Search Results (1,457)

Background: Myasthenia gravis (MG) is a chronic autoimmune disorder characterized by fluctuating skeletal muscle weakness and fatigue, leading to reduced functional independence and impaired quality of life (QoL). Although exercise has historically been discouraged due to concerns about symptom exacerbation, emerging evidence suggest that structured exercise programs may be safe and beneficial in clinically stable patients. This systematic review critically evaluates current evidence on exercise and physical activity interventions in MG, focusing on effectiveness, safety, and impact on functional outcomes, fatigue, and QoL. Materials and Methods: A systematic review was conducted following PRISMA guidelines. Searches were performed in PubMed, Web of Science, Google Scholar, Scopus and ScienceDirect for studies published between 2015 and 2025. Keywords included MG, physical activity, aerobic training, resistance training, and respiratory muscle training. Methodological quality was assessed using the Downs and Black checklist. Results: Eight controlled studies met the inclusion criteria, encompassing aerobic, resistance, combined, and respiratory muscle training interventions. Sample sizes ranged from small pilot studies to moderate-size randomized controlled trials. Overall, exercise interventions were well tolerated, with no evidence of sustained symptoms exacerbation. Aerobic and combined programs consistently improved functional capacity, muscle strength, and activities of daily living. Respiratory muscle training demonstrated improvements in pulmonary function and inspiratory muscle strength, although findings were more heterogeneous. Study quality ranged from poor to excellent, with common limitations including small sample size, short follow-up duration, and heterogeneity in exercise programs. Conclusions: Current evidence supports the safety and potential efficacy of individualized, symptom-guided exercise interventions in clinically stable MG. Regular physical activity exercise may reduce secondary deconditioning, improve functional outcomes, and enhance QoL. However, larger, high-quality randomized controlled trials with standardized programs and longer follow-up periods are required to strengthen clinical recommendations and clarify long-term effects. Full article

Soleus muscle fibres display modest changes in tetanic force and [Ca²⁺]_i during repeated contractions. In this study, we investigate whether increasing mitochondrial Ca²⁺ load during repeated contractions could induce premature fatigue. Intact, single fibres were dissected from the soleus muscles of adult mice. Mitochondrial Ca²⁺ was measured with rhod-2 in intact fibres. Fatigue was induced by 70 Hz, 350 ms tetani given at 2 s intervals in the absence and presence of 10 µM CGP-37157, a potent inhibitor of the mitochondrial Na⁺-Ca²⁺ exchanger. In soleus fibres fatigued in the absence of CGP-37157, tetanic force was significantly reduced by about 30% at the end of the fatiguing stimulation, while mitochondrial [Ca²⁺] increased to a maximum after about 50 tetani and returned to its resting level within 20 min after the end of the stimulation. In the presence of CGP-37157, the maximal mitochondrial [Ca²⁺] increase was more than twice that in control fibres. In addition, fatigue developed more rapidly and force remained depressed after the end of the stimulation. No difference in mitochondrial membrane potential or ROS production was seen between control and CGP-37157 conditions. We conclude that while modest increases in mitochondrial Ca² may be beneficial, excessive mitochondrial Ca² loading depresses muscle function. Full article

Sports-related muscle injuries represent a major challenge in both recreational and professional sports, accounting for a substantial proportion of time-loss injuries and frequently leading to recurrent episodes. The aim of this narrative review was to analyze the biomechanical and neuromuscular mechanisms involved in the occurrence of muscle injuries and to synthesize evidence-based prevention strategies reported in the scientific literature. The literature search was conducted in the Web of Science database using the keyword “muscle injury prevention”, focusing on studies published between 2010 and 2025. The analyzed literature indicates that muscle injuries are strongly associated with eccentric contractions at long muscle lengths, neuromuscular fatigue, strength imbalances, impaired lumbopelvic stability, and inadequate load management. Preventive strategies based on biomechanical principles, particularly eccentric strength training, neuromuscular training programs, and core stability exercises, have demonstrated consistent effectiveness in reducing injury incidence and recurrence rates across multiple sports disciplines. In addition, emerging technological approaches, including wearable sensors and machine learning models, show promising potential for injury risk prediction and individualized prevention strategies. Full article

This study examined whether different body fat percentages (BF%) may influence performance, physiological responses, and fatigue in professional soccer players during a simulated soccer game protocol on a treadmill. Twenty professional male soccer players were categorized in higher (HBF%) and lower (LBF%) body fat percentage groups [HBF% > 11.5%; n = 11, BF% = 14.2 ± 2, LBM = 65.3 ± 8 kg, age = 22.7 ± 4 years, height = 177 ± 7 cm, weight = 76 ± 9 kg, V̇O₂max = 60.1 ± 4.5]; [LBF% < 11.5%, n = 9; BF% = 8.1 ± 1, LBM = 65.9 ± 5 kg, age = 20.1 ± 3 years, height = 179 ± 4 cm, weight = 72 ± 5 kg, V̇O₂max = 61.6 ± 4). Players underwent a simulated soccer game protocol on a treadmill. Cardiometabolic and hormonal responses, and fuel oxidation and performance, were evaluated. At baseline, apart from the BF% variable (p < 0.0001), the groups did not differ in any other physiological or physical characteristic (p > 0.05). There were no differences between the groups in any performance or biological parameters evaluated (p > 0.05), except for plasma glucose, which was higher in the HBF% group at rest and during the soccer game protocol (p < 0.05). In conclusion, the theory of a uniform ideal (~10 ± 2%) of BF% in elite soccer is not supported by the present study. This study suggests that when muscle mass and fitness levels of the soccer players are maintained at high levels during the competitive period, BF% represents a highly individualized characteristic rather than a uniform target across players. However, a higher BF% increased resting and exercising blood glucose concentrations, even in highly trained professional soccer players, without concomitant effects on metabolism or fuel oxidation during match play. Full article

Background/Objective: Delaying muscle fatigue could alleviate economic and food security, and welfare concerns associated with transporting market-weight pigs to harvest. Previous research demonstrates barrow nicotinamide riboside (NR) supplementation at varying doses during the last 10 d of finishing shows to be a countermeasure to muscle fatigue by reducing muscle fiber recruitment and increasing mitochondrial DNA expression in a dose-dependent manner. Therefore, this study aims to determine if a greater NR dose further enhances barrow fatigue resistance and characterize muscle mitochondria content and efficiency. Methods: Barrows (N = 87) were assigned to one of two dietary NR supplementation doses (TRT): 0 (0NR) or 150 (150NR) mg/kg body weigh NR administered during the last 14 d of finishing. Muscle (MUS) biopsies were collected on supplementation d (DAY) 0, 7 and 14 from three hind-leg muscles for NAD+ quantification and mitochondrial DNA expression and efficiency. On days 15 and 16, barrows were subjected to a performance test until they were subjectively exhausted. Electromyography data collection during the performance test were divided into five periods (PER) and included normalized root mean square (nRMS) from the same muscles. Results: There were no three-way interaction for nRMS (p > 0.83), but there were MUS × TRT and PER × TRT interactions (p < 0.05). During performance testing, 150NR had greater nRMS than 0NR in the bicep femoris (BF) and tensor fasciae latae (TFL; p < 0.01), but there were no differences in the semitendinosus (ST; p = 0.77). Treatments did not differ during PER 1 and 2 (p > 0.14) but 150NR had greater nRMS than 0NR during PER 3, 4 and 5 (p < 0.01) across all muscles. There was no three-way interaction for normalized (nNAD+; p = 0.14), but there was a DAY × TRT interaction (p < 0.05). There were no differences between 0NR and 150NR at d 0 (p = 0.95); however, by d 7 and 14, 150NR muscles had greater nNAD+ than 0NR muscles (p < 0.01). There tended to be a three-way interaction for mitochondrial DNA expression (p = 0.09). At supplementation d 14, all 150NR muscles had greater mitochondrial DNA expression and electron transport chain complex I and II activities (p < 0.01). When normalized to citrate synthase activity, electron transport chain complex I and II activity did not differ (p > 0.05). Conclusions: Large-dose NR supplementation appears to support sustained muscle fiber recruitment during prolonged activity and enhance fatigue resilience, primarily through increased NAD+ and mitochondrial biomarkers abundance and not through mitochondrial efficiency. Full article

Introduction: Chronic kidney disease and kidney failure are associated with a decline in physical abilities resulting in severe health-related complications. Existing systematic reviews and meta-analyses show that exercise interventions in patients on haemodialysis enhance physical functioning, cardiovascular health, muscle strength, and overall quality of life. However, the available literature mostly stem from adult cohorts outside Africa. Thus, this scoping review aims to evaluate existing literature on the impact of exercise programs on paediatric patients undergoing haemodialysis in Africa. Methods: A systematic search of electronic databases, including CINAHL, EBSCO, Medline, PubMed, and Scopus, was conducted following the Arksey and O’Malley methodological framework for scoping reviews and complied with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) reporting guidelines. The inclusion criteria was applied to identify peer-reviewed articles published between 2015 and 2025, focusing on the effects, impact, and benefits of exercises and physical activity programs in paediatric patients undergoing haemodialysis aged up to 18 years. The selection process was done by two researchers pertaining to importing search results, removing duplicates, screening titles and abstracts, and analysis the reference lists of selected studies to ensure comprehensive coverage. Results: Two exercise-based intervention studies were eligible in the final review. In both studies, the duration of the intervention was about two months, and they included sample sizes of 60 and 50 participants. The first study, using the Paediatric Quality of Life Inventory (PedsQL-I), reported significant improvements across all dimensions in quality-of-life following muscle stretching and isometric exercises. The second study, employing the Paediatric Quality of Life Multidimensional Fatigue Scale (PedsQL-MFS) and the Depression Anxiety Stress Scale (DASS), found reductions in fatigue and psychological distress, and positive biochemical changes. A notable omission was the lack of detail regarding contraindications and precautionary measures. These are essential for informing clinical decision-making and ensuring exercises are safe. Discussion: The findings underscore the importance of incorporating exercise into the standard care of paediatric patients undergoing haemodialysis to facilitate better health outcomes. The fact that only two relevant studies were found highlights a narrow regional scope within Africa as both studies originated from a single country. Further research is needed to develop and implement effective exercise interventions tailored to other countries in Africa. Full article

Myasthenia gravis (MG) is a rare autoimmune disorder characterized by muscle weakness and fatigue, caused by autoantibodies produced by B-cells that target proteins in the postsynaptic membrane of the neuromuscular junction. Clinical manifestations are heterogeneous and may include diplopia, ptosis, dysarthria, dysphagia, and limb muscle weakness, with severity ranging from mild symptoms to life-threatening myasthenic crisis. Despite advances in diagnostic approaches and the availability of immunomodulatory and biological therapies, there remains a need for an improved understanding of the disease mechanisms and biomarker development in MG. Blood-derived exosomes are small extracellular vesicles that carry proteins, lipids, nucleic acids, and glycoconjugates, and are involved in intercellular communication and the transfer of biological material between cells. Circulating exosomes may reflect aspects of cellular and immune status and have been proposed as a minimally invasive source of biomarkers in various diseases. In this review, we summarize current evidence on the potential role of exosomes in MG, with a focus on their involvement in disease-associated processes and their possible utility as biomarkers, as well as directions for future research. Full article

Compound sugars (Cs) and creatine (Cr) have the potential to enhance exercise endurance; however, the mechanisms underlying their effects and the stability of their formulations still require further investigation. This study investigated the effects of Cs and Cr supplementation on exercise performance in C57BL/6 mice, as well as the processing properties of Cs and Cr powder. The exhaustion time, serum fatigue indices, creatine contents, the morphology of muscle tissue in mice were determined. The results demonstrated that combined supplementation of sugar and creatine (Cs-Cr, Cs 6.2 mg/g + Cr 1.0 mg/g) could significantly increase exhaustion time and forelimb grip strength and reduce the levels of lactate and blood urea nitrogen by 22.3% and 25.86%, respectively. In addition, Cs-Cr supplementation increased muscle mass and muscle fiber density in exercise-trained mice and thus alleviated muscle damage caused by exercise. However, Cs-Cr powder exhibits poor stability during processing. Xanthan gum and locust bean gum (m/m = 6:4) has been demonstrated to increase the stability and viscosity of Cs-Cr beverages. Moreover, the addition of 1.5% CaSiO₃ also reduced the caking of the powder and increased the stability of the product. This study provides a theoretical basis for the application of Cs-Cr in a functional solid beverage. Full article

Aiming to reduce muscle fatigue and prevent occupational injuries caused by prolonged lifting in insulator replacement operations, this study presents the design of an upper-limb exoskeleton. Firstly, this study performs kinematic analysis and phase segmentation of the lifting motion in the insulator replacement operation. Based on the analysis, in terms of mechanical structure, the proposed upper-limb exoskeleton adopts a unilateral three-degree-of-freedom shoulder mechanism that biomimics the human glenohumeral joint, which reduces the misalignment between the exoskeleton and the human body. Meanwhile, a waist–back support structure is integrated into the exoskeleton to realize a more reasonable torque transmission path. In terms of the control strategy, based on the operation’s phase segmentation and dynamic modeling of the human upper limb, this study develops a neural network-based assistive control algorithm for insulator replacement operations, enabling the exoskeleton to provide phase-specific torque output. Experimental results demonstrate that, under a simulated insulator replacement operation with a 20 kg load, the exoskeleton significantly reduces the subject’s sEMG activity of the biceps brachii and triceps brachii, effectively alleviating muscle fatigue. Full article

Background: Regular aerobic exercise during childhood promotes critical physiological adaptations in the cardiovascular and respiratory system. Finswimming, a unique aquatic sport, requires high-intensity demands and specific breathing patterns. The present study aimed to compare respiratory function and cardiorespiratory responses between young male finswimmers and sedentary age-matched non-athletes. Methods: Thirty-two boys aged 8 to 12 years old were stratified into the finswimmers group (FSG, n = 16) and the non-athletes group (NAG, n = 16). Assessments included pulmonary function (spirometry) and respiratory muscle strength (Maximum Inspiratory Pressure, MIP/Maximum Expiratory Pressure, MEP). Exercise capacity was evaluated using the modified shuttle walk test (MSWT). Results: The FSG exhibited significantly higher pulmonary function (Forced Vital Capacity, Forced Expiratory Volume in 1 s, Maximum Voluntary Ventilation; p < 0.05) and superior MIP compared to the NAG (105.3 ± 24.8 versus 87.3 ± 24.7 cmH₂O; p = 0.022). During the MSWT, FSG covered substantially greater distances (746.6 ± 97.2 versus 591.1 ± 86.4 m; p < 0.001) with lower levels of leg fatigue (Borg 0–10) (0.53 ± 0.39 versus 2.13 ± 1.93; p = 0.004) and demonstrated lower heart rate recovery time (4.47 ± 0.68 versus 5.75 ± 0.68 min; p < 0.001) compared to NAG. At the iso-level (8th level of MSWT), FSG scored lower levels of leg fatigue (0.13 ± 0.12 versus 2.02 ± 2.0; p = 0.001) compared to NAG, indicating better peripheral oxygen % saturation (100 ± 0.0 versus 98.14 ± 1.16; p < 0.001). Conclusions: Systematic exercise training enhances profound cardiorespiratory and peripheral muscle adaptations in children. Enhanced cardiorespiratory function allows young athletes to achieve higher workloads and recover faster than sedentary peers, highlighting the sport’s role in establishing a robust cardiorespiratory fitness. Full article

Background: Patients with pancreatic cancer (PC) commonly present with reduced aerobic fitness, sarcopenia, and malnutrition, which may increase perioperative risk and compromise access to chemotherapy treatments. Although exercise-based prehabilitation can improve physical fitness, its implementation is often limited by short diagnostic-to-surgery intervals and treatment-related toxicity. Methods: We conducted a pilot prospective pretest–posttest feasibility study in Torino, Italy. Patients with PC undergoing neoadjuvant chemotherapy prior to surgery were offered a 4-week, partially supervised, home-based bimodal exercise prehabilitation program (single-arm design) combining remotely monitored high-intensity interval training (HIIT) on a cycle ergometer with functional and resistance exercises. The primary outcome was adherence to prescribed exercise frequency, intensity, and duration, objectively assessed via remote monitoring. Secondary outcomes included cardiorespiratory fitness (CPET), muscle function, body composition, fatigue, quality of life, and circulating inflammatory markers. Results: From July 2022 to February 2024, 23 patients were screened; 15 were eligible and 10 enrolled. Four participants discontinued the intervention (two due to asthenia/fatigue, one due to chemotherapy-related adverse events, and one for organizational reasons), leaving six participants who completed the program. Among completers, fatigue and quality of life did not change meaningfully. Aerobic capacity and muscle function outcomes were generally stable, with few pre–post changes exceeding the minimum clinically important difference (MCID) thresholds used. Body composition markers and the assessed circulating cytokines/chemokines remained unchanged except for IL-6 levels, which decreased significantly (p < 0.05). Conclusions: A partially supervised, home-based HIIT-based prehabilitation program is feasible for a subset of PC patients undergoing neoadjuvant therapy, but a substantial attrition rate suggests the need for more flexible symptom-adapted prescriptions and enhanced supportive strategies. Full article

Objective: The effects of fatigue on swimming propulsion are unclear. This study examined upper-limb propulsive force and bilateral coordination during constant-speed front crawl performed until exhaustion. Methods: Twelve competitive swimmers completed a visually paced front-crawl trial performed at a constant speed (95% of maximal speed) until volitional exhaustion. Upper-limb propulsion (pressure-derived) was quantified using wearable differential-pressure mini-paddles synchronized with high-speed video. Propulsive force and impulse were analyzed at ten standardized time points (10–100% of test duration), distinguishing the early (entry–catch–pull) phase and the push phase of the stroke cycle. Results: Total overall propulsive impulse (time-integral of propulsive force) and mean propulsive force decreased significantly as early as 30–40% of test duration, with the largest reductions occurring during the push phase. Interestingly, push-phase impulse declined earlier in the non-dominant left arm (from 20% of test duration) compared to the dominant right arm (from 40%), whereas force generated during the early phase did not change. Peak propulsive force decreased at later stages, while intra-cycle timing indices (peak timing and force centroid) and inter-limb asymmetry remained unchanged. Stroke frequency increased from mid-test onward and was strongly negatively associated with stroke efficiency (r = −0.79). Stroke efficiency correlated positively with push-phase impulse and peak force. Conclusions: During constant-speed front crawl performed to exhaustion, propulsion progressively declines, primarily through reduced force and impulse during the push phase rather than changes in the early (entry–catch–pull) phase or temporal and asymmetry-related variables. Increased stroke frequency initially compensates for declining propulsion but ultimately fails to maintain the imposed swimming velocity. Full article

This two-step design used the unilateral bench press to examine the effect of breast cancer surgery on upper-limb muscle activation under low and moderate fatigue conditions. First, we studied the proper method to normalize the activation values obtained during dynamic contractions. For that, the muscle activation was relativized to the maximal value obtained during (i) an isometric contraction (ISO_Norm), and the concentric phase of the (ii) repetition maximum load (1RM_Norm), and (iii) the first three repetitions of an 80% 1RM set (Max80%_Norm). The normalization method with the lowest inter-subject variability was further used to compare the muscle activation of the affected and non-affected sides of twelve women who underwent unilateral breast surgery (eight mastectomies and four lumpectomies). Both sides were tested using dynamic sets at 60 and 80% of their 1RM until reaching 40% velocity loss (VL). Repetitions completed at each %1RM were then divided into two groups: low fatigue (first half of repetitions) and moderate fatigue (second half of repetitions). On results, the ISO_Norm and the Max80%_Norm showed the highest (mean CV = 32.9%) and lowest (mean CV = 12.9%) inter-subject variability, respectively. The affected side showed higher activation for the deltoid and triceps (Δ = 6.9 to 15.9%) but lower for the pectoralis (Δ = −5.7 to −13.2%) against 60% 1RM. These differences were lower and without a consistent trend against 80% 1RM. Between-side comparisons were not significant for either 60% 1RM (p > 0.270) or 80% 1RM (p > 0.500). Although these results should be interpreted with caution due to the small and heterogeneous sample, our analyses did not reveal meaningful differences in upper-limb muscle activation following breast cancer surgery. Full article

Background/Objectives: Understanding how different fatigue contexts influence muscle architecture is essential for optimizing training and recovery strategies in endurance athletes. Ultramarathon running involves prolonged mechanical load and high eccentric demands, which may elicit different acute responses compared to controlled laboratory protocols. This study aimed to examine the effects of time, condition (laboratory vs. race), and muscle on ultrasound-derived muscle architecture in ultratrail runners. Methods: A repeated-measures within-subject design was employed. Forty ultratrail runners completed two fatigue conditions: (1) a standardized laboratory downhill running protocol and (2) an ultramarathon race (CSP 2025; 106 km, +5600 m elevation gain). Muscle thickness and pennation angle of the rectus femoris, vastus lateralis, and medial gastrocnemius were assessed using ultrasound before and after each condition. Linear mixed models were used to evaluate the effects of time, condition, muscle, and their interactions. Results: Forty participants were recruited; 29 completed all assessments. No significant effects of time or condition were observed for muscle thickness, and no interaction effects were detected, indicating that muscle size remained stable across conditions and time points. A significant main effect of muscle was identified (p < 0.001), reflecting inherent morphological differences, with greater thickness in the vastus lateralis compared to the rectus femoris and medial gastrocnemius. In contrast, pennation angle showed a significant main effect of condition (p = 0.031) and a significant condition × muscle interaction (p = 0.005), indicating muscle-specific differences between laboratory and race contexts. No significant effect of time was observed for pennation angle. Conclusions: Muscle thickness appears to remain stable following acute fatigue, regardless of the assessment context. In contrast, pennation angle may be more sensitive to condition-specific and muscle-dependent factors. These findings suggest that ultrasound-derived architectural changes observed immediately after exercise likely reflect acute physiological responses rather than true structural adaptations. Therefore, the interpretation of muscle architecture should consider both contextual factors and methodological constraints. Full article

Objective: This study investigated the effects of menthol (MEN) mouth rinsing (MR) on cycling performance, neuromuscular activation, and perceptual responses during high-intensity exercise in the heat. Methods: A total of 10 trained adolescent male cyclists (16.7 ± 1.3 yrs; VO_2peak: 62.3 ± 7.6 mL·kg⁻¹·min⁻¹) completed a familiarization and two randomized, single-blind trials using a modified variable cycling test (M-VCT) in the heat (31.45 ± 0.59 °C; 23.40 ± 2.55% RH). The participants rinsed with 0.01% L-menthol or a placebo every 6 min during exercise. Power output (PO), cadence (RPM), rating of fatigue (ROF), affective feeling (FS), and surface electromyography (sEMG) were recorded. Results: Menthol MR significantly increased mean PO by 1.67 ± 1.59% (MEN: 177.1 ± 33.0 W; PLA: 174.1 ± 32.1 W; p = 0.002; d = 1.42) and enhanced cadence (MEN: 87.4 ± 5.1 RPM; PLA: 84.5 ± 5.2 RPM; p = 0.027; d = 0.84), particularly during high-intensity intervals. No significant differences were observed in ROF or FS between conditions (p > 0.05). Five muscles were monitored for activation (RF, VM, VL, TA, Gast). A significant main effect of time demonstrated decreased activation in VM, TA, RF, and Gast. VL showed a trend toward a main effect of condition (p = 0.057), with lower activation in MEN. Both VL and RF exhibited significant condition × lap interactions (p = 0.007 and p = 0.017), with progressively lower activation in MEN as fatigue progressed. Conclusions: Menthol MR significantly improved cycling performance in the heat without altering perceptual or physiological strain. Some muscles demonstrated reduced activation with menthol MR, and further study is needed to confirm the magnitude of ergogenic effects and elucidate the physiological mechanism. Full article