Muscle Physiology

Cost-effective and portable ultrasonography offers a promising approach for monitoring skeletal muscle damage and quality in many contexts. However, echogenicity analysis relies on precise transducer orientations and machine parameters, posing challenges for data pooling across different raters and settings. Muscle texture analysis offers a potential means of reducing interrater and machine-setting variability. Scans were assessed at nine angles, controlled using a custom transducer shell and software. Scans were performed three times, and different gains were applied. All scans were performed on a muscle tissue-mimicking phantom to eliminate biological variability. Intra-angle and intra-gain variability and internal consistency were assessed via coefficient of variation (CV%) and Cronbach's alpha (α c). Spearman's (ρ) correlations were employed to determine the relationship between echogenicity and each texture feature. Entropy (angle: CV=2.7-7.6%; gain: CV=10.5%; α c =0.86), and inverse difference moment (angle: CV=3.7-9.8%; gain: CV=16.5%; α c =0.87) were less variable than echogenicity (angle: CV=6.4-19.4%; gain: CV=39.0%; α c =0.82). Angular second moment (angle: CV=17.9-116.6%; gain: CV=71.6%; α c =0.68), contrast (angle: CV=7.8-14.7%; gain: CV=41.8%; α c =0.75), and correlation (angle: CV=9.0-13.5%; gain: CV=28.6%; α c =0.49) features were generally more variable. Entropy (ρ=0.82-0.98, p≤0.011) and inverse difference moment (ρ=-0.98-0.83, p≤0.008), were more strongly correlated with echogenicity than angular second moment (ρ=-0.98-0.77, p≤0.016), contrast (ρ=0.53-0.98, p≤0.15), and correlation (ρ=-0.25-0.19, p=0.520-0.631). Entropy and inverse difference moment features may allow data sharing between laboratory and clinical settings with ultrasound machine parameters and raters of varying skill levels. Clinical and mechanistic studies are required to determine if texture features can replace echogenicity assessments.

ATP transfer from mitochondria to the cytoplasm occurs mainly through phosphate transfer to creatine by mitochondrial creatine kinase (miCK) but also by transport and/or diffusion of ADP and ATP through specific mitochondrial transport protein complexes. • Determining the effect of exercise on phosphate shuttling may require contractile signals in situ and varying creatine concentrations to alter miCK activity. • Mitochondrial respiratory sensitivity to ADP was assessed in permeabilized muscle fibre bundles (PmFBs) before and after 2 h cycling exercise in human skeletal muscle. • In relaxed PmFBs, ADP sensitivity decreased post-exercise when miCK phosphate shuttling was low (no creatine) with no change in net ADP sensitivity in the presence of creatine, whereas in contracting fibres post-exercise ADP sensitivity was higher with creatine. • This shows miCK activity is increased post-exercise, especially during contraction in PmFBs, and suggests exercise regulates phosphate shuttling, which would improve maintenance of energy homeostasis during contraction.

Skeletal muscle injuries are the most common sports-related injuries in sports medicine. In this work, we have generated a new surgically-induced skeletal muscle injury in rats, by using a biopsy needle, which could be easily reproduced and highly mimics skeletal muscle lesions detected in human athletes. By means of histology, immunofluorescence and MRI imaging, we corroborated that our model reproduced the necrosis, inflammation and regeneration processes observed in dystrophic mdx-mice, a model of spontaneous muscle injury, and realistically mimicked the muscle lesions observed in professional athletes. Surgically-injured rat skeletal muscles demonstrated the longitudinal process of muscle regeneration and fibrogenesis as stated by Myosin Heavy Chain developmental (MHCd) and collagen-I protein expression. MRI imaging analysis demonstrated that our muscle injury model reproduces the grade I-II type lesions detected in professional soccer players, including edema around the central...

Circadian rhythms, governed by the dominant central clock, in addition to various peripheral clocks, regulate almost all biological processes, including sleep-wake cycles, hormone secretion and metabolism. In certain contexts, the regulation and function of the peripheral oscillations can be decoupled from the central clock. However, the specific mechanisms underlying muscle-intrinsic clock-dependent modulation of muscle function and metabolism remain unclear. We investigated the outcome of perturbations of the primary and secondary feedback loops of the molecular clock in skeletal muscle by specific gene ablation of Period circadian regulator 2 (Per2) and RAR-related orphan receptor alpha (Rorα), respectively. In both models, a dampening of core clock gene oscillation was observed, while the phase was preserved. Moreover, both loops seem to be involved in the homeostasis of amine groups. Highly divergent outcomes were seen for overall muscle gene expression, primarily affecting circadian rhythmicity in the PER2 knockouts and non-oscillating genes in the RORα knockouts, leading to distinct outcomes in terms of metabolome and phenotype. These results highlight the entanglement of the molecular clock and muscle plasticity and allude to specific functions of different clock components, i.e. the primary and secondary feedback loops, in this context. The reciprocal interaction between muscle contractility and circadian clocks might therefore be instrumental to determining a finely tuned adaptation of muscle tissue to perturbations in health and disease. KEY POINTS: Specific perturbations of the primary and secondary feedback loop of the molecular clock result in specific outcomes on muscle metabolism and function. Ablation of Per2 (primary loop) or Rorα (secondary loop) blunts the amplitude of core clock genes, in absence of a shift in phase. Perturbation of the primary feedback loop by deletion of PER2 primarily affects muscle gene oscillation. Knockout of RORα and the ensuing modulation of the secondary loop results in the aberrant expression of a large number of non-clock genes and proteins. The deletion of PER2 and RORα affects muscle metabolism and contractile function in a circadian manner, highlighting the central role of the molecular clock in modulating muscle plasticity.

Human skeletal muscle demonstrates remarkable plasticity, adapting to numerous external stimuli including the habitual level of contractile loading. Accordingly, muscle function and exercise capacity encompass a broad spectrum, from inactive individuals with low levels of endurance and strength to elite athletes who produce prodigious performances underpinned by pleiotropic training-induced muscular adaptations. Our current understanding of the signal integration, interpretation, and output coordination of the cellular and molecular mechanisms that govern muscle plasticity across this continuum is incomplete. As such, training methods and their application to elite athletes largely rely on a "trial-and-error" approach, with the experience and practices of successful coaches and athletes often providing the bases for "post hoc" scientific enquiry and research. This review provides a synopsis of the morphological and functional changes along with the molecular mechanisms underlying exercise adaptation to endurance-and resistance-based training. These traits are placed in the context of innate genetic and interindividual differences in exercise capacity and performance, with special consideration given to aging athletes. Collectively, we provide a comprehensive overview of skeletal muscle plasticity in response to different modes of exercise and how such adaptations translate from "molecules to medals."

Skeletal muscle plasticity enables an enormous potential to adapt to various internal and external stimuli and perturbations. Most notably, changes in contractile activity evoke a massive remodeling of biochemical, metabolic and force-generating properties. In recent years, a large number of signals, sensors, regulators and effectors have been implicated in these adaptive processes. Nevertheless, our understanding of the molecular underpinnings of training adaptation remains rudimentary. Specifically, the mechanisms that underlie signal integration, output coordination, functional redundancy and other complex traits of muscle adaptation are unknown. In fact, it is even unclear how stimulus-dependent specification is brought about in endurance or resistance exercise. In this review, we will provide an overview on the events that describe the acute perturbations in single endurance and resistance exercise bouts. Furthermore, we will provide insights into the molecular principles of long-term training adaptation. Finally, current gaps in knowledge will be identified, and strategies for a multi-omic and-cellular analyses of the molecular mechanisms of skeletal muscle plasticity that are engaged in individual, acute exercise bouts and chronic training adaptation discussed. ☆ This article is a contribution to the special issue entitled "Unlocking Athletic Potential: Exploring Exercise Physiology from Mechanisms to Performance.

Biomarkers of aging are indispensable for testing interventions. While promising, the recent focus on molecular aspects should not detract from the functional parameters for which excellent correlation with mortality, and ample clinical human data exist.

Polyamines (PAs) are low molecular weight aliphatic nitrogenous base-containing molecules, are considered an organic compound having more than two amino groups, and they have potent biological activities. They play an important role in both eukaryotic and prokaryotic cells. In living organisms, PAs are mainly available as free PAs, covalently conjugated PAs, or non-covalently conjugated forms. The natural PAs, spermidine and spermine, are synthesized in every living cell and are therefore contained in foods, and their precursor, putrescine, are subcutaneous low molecular weight amines that contain multiple amino groups. Polyamines are synthesized within all living cells, in eukaryotes, polyamine synthesis begins with ornithine, which is synthesized through the urea cycle from arginine. The decarboxylation of ornithine catalyzed by Ornithine Decarboxylases (ODC) is the rate-limiting step in polyamine synthesis. In mammals, polyamines are involved in the most important physiological process. Cell proliferation and viability, nutrition, fertility, as well as nervous and immune system. In some instances where altered synthesis or metabolism of polyamines lead to several types of pathological conditions. Therefore, this review aims to collect and introduce data on the health effects of polyamines, concerning the biological roles of polyamine in humans. Such as its role in the intestine, as an antioxidant, in cancer, in the aging process, in the cardiac process, etc.

Shortening deactivation (SD) is a delayed decrease in force following rapid muscle shortening, while stretch activation (SA) is a delayed rise in force following muscle lengthening. Together, SD and SA enable power production at constant calcium concentrations in insect indirect flight muscles (IFM), and assist calcium in modulating force levels in vertebrate cardiac muscle. However, the molecular mechanisms behind SA and SD remain unknown. Specifically, the SD mechanism has not been investigated, likely because muscle physiologists have presumed that it is the same as SA. But, no experiments have been conducted to test this. Therefore, we performed fiber mechanics with highly SA Drosophila and Lethocerus IFM, and minimally SA Drosophila jump muscle (TDT), to define SD characteristics and compare them to SA. We found that all fiber types exhibited SD. Lethocerus presented the greatest SD tension decrease of 20 mN/mm 2 . This was $1.5-fold greater than Drosophila TDT, and $6.5-fold greater than Drosophila IFM. However, isometric tension in Drosophila TDT (69 mN/mm 2 ) was higher than Lethocerus (37 mN/mm 2 ) and Drosophila IFM (3 mN/mm 2 ). Thus, when normalized to isometric tension, Drosophila IFM exhibited a 75% SD tension decrease, while Lethocerus and Drosophila TDT decreased by 38% and 18%, respectively. A similar order was found when comparing normalized SA tension: 127% for Drosophila IFM, 40% for Lethocerus IFM, and 6% for Drosophila TDT. The IFM in each species showed the same percent change in tension when comparing SD to SA, but surprisingly, this was not the case in the TDT where SD tension was $3.5-fold greater than SA tension. With an understanding of the SD characteristics of each fiber type, we can now perform experiments, such as protein isoform exchanges between Drosophila muscle types, to elucidate the mechanism behind SD.

The function of a paralyzed axial (laryngeal, facial, extraocular) muscle could conceivably be restored if it were made to contract again like its contralateral partner. A muscle stimulation device was designed and constructed so that the stimulus delivered to a given paralysed muscle was modulated by a signal reflecting the contractile state of its contralateral partner. Studies in dog laryngeal muscles indicate that paralyzed muscles stimulated by such an open-loop device could mimic their partners. However, their tracking accuracies were limited by the nature of their stimulus-reponse characteristics. On the other hand, significantly greater tracking accuracies were observed if a closed-loop device was employed, that is, if feedback information from the stimulated muscles was also used to control the device stimulus level. Considerations in implanting such a (closed-loop or open-loop) device in paralyzed axial muscles for chronic stimulation are discussed.

Purpose The aim of this study was to assess the effects of experimentally induced photothrombotic stroke on structural and mechanical properties of rat m. flexor carpi ulnaris. Methods Two groups of Young-adult male Sprague–Dawley rats were measured: stroke (n = 9) and control (n = 7). Photothrombotic stroke was induced in the forelimb region of the primary sensorimotor cortex. Four weeks later, muscle–tendon unit and muscle belly length–force characteristics of the m. flexor carpi ulnaris, mechanical interaction with the neighbouring m. palmaris longus, the number of sarcomeres in series within muscle fibres, and the physiological cross-sectional area were measured. Results Stroke resulted in higher force and stiffness of the m. flexor carpi ulnaris at optimum muscle–tendon unit length, but only for the passive conditions. Stroke did not alter the length–force characteristics of m. flexor carpi ulnaris muscle belly, morphological characteristics, and the extent of mechanical intera...

A three-dimensional biomechanical model has been developed to understand and quantify the effect of the triceps brachii force during bench press exercises executed with different external loads, grip widths, and positions of the barbell relative to the shoulders at the beginning of the lift. The upper limbs, chest, and barbell were modeled as a closed three-dimensional articulated system. The elbow extension torque [Formula: see text] developed by the triceps brachii is transferred through the links of the closed chain, yielding a shoulder transverse-flexion torque [Formula: see text], shoulder adduction torque [Formula: see text], and shoulder internal-rotation torque [Formula: see text] proportional to [Formula: see text]. The proportionality factors [Formula: see text], [Formula: see text], and [Formula: see text] are independent of the load and displayed a considerable change during the lift: [Formula: see text] increased from 0.5 to 2, while [Formula: see text] and [Formula: se...

The demand to the physiotherapy continues to increase, due to the increasing of aging population. The University Grant Commission (UGC) has started degree program in physiotherapy to address this demand in 2007, by providing high school level science students to enter this program based on the grade achieved from the advanced level exam. The aim of this study was to assess the level of awareness about physiotherapy among advanced level science students in the Kandy educational zone and to assess the sources form which they could obtain information regarding physiotherapy. A structured survey consisting of three parts was used, and eight hundred and fifteen high school level Sinhala medium science students from nine schools in Kandy zone in Sri Lanka were approached. Of these, Seven hundred and seventy six completed questionnaires were returned (95% response rate). The students were not much aware of physiotherapy as a career, treatment method and its applications in disease conditions other than sports injuries. Television, internet, and newspapers/magazine were the most cited source of information for physiotherapy. There is a need for a programme to educate the general public in Sri Lanka about Physiotherapy both as a therapeutic modality and as a prospective career pathway

This self-tracked case study compares the effects of high-volume and low-volume resistance training over a 60-day period in a 13-year-old male. Nutritional intake was held constant, and data was collected daily on strength, body composition, and elbow joint pain. In the first 30 days (high volume), the subject trained longer with more sets; in the following 30 days (low volume), the same exercises were performed with fewer sets and overall gym time. Results show that the low-volume phase led to similar or even superior gains in strength and lean body mass, with reduced elbow joint pain. This study also notes visual physique changes and proposes energy expenditure as a factor in weight gain.

RESULTS: EIAH was found in six trained subjects (ΔSaO2 -8.25±4.03 %). After exercise, ED was reduced in sedentary (-3.51±1.57 %, p<0.001) and non-EIAH trained subjects (-3.10±0.83 %, p<0.001), while no effect on ED was found in EIAH trained subjects (0.00±2.38 %, p<0.001). MCV rose equally in all groups (Sedentary: 2.21±0.85 fL; Non-EIAH trained: 1.83±0.26 fL; EIAH-trained: 1.80±0.15 fL; p=0.468). The ability of erythrocyte to undergo shape deformations depends of the ratio of cellular surface to cellular volume. Thus an increment of MCV would reduce ED. However this effect was not observed in EIAH subjects. The weakening of membrane-cytoskeleton interactions, which have been found to be O 2 -regulated, leads to decreased membrane stability and improved ED. So, the lowered SaO 2 during exercise in the trained-EIAH subjects can explains the lack of exercise-induced effects on ED. This would prove to be an adaptive mechanism to improve pulmonary and muscular perfusion, and thus allows stabilization of muscular O 2 and metabolism. It could, therefore, explain why high exercise intensity can be achieved despite impaired O 2 arterial transport in the EIAH subjects.

The explosive growth of scientific visualization in the past 10 years demonstrate a consistent and tacit agreement among scientists that visualization offers a better representation system for displaying complex data than traditional charting methods. However, most visualization works have not been unable to exploit the full potential of visualization techniques. The reason may be that these attempts have been largely executed by scientists. While they have the technical skills for conducting research, they do not have the design background that would allow them to display data in easy to understand formats.

The Max Growth Formula (MGF) is a revolutionary approach to hypertrophy training, built on the foundational principles of neuroscience, recovery physiology, and mechanical tension. Developed by Sa’Quan Hicks, an exercise scientist, MGF challenges the outdated belief that more sets and longer workouts lead to superior growth. Instead, it offers a radically efficient protocol: one set per exercise, performed to absolute failure, every 72 hours.

Rooted in the legacy of Mike Mentzer’s Heavy Duty system, MGF refines and modernizes high-intensity training by integrating controlled tempo reps, static holds, and extended recovery windows. This method fully activates high-threshold motor units, increases time under tension where it matters most, and allows the central nervous system (CNS) to recover and supercompensate — ensuring consistent strength gains and hypertrophy over time.

“As an exercise scientist, I created MGF after years of experimenting with both traditional and high-intensity models. I noticed that lifters were hitting plateaus not because they lacked effort, but because they were training too often, with too much volume, and too little intention. MGF was my answer — a way to build maximum size and strength without compromising the nervous system or recovery.”

MGF isn’t just efficient — it’s brutal. The combination of extremely heavy loads, deliberate execution, and a scientifically calculated recovery model has produced visible muscular transformation in athletes and clients in just a few short weeks. One set to failure, static holds at the point of peak contraction, and a strict 72-hour recovery protocol elevate this system above traditional push/pull splits or high-volume body part training.

“I don’t train for the pump anymore — I train to signal adaptation. Every rep is a command to grow. Every session is a test of focus, effort, and precision. That’s the mindset behind MGF.”

Whether you’re a seasoned lifter or someone who’s struggled with stalled progress, MGF is a complete shift in philosophy. It is not for the faint of heart — but for those who embrace effort and demand results, it’s a blueprint for size, strength, and mastery over your physiology.

Emerging research indicates that lower body strength, particularly gluteal muscle strength, is inversely correlated with markers of cardiovascular health decline and mortality risk. While traditional focus has centered on aerobic capacity and dietary factors, recent evidence suggests that muscular strength, especially in the lower extremities, plays a critical role in systemic health and lifespan. This review synthesizes current findings on the relationship between lower limb strength and cardiovascular outcomes, emphasizing the importance of targeted resistance training in promoting healthy aging.

Calpainopathy, or limb-girdle muscular dystrophy type R1/2A (LGMDR1/2A), is the most prevalent form of LGMD, comprising about 32% of all cases. The disease is caused by mutations in the CAPN3 gene, leading to dysfunction of the corresponding protein-an enzyme critical for muscle fiber cytoskeleton remodeling and protein signaling regulation through selective proteolysis. Clinical manifestations demonstrate significant phenotypic polymorphisms, ranging from oligosymptomatic forms to severe early-onset cases, with the loss of ambulation occurring 10-25 years after disease onset. A characteristic feature is predominantly symmetrical involvement of limb and trunk muscles, leading to early mobility loss, disability, and reduced work capacity. Noninvasive imaging can suggest dystrophic muscle disease but requires differentiation from other myopathies. Confirming the diagnosis involves histological, immunological, and molecular genetic studies to identify calpain-3 activity or CAPN3 gene expression alterations. Currently, no targeted or etiological therapies are available for calpainopathy. Treatment focuses on symptom management, complication prevention, and slowing disease progression. Preclinical research demands the development of an appropriate animal model that displays disease phenotypes mirroring those observed in humans. Preclinical and clinical research are also investigating therapeutic options, including the use of drugs that have proven effective in other myopathies and genome editing via transgenic CAPN3 delivery to restore protein activity. Gene therapy has shown promise in murine models, but safety concerns, particularly systemic toxicity affecting the heart and other organs, remain significant. This review comprehensively analyzes the clinical features, diagnostic approaches, and advancements in modeling and therapeutic development for calpainopathy.

This study investigates the neuroprotective effects of Euphorbia hirta in an acrylamide-induced Parkinson's disease (PD) model, focusing on its ability to mitigate oxidative stress, neuroinflammation, and dopaminergic neuron loss. Acrylamide, a known neurotoxin, induces PD-like pathologies, including motor deficits, oxidative damage, and neurodegeneration. Euphorbia hirta, a medicinal plant with antioxidant and anti-inflammatory properties, was administered to experimental animals, and its effects were evaluated through behavioral assessments, biochemical assays, and histopathological analysis. The results demonstrated significant improvements in motor function, reduced oxidative stress markers (malondialdehyde), increased antioxidant enzyme activity (superoxide dismutase, catalase). Histological examination of the substantia nigra revealed preserved dopaminergic neurons, supporting the neuroprotective role of Euphorbia hirta. These findings suggest that Euphorbia hirta may serve as a potential therapeutic agent for neurodegenerative disorders like PD, warranting further investigation into its mechanisms and clinical applications.

The plantarflexors of the lower limb are often assumed to act as independent actuators, but the validity of this assumption is the subject of considerable debate. This study aims to determine the degree to which passive changes in gastrocnemius muscle length, induced by knee motion, affect the tension in the adjacent soleus muscle. A second aim is to quantify the magnitude of myofascial passive force transmission between gastrocnemius and adjacent soleus. Fifteen healthy volunteers participated. Simultaneous ultrasound images of the gastrocnemius and soleus muscles were obtained during passive knee flexion (0–90°), while keeping the ankle angle fixed at either 70° or 115°. Image correlation analysis was used to quantify muscle fascicle lengths in both muscles. The data show that the soleus muscle fascicles elongate significantly during gastrocnemius shortening. The approximate change in passive soleus force as a result of the observed change in fascicle length was estimated and appe...

The human gut microbiota, a complex community of trillions of microorganisms, plays a crucial role in nutrient absorption, metabolism, and overall health. Recent research has illuminated the interconnectedness between gut health, dietary patterns, and metabolic processes, revealing that the microbiota can influence not just digestion but also the pathogenesis of various diseases. This white paper explores the mechanisms by which gut microbiota affects nutrition and metabolism, emphasizing its implications for health and disease management.

Background: Various studies have used different exercise protocols as post-activation performance enhancement (PAPE) stimulus; however, little attention has been given to the effects of exercise range of motion on the PAPE effect and subsequent performance enhancement. This study aimed to compare the PAPE responses induced by the bench press performed with different ranges of motion on subsequent bench press throw performance. Methods: Ten resistance-trained males (age: 26 ± 3 years; body mass: 93.2 ± 9.4 kg; height: 181 ± 6 cm; experience in resistance training: 6.3 ± 2.4 years; relative bench press one-repetition maximum (1RM) 1.54 ± 0.2 kg/body mass) performed four experimental sessions consisting of a single set of the bench press at 80%1RM until mean barbell velocity dropped by 10% as the conditioning activity (CA) with a (1) standard, (2) cambered, (3) and reversed cambered barbell or a control condition in which the participants did not perform any CA. To assess the PAPE effect, single-sets of 2 repetitions of the bench press throw at 30%1RM were performed before and after the CA at the following time points: 2, 4, 6, 8, 10 min. Results: The two-way ANOVA (4 conditions × 2time points) showed a significant interaction for peak power (p < 0.001; η 2 = 0.556) and peak velocity (p = 0.001; η 2 = 0.457). The standard barbell bench press CA led to the greatest performance enhancement in peak power (p = 0.001; ES = 0.54) and in peak velocity (p = 0.002; ES = 0.71) within the examined conditions. Conclusions: The results of this study indicate that the range of motion of the CA has a significant impact on the magnitude of the PAPE response, and the greatest effect can be reached when the range of motion of the CA and the subsequent explosive task is similar.

This study aimed to determine whether the intra-complex active recovery within the strengthpower potentiating complex will impact the upper-body post-activation performance enhancement effect and how the magnitude of this effect will change across the upperbody complex training session. Thirteen resistance-trained males [the age, body mass, height, experience in resistance training, and one-repetition maximum (1RM) in bench press were 27 ± 4 years; 92.3 ± 15.4 kg; 182 ± 6 cm; 6.4 ± 2.4 years, and 118 ± 29 kg, respectively) participated in this study. Each participant completed a baseline bench press throw performance assessment at 30% 1RM. Next, five strength-power potentiating complexes consisting of a bench press at 80% 1RM were tested until the average barbell velocity decreased by 10% as a conditioning activity, and 6 min later, a re-test of bench press throw was carried out. During one experimental session during the rest interval inside the complex, they performed swiss ball leg curls, while between the complexes, a plank exercise (PAP-A) was performed. During the second experimental session, participants performed no exercises within the strength-power potentiating complexes and between them (PAP). Under control conditions, participants ran the same protocol (as the PAP condition) without the conditioning activity (CTRL). Friedman's test showed significant differences in peak (test = 90.634; p < 0.0001; Kendall's W = 0.410) and average (test = 74.172; p < 0.0001; Kendall's W = 0.336) barbell velocities during bench press throw. Pairwise comparisons indicated that the peak and average barbell velocities significantly increased in the fourth set [p = 0.022, effect size (ES) = 0.76 and p = 0.013, ES = 0.69, respectively], and the average barbell velocity was also increased in the second set (p = 0.018, ES = 0.77) in comparison to the baseline value during the PAPA condition. Moreover, the peak barbell velocity was increased in the second (p = 0.008, ES = 0.72) and third (p = 0.019, ES = 0.76) sets compared to the baseline value during the PAP condition. This study showed that bodyweight lower-body exercise as an intracomplex active recovery did not impair the upper-body post-activation performance enhancement effect across the complex training session.

This paper investigates the effect of varying muscle pinnation angles on force generation during the flat barbell bench press, analyzing how these angles change through the strength curve of the lift. By integrating insights from muscle physiology and biomechanics, the paper explores how changes in pinnation angle affect force production and overall performance in resistance training.

We determined anti-Parkinson’s activity of M. chamomilla L. tea in chlorpromazine (CPZ) developed investigational animal model. In this research, effects of M. chamomilla L. tea 2.14ml/ kg P.O were studied on cataleptic behavior and its effect on brain histopathological changes and immunohistochemistry (IHC) in rats. The experimental design was developed by administering CPZ (3mg/kg, I/P) for twenty-one days to produce Parkinson’s disease-like symptoms to 4 animal groups. We observed that chlorpromazine significantly produced motor dysfunctions (catalepsy) in a time period of twenty-one days. The M. chamomilla L. significantly (P&lt;0.005) minimized/shorten/taper down catalepsy in rats just like standard group (Levodopa/carbidopa treated group). The maximum reduction was observed from both treated and standard groups on the 21st day. M. chamomilla L. treated rats mid brain sections showed presence of proliferative blood vessels, increase cellularity with reactive glial cells as comp...

Objectives: Identifying the effect of special exercises in learning some basic skills in volleyball, as well as the extent of improvement by inferring them through biomechanical variables(Fleisig, 2010), in addition to identifying the differences between players in the level of skill performance based on some special measurements of muscles (the shoulder deltoid, biceps brachii, triceps brachii) and tendons and tendon fusion points in the bon(Journal et al., 2020). Design: The study adopted the experimental method by designing the pre and post-tests. Methods: The study relied on the use of magnetic resonance imaging (MRI)(Cagnie et al., 2011) technology to identifying some measurements of the length, size and mass of the muscles under study, as well as tendons and fusion points(Ammar et al., 2018). As well as adopting recommended tests for the purpose of identifying kinetic expectation as a criterion for the stability of kinetic behavior in terms of mechanical variables(Takei et al., 2020). The two-dimensional kinematic analysis technique was also adopted using digital cameras at a speed of (120 puls / sec), and the use of the kinetic analysis program (Kenovea) to reach the results of the biomechanical variables in the specified tests(Peter M McGinnis, 2013). Results: The results showed significant differences in favor of the post-tests through the application of special educational exercises. It was found that there are indications associated with some structural standards of muscles and tendons that support the process of rapid learning and the stability of kinetic behavior(Journal et al., 2020), which can contribute to strengthening the work of athletes and coaches.

This review focuses on recent discoveries in skeletal and cardiac muscles indicating that mitochondria behave as an interactive cohort with inter-organelle communication and specific reactions to stress signals. Our new finding is that intermitochondrial communications in cardiac and skeletal muscles rely on two distinct methods. In cardiac muscle, mitochondria are discrete entities and are fairly well immobilized in a structural context. The organelles have developed a unique method of communication, via nanotunnels, that allow temporary connection from one mitochondrion to another over distance of up to several microns, without overall movement of the individual organelles and loss of their identity. Skeletal muscle mitochondria, on the other hand, are quite dynamic. Through fusion, fission and elongation they form connections that include constrictions and connecting ducts (quite distinct from nanotunnels) and loose individual identity in the formation of extensive networks. Connecting elements in skeletal muscle are distinct from nanotunnels in Disclaimer: This is a confidential document.

New Findings What is the topic for this review? This review summarizes recent discoveries in mitochondrial development and morphology studied with electron microscopy. What advances does it highlight? Although mitochondria are generally considered to be isolated from each other, this review highlights recently discovered evidence for the presence of intermitochondrial communication structures in cardiac and skeletal muscle, in animal models and humans. Within striated muscles, the means of intermitochondrial exchange and the reaction of mitochondria to external stimuli are uniquely dependent on the tissue, and we clearly differentiate between nanotunnels, the active protrusion of cardiac mitochondria, and the connecting ducts of skeletal muscle derived from fusion–fission and elongation events. This review focuses on recent discoveries in skeletal and cardiac muscles indicating that mitochondria behave as an interactive cohort with inter‐organelle communication and specific reaction...

Ultrasonographic elastography is a relatively new imaging modality for the qualitative and quantitative assessments of tissue elasticity. While it has steadily gained use in adult clinical practice, including for liver diseases, breast cancer, thyroid pathologies, and muscle and tendon diseases, data on its paediatric application is still limited. Moreover, diagnosis of muscular diseases in children remains challenging. The gold standard methods, namely biopsy, electroneurography, and electromyography, are often limited owing to their invasive characteristics, possible contraindications, complications, and need for good cooperation, that is, a patient’s ability to perform certain tasks during the examination while withstanding discomfort, which is a significant problem especially in younger or uncooperative children. Genetic testing, which has broad diagnostic possibilities, often entails a high cost, which limits its application. Thus, a non-invasive, objective, repeatable, and acc...

Basketball is a popular team sport worldwide. Nutrition is one of the key aspects for the optimization of performance and subsequent recovery. Female athletes have unique nutritional requirements as a result of daily training and competition, in addition to the specific demands of gender-related physiological changes. However, inadequate, or erroneous nutritional behaviours are commonly observed. Thus, the aim of our work is to provide concise nutritional recommendations for female basketball players. Based on a review of the literature, there is limited evidence that comprehensively assesses health attributes as well as behaviours, habits, and nutritional knowledge of physical activity by gender in basketball players. Recent research highlights the need for nutritional strategies to develop tools to help manage energy deficiency in women's sports. We suggest that individual adjustment of dietary energy value is the key factor in the physical performance of female basketball players; information that could be used to optimize the training process and health maintenance. The recommended intake for athletes involved in moderate levels of training, such as elite basketball players (2-3 h/day for 5-6 times/week), is 50-80 kcal•(kg•day)-1 , with specific recommendations of 1.6-1.8 g•(kg•day)-1 protein. For physically active women, it is recommended that 1.2-2 g•(kg•day)-1 of protein be consumed, with fat intake of 20-35% of total kilocalories and 5-8 g•(kg•day)-1 of carbohydrate to adequately meet performance demands.

In-Press Preview Heterozygous truncating variants in the sarcomere protein titin (TTN) are the most common genetic cause of heart failure. To understand mechanisms that regulate abundant cardiomyocyte TTN expression we characterized highly conserved intron 1 sequences that exhibited dynamic changes in chromatin accessibility during differentiation of human cardiomyocytes from induced pluripotent stem cells (hiPSC-CMs). Homozygous deletion of these sequences in mice caused embryonic lethality while heterozygous mice demonstrated allele-specific reduction in Ttn expression. A 296 bp fragment of this element, denoted E1, was sufficient to drive expression of a reporter gene in hiPSC-CMs. Deletion of E1 downregulated TTN expression, impaired sarcomerogenesis, and decreased contractility in hiPSC-CMs. Site-directed mutagenesis of predicted NKX2-5-and MEF2-binding sites within E1 abolished its transcriptional activity. Embryonic mice expressing E1 reporter gene constructs validated in vivo cardiac-specific activity of E1 and the requirement for NKX2-5 and MEF2 binding sequences. Moreover, isogenic hiPSC-CMs containing a rare E1 variant in the predicted MEF2 binding motif that was identified in a patient with unexplained DCM showed reduced TTN expression. Together these discoveries define an essential, functional enhancer that regulates TTN expression. Manipulation of this element may advance therapeutic strategies to treat DCM caused by TTN haploinsufficiency.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic multi-system disease that can lead to striking debilitation . The pathophysiology is related to activation of immunoinflammatory pathways and autoimmune responses underpinned by a state of energy depletion [4] and elderly patients with ME/CFS are at increased risk for non-Hodgkin's lymphoma . Jason et al. the median age of death for cancer in the United States is 72 versus an average age of 47.8 if the person also has ME/ CFS and the average age of death of heart failure is 83.1 versus 58.7 years if the person also has ME/CFS [6]. What this means is that ME/CFS patients

This article explores the relationship between the psyche and the musculoskeletal system, focusing on the effects of psychogenic stress on the muscular system. The review presents research demonstrating correlations between stressful experiences and the development of muscle imbalances, myofascial pain syndrome, and other disorders. Studies describing physiological and mental correlations leading to altered respiratory and motor responses are analyzed, which is important in musculoskeletal work.

Ramadan fasting increases subjective feelings of fatigue and reduces selfmotivation during exercise. Exercising in the Ramadan fasted state leads to a quality of training that is lower than normal due to a reduction in exercise intensity and/or physical efforts. This field investigation examined the impact of Ramadan fasting on perceived exercise intensity during highintensity training sessions and its impact on maximal aerobic performance, in elite-level youth soccer players. The National Under-18 squad was organized into a fasting (FAS) and a non-fasting (control, CON) groups. During the Ramadan month, in addition to the normal soccer-specific training, both FAS and CON underwent six specific conditioning sessions consisting of high-intensity aerobic and anaerobic interval running. There were no significant differences between groups’ post-exercise ratings of perceived exertion in all sessions. There were no significant differences between groups for Beep test performances at prea...

Young people in this group bring a wide variety of skills, talents and levels of motivation to their learning in physical education. They are represented at all points of the physical activity. Students' learning in physical education supports the overall vision of senior cycle education which is to develop students as resourceful, confident, engaged and active learners. Students grow in confidence and competence as they acquire the knowledge, skills and attitudes necessary to enjoy and succeed in a variety of physical activities while in senior cycle and in their future lives. Physical activity, in its many forms, provides the medium through which students learn in, through and about physical education. The purpose of the study was to find out the significant difference in among under-graduate students. 60 students between the ages of 18-23 years were selected for the study from Swami Vivekanand Subharti University, Meerut, Uttar-Pradesh. These subjects were further equally divided into groups i.e. 30 students (experimental group) and 30 students (control group). The subject's age range was from 18 to 23 years. The consent form was collected from the subject before start in the experiment as the subjects were physically fit and having no disease which may affect the research. The assessment includes the dietary habits and daily schedule of the students. All the subjects were assessed for Aerobic capacity. To analyze the data, the dependent t-test was applied and it was found that the Aerobic capacity was found better after the treatment (training) was given to the under-graduate students.

Simulation of high flexion tasks such as squatting is hindered through invalid moment length estimation when using generic musculoskeletal (MSK) models. The purpose of this study was to examine the effect of wrapping surface (WS) at the knee and hip joints on the muscle moment arms calculated using a MSK model during squatting tasks. A generic full body model was modified by (1) increasing knee and hip flexion range of motion (ROM), (2) adjusting translation and size parameters of two WS, and (3) implementing three additional WS. Muscle moment-arm lengths were calculated in OpenSim using motion capture data. The WS prevent muscles to cross into the bones, and the moment arm length of several hip extensors reach a plateau after 85º of hip flexion. The use of the modified MSK that includes additional WS is suited for the analysis of high flexion tasks.

A viscoelastic model has been developed for the dynamic behavior of a muscle and tendon pair suitable for use as an actuator in neuromusculoskeletal control simulation. This model accounts for the steady-state force generator characteristics of the musculotendon unit, such as force variation with length, velocity with length and velocity with load, as well as accounting for the transient behavior of the system in response to dynamic changes in activation and loading. This model is formulated as a bond graph in a manner to be implemented with standard system simulation software. A careful and thorough section on parameter estimation from available physiologic data is included. The bond graph is compatible with inclusion into an anatomically more comprehensive model, based on its inherent hierarchic capability for system building.

Background: The health effect of rapidly increasing everyday exposure of humans to radiofrequency radia on is a major global concern. Mobile phone jammers prevent the mobile phones from receiving signals from base sta ons by interfering with authorized mobile carriers’ services. In spite of the fact that mobile jammer use is illegal, they are occasionally used in offices, shrines, conference rooms and cinemas. The purpose of this study was to inves gate the biological effects of short term exposure of human sperm to radiofrequency radia on emi$ed from a commercial mobile phone jammer. Materials and Methods: Fresh semen samples were obtained by masturba on from 50 healthy donors who had referred with their wives to Infer lity Treatment Center at the Mother and Child Hospital, Shiraz University of Medical Sciences. Female problem was diagnosed as the reason for infer lity in these couples. The semen sample of each par cipant was divided into 4 aliquots. The first aliquot was subjected...

Bu araştırma Ege Üniversitesi Bilimsel Araştırma Projeleri Birimi tarafından desteklenmektedir. Three Different Upper Body Exercises The aim of this study is to investigate the muscular activation of latissimus dorsi (LD), trapezius middle (TM) and deltoid posterior (DP) during three different upper body exercises (Lat pull down, barbell bent over row, dumbbell row). Knowing the agonist muscles for exercises is a critical factor when designing training programs. Much research supports the notion that greater muscular strength can enhance the ability to perform in general sport skills. Lat pull down, barbell bent over row, dumbbell row are widely used exercises for improving performance involving the upper body muscles of the posterior kinetic chain. However, although these are popular exercises, their activation during exercise performance remains unclear.

Koury, JC, Daleprane, JB, Pitaluga-Filho, MV, de Oliveira, CF, Gonçalves, MC, and Passos, MCF. Aerobic conditioning might protect against liver and muscle injury caused by short-term military training. J Strength Cond Res 30(2): 454-460, 2016-This study aimed to compare the biochemical markers of muscle and liver injury and total antioxidant capacity in army cadets after a traditional army physical training program and to correlate these effects with aerobic conditioning. Male army cadets (n = 87; age, 20 ± 2 years) were evaluated 12 hours before the start of training (T0), 12 hours after a 30-km march (T1), and 48 hours after military training (T2). Creatine kinase (CK), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) serum levels were measured using an autoanalyzer. Total antioxidant capacity was determined by 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (Sc%). Seventy-four percent of army cadets were classified as having excellent aerobic conditi...

This paper reviews the major intramuscular extracellular matrix (IM-ECM) structures (endomysium, perimysium and epimysium) and their possible mechanical contributions to muscle functions. The endomysium appears to provide an efficient mechanism for transmission of contractile forces from adjacent muscle fibres within fascicles. This coordinates forces and deformations within the fascicle, protects damaged areas of fibres against over-extension, and provides a mechanism whereby myofibrils can be interrupted to add new sarcomeres during muscle growth without loss of contractile functionality of the whole column. Good experimental evidence shows that perimysium and epimysium are capable in some circumstances to act as pathways for myofascial force transmission. However, an alternative role for perimysium is reviewed, which involves the definition of slip planes between muscle fascicles which can slide past each other to allow large shear displacements due to shape changes in the whole muscle during contraction. As IM-ECM is continually remodelled so as to be mechanically adapted for its roles in developing and growing muscles, control of the processes governing IM-ECM turnover and repair may be an important avenue to explore in the reduction of fibrosis following muscle injury.

Background: The vast majority of dynamometer-based animal models for investigation of the response to chronic muscle contraction exposure has been limited to analysis of isometric, lengthening, or shortening contractions in isolation. An exception to this has been the utilization of a rat model to study stretch-shortening contractions (SSCs), a sequence of consecutive isometric, lengthening, and shortening contractions common during daily activity and resistance-type exercise. However, the availability of diverse genetic strains of rats is limited. Therefore, the purpose of the present study was to develop a dynamometer-based SSC training protocol to induce increased muscle mass and performance in plantarflexor muscles of mice. Methods: Young (3 months old) C57BL/6 mice were subjected to 1 month of plantarflexion SSC training. Hindlimb muscles were analyzed for muscle mass, quantitative morphology, myogenesis/myopathy relevant gene expression, and fiber type distribution. Results: The main aim of the research was achieved when training induced a 2-fold increase in plantarflexion peak torque output and a 19% increase in muscle mass for the agonist plantaris (PLT) muscle. In establishing this model, several outcomes emerged which raised the value of the model past that of being a mere recapitulation of the rat model. An increase in the number of muscle fibers per transverse muscle section accounted for the PLT muscle mass gain while the antagonist tibialis anterior (TA) muscle atrophied by 30% with preferential atrophy of type IIb and IIx fibers. These alterations were accompanied by distinct gene expression profiles. Conclusions: The findings confirm the development of a stretch-shortening contraction training model for the PLT muscle of mice and demonstrate that increased cross-sectional fiber number can occur following high-intensity SSC training. Furthermore, the TA muscle atrophy provides direct evidence for the concept of muscle imbalance in phasic non-weight bearing muscles, a concept largely characterized based on clinical observation of patients. The susceptibility to this imbalance is demonstrated to be selective for the type IIb and IIx muscle fiber types. Overall, the study highlights the importance of considering muscle fiber number modulation and the effect of training on surrounding muscles in exercise comprised of SSCs.

Ageing of the population, together with population growth, has brought along an ample increase in the number of older individuals living with dementia and disabilities. Dementia is the main cause of disability in old age, and promoting healthy brain ageing is considered as a key element in diminishing the burden of age‐related disabilities. The World Health Organization recently launched the first risk reduction guidelines for cognitive impairment and dementia. According to recent estimates, approximately 40% of dementia cases worldwide could be attributable to 12 modifiable risk factors: low education; midlife hypertension and obesity; diabetes, smoking, excessive alcohol use, physical inactivity, depression, low social contact, hearing loss, traumatic brain injury and air pollution indicating clear prevention potential. Dementia and physical disability are closely linked with shared risk factors and possible shared underlying mechanisms supporting the possibility of integrated pre...

INTRODUCTION: Synergistic muscle have different architecture, and therefore could have different force-length relationships for the same joint angle changes. Previous studies have failed to reveal the force-length relationships of synergistic muscles. The purpose of this study was to investigate the force-length relationships of the triceps surae muscles for humans in vivo. METHODS: Five male subjects (25.2±2.5years; 170.1±5.8cm; 65.9±9.2kg; mean±SD) performed isometric plantar flexion, with the exerted torque from zero to voluntary maximum (MVC) at 30deg (plantar-flexed), 20deg, 10deg, 0deg (anatomical position),-10deg,-20deg (dorsiflexed). Simultaneously, fascicle length (FL) and pennation angle (PA) of the medial gastrocnemius (MG) and soleus (SOL) muscles were measured by using ultrasonography. The Fascicle forces(Ff) of MG and SOL were calculated by Ff=Ft･K/cosθ, where Ft (tendon force)=TQ(Torque)/MA, K is the relative PCSA(Physiological cross sectional area) of MG=20% and SOL=59.6% (Fukunaga et al., 1992), θ is PA of MG and SOL, and MA is the moment arm lengths derived from Rugg et al (1990).