, dynamics, autophagy, and redox balance. These mechanisms contribute to the maintenance of mitochondrial homeostasis, thereby supporting skeletal muscle metabolism and mitochondrial health. Conclusions: Through a comprehensive investigation of the molecular mechanisms within mitochondria, the context reveals new insights into the potential of exerkines as key exercise-protective sensors for combating sarcopenia.

Association of blood cadmium and physical activity with mortality: A prospective cohort study

Physical activity (PA) may be considered an alternative method to ameliorate the elevated mortality risks associated with cadmium exposure. In this prospective cohort study, a total of 20,253 participants (weighted mean age, 47.79 years), including 10,247 men (weighted prevalence: 50.1 %), aged 18 years or older, were selected from the National Health and Nutrition Examination Survey from 2007 to 2018. Multivariable Cox proportional hazards regression models were utilized to evaluate the associations between blood cadmium levels, PA, and the risks of mortality. Restricted cubic spline analyses were employed to investigate the nonlinear relationships between blood cadmium and PA levels and mortality risks. During a median follow-up of 7.6 years, a total of 2002 (9.89 %) all-cause deaths occurred, of which 581 (2.87 %) participants were due to cardiovascular disease (CVD) and 498 (2.46 %) died of cancer. J-shaped associations were observed for blood cadmium with risks of mortality (all Poverall < 0.001; all Pnonlinearity < 0.001). Blood cadmium and PA had multiplicative interactions on mortality risk (all Pinteraction < 0.05). Compared with the subgroup with the lowest quartile of blood cadmium and recommended PA, the combination of the highest quartile of blood cadmium and without recommended PA was associated with the highest risks of all-cause and cancer mortality, followed by those meeting recommended PA but in the highest quartile of blood cadmium (hazard ratios, 2.43; 95 % confidence interval, 1.95-3.02). Achieving recommended PA significantly attenuated the detrimental effects of blood cadmium on all-cause, CVD, and cancer mortality risks.

The impact of different exercise modalities on chronic kidney disease: an umbrella review of meta-analyses

Introduction

Exercise is widely recognized for its benefits to chronic kidney disease (CKD) patients. However, the specific impact of different exercise modalities on CKD-related outcomes remains unclear. This study sought to summarize the effects of different exercise modalities on the main outcomes impacted by CKD.

Methods

We searched for systematic review with meta-analysis in PubMed, Embase, Web of Science, Scopus, and Cochrane databases. We evaluated the methodological quality of included studies by AMSTAR2 tool and by individually evaluating the heterogeneity, sample power, and statistical significances from meta-analyses.

Results

We included 44 meta-analyses, encompassing 35,432 CKD patients in pre-dialysis and dialysis stages (peritoneal and hemodialysis). Data from meta-analyses with highly suggestive or strong evidence grading suggests that aerobic and combined training were most effective in improving cardiorespiratory fitness (main effect: 2.1, 95% CI: 0.8-3.4, and main effect: 3.4; 95% CI: 2.4-4.6, respectively). Combined training showed a consistent benefit in psychosocial domains (main effect: -7.3; 95% CI: -9.31 to -53). All exercise modalities significantly improve functional performance, except isometric training, which impacted just fistula maturation (main effect: 0.84; 95% CI: 0.5-1.2).

Conclusion

Exercise emerges as a potential non-pharmacological therapy for CKD patients. Tailoring exercise to specific outcomes appears to be crucial, as different exercise modalities exhibit varying effectiveness.

Exercise-driven cellular autophagy: A bridge to systematic wellness

BACKGROUND

Exercise enhances health by supporting homeostasis, bolstering defenses, and aiding disease recovery. It activates autophagy, a conserved cellular process essential for maintaining balance, while dysregulated autophagy contributes to disease progression. Despite extensive research on exercise and autophagy independently, their interplay remains insufficiently understood.

AIM OF REVIEW

This review explores the molecular mechanisms of exercise-induced autophagy in various tissues, focusing on key transduction pathways. It examines how different types of exercise trigger specific autophagic responses, supporting cellular balance and addressing systemic dysfunctions. The review also highlights the signaling pathways involved, their roles in protecting organ function, reducing disease risk, and promoting longevity, offering a clear understanding of the link between exercise and autophagy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Exercise-induced autophagy is governed by highly coordinated and dynamic pathways integrating direct and indirect mechanical forces and biochemical signals, linking physical activity to cellular and systemic health across multiple organ systems. Its activation is influenced by exercise modality, intensity, duration, and individual biological characteristics, including age, sex, and muscle fiber composition. Aerobic exercises primarily engage AMPK and mTOR pathways, supporting mitochondrial quality and cellular homeostasis. Anaerobic training activates PI3K/Akt signaling, modulating molecules like FOXO3a and Beclin1 to drive muscle autophagy and repair. In pathological contexts, exercise-induced autophagy enhances mitochondrial function, proteostasis, and tissue regeneration, benefiting conditions like sarcopenia, neurodegeneration, myocardial ischemia, metabolic disorders, and cancer. However, excessive exercise may lead to autophagic overactivation, leading to muscle atrophy or pathological cardiac remodeling. This underscores the critical need for balanced exercise regimens to maximize therapeutic efficacy while minimizing risks. Future research should prioritize identifying reliable biomarkers, optimizing exercise protocols, and integrating exercise with pharmacological strategies to enhance therapeutic outcomes.

A subcellular sampling instrument allows spatial resolution of amyloid deposit-derived organelle-specific effects in microglia

Methodological developments in biomedical research are currently moving towards single-cell approaches. This allows for a much better spatial and functional characterization of, for example, the deterioration of cells within a tissue in response to noxae. However, subcellular resolution is also essential to elucidate whether observed impairments are driven by an explicit organelle. Here, we use the Single Cellome™ System SS2000 (Yokogawa) to investigate the local effects of Aβ plaque-like deposits (characteristic for Alzheimer's disease) on mitochondria in the mouse microglial cell line SIM-A9. First, the specificity of subcellular extraction is demonstrated by detecting subcellular staining and RT-qPCR concerning marker genes by comparing nuclear and mitochondrial samples. Oxygen consumption and gene expression is then assessed in cells near and far from peptide deposits. Mostly, all analyses confirm the high specificity and integrity of the sampled material. In addition, impact of the peptide deposits occur concerning spatial distribution of the cells: e.g., oxygen consumption is only reduced in cells close to Aβ deposits but not in proximity to deposits of biologically inactive Aβ (scrambled) or in far distance. Moreover, a distance-related gene expression pattern occurs, demonstrating the local initiation of mitochondrial changes of microglia when approaching toxic peptide deposits.

A Review over Mitochondrial Diseases Due to mtDNA Mutations: Recent Advances and Remedial Aspects

Mitochondria, also called 'powerhouse of the cell', is meant for energy generation in eukaryotic cells. This action is performed by mitochondria through the oxidative phosphorylation (OXPHOS) of the respiratory chain (RC). Based on the functioning of the cell, the number of mitochondria varies up to thousands in number. Mutations in the mitochondrial DNA (mtDNA) and/or nuclear DNA (nDNA) genes may lead to the generation of primary mitochondrial disease (PMD) that affects the structure and function of mitochondria. The diagnosis of such mitochondrial diseases occurs in early childhood and it can lead to serious, fetal and multi-organ diseases. Understanding epigenetic events and changes in the pathway can help improve the effectiveness of treatment. However, there are several reasons lack of the disease symptoms (age, sign, symptoms, morbidity and lethality), restricted availability of preclinical models along with extensive phenotypes that hamper the development of efficient drugs. Despite the introduction of new treatments and the encouraging results of treatments and therapies, there is no effective cure for PMD. This article contains information about the changes associated with cytopathic diseases that make possible the analysis of various diseases by genetic techniques. Increasing our understanding of how mitochondrial DNA mutations affect mitochondrial metabolism and subsequently result in neurodegenerative disease will prove vital to the development of targeted therapies and treatments.

Dose-response relationship between leisure-time physical activity and metabolic syndrome in short sleep US adults: evidence from a nationwide investigation

Metabolic syndrome (MetS) and short sleep are prevalent health concerns in the United States, yet the relationship between leisure-time physical activity (LTPA) and MetS among individuals with short sleep duration remains unclear. This cross-sectional study analyzed data from 8999 US adults aged 20 years and older in the National Health and Nutrition Examination Survey. Short sleep duration was defined as less than 7 h per night, and MetS was diagnosed based on criteria from the American Endocrine Society and the American Society of Clinical Endocrinology. Weighted regression analyses revealed a significant inverse association between LTPA and MetS, with higher LTPA levels linked to lower MetS (OR (95% CI): 0.990 (0.984, 0.997), p = 0.003). Participants who achieved the World Health Organization's recommended LTPA levels had a substantially lower MetS compared to those with no LTPA (OR (95% CI): 0.624 (0.527, 0.738), p = 0.001). Stratified analyses showed that this protective effect varied across demographic subgroups, and a threshold effect was observed at 2000 MET-min/week, beyond which further LTPA did not significantly enhance protection against MetS. These findings highlight the importance of regular LTPA that is negatively associated with MetS among individuals with inadequate sleep, emphasizing the need for targeted health promotion efforts in this population.

Mechanisms that Alter Capacity for Adenosine Triphosphate Production and Oxidative Phosphorylation: Insights from Avian Migration

Avian migration is among the most energetically demanding feats observed in animals. Studies evaluating the physiological underpinnings of migration have repeatedly shown that migratory birds display numerous adaptations that ultimately supply the flight muscle mitochondria with abundant fuel and oxygen during long-distance flights. To make use of this high input, the organs and mitochondria of migrants are predicted to display several traits that maximize their capacity to produce adenosine triphosphate (ATP). This review aims to introduce readers to several mechanisms by which organs and mitochondria can alter their capacity for oxidative phosphorylation and ATP production. The role of organ size, mitochondrial volume, substrate, and oxygen delivery to the electron transport system are discussed. A central theme of this review is the role of changes in electron chain complex activity, mitochondrial morphology and dynamics, and supercomplexes in allowing avian migrants and other taxa to alter the performance of the electron transport system with predictable shifts in demand. It is my hope that this review will serve as a springboard for future studies exploring the mechanisms that alter bioenergetic capacity across animal species.

Exercise and nutrition benefit skeletal muscle: From influence factor and intervention strategy to molecular mechanism

Sarcopenia is a progressive systemic skeletal muscle disease induced by various physiological and pathological factors, including aging, malnutrition, denervation, and cardiovascular diseases, manifesting as the decline of skeletal muscle mass and function. Both exercise and nutrition produce beneficial effects on skeletal muscle growth and are viewed as feasible strategies to prevent sarcopenia. Mechanisms involve regulating blood flow, oxidative stress, inflammation, apoptosis, protein synthesis and degradation, and satellite cell activation through exerkines and gut microbiomes. In this review, we summarized and discussed the latest progress and future development of the above mechanisms for providing a theoretical basis and ideas for the prevention and treatment of sarcopenia.

The role of exercise in the prevention and treatment of Alzheimer's disease and mild cognitive impairments

Large retrospective cohort studies have consistently shown that people who exercise regularly are at a markedly reduced risk of dementias such as Alzheimer's Disease (AD). Animal studies have also found that exercise can prevent cognitive decline, and recent studies have identified possible mechanisms. However, randomized controlled trials of exercise interventions in AD and mild cognitive impairment have not reached a consensus regarding the efficacy of this treatment, hampering clinical adoption of this technique. This review examines these randomized controlled trials to assess potential causes for the variability in the measured outcomes. We posit that great variance in the methods used in these studies may account for some of the differences seen in outcomes. We determined that aerobic exercise led to the most benefits, that many cognitive domains improve with exercise, and that aerobic exercise enhances the ability for independent living. However, cognitive improvements were more pronounced and consistent in patients with mild cognitive impairment than AD, suggesting a narrow window of opportunity for exercise intervention.

Effect of bariatric surgery on mitochondrial remodeling in human skeletal muscle: a narrative review

In the context of obesity epidemic as a major global public health challenge, bariatric surgery stands out for its significant and long-lasting effectiveness in addressing severe obesity and its associated comorbidities. Skeletal muscle mitochondrial function, which is crucial for maintaining metabolic health, tends to deteriorate with obesity. This review summarized current evidence on the effects of bariatric surgery on skeletal muscle mitochondrial function, with a focus on mitochondrial content, mitochondrial dynamics, mitochondrial respiration and mitochondrial markers in glucolipid metabolism. In conclusion, bariatric surgery impacts skeletal muscle through pathways related to mitochondrial function and induces mitochondrial remodeling in skeletal muscle in various aspects. Future studies should focus on standardized methodologies, larger sample sizes, and better control of confounding factors to further clarify the role of mitochondrial remodeling in the therapeutic benefits of bariatric surgery.

Continuous Use During Disuse: Mechanisms and Effects of Spontaneous Activity of Unloaded Postural Muscle

In most mammals, postural soleus muscles are involved in the maintenance of the stability of the body in the gravitational field of Earth. It is well established that immediately after a laboratory rat is exposed to conditions of weightlessness (parabolic flight) or simulated microgravity (hindlimb suspension/unloading), a sharp decrease in soleus muscle electrical activity occurs. However, starting from the 3rd day of mechanical unloading, soleus muscle electrical activity begins to increase and reaches baseline levels approximately by the 14th day of hindlimb suspension. This phenomenon, observed in the course of rat hindlimb suspension, was named the "spontaneous electrical activity of postural muscle". The present review discusses spinal mechanisms underlying the development of such spontaneous activity of rat soleus muscle and the effect of this activity on intracellular signaling in rat soleus muscle during mechanical unloading.

Normobaric hypoxia accelerates high-intensity intermittent training-induced mitochondrial biogenesis (PGC-1α)- and dynamics (OPA1)-related protein expressions in rat gastrocnemius muscle

High-intensity intermittent training (HIIT) in a normobaric hypoxic environment enhances exercise capacity, possibly by increasing the mitochondrial content in skeletal muscle; however, the molecular mechanisms underlying these adaptations are not well understood. Therefore, we investigated whether HIIT under normobaric hypoxia can enhance the expression of proteins involved in mitochondrial biogenesis and dynamics in rat gastrocnemius muscle. Five-week-old male Wistar rats (n = 24) were randomly assigned to the following four groups: (1) sedentary under normoxia (20.9% O2) (NS), (2) training under normoxia (NT), (3) sedentary under normobaric hypoxia (14.5% O2) (HS), and (4) training under normobaric hypoxia (HT). The training groups in both conditions were engaged in HIIT on a treadmill five to six days per week for nine weeks. From the fourth week of the training period, the group assigned to hypoxic conditions was exposed to normobaric hypoxia. Forty-eight hours after completing the final training session, gastrocnemius muscles were surgically removed, and mitochondrial enzyme activity and mitochondrial biogenesis and dynamics regulatory protein levels were determined. Citrate synthase (CS) activity and mitochondrial oxygen phosphorylation (OXPHOS) subunits in the gastrocnemius muscle in the HT significantly exceeded those in the other three groups. Moreover, the levels of a master regulator of mitochondrial biogenesis, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), and a mitochondrial fusion-related protein, optic atrophy 1 (OPA1), were significantly increased by HIIT under normobaric hypoxia. Our data indicates that HIIT and normobaric hypoxia increase the expression of mitochondrial biogenesis- and dynamics-related proteins in skeletal muscles.

Integrative effects of resistance training and endurance training on mitochondrial remodeling in skeletal muscle

Resistance training activates mammalian target of rapamycin (mTOR) pathway of hypertrophy for strength gain, while endurance training increases peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) pathway of mitochondrial biogenesis benefiting oxidative phosphorylation. The conventional view suggests that resistance training-induced hypertrophy signaling interferes with endurance training-induced mitochondrial remodeling. However, this idea has been challenged because acute leg press and knee extension in humans enhance both muscle hypertrophy and mitochondrial remodeling signals. Thus, we first examined the muscle mitochondrial remodeling and hypertrophy signals with endurance training and resistance training, respectively. In addition, we discussed the influence of resistance training on muscle mitochondria, demonstrating that the PGC-1α-mediated muscle mitochondrial adaptation and hypertrophy occur simultaneously. The second aim was to discuss the integrative effects of concurrent training, which consists of endurance and resistance training sessions on mitochondrial remodeling. The study found that the resistance training component does not reduce muscle mitochondrial remodeling signals in concurrent training. On the contrary, concurrent training has the potential to amplify skeletal muscle mitochondrial biogenesis compared to a single exercise model. Concurrent training involving differential sequences of resistance and endurance training may result in varied mitochondrial biogenesis signals, which should be linked to the pre-activation of mTOR or PGC-1α signaling. Our review proposed a mechanism for mTOR signaling that promotes PGC-1α signaling through unidentified pathways. This mechanism may be account for the superior muscle mitochondrial remodeling change following the concurrent training. Our review suggested an interaction between resistance training and endurance training in skeletal muscle mitochondrial adaptation.

The bioenergetics of traumatic brain injury and its long-term impact for brain plasticity and function

Mitochondria provide the energy to keep cells alive and functioning and they have the capacity to influence highly complex molecular events. Mitochondria are essential to maintain cellular energy homeostasis that determines the course of neurological disorders, including traumatic brain injury (TBI). Various aspects of mitochondria metabolism such as autophagy can have long-term consequences for brain function and plasticity. In turn, mitochondria bioenergetics can impinge on molecular events associated with epigenetic modifications of DNA, which can extend cellular memory for a long time. Mitochondrial dysfunction leads to pathological manifestations such as oxidative stress, inflammation, and calcium imbalance that threaten brain plasticity and function. Hence, targeting mitochondrial function may have great potential to lessen the outcomes of TBI.

Mitochondrial membrane lipids in the regulation of bioenergetic flux

Oxidative phosphorylation (OXPHOS) occurs through and across the inner mitochondrial membrane (IMM). Mitochondrial membranes contain a distinct lipid composition, aided by lipid biosynthetic machinery localized in the IMM and class-specific lipid transporters that limit lipid traffic in and out of mitochondria. This unique lipid composition appears to be essential for functions of mitochondria, particularly OXPHOS, by its effects on direct lipid-to-protein interactions, membrane properties, and cristae ultrastructure. This review highlights the biological significance of mitochondrial lipids, with a particular spotlight on the role of lipids in mitochondrial bioenergetics. We describe pathways for the biosynthesis of mitochondrial lipids and provide evidence for their roles in physiology, their implications in human disease, and the mechanisms by which they regulate mitochondrial bioenergetics.

Tissue-specific roles of mitochondrial unfolded protein response during obesity

Obesity is a worldwide multifactorial disease caused by an imbalance in energy metabolism, increasing adiposity, weight gain, and promoting related diseases such as diabetes, cardiovascular diseases, neurodegeneration, and cancer. Recent findings have reported that metabolic stress related to obesity induces a mitochondrial stress response called mitochondrial unfolded protein response (UPRmt), a quality control pathway that occurs in a nuclear DNA-mitochondria crosstalk, causing transduction of chaperones and proteases under stress conditions. The duality of UPRmt signaling, with both beneficial and detrimental effects, acts in different contexts depending on the tissue, cell type, and physiological states, affecting the mitochondrial function and efficiency and the metabolism homeostasis during obesity, which remains not fully clarified. Therefore, this review discusses the most recent findings regarding UPRmt signaling during obesity, bringing an overview of UPRmt across different metabolic tissues.

Unlocking the biochemical secrets of longevity: balancing healthspan and lifespan

In an era of rising global life expectancies, research focuses on enhancing the quality of extended years. This review examines the link between mitochondrial function and aging, highlighting the importance of healthspan alongside lifespan. This involves significant human and economic challenges, with longer lifespans often accompanied by reduced well-being. Addressing mitochondrial decline, exploring targeted interventions, and understanding the complexities of research models are vital for advancing our knowledge in this field. Additionally, promoting physical exercise and adopting personalized supplementation strategies based on individual needs can contribute to healthy aging. The insights from this Perspective article offer a hopeful outlook for future advances in extending both lifespan and healthspan, aiming to improve the overall quality of life in aging populations.

Daily Physical Activity Does Not Contribute to Differences in Muscle Oxidative Capacity Between Overweight and Obesity

BACKGROUND

The interaction between physical activity, skeletal muscle health, and adiposity has been explored in normal weight and overweight/obesity grouped together; however, the overall risks associated with being overweight are less than those observed with obesity and can be confounded by disparities in both sex and race. Thus, the present study sought to investigate the intricate interplay of daily physical activity and skeletal muscle oxidative capacity (SMOC) in overweight and obesity, while exploring how sex and race impact this dynamic relationship.

METHODS

One hundred and forty participants were grouped by body mass index (BMI) as overweight (n = 73; BMI >25-<30 kg/m2) or obese (n = 67; BMI ≥30 kg/m2). SMOC was assessed using near-infrared spectroscopy and daily physical activity was assessed for 7 days using accelerometry.

RESULTS

Overweight individuals exhibited a higher (p = 0.004) SMOC and engaged in more (p = 0.007) vigorous physical activity compared to obese individuals. In addition, SMOC was lower (p = 0.005) in obese non-Hispanic Black (NHB) men compared to overweight NHB men. No relationships between physical activity and SMOC were observed.

CONCLUSION

Physical activity is not associated with differences in SMOC in overweight and obesity. Obese individuals engage in less vigorous physical activity and exhibit lower SMOC compared to overweight individuals and these differences are emphasised in NHB men.

Associations of accelerometry-measured and self-reported physical activity and sedentary behavior with skeletal muscle energetics: The Study of Muscle, Mobility and Aging (SOMMA)

BACKGROUND

Skeletal muscle energetics decline with age, and physical activity (PA) has been shown to offset these declines in older adults. Yet, many studies reporting these effects were based on self-reported PA or structured exercise interventions. Therefore, we examined the associations of accelerometry-measured and self-reported PA and sedentary behavior (SB) with skeletal muscle energetics and explored the extent to which PA and sedentary behavior would attenuate the associations of age with muscle energetics.

METHODS

As part of the Study of Muscle, Mobility and Aging, enrolled older adults (n = 879), 810 (age = 76.4 ± 5.0 years old, mean ± SD; 58% women) had maximal muscle oxidative capacity measured ex vivo via high-resolution respirometry of permeabilized myofibers (maximal oxidative phosphorylation (maxOXPHOS)) and in vivo by 31phosphorus magnetic resonance spectroscopy (maximal adenosine triphosphate (ATPmax)). Accelerometry-measured sedentary behavior, light activity, and moderate-to-vigorous PA (MVPA) were assessed using a wrist-worn ActiGraph GT9X over 7 days. Self-reported sedentary behavior, MVPA, and all PA were assessed with the Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire. Linear regression models with progressive covariate adjustments evaluated the associations of sedentary behavior and PA with muscle energetics, as well as the attenuation of the age/muscle energetics association by MVPA and sedentary behavior. As a sensitivity analysis, we also examined activPAL-measured daily step count and time spent in sedentary behavior and their associations with muscle energetics.

RESULTS

Every 30 min/day more of ActiGraph-measured MVPA was associated with 0.65 pmol/(s × mg) higher maxOXPHOS and 0.012 mM/s higher ATPmax after adjusting for age, site/technician, and sex (p < 0.05). Light activity was not associated with maxOXPHOS or ATPmax. Meanwhile, every 30 min/day spent in ActiGraph-measured sedentary behavior was associated with 0.39 pmol/s × mg lower maxOXPHOS and 0.006 mM/s lower ATPmax (p < 0.05). Only associations with ATPmax held after further adjusting for socioeconomic status, body mass index, lifestyle factors, and multimorbidity. CHAMPS MVPA and all PA yielded similar associations with maxOXPHOS and ATPmax (p < 0.05), but sedentary behavior did not. Higher activPAL step count was associated with higher maxOXHPOS and ATPmax (p < 0.05), but time spent in sedentary behavior was not. Additionally, age was significantly associated with muscle energetics for men only (p < 0.05); adjusting for time spent in ActiGraph-measured MVPA attenuated the age association with ATPmax by 58% in men.

CONCLUSION

More time spent in accelerometry-measured or self-reported daily PA, especially MVPA, was associated with higher skeletal muscle energetics. Interventions aimed specifically at increasing higher intensity activity might offer potential therapeutic interventions to slow age-related decline in muscle energetics. Our work also emphasizes the importance of taking PA into consideration when evaluating associations related to skeletal muscle energetics.

Temporal expression of mitochondrial life cycle markers during acute and chronic overload of rat plantaris muscles

Skeletal muscle hypertrophy is generally associated with a fast-to-slow phenotypic adaptation in both human and rodent models. Paradoxically, this phenotypic shift is not paralleled by a concomitant increase in mitochondrial content and aerobic markers that would be expected to accompany a slow muscle phenotype. To understand the temporal response of the mitochondrial life cycle (i.e., biogenesis, oxidative phosphorylation, fission/fusion, and mitophagy/autophagy) to hypertrophic stimuli, in this study, we used the functional overload (FO) model in adult female rats and examined the plantaris muscle responses at 1 and 10 weeks. As expected, the absolute plantaris muscle mass increased by ∼12 and 26% at 1 and 10 weeks following the FO procedure, respectively. Myosin heavy-chain isoform types I and IIa significantly increased by 116% and 17%, respectively, in 10-week FO plantaris muscles. Although there was a general increase in protein markers associated with mitochondrial biogenesis in acute FO muscles, this response was unexpectedly sustained under 10-week FO conditions after muscle hypertrophy begins to plateau. Furthermore, the early increase in mito/autophagy markers observed under acute FO conditions was normalized by 10 weeks, suggesting a cellular environment favoring mitochondrial biogenesis to accommodate the aerobic demands of the plantaris muscle. We also observed a significant increase in the expression of mitochondrial-, but not nuclear-, encoded oxidative phosphorylation (OXPHOS) proteins and peptides (i.e., humanin and MOTS-c) under chronic, but not acute, FO conditions. Taken together, the temporal response of markers related to the mitochondrial life cycle indicates a pattern of promoting biogenesis and mitochondrial protein expression to support the energy demands and/or enhanced neural recruitment of chronically overloaded skeletal muscle.

SIRT1 signaling pathways in sarcopenia: Novel mechanisms and potential therapeutic targets

Sarcopenia is an aging-related skeletal disease characterized by decreased muscle mass, strength, and physical function, severely affecting the quality of life (QoL) of the elderly population. Sirtuin 1 (SIRT1), as a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylases, has been reported to participate in various aging-related signaling pathways and exert protective effect on many human diseases. SIRT1 functioned as an important role in the occurrence and progression of sarcopenia through regulating key pathways related to protein homeostasis, apoptosis, mitochondrial dysfunction, insulin resistance and autophagy in skeletal muscle, including SIRT1/Forkhead Box O (FoxO), AMP-activated protein kinase (AMPK)/SIRT1/nuclear factor κB (NF-κB), SIRT1/p53, AMPK/SIRT1/peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), and SIRT1/live kinase B1 (LKB1)/AMPK pathways. However, the specific mechanisms of these processes have not been fully illuminated. Currently, several SIRT1-mediated interventions on sarcopenia have been preliminarily developed, such as SIRT1 activator polyphenolic compounds, exercising and calorie restriction. In this review, we summarized the predominant mechanisms of SIRT1 involved in sarcopenia and therapeutic modalities targeting the SIRT1 signaling pathways for the prevention and prognosis of sarcopenia.

Exercise epigenetics is fueled by cell bioenergetics: Supporting role on brain plasticity and cognition

Exercise has the unique aptitude to benefit overall health of body and brain. Evidence indicates that the effects of exercise can be saved in the epigenome for considerable time to elevate the threshold for various diseases. The action of exercise on epigenetic regulation seems central to building an "epigenetic memory" to influence long-term brain function and behavior. As an intrinsic bioenergetic process, exercise engages the function of the mitochondria and redox pathways to impinge upon molecular mechanisms that regulate synaptic plasticity and learning and memory. We discuss how the action of exercise uses mechanisms of bioenergetics to support a "epigenetic memory" with long-term implications for neural and behavioral plasticity. This information is crucial for directing the power of exercise to reduce the burden of neurological and psychiatric disorders.

Role of the gut-muscle axis in mitochondrial function of ageing muscle under different exercise modes

The fundamental role of the gut microbiota through the gut-muscle axis in skeletal muscle ageing is increasingly recognised. Metabolites derived from the intestinal microbiota are essential in maintaining skeletal muscle function and metabolism. The energy produced by mitochondria and moderate levels of reactive oxygen species can contribute to this process. Metabolites can effectively target the mitochondria, slowing the progression of muscle ageing and potentially representing a marker of ageing-related skeletal muscle loss. Moreover, mitochondria can contribute to the immune response, gut microbiota biodiversity, and maintenance of the intestinal barrier function. However, the causal relationship between mitochondrial function and gut microbiota crosstalk remains poorly understood. In addition to elucidating the regulatory pathways of the gut-muscle axis during the ageing process, we focused on the potential role of the "exercise-gut-muscle axis", which represents a pathway under stimulation from different exercise modes to induce mitochondrial adaptations, skeletal muscle metabolism and maintain intestinal barrier function and biodiversity stability. Meanwhile, different exercise modes can induce mitochondrial adaptations and skeletal muscle metabolism and maintain intestinal barrier function and biodiversity. Resistance exercise may promote mitochondrial adaptation, increase the cross-sectional area of skeletal muscle and muscle hypertrophy, and promote muscle fibre and motor unit recruitment. Whereas endurance exercise promotes mitochondrial biogenesis, aerobic capacity, and energy utilisation, activating oxidative metabolism-related pathways to improve skeletal muscle metabolism and function. This review describes the effects of different exercise modes through the gut-muscle axis and how they act through mitochondria in ageing to define the current state of the field and issues requiring resolution.

Modulation of ER-mitochondria tethering complex VAPB-PTPIP51: Novel therapeutic targets for aging-associated diseases

Aging is a gradual and irreversible natural process. With aging, the body experiences a functional decline, and the effects amplify the vulnerability to a range of age-related diseases, including neurodegenerative, cardiovascular, and metabolic diseases. Within the aging process, the morphology and function of mitochondria and the endoplasmic reticulum (ER) undergo alterations, particularly in the structure connecting these organelles known as mitochondria-associated membranes (MAMs). MAMs serve as vital intracellular signaling hubs, facilitating communication between the ER and mitochondria when regulating various cellular events, including calcium homeostasis, lipid metabolism, mitochondrial function, and apoptosis. The formation of MAMs is partly dependent on the interaction between the vesicle-associated membrane protein-associated protein-B (VAPB) and protein tyrosine phosphatase-interacting protein-51 (PTPIP51). Accumulating evidence has begun to elucidate the pivotal role of the VAPB-PTPIP51 tether in the initiation and progression of age-related diseases. In this study, we delineate the intricate structure and multifunctional role of the VAPB-PTPIP51 tether and discuss its profound implications in aging-associated diseases. Moreover, we provide a comprehensive overview of potential therapeutic interventions and pharmacological agents targeting the VAPB-PTPIP51-mediated MAMs, thereby offering a glimmer of hope in mitigating aging processes and treating age-related disorders.

Effect of VBIT-4 on the functional activity of isolated mitochondria and cell viability

VBIT-4 is a new inhibitor of the oligomerization of VDAC proteins of the outer mitochondrial membrane preventing the development of oxidative stress, mitochondrial dysfunction, and cell death in various pathologies. However, as a VDAC inhibitor, VBIT-4 may itself cause mitochondrial dysfunction in healthy cells. The article examines the effect of VBIT-4 on the functional activity of rat liver mitochondria and cell cultures. We have demonstrated that high concentrations of VBIT-4 (15-30 μM) suppressed mitochondrial respiration in state 3 and 3UDNP driven by substrates of complex I and II. VBIT-4 induced depolarization of organelles fueled by substrates of complex I but not complex II of the respiratory chain. VBIT-4 has been found to inhibit the activity of complexes I, III, and IV of the respiratory chain. Molecular docking demonstrated that VBIT-4 interacts with the rotenone-binding site in complex I with similar affinity. 15-30 μM VBIT-4 caused an increase in H2O2 production in mitochondria, decreased the Ca2+ retention capacity, but increased the time of Ca2+-dependent mitochondrial swelling. We have found that the incubation of breast adenocarcinoma (MCF-7) with 30 μM VBIT-4 for 48 h led to the decrease of the mitochondrial membrane potential, an increase in ROS production and death of MCF-7 cells. The mechanism of action of VBIT-4 on mitochondria and cells is discussed.

Mitochondrial disorders leading to Alzheimer's disease-perspectives of diagnosis and treatment

Alzheimer's disease (AD) is a neurodegenerative disorder and the most common cause of dementia globally. The pathogenesis of AD remains still unclear. The three main features of AD are extracellular deposits of amyloid beta (Aβ) plaque, accumulation of abnormal formation hyper-phosphorylated tau protein, and neuronal loss. Mitochondrial impairment plays an important role in the pathogenesis of AD. There are problems with decreased activity of multiple complexes, disturbed mitochondrial fusion, and fission or formation of reactive oxygen species (ROS). Moreover, mitochondrial transport is impaired in AD. Mouse models in many research show disruptions in anterograde and retrograde transport. Both mitochondrial transportation and network impairment have a huge impact on synapse loss and, as a result, cognitive impairment. One of the very serious problems in AD is also disruption of insulin signaling which impairs mitochondrial Aβ removal.Discovering precise mechanisms leading to AD enables us to find new treatment possibilities. Recent studies indicate the positive influence of metformin or antioxidants such as MitoQ, SS-31, SkQ, MitoApo, MitoTEMPO, and MitoVitE on mitochondrial functioning and hence prevent cognitive decline. Impairments in mitochondrial fission may be treated with mitochondrial division inhibitor-1 or ceramide.