Editor’s Choice Articles

The Nordic hamstring exercise (NHE) is effective at decreasing hamstring strain injury risk. Limited information is available on the in vivo mechanics of the bicep femoris long head (BF_LH) during the NHE. Therefore, the purpose of this study was to observe kinematic, neuromuscular and in-vivo mechanics of the BF_LH during the NHE. Thirteen participants (24.7 ± 3.7 years, 79.56 ± 7.89 kg, 177.40 ± 12.54 cm) performed three repetitions of the NHE at three horizontal planes (0°, 20° and −20°). Dynamic ultrasound of the dominant limb BF_LH, surface electromyography (sEMG) of the contralateral hamstrings and sagittal plane motion data were simultaneously collected. Repeated measures analysis of variance with Bonferroni post hoc corrections were used on the in vivo mechanics and the kinematic and sEMG changes in performance of the NHE. Likely differences in ultrasound waveforms for the BF_LH were determined. Significant and meaningful differences in kinematics and in vivo mechanics between NHE variations were observed. Non-significant differences were observed in sEMG measures between variations. Changes to the NHE performance angle manipulates the lever arm, increasing or decreasing the amount of force required by the hamstrings at any given muscle length, potentially changing the adaptive response when training at different planes and providing logical progressions ore regressions of the NHE. All NHE variations result in a similar magnitude of fascicle lengthening, which may indicate similar positive adaptations from the utilization of any variation. Full article

Despite ongoing efforts, the relationship between groin strength and injury remains unclear. The challenge of accurately predicting injuries presents an opportunity for researchers to develop prevention strategies to reduce the occurrence of such injuries. Consequently, this issue requires further investigation to obtain insights into effective mitigation strategies. In 120 male soccer players, the maximum isometric strength of the hip muscle groups was measured, and the strength ratios were calculated. Previous injury and anthropometric data were registered. Injury data were collected following the FIFA/UEFA consensus. k-nearest neighbor (k-NN) was used to predict the incidence of injury, while the significant predictive variables of the k-NN algorithm were fitted into a multivariate logistic regression model (LR) to analyze the likelihood of players sustaining a groin injury. The LR model determined two variables as significant predictors of groin injury. Players were less likely to sustain a groin injury by 76% for each decrease of the adductor/abductor isometric strength ratio in the non-dominant limb (OR = 0.238, CI 95% = [(0.098–0.572]). Players with a history of previous injury had a 67% greater risk of sustaining an injury (OR = 0.333, CI 95% = [(0.1068–1.038]). Isometric hip adductor and abductor strength imbalances of the non-dominant lower limb and a history of previous injury were risk factors for groin injury in soccer players. Full article

Previous studies have revealed decreased proprioception and perception of joint position in elderly adults. Joint position sense, indicating an individual’s ability to perceive the position of limbs without visual aid, is essential for everyday movements. A few studies have shown a positive effect of muscle stretching on joint position sense (JPS). However, these studies have only been conducted with younger participants. The impact of stretching on JPS in elderly adults remains unclear. Therefore, the aim of this study is to compare the acute effects of muscle stretching on joint position sense in young and elderly adults. An experimental group of younger adults (n = 15; 25.4 ± 2.9 years) and an experimental group of active, healthy elderly adults (n = 15; 64 ± 3.5 years) stretched their knee flexor muscles. The absolute error (AE) of the joint position sense was calculated before and after muscle stretching. The results indicated no significant difference in the AE between groups (p > 0.05) after the stretching intervention. The similarity in the physical activity status of the subjects may have influenced the results. Even though no significant age-specific differences were found in this study, its results may not be applicable to non-active elderly adults. Full article

Exertional rhabdomyolysis (ER) is a condition where muscle breakdown occurs after intense and unaccustomed exercise in healthy individuals. It is characterized by muscle pain, weakness, and myoglobinuria, potentially leading to acute kidney injury and worsening the patients’ prognosis. Ultra-trail races (UT) necessitate high energy and extreme muscular exertion, which can result in significant muscle breakdown, leading to ER and elevated biomarkers such as creatine kinase (CK) and lactate dehydrogenase (LDH). These races involve longer durations and both uphill and downhill elevations, with the latter causing more muscle damage. This systematic review aims to analyse the effect of downhill elevation (at least 1000 m) in UT on muscle and liver damage biomarkers. We conducted a systematic review of four electronic databases (Pubmed, Web of Science, Scopus, and Sportdiscus) based on PRISMA guidelines for systematic reviews. We included a total of 15 articles out of 6670 published between January 2005 and March 2024. The total population sample included 348 subjects, comprising 294 men (84.48%) and 54 women (15.52%) with a mean age of 39.82 ± 6.89 years. Only one subject (0.28%) was diagnosed with ER. The median increase in CK post vs. pre was 5370.63 ± 7289.71%, LDH post vs. pre was 311.20 ± 164.4%, and liver damage biomarkers aspartate transaminase (AST) and alanine aminotransferase (ALT) obtained mean increases of 1009.94 ± 743.97% and 207.02 ± 92.84%, respectively. No liver injury cases were reported. These findings suggest that ER is often misdiagnosed in UT and may result in acute kidney injury under certain circumstances. Therefore, it is crucial to define and prepare the characteristics required for ultra runners to safely participate in these extreme races. Full article

The prevalence of skeletal muscle atrophy, caused by disease and aging, is rising as life expectancy increases. Exercise is the most effective treatment option; however, it is often impractical for individuals suffering from disease or bedridden. The formulation of non-exercise-based interventions is necessary. This study assessed the impact of acupuncture (AC), electro-acupuncture (EA), and electrical stimulation (ES) on muscle mass and contractile properties in a model of casting-induced muscle atrophy. Sprague-Dawley rats (n = 40) were assigned to five groups: control (CON), cast (CT), cast receiving AC (CT-AC), cast receiving EA (CT-EA), and cast receiving ES (CT-ES) (n = 8 each). Treatments were 15 min and three times/week for 14 days. Contractile properties and protein markers of atrophy and inflammation were measured. Casting decreased muscle mass and fiber cross-sectional area, but AC, EA, and ES attenuated cast-induced muscle atrophy. All treatments increased peak twitch tension compared to CT. CT increased the protein levels of MAFbx and MuRF1, while AC, EA, and ES mitigated the elevation of these proteins. Our results indicate that acupuncture, electro-acupuncture, and electrical stimulation show promise as therapeutic strategies to counteract skeletal muscle loss and dysfunction resulting from disuse atrophy caused by injury, disease, and aging. Full article

Background: Musculoskeletal pain is a non-negligible multifaceted condition affecting more than 30% of the global population. Superficial heat therapy (HT), through increasing tissue temperatures, plays a role in increasing local metabolism and function and relieving pain. Knee (KP) and sports pain represent two relevant fields of superficial HT application. Methods: In the present paper, a panel of experts performed a narrative review of the literature regarding the role of superficial HT in the management of knee and sports activity-related pain. Results: According to the reviewed literature, HT represents a therapeutic option in the management of musculoskeletal pain due to three main effects: pain relief, promotion of healing, and return to normal function and activity. Moreover, HT plays a role in sport activities both before and after exercise. Before performing sports, HT helps in preparing muscles for performance. After performing sports, it is capable to promote recovery and healing pathways. Combining and sequencing superficial heat and cold therapy represent an interesting topic of study. Overall, the application of heat wraps for superficial HT can be considered safe. Conclusions: HT has been shown to be a potentially beneficial and safe option in the management of several conditions including KP and sports. The key in the application of superficial HT is a multimodal and multidisciplinary approach. Full article

Myokines released by exercise are identified as factors that can influence a person’s health and wellbeing. While myokine secretion in response to an acute bout of endurance and resistance-type exercise has been examined, the influence of resistance-exercise training on myokines at rest is less well established. Therefore, this study was designed to evaluate a panel of myokines at rest following a 12-week resistance-exercise training program in younger and older males. Participants (n = 15) completed a 12-week progressive resistance-exercise training program supervised by a certified fitness professional. The training protocol targeted all major muscle groups of the upper and lower body. Resting blood samples were collected before and after completion of the training program to determine concentrations of apelin, fibroblast growth factor-21 (FGF-21), interleukin (IL)-4, IL-6, IL-7, IL-15, leukemia inhibitory factor (LIF), and irisin. Two-way repeated ANOVAs were used to compare variables between time-points and age groups. There was a main effect of time found for apelin (p = 0.003) and IL-15 (p < 0.001), while no main effects for group or time were found for the other myokines (all p > 0.05). Age group × training status interactions were found for IL-6 (p = 0.04) and irisin (p = 0.014) without pairwise differences for IL-6 (p > 0.05), and younger males had higher concentrations of irisin compared to older males post-training (p = 0.036). Overall, the 12-week resistance-exercise training program significantly increased apelin and IL-15 over time but did not change the other resting myokine concentrations for the younger or older males. However, the higher concentration of irisin in younger versus older males post-training suggests a potential explanation for the anabolic resistance observed with aging. Full article

Recent studies indicate a significant relationship between malnutrition, frailty, and pleural effusion (PE), highlighting the critical role of muscle mass in patient outcomes. This review investigates the association between sarcopenia—characterized by a decline in skeletal muscle mass and function—and PE, marked by fluid accumulation in the pleural space. The findings reveal that sarcopenia is prevalent in patients with PE and is linked to increased postoperative complications and mortality rates. In liver transplantation, esophagectomy, and lung cancer surgeries, sarcopenia exacerbates the risk of adverse outcomes. Notably, preoperative muscle mass assessment serves as a predictive tool for identifying patients at higher risk of complications. This review underscores the importance of early diagnosis and intervention for sarcopenia to improve clinical outcomes in PE patients. The therapeutic approach should include comprehensive nutritional evaluations and targeted muscle-strengthening interventions. By addressing sarcopenia, healthcare providers can significantly reduce PE-related complications, enhance patient recovery, and improve survival rates. This review provides a foundation for future research to develop effective strategies for the management and treatment of sarcopenia in the context of PEs, aiming to optimize patient care and quality of life. Full article

Measuring the bicep femoris long head fascicle length via the use of diagnostic ultrasound has become common practice within elite sport, using single images of between 4 and 6 cm. No study to date has compared single image estimations in terms of the varying fields of view (i.e., 4, 6, and 10 cm). Therefore, the aim of this study was to determine whether differences occur when estimating the bicep femoris long head fascicle length using short (4 cm), medium (6 cm), and long (10 cm) fields of view across three estimation equations. A total of 36 male athletes (age: 23.8 ± 3.8 years, body mass: 83.7 ± 14.0 kg, height: 1.81 ± 0.06 m) had three ultrasound images of the bicep femoris long head collected on a single occasion with the fascicle length estimated. A significant main effect was observed (p < 0.001) with moderate–very large differences (p < 0.078, d = 0.91–4.01). The smallest fields of view resulted in the greatest fascicle length. There were significant moderate–large associations between the fields of view (p < 0.001, r = 0.542–0.892). Unacceptable limits of agreement were observed, and the developed correction equations remained unacceptable. The partial measure equation is the most accurate whilst using the 10 cm fields of view, while the basic trigonometry equation had the lowest variability between fields of view and the smallest differences between fields of view; hence, this equation may be more appropriate when a <6 cm field of view is the only field of view available. Full article

Fatty infiltration of the rotator cuff muscles is very common following rotator cuff tears and is one of the most important factors in determining treatment. Current clinical practice relies on subjective evaluation of fatty infiltration through categorical scoring based on the Goutallier classification system. The Dixon magnetic resonance imaging (MRI) sequence provides flexibility in selecting echo times for water–fat separation. The Dixon method, therefore, has the potential to provide robust and high-quality fat quantification that allows for more accurate calculation of fat fraction (%Fat) of the rotator cuff muscles than the Goutallier classification system. However, significant variance exists in sequencing and post-processing methodology within the recent application of Dixon sequences to quantify rotator cuff fatty infiltration. In this paper, we conducted a systematic review to synthesize the relevant literature utilizing Dixon sequencing for the quantification of rotator cuff fatty infiltration. The literature search was extracted from 1094 articles, with 12 studies included in the final review. Regardless of the varying sequencing pattern and post-processing techniques among studies, the findings suggest the Dixon method is reliable for quantitatively calculating the fat fraction of the rotator cuff muscles, even at very low levels of fatty infiltration. In addition, a quantitative difference in fat fraction was observed between participants with different degrees of tear vs. those without any shoulder pathologies. Multi-point Dixon imaging has the potential to be utilized clinically to objectively quantify fatty infiltration and may lead to improved clinical decision making for patients with rotator cuff tears. Full article

(1) Background: Sarcopenia, or low skeletal mass index (SMI), contributes to higher lung cancer mortality. The SMI at third lumbar vertebrae (L3) is the reference standard for body composition analysis. However, there is a need to explore the validity of alternative landmarks in this population. We compared the agreement of sarcopenia identification at the first lumbar (L1) and second lumbar (L2) to L3 in non-Hispanic Black (NHB) and White (NHW) individuals with lung cancer. (2) Methods: This retrospective, cross-sectional study included 214 NHB and NHW adults with lung cancer. CT scans were analyzed to calculate the SMI at L1, L2, and L3. T-tests, chi-square, Pearson’s correlation, Cohen’s kappa, sensitivity, and specificity analysis were used. (3) Results: Subjects presented with a mean age of 68.4 ± 9.9 years and BMI of 26.3 ± 6.0 kg/m². Sarcopenia prevalence varied from 19.6% at L1 to 39.7% at L3. Cohen’s kappa coefficient was 0.46 for L1 and 0.64 for L2, indicating weak and moderate agreement for the identification of sarcopenia compared to L3. (4) Conclusions: Sarcopenia prevalence varied greatly depending on the vertebral landmark used for assessment. Using L2 or L1 alone resulted in a 16.8% and 23.8% misclassification of sarcopenia in this cohort of individuals with lung cancer. Full article

Neuromuscular diseases (NMD) cover a broad spectrum of different rare diagnoses in which the primary lesion is in the peripheral nervous system. The impairment caused by an NMD does not only interfere with physical status but also has a clear impact on health-related quality of life (HRQoL). It is therefore essential to know the coping style used by these patients. This study aims to analyze the coping strategies in a sample of people with NMD and how their coping style affects their HRQoL. This cross-sectional study included 61 adult patients diagnosed with a rare NMD. WHO-DAS II, SIP, SF-36, and COPE-60 instruments were administered. The results showed that people affected by NMDs tend to use more frequent coping strategies such as active planning, personal growth, and acceptance. In contrast, the least-used strategies were restraint, mental disengagement, venting, humor, and religion, which affected HRQoL negatively. Moreover, the degree of disability was a relevant variable, with an impact on HRQoL. Social support can be considered the main coping strategy that leads to an improvement in the psychosocial HRQoL (β = 503, p < 0.001). These findings are relevant to clinical practice, given the need to understand the coping variable to improve HRQoL. Full article

SYNE2 mutations have been associated with skeletal and cardiac muscle diseases, including Emery-Dreifuss muscular dystrophy (EDMD). Here, we present a 70-year-old male patient with muscle pain and elevated serum creatine kinase levels in whom whole-exome sequencing revealed a novel heterozygous SYNE2 splice site mutation (NM_182914.3:c.15306+2T>G). This mutation is likely to result in the loss of the donor splice site in intron 82. While a diagnostic muscle biopsy showed unspecific myopathological findings, immunofluorescence analyses of skeletal muscle and dermal cells derived from the patient showed nuclear shape alterations when compared to control cells. In addition, a significantly reduced nesprin-2 giant protein localisation to the nuclear envelope was observed in patient-derived dermal fibroblasts. Our findings imply that the novel heterozygous SYNE2 mutation results in a monoallelic splicing defect of nesprin-2, thereby leading to a rare cause of myalgia and hyperCKemia. Full article

This study’s primary objective was to examine the differences in body composition, abdominal strength, absolute and relative power, handgrip strength, one repetition maximum for squat and bench press, and the maximum count of push-up and sit-up repetitions executed within a minute across different age cohorts of firefighters. Furthermore, this study aimed to evaluate the age-related differences in firefighters’ completion times of six firefighting tasks. Eighty-four male volunteer firefighters (age 33.79 ± 6.97 years) were grouped into three age categories, 20–30 years, 31–40 years, and 41–50 years, and underwent the aforementioned evaluations. One-way analysis of variance (MANOVA) revealed that age exerts a statistically significant influence (p < 0.001) on body fat percentage, waist circumference, and waist-to-hip ratio. Furthermore, age significantly affected the overall time of the ability test (p < 0.001) and the duration required to accomplish each individual task (p < 0.001). Additionally, age significantly affected abdominal strength, relative power (as measured by the step test), and the maximum count of push-up and sit-up repetitions performed within a minute. These outcomes support earlier research indicating an age-associated decrement in physical fitness parameters among firefighters. It is recommended that firefighters prioritize maintaining strength and endurance of the abdominal muscles, upper body muscular endurance, and a healthy body weight. The emphasis on specific muscular groups is essential for improving task performance within this profession. Full article

This comprehensive review focuses on the dynamics of branched-chain amino acids (BCAAs) metabolism and its clinical implications in chronic liver disease, with emphasis on the emerging concept of muscle–liver crosstalk. BCAAs, indispensable for protein synthesis and metabolic pathways, undergo unique tissue-specific processing in skeletal muscle and liver. The liver, responsible for amino acid metabolism, plays a distinctive role in sensing BCAAs catabolism, influencing glucose regulation and contributing to the systemic metabolism of BCAAs. Within the context of chronic liver disease, compromised liver metabolism becomes evident through amino acid abnormalities, particularly in the decrease of the Fischer ratio (BCAAs/aromatic amino acids concentrations in plasma). This reduction becomes important in assessing the severity of liver dysfunction due to its associations with adverse outcomes, including increased mortality and complications related to the liver disease. BCAAs supplementation, as explored in this review, emerges as a promising avenue, displaying positive effects on skeletal muscle mass, strength, and overall nutritional status in cirrhosis management. Understanding this interplay offers insights into therapeutic strategies for chronic liver diseases, exploring the way for precision interventions in clinical practice. Full article

Muscle strength and mass strongly influence performance. The role of the trunk, upper limbs, and lower limbs in a specific performance is important but unclear in terms of muscle strength, muscle mass, and the degree of influence of each part. Standing long jump is a performance that produces results by not only the muscles of the lower limbs working together but also the entire body, including the trunk and upper limbs. To determine the influence of muscle strength and the mass of each body part on standing long jump, 31 healthy young adults (18 males and 13 females) participated in this study. Abdominal trunk muscle strength, grip strength, and knee extension muscle strength were measured, each of which was defined as trunk, upper limb, and lower limb muscle strength. The trunk, upper limb, and lower limb muscle masses were measured using a body composition analyzer. Performance was measured using the standing long jump test (jumping power). Factors influencing standing long jump were examined. A multiple regression analysis revealed that trunk (β = 0.367, p = 0.006) and upper limb (β = 0.608, p < 0.001) muscle strength values were extracted for standing long jump (adjusted R² = 0.574, p < 0.01). Trunk and upper limb muscle strength influence standing long jumps. Full article

Pleural mesothelioma (PM) is a tumor related to adverse prognosis. The PM WHO classification has mainly identified three major subtypes of PM which are epithelioid, biphasic, and sarcomatoid. Sarcopenia is a medical issue related to a reduction in muscle mass and strength. It represents a major health issue globally because it is related to adverse effects such as hospitalization, increased length of stay, disability, increased morbidity and mortality and augmented health care expenditures. In this literature review, we attempted to examine the upcoming association between sarcopenia and PM. As recorded by the current literature, muscle loss in PM subjects was related to poorer survival and lower levels of activity. Subjects with PM had increased rates of pre-sarcopenia and malnutrition, while pre-sarcopenia was related to worse activity levels, and malnutrition was related to worse quality of life (QoL). Both tumor volume and sarcopenia were related to long-term mortality in surgically treated PM subjects, while sarcopenia was present both pre-operatively and post-operatively in these subjects. In addition, post-operative sarcopenic subjects showed a decreased 3-year overall survival (OS) in comparison with those who did not have sarcopenia, while pre-operative sarcopenia was importantly related to an increased rate of post-operative adverse outcomes. More studies are needed to validate these claims. Full article

Eculizumab is a monoclonal antibody blocking the terminal complement protein C5. As demonstrated in the phase III randomized, placebo-controlled, REGAIN clinical trial, eculizumab is efficacious in acetylcholine receptor antibody (AChR-Ab)-positive refractory generalized myasthenia gravis (gMG) (Myasthenia Gravis Foundation of America—MGFA class II–IV). It has not been studied in severe myasthenic exacerbation or myasthenic crisis (MGFA V). A 73-year-old man diagnosed with myasthenia gravis AChR-Ab positivity came to our observation for symptoms of bulbar and ocular weakness and unresponsiveness or intolerability to conventional immunosuppressive therapies (prednisone and azathioprine). Due to the recurrent clinical worsening with intubation over a short-term period, the patient was treated with eculizumab. After 15 days of eculizumab treatment, we observed a significant recovery of clinical condition. We discharged the patient to an outpatient regimen, where he is continuing with maintenance doses of eculizumab and slowly tapering steroid intake. The use of eculizumab in myasthenic crises is still anecdotal. Our case aims to provide eculizumab benefit for refractory severe gMG in a practical, real-world setting beyond the criteria of the REGAIN study. Further studies are needed to evaluate the efficacy and safety of eculizumab in myasthenic crises. Full article

The use of electromyographic biofeedback (EMG-BF) in the rehabilitation of injuries has been widely referenced in the psychological literature. However, despite some pioneering work in the field of sports, its use in the rehabilitation of sports injuries has hardly been explored. A case of two professional soccer players who each suffered a distal radius fracture is presented here. Parallel to the rehabilitation plan established by medical services, an intervention strategy using EMG-BF was established. An EMG-BF intervention was performed on the brachioradialis muscle with the aim of improving the voluntary control of its electromyographic activity. The study protocol was registered with the identifier NCT05376072. An ABA design was used. In each session, a pre- and postline was recorded to determine the EMG gain acquired at each point of the session. After six sessions, the intervention was terminated. One more follow-up session was performed. The results obtained indicated the efficacy of the intervention; a statistically significant increase in muscle activity in the brachioradialis muscle was observed. Full article

This study evaluated muscle composition, quality, and strength of non-weight bearing and weight bearing muscles between males and females. Twenty-eight, healthy males (n = 14; mean ± SD; age = 25.1 ± 4.2 years; height = 181.9 ± 10.6 cm; weight = 91.6 ± 17.2 kg) and females (n = 14; age = 25.0 ± 3.4 years; height = 165.9 ± 6.9 cm; weight = 66.0 ± 10.2 kg) underwent body composition assessment to estimate body fat (%BF) and total-body, arm, and leg fat-free mass (TFFM, ArmFFM, and LegFFM, respectively) and muscle composition via B-mode ultrasound to measure muscle cross-sectional area (mCSA), echo intensity (EI), and thickness (mT) of four muscles [rectus femoris (RF), vastus lateralis (VL), flexor digitorum superficialis (FDS), and flexor carpi radialis (FCR)]. Additionally, upper- [handgrip strength (HG)] and lower-body [leg extension (LE)] maximal strength were measured, recorded, and expressed relative to FFM to determine muscle quality (MQ) for the dominant arm and leg, respectively. Males had greater TFFM, ArmFFM, and LegFFM (p < 0.001), mCSA for RF, VL, FCR, and FDS (p < 0.001), and mT for RF, VL (p < 0.001–0.006). Females had greater EI for RF, VL, and FDS (p = 0.003–0.01). Negative correlations were identified between EI and MQ for all muscles in males and females, however, no significance was determined. Despite the sex differences in absolute strength and size, muscle quality (relative strength) was not different for the upper nor lower body. Full article

Skeletal muscle MRI studies in limb-girdle muscular dystrophy (LGMD) have increased over the past decades, improving the utility of MRI as a differential diagnostic tool. Nevertheless, the relative rarity of individual genotypes limits the scope of what each study can address, making it challenging to obtain a comprehensive overview of the MRI image of this splintered group. Furthermore, MRI studies have varied in their methods for assessing fat infiltration, which is essential in skeletal muscle MRI evaluation. It stayed problematic and impeded attempts to integrate multiple studies to cover the core MRI features of a distinct LGMD. In this study, we conducted a systematic review of LGMD in adults published until April 2023; 935 references were screened in PubMed and EMBASE, searches of the gray literature, and additional records were added during the screening process. Finally, 39 studies were included in our final analysis. We attempted to quantitatively synthesize the MRI data sets from the 39 individual studies. Finally, we illustrated ideal and simple MRI muscle involvement patterns of six representative LGMD genotypes. Our summary synthesis reveals a distinct distribution pattern of affected muscles by LGMD genotypes, which may be helpful for a quick first-tier differential diagnosis guiding genetic diagnostics. Full article

Electromyographic biofeedback (EMG-BF) is a technique that can contribute to the improvement of muscle tone and control in the rehabilitation process after injury. The aim of this research was to determine the effectiveness of EMG-BF in increasing the electromyographic activity of the vastus lateralis after knee injury. The sample consisted of four individuals who had undergone surgery or rehabilitation to resolve either a partial meniscal tear or a patellar tendon strain. The intervention consisted of a program of ten sessions of EMG-BF work. Twelve trials were performed in each session, in which participants were instructed to target the muscle tension produced by the vastus lateralis of the uninjured hemilateral limb. Of the twelve trials in each session, the first three and the last three were performed without feedback, and the intermediate six with feedback. The recording of muscle activity was performed using CY-351/2 Mioback equipment, which allowed the amplitude of the electromyographic signal to be evaluated. The results indicated that the sample analyzed reached greater amplitude during the biofeedback trials, both for the maximum (Z = −13.43, p < 0.001, Cohen’s d = 0.64, 95% CI (0.27, 1.01)) and mean (Z = −7.26, p < 0.001, Cohen’s d = 0.24, 95% CI (−0.12, 0.60)) values. The amplitude also increased throughout the ten sessions, both for the maximum (Z = −3.06, p < 0.01, Cohen’s d = 1.37, 95% CI (0.29, 2.45)) and mean (Z = −3.06, p < 0.01, Cohen’s d = 1.20, 95% CI (0.34, 2.08)) values. Thus, the results highlight the efficacy of this technique in improving muscle activity, suggesting that it is a useful therapeutic procedure in injury recovery. Full article

The heart is composed of muscle cells called cardiomyocytes, including a specialized population named pacemaker cells that form the cardiac conduction system (CCS), which is responsible for generating the action potential dictating heart contractions. Failure of the CCS system leads to cardiac arrhythmias, which require complicated therapies and often the surgical implantation of electrical pacemakers. However, recent research has focused on the development of novel therapies using biological pacemakers that aim to substitute electrical devices. While most signaling pathways and transcription factors involved in the development of the pacemaker cells are known, the upstream regulatory networks need to be predicted through computer-based databases, mathematical modeling, as well as the functional testing of the regulatory elements in vivo, indicating the need for further research. Here, we summarize the current knowledge about the vertebrate myocardial CCS system and the development of the pacemaker cells, as well as emphasize the areas of future research to clarify the regulation of muscle pacemaker cells and the ease of development of biological therapies. Full article

Skeletal muscle is a complex tissue comprising multinucleated and post-mitotic cells (i.e., myofibers). Given this, skeletal muscle must maintain a fine balance between growth and degradative signals. A major system regulating the remodeling of skeletal muscle is autophagy, where cellular quality control is mediated by the degradation of damaged cellular components. The accumulation of damaged cellular material can result in elevated apoptotic signaling, which is particularly relevant in skeletal muscle given its post-mitotic nature. Luckily, skeletal muscle possesses the unique ability to regenerate in response to injury. It is unknown whether a relationship between autophagy and apoptotic signaling exists in injured skeletal muscle and how autophagy deficiency influences myofiber apoptosis and regeneration. In the present study, we demonstrate that an initial inducible muscle-specific autophagy deficiency does not alter apoptotic signaling following cardiotoxin injury. This finding is presumably due to the re-establishment of ATG7 levels following injury, which may be attributed to the contribution of a functional Atg7 gene from satellite cells. Furthermore, the re-expression of ATG7 resulted in virtually identical regenerative potential. Overall, our data demonstrate that catastrophic injury may “reset” muscle gene expression via the incorporation of nuclei from satellite cells. Full article

The present study is the first research that analyzes the quality of life (QoL) of people affected by a dominant form of limb–girdle muscular dystrophy, specifically limb–girdle muscular dystrophy D2 (LGMD-D2). Additionally, clinical forms of the individual cases of the six affected patients are presented. This study also aims to explore the differences between patients’ reports and caregivers’ reports, and between LGMD-D2 and recessive forms of LGMD. The instruments used were as follows: sociodemographic data, GSGC, and INQoL instrument. The sample consisted of six people affected by LGMD-D2: three caregivers of three affected people, and three patients with recessive LGMD. They came from associations of affected people and a hospital in Padua. Those affected have multiple symptoms that lead to disability, which ultimately leads to dependence on the assistance. The present study shows that LGMD-D2 has a greater impact on activities of daily living, fatigue, muscle pain, and independence than other LGMD pathologies or other neuromuscular diseases. It also appears that age could influence QoL, and that muscle weakness is a very disabling symptom in this variant. In the current context of constantly developing research for new treatments, it is essential to analyze which aspects are most affected. Finally, caregivers can play an essential role in symptom reporting, as certain psychological adjustment mechanisms in the patient may be interfering with the objectivity of the report. Full article

Background: Falls risk assessment tools are used in hospital inpatient settings to identify patients at increased risk of falls to guide and target interventions for fall prevention. In 2022, Western Health, Melbourne, Australia, introduced a new falls risk assessment tool, the Western Health St. Thomas’ Risk Assessment Tool (WH-STRATIFY), which adapted The Northern Hospital’s risk tool (TNH-STRATIFY) by adding non-English speaking background and falls-risk medication domains to reflect patient demographics. WH-STRATIFY replaced Peninsula Health Risk Screening Tool (PH-FRAT) previously in use at Western Health. This study compared the predictive accuracy of the three falls risk assessment tools in an older inpatient high-risk population. Aims: To determine the predictive accuracy of three falls risk assessment tools (PH-FRAT, TNH-STRATIFY, and WH-STRATIFY) on admission to Geriatric Evaluation Management (GEM) units (subacute inpatient wards where the most frail and older patients rehabilitate under a multi-disciplinary team). Method: A retrospective observational study was conducted on four GEM units. Data was collected on 54 consecutive patients who fell during admission and 62 randomly sampled patients who did not fall between December 2020 and June 2021. Participants were scored against three falls risk assessment tools. The event rate Youden (Youden Index^ER) indices were calculated and compared using default and optimal cut points to determine which tool was most accurate for predicting falls. Results: Overall, all tools had low predictive accuracy for falls. Using default cut points to compare falls assessment tools, TNH-STRATIFY had the highest predictive accuracy (Youden Index^ER = 0.20, 95% confidence interval CI = 0.07, 0.34). The PH-FRAT (Youden Index^ER = 0.01 and 95% CI = −0.04, 0.05) and WH-STRATIFY (Youden Index^ER = 0.00 and 95% CI = −0.04, 0.03) were statistically equivalent and not predictive of falls compared to TNH-STRATIFY. When calculated optimal cut points were applied, predictive accuracy improved for PH-FRAT (Cut point 17, Youden Index^ER = 0.14 and 95% CI = 0.01, 0.29) and WH-STRATIFY (Cut point 7, Youden Index^ER = 0.18 and 95% CI = 0.00, 0.35). Conclusions: TNH-STRATIFY had the highest predictive accuracy for falls. The predictive accuracy of WH-STRATIFY improved and was significant when the calculated optimal cut point was applied. The optimal cut points of falls risk assessment tools should be determined and validated in different clinical settings to optimise local predictive accuracy, enabling targeted fall risk mitigation strategies and resource allocation. Full article

This study aimed to examine the chronic effect of a stair climbing–descending exercise (ST-EX) program on glycemic control in individuals with type 2 diabetes (T2D). Sixteen T2D participants were randomly divided into two groups and followed up over 12 weeks: they either performed regular ST-EX after meals at home (n = 8) or maintained their daily routine (CON; no training) (n = 8). The participants in the ST-EX group were instructed to perform a minimum of 12 sessions/week of ST-EX for more than three days/week. One session of ST-EX consisted of two repetitions of 3 min bouts of climbing to the second floor, followed by walking down to the first floor. Fourteen participants completed the study (seven for each group). The decrease in glycoalbumin levels was significantly greater in the ST-EX group (mean value: −1.0%) than in the CON group (+0.4%). Moreover, the knee extension force increased greatly in the ST-EX group (+0.2 Nm/kg) compared with that in the CON group (−0.1 Nm/kg), with no significant change in the skeletal muscle mass. Performing regular ST-EX after meals may be an effective strategy to improve glycemic control and lower-extremity muscle strength in individuals with T2D. Full article

The skeletal muscle is a highly plastic tissue that shows a remarkable adaptive capacity in response to acute and resistance exercise, and modifies its composition to adapt to use and disuse, a process referred to as muscle plasticity. Heat shock proteins (HSPs), a class of evolutionarily conserved molecular chaperones, have been implicated in the regulation of skeletal muscle plasticity. Here, we summarize key findings supporting the notion that HSPs are important components required to maintain skeletal muscle integrity and functionality. HSPs participate in the transcriptional program required for myogenesis and are activated following muscle exercise and injury. Their dysfunction, either as a consequence of improper expression or genetic mutations, contributes to muscle atrophy and leads to the development of myopathies and peripheral motor neuropathies. Denervation/reinnervation and repeated rounds of nerve degeneration/regeneration have been observed in motor neuropathies, suggesting that an imbalance in HSP expression and function may impair the repair of the neuromuscular junctions. Boosting HSP activity may help preventing muscle atrophy by promoting muscle differentiation and helping the repair of NMJs. Boosting HSP function may also help to combat the development of rhabdomyosarcoma (RMS), a highly aggressive type of pediatric soft tissue sarcoma whose cells have skeletal muscle features but are unable to fully differentiate into skeletal muscle cells. Full article

Musculoskeletal health is directly linked to independence and longevity, but disease and aging impairs muscle mass and health. Complete repair after a pathological or physiological muscle injury is critical for maintaining muscle function, yet muscle repair is compromised after disuse, or in conditions such as metabolic diseases, cancer, and aging. Regeneration of damaged tissue is critically dependent upon achieving the optimal function of satellite cells (muscle stem cells, MSCs). MSC remodeling in muscle repair is highly dependent upon its microenvironment, and metabolic health of MSCs, which is dependent on the functional capacity of their mitochondria. Muscle repair is energy demanding and mitochondria provide the primary source for energy production during regeneration. However, disease and aging induce mitochondrial dysfunction, which limits energy production during muscle regeneration. Nevertheless, the role of mitochondria in muscle repair likely extends beyond the production of ATP and mitochondria could provide potentially important regulatory signaling to MSCs during repair from injury. The scope of current research in muscle regeneration extends from molecules to exosomes, largely with the goal of understanding ways to improve MSC function. This review focuses on the role of mitochondria in skeletal muscle myogenesis/regeneration and repair. A therapeutic strategy for improving muscle mitochondrial number and health will be discussed as a means for enhancing muscle regeneration. Highlights: (a). Mitochondrial dysfunction limits muscle regeneration; (b). Muscle stem cell (MSC) function can be modulated by mitochondria; (c). Enhancing mitochondria in MSCs may provide a strategy for improving muscle regeneration after an injury. Full article

Skeletal muscle physiology is regulated by microRNA that are localized within skeletal muscle (myomiRs). This study investigated how the expression of myomiRs and genes regulating skeletal muscle mass and myogenesis are influenced in response to acute and consecutive days of exercise-related signaling using the exercise mimetic, formoterol, in vitro. Human skeletal muscle cells were proliferated and differentiated for 6 days. Experimental conditions included: (a) control, (b) acute formoterol stimulation (AFS), and (c) consecutive days of formoterol stimulation (CFS). For AFS, myotubes were treated with 30 nM of formoterol for three hours on day 6 of differentiation, and this was immediately followed by RNA extraction. For CFS, myotubes were treated with 30 nM of formoterol for three hours on two or three consecutive days, with RNA extracted immediately following the final three-hour formoterol treatment. We observed increased myomiR expression for both AFS and CFS. AFS appeared to promote myogenesis, but this effect was lost with CFS. Additionally, we observed increased expression of genes involved in metabolism, mitochondrial biogenesis, and muscle protein degradation in response to AFS. myomiR and gene expression appear to be sensitive to acute and long-term exercise-related stimuli, and this likely contributes to the regulation of skeletal muscle mass. Full article

Amyotrophic lateral sclerosis (ALS) is a complex systemic disease that primarily involves motor neuron dysfunction and skeletal muscle atrophy. One commonly used mouse model to study ALS was generated by transgenic expression of a mutant form of human superoxide dismutase 1 (SOD1) gene harboring a single amino acid substitution of glycine to alanine at codon 93 (G93A*SOD1). Although mutant-SOD1 is ubiquitously expressed in G93A*SOD1 mice, a detailed analysis of the skeletal muscle expression pattern of the mutant protein and the resultant muscle pathology were never performed. Using different skeletal muscles isolated from G93A*SOD1 mice, we extensively characterized the pathological sequelae of histological, molecular, ultrastructural, and biochemical alterations. Muscle atrophy in G93A*SOD1 mice was associated with increased and differential expression of mutant-SOD1 across myofibers and increased MuRF1 protein level. In addition, high collagen deposition and myopathic changes sections accompanied the reduced muscle strength in the G93A*SOD1 mice. Furthermore, all the muscles in G93A*SOD1 mice showed altered protein levels associated with different signaling pathways, including inflammation, mitochondrial membrane transport, mitochondrial lipid uptake, and antioxidant enzymes. In addition, the mutant-SOD1 protein was found in the mitochondrial fraction in the muscles from G93A*SOD1 mice, which was accompanied by vacuolized and abnormal mitochondria, altered OXPHOS and PDH complex protein levels, and defects in mitochondrial respiration. Overall, we reported the pathological sequelae observed in the skeletal muscles of G93A*SOD1 mice resulting from the whole-body mutant-SOD1 protein expression. Full article

It is well known that muscular dystrophy disease severity is controlled by genetic modifiers. The expectation is that by identifying these modifiers, we can illuminate additional therapeutic targets with which to combat the disease. To this end we have been investigating the MRL mouse strain, which is highly resistant to muscular dystrophy-mediated fibrosis. The MRL mouse strain contains two mitochondrial-encoded, naturally occurring heteroplasmies: T3900C in tRNA-Met, and variable adenine insertions at 9821 in tRNA-Arg. Heteroplasmies are mitochondrial mutations that are variably present in a cell’s mitochondria. Therefore, MRL cells can contain 0 to 100% of each mitochondrial mutation. We have chosen the severely affected ϒ-sarcoglycan (Sgcg–/–) deficient mice on the DBA2/J background as our muscular dystrophy model to demonstrate the effects of these mitochondrial heteroplasmies on disease severity. Mice from the (Sgcg–/–) DBA2/J (D) and wildtype MRL (M) strains were crossed for more than 10 generations to establish two separate, pure breeding mouse lines: Sgcg+/–Nuc^DMito^%M and Sgcg+/–Nuc^MMito^%M. The Sgcg–/– mice from these separate lines were analyzed at 8 weeks old for membrane permeability, hydroxyproline content, pAMPK content, fibronectin content, and percentage of each heteroplasmy. We have identified that the MRL mitochondrial mutation T3900C confers a portion of the fibrosis resistance identified in the MRL mouse strain. These results have been extended to significantly correlate increased MRL mitochondria with increased pAMPK and decreased muscular dystrophy fibrosis. The beneficial mechanisms controlled by the MRL mitochondria will be discussed. We are establishing metabolic aspects of muscular dystrophy pathogenesis. These metabolic pathways will now be investigated for therapeutic targets. Full article

Efficacy of obesity treatments varies between individuals, highlighting the presence of responders and non-responders. Whilst exercise alone or exercise combined with diet leads to underwhelming weight loss for most, there exist super responders losing significant weight. Furthermore, in response to weight loss, the majority but not all patients tend to regain weight. Within the biopsychosocial model, biology as a determinant of response has been underappreciated. The understanding of the role that organs beyond adipose tissue and the gastrointestinal tract play in appetite control and body weight regulation has developed in recent years. The aim of this review is to highlight potential myokines that may be important in appetite physiology and overall energy balance. A number of attractive targets are described that warrant further investigation. A deeper understanding of how these myokines may drive feeding behaviours has the potential to improve measures to prevent and treat obesity through a precision medicine approach. Full article