Muscle fatigue: general understanding and treatment

Metaplastic neuromodulation via transcranial direct current stimulation has no effect on corticospinal excitability and neuromuscular fatigue

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation tool with potential for managing neuromuscular fatigue, possibly due to alterations in corticospinal excitability. However, inconsistencies in intra- and inter- individual variability responsiveness to tDCS limit its clinical use. Emerging evidence suggests harnessing homeostatic metaplasticity induced via tDCS may reduce variability and boost its outcomes, yet little is known regarding its influence on neuromuscular fatigue in healthy adults. We explored whether cathodal tDCS (ctDCS) prior to exercise combined with anodal tDCS (atDCS) could augment corticospinal excitability and attenuate neuromuscular fatigue. 15 young healthy adults (6 males, 22 ± 4 years) participated in four pseudo-randomised neuromodulation sessions: sham stimulation prior and during exercise, sham stimulation prior and atDCS during exercise, ctDCS prior and atDCS during exercise, ctDCS prior and sham stimulation during exercise. The exercise constituted an intermittent maximal voluntary contraction (MVC) of the right first dorsal interosseous (FDI) for 10 min. Neuromuscular fatigue was quantified as an attenuation in MVC force, while motor evoked potential (MEP) amplitude provided an assessment of corticospinal excitability. MEP amplitude increased during the fatiguing exercise, whilst across time, force decreased. There were no differences in MEP amplitudes or force between neuromodulation sessions. These outcomes highlight the ambiguity of harnessing metaplasticity to ameliorate neuromuscular fatigue in young healthy individuals.

Activation of α7 Nicotinic Acetylcholine Receptor Improves Muscle Endurance by Upregulating Orosomucoid Expression and Glycogen Content in Mice

There are presently no acknowledged therapeutic targets or official drugs for the treatment of muscle fatigue. The alpha7 nicotinic acetylcholine receptor (α7nAChR) is expressed in skeletal muscle, with an unknown role in muscle endurance. Here, we try to explore whether α7nAChR could act as a potential therapeutic target for the treatment of muscle fatigue. Results showed that nicotine and PNU-282987 (PNU), as nonspecific and specific agonists of α7nAChR, respectively, could both significantly increase C57BL6/J mice treadmill-running time in a time- and dose-dependent manner. The improvement effect of PNU on running time and ex vivo muscle fatigue index disappeared when α7nAChR deletion. RNA sequencing revealed that the differential mRNAs affected by PNU were enriched in glycolysis/gluconeogenesis signaling pathways. Further studies found that PNU treatment significantly elevates glycogen content and ATP level in the muscle tissues of α7nAChR+/+ mice but not α7nAChR-/- mice. α7nAChR activation specifically increased endogenous glycogen-targeting protein orosomucoid (ORM) expression both in vivo skeletal muscle tissues and in vitro C2C12 skeletal muscle cells. In ORM1 deficient mice, the positive effects of PNU on running time, glycogen and ATP content, as well as muscle fatigue index, were abolished. Therefore, the activation of α7nAChR could enhance muscle endurance via elevating endogenous anti-fatigue protein ORM and might act as a promising therapeutic strategy for the treatment of muscle fatigue.

Efficacy of amino acids in sports nutrition- review of clinical evidences

The efficacy of amino acids as popular sports supplements has triggered debates, with their impact on athletic performance varying across sports disciplines due to diversity and heterogeneity in clinical trials. This review evaluates the ergogenic potential of amino acids, by critical appraisal of results of clinical trials of Branched chain amino acids (BCAAs), arginine, glutamine, citrulline, β-alanine, and taurine, performed on elite sportsmen from various land and water sports. Clinical trials reviewed here confirm notable physiological benefits thereby supporting the claim that BCAA, citrulline and arginine in various doses can have positive effects on endurance and overall performance in sportsperson. Furthermore, results of clinical trials and metabolomic studies indicate that in future it would be more beneficial to design precise formulations to target the requirement of specific sports. For instance, some combinations of amino acids may be more suitable for long term endurance and some others may be suitable for short burst of excessive energy. The most important insights from this review are the identification of three key areas where research is urgently needed: a) Biomarkers that can identify the physiological end points and to distinguish the specific role of amino acid as anti-fatigue or reducing muscle soreness or enhancing energy b) In-depth sports-wise clinical trials on elite sportsperson to understand the ergogenic needs for the particular sports c) Design of precision formula for similar types of sports instead of common supplements.

A non-antibiotic erythromycin derivative improves muscle endurance by regulating endogenous anti-fatigue protein orosomucoid in mice

At present, there are no official approved drugs for improving muscle endurance. Our previous research found acute phase protein orosomucoid (ORM) is an endogenous anti-fatigue protein, and macrolides antibiotics erythromycin can elevate ORM level to increase muscle bioenergetics and endurance parameters. Here, we further designed, synthesized and screened a new erythromycin derivative named HMS-01, which lost its antibacterial activity in vitro and in vivo. Data showed that HMS-01 could time- and dose-dependently prolong mice forced-swimming time and running time, and improve fatigue index in isolated soleus muscle. Moreover, HMS-01 treatment could increase the glycogen content, mitochondria number and function in liver and skeletal muscle, as well as ORM level in these tissues and sera. In Orm-deficient mice, the anti-fatigue and glycogen-elevation activity of HMS-01 disappeared. Therefore, HMS-01 might act as a promising small molecule drug targeting ORM to enhance muscle endurance.

Impact of Pediococcus pentosaceus YF01 on the exercise capacity of mice through the regulation of oxidative stress and alteration of gut microbiota

Using treadmill training, this study replicated human exercise conditions and triggered exercise-induced fatigue in mice to examine the potential of Pediococcus pentosaceus YF01 in delaying this fatigue by regulating oxidative stress and its impact on the exercise capacity and gut microbiota of mice. The exercise capacity of mice was tested by conducting exhaustion tests, determining histopathological changes in mouse tissues, detecting the levels of serum biochemical markers, and evaluating the mRNA expression levels of relevant genes. YF01 prolonged the exhaustion time of mice, increased the serum levels of oxidative stress-related markers T-AOC, CAT, and GSH, as well as GLU and LA levels in the mice. YF01 decreased the levels of hepatic-related markers AST and ALT, as well as exercise-related markers LDH, BUN, UA, and CRE in the mice. YF01 upregulated the mRNA expression of MyHc I, SIRT1, and PGC in muscle tissues, as well as SOD1, SOD2, and CAT in both liver and muscle tissues. YF01 also downregulated the mRNA expression of MyHc IIa, MyHc IIb, and MyHc IIx in muscle tissues. Furthermore, YF01 increased the abundance of beneficial bacteria such as Lactobacillus and Lachnospiraceae in the gut microbiota of mice. In conclusion, P. pentosaceus YF01 may affect the exercise capacity of mice by modulating oxidative stress levels, thereby offering novel ideas for developing of sports science and human health.

Diapocynin treatment induces functional and structural improvements in an advanced disease state in the mdx5Cv mice

Duchenne muscular dystrophy (DMD) is the most common muscular disorder affecting children. It affects nearly 1 male birth over 5000. Oxidative stress is a pervasive feature in the pathogenesis of DMD. Recent work shows that the main generators of ROS are NADPH oxidases (NOX), suggesting that they are an early and promising target in DMD. In addition, skeletal muscles of mdx mice, a murine model of DMD, overexpress NOXes. We investigated the impact of diapocynin, a dimer of the NOX inhibitor apocynin, on the chronic disease phase of mdx5Cv mice. Treatment of these mice with diapocynin from 7 to 10 months of age resulted in decreased hypertrophy of several muscles, prevented force loss induced by tetanic and eccentric contractions, improved muscle and respiratory functions, decreased fibrosis of the diaphragm and positively regulated the expression of disease modifiers. These encouraging results ensure the potential role of diapocynin in future treatment strategies.

Bioactive Compounds in Citrus reticulata Peel Are Potential Candidates for Alleviating Physical Fatigue through a Triad Approach of Network Pharmacology, Molecular Docking, and Molecular Dynamics Modeling

Physical fatigue (peripheral fatigue), which affects a considerable portion of the world population, is a decline in the ability of muscle fibers to contract effectively due to alterations in the regulatory processes of muscle action potentials. However, it lacks an efficacious therapeutic intervention. The present study explored bioactive compounds and the mechanism of action of Citrus reticulata peel (CR-P) in treating physical fatigue by utilizing network pharmacology (NP), molecular docking, and simulation-based molecular dynamics (MD). The bioactive ingredients of CR-P and prospective targets of CR-P and physical fatigue were obtained from various databases. A PPI network was generated by the STRING database, while the key overlapping targets were analyzed for enrichment by adopting KEGG and GO. The binding affinities of bioactive ingredients to the hub targets were determined by molecular docking. The results were further validated by MD simulation. Five bioactive compounds were screened, and 56 key overlapping targets were identified for CR-P and physical fatigue, whereas the hub targets with a greater degree in the PPI network were AKT1, TP53, STAT3, MTOR, KRAS, HRAS, JAK2, IL6, EGFR, and ESR1. The findings of the enrichment analysis indicated significant enrichment of the targets in three key signaling pathways, namely PI3K-AKT, MAPK, and JAK-STAT. The molecular docking and MD simulation results revealed that the bioactive compounds of CR-P exhibit a stronger affinity for interacting with the hub targets. The present work suggests that bioactive compounds of CR-P, specifically Hesperetin and Sitosterol, may ameliorate physical fatigue via the PI3K-AKT signaling pathway by targeting AKT1, KRAS, and MTOR proteins.

Connecting the dots: the role of fatigue in female infertility

Fatigue, an increasingly acknowledged symptom in various chronic diseases, has garnered heightened attention, during the medical era of bio-psycho-social model. Its persistence not only significantly compromises an individual's quality of life but also correlates with chronic organ damage. Surprisingly, the intricate relationship between fatigue and female reproductive health, specifically infertility, remains largely unexplored. Our exploration into the existing body of evidence establishes a compelling link between fatigue with uterine and ovarian diseases, as well as conditions associated with infertility, such as rheumatism. This observation suggests a potentially pivotal role of fatigue in influencing overall female fertility. Furthermore, we propose a hypothetical mechanism elucidating the impact of fatigue on infertility from multiple perspectives, postulating that neuroendocrine, neurotransmitter, inflammatory immune, and mitochondrial dysfunction resulting from fatigue and its co-factors may further contribute to endocrine disorders, menstrual irregularities, and sexual dysfunction, ultimately leading to infertility. In addition to providing this comprehensive theoretical framework, we summarize anti-fatigue strategies and accentuate current knowledge gaps. By doing so, our aim is to offer novel insights, stimulate further research, and advance our understanding of the crucial interplay between fatigue and female reproductive health.

Effect of high-definition transcranial direct current stimulation among late-subacute and chronic stroke survivors with fatigue: A randomized-controlled crossover trial protocol

Post-stroke fatigue (PSF) is a commonly overlooked symptom that impacts daily functioning and quality of life. It is caused by altered functional connectivity within the brain networks, which can potentially be influenced by neuromodulation. Multiple cortical regions have been targeted to reduce PSF, but the most efficient ones remain uncertain. Therefore, we aim to identify the most appropriate cortical stimulation site to reduce PSF. Twenty participants with PSF will be included in this cross-over trial. Each participant will receive one session of active anodal high definition- transcranial direct current stimulation (HD-tDCS) over three different cortical areas and one session of sham tDCS in a cross-over manner, with a two-week of washout period in between. Pre- and post- fatigue will be assessed using Fatigue Severity Scale and fatigability using electromyography by determining the time to task failure. Resting-state electroencephalography will be performed before and after each stimulation session to determine the functional connectivity of the cortical areas stimulated.

Adenosine A2A and dopamine D2 receptor interaction controls fatigue resistance

Introduction: Caffeine and the selective A2A receptor antagonist SCH58261 both have ergogenic properties, effectively reducing fatigue and enhancing exercise capacity. This study investigates in male Swiss mice the interaction between adenosine A2A receptors and dopamine D2 receptors controlling central fatigue, with a focus on the striatum where these receptors are most abundant. Methods: We employed DPCPX and SCH58261 to antagonize A1 and A2A receptors, caffeine as a non-competitive antagonist for both receptors, and haloperidol as a D2 receptor antagonist; all compounds were tested upon systemic application and caffeine and SCH58261 were also directly applied in the striatum. Behavioral assessments using the open field, grip strength, and treadmill tests allowed estimating the effect of treatments on fatigue. Results and discussion: The results suggested a complex interplay between the dopamine and adenosine systems. While systemic DPCPX had little effect on motor performance or fatigue, the application of either caffeine or SCH58261 was ergogenic, and these effects were attenuated by haloperidol. The intra-striatal administration of caffeine or SCH58261 was also ergogenic, but these effects were unaffected by haloperidol. These findings confirm a role of striatal A2A receptors in the control of central fatigue but suggest that the D2 receptor-mediated control of the ergogenic effects of caffeine and of A2A receptor antagonists might occur outside the striatum. This prompts the need of additional efforts to unveil the role of different brain regions in the control of fatigue.

Efficacy of simple and very brief handgrip and isometric exercises for reducing withdrawal symptoms in cigarette smokers: A pilot randomized controlled trial

INTRODUCTION

Withdrawal symptoms lead to smoking relapse and reduce the intention to quit. The present pilot RCT examined the effect of simple and very brief handgrip and isometric exercises on reducing withdrawal symptoms, measured by the strength of tobacco craving, Questionnaire of Smoking Urges-Brief (QSU-B), Mood and Physical Symptoms Scale (MPSS), and Positive and Negative Affect Schedule (PANAS).

METHODS

In this 2-arm, open-labeled pilot RCT, 30 current smokers who had abstained from tobacco for at least 9 hours were randomly assigned (allocation ratio 1:1) to either the intervention group that watched a 5-minute video and did 5-minute handgrip and isometric exercises (pulling and pushing) or control group that watched 10-minute healthy-diet videos. Measurements were taken before, immediately after, and 10 minutes post-intervention. Outcomes were self-reported strength of tobacco craving, QSU-B, MPSS, and PANAS scores. The effect size for group-by-time interaction was assessed using Cohen's f2 (small=0.02, medium=0.15, large=0.35).

RESULTS

Group-by-time interactions showed that the intervention group showed larger reductions than the control group in the strength of tobacco craving (Cohen's f2=0.54, 95% CI: 0.52-0.57), QSU-B (Cohen's f2=0.77; 95% CI: 0.74-0.80), and MPSS (Cohen's f2=0.51; 95% CI: 0.46-0.56) over the three measurement points.

CONCLUSIONS

This RCT showed that simple and brief handgrip and isometric exercises could immediately reduce withdrawal symptoms and up to 10 minutes.

CLINICAL TRIAL REGISTRATION

in https://clinicaltrials.gov/.

IDENTIFIER

NCT04059497.

Research application of session-RPE in monitoring the training load of elite endurance athletes

Purpose

TRIMP and sRPE are both representative indicators of training load(TL), and the correlation between two has been widely demonstrated across various sports. The aim of this study was to investigate the reliability of sRPE-TRIMP correlation across different intensities/duration of training in cross-country skiing, and whether sRPE can serve as an validity supplement to TRIMP data in cases of lost heart rate data.

Method

10 athletes were used as the experimental objects. The intensity, duration and RPE of 273 different types of training sessions were collected, and statistical methods were used for data analysis.

Results

1. There was a significant correlation between sRPE and TRIMP (r = 0.68, p < 0.05), but the correlation differs among the LIT, MIT and HIT groups (r = 0.70, 0.46, r = 0.31, p < 0.05) 2. sRPE-TRIMP correlation among three different time duration in the LIT group (0-60 min, 60-120 min and 120-180 min), are all highly significant (r = 0.70, 0.67, 0.69, p < 0.05) and the LRsRPE-TRIMP of 3 duration have no significant differences (chow test, p > 0.05). 3. The difference in actual training duration between samples was the main reason for the difference in the application effect of sRPE, because the actual training duration ratio of LIT was 89.7 ± 16.4%; MIT, 98.5 ± 6.2%; and HIT, 94.4 ± 13.5%.

Conclusion

1. The linear relationship between sRPE and TRIMP (LRsRPE-TRIMP) is more significant in LIT compared to that in MIT and HIT. 2. Variations in the duration of LIT sessions do not affect the consistency of the relationship between sRPE and TRIMP. 3. Discrepancies between actual and planned training durations directly impact the significance of the LRsRPE-TRIMP.

The measurement of fatigability severity in individuals with multiple sclerosis and healthy controls

BACKGROUND

Multiple Sclerosis (MS) is a chronic disease that substantially diminishes one's ability to undertake daily living activities. Fatigue has been reported by at least 80 % of persons with MS (PwMS). Yet, little is known concerning the quantification of fatigability using prolonged walking tests.

OBJECTIVES

To compare fatigability severity measures using the 10-minute walk test for PwMS against age- and gender-matched healthy controls (HCs).

METHODS

Participants included 53 ambulatory PwMS and 49 HCs. Perceived fatigability was measured by dividing a participant's change in self-reported tiredness by the number of meters walked. Performance fatigability was calculated by dividing the change in walking speed (at 2.5 and 10 min) by the total distance walked in meters.

RESULTS

There was a significant difference in perceived fatigability between PwMS and HCs (mean difference: 2.73 ± 0.83; p = 0.001) and in performance fatigability (mean difference: 0.24 ± 0.11; p = 0.01). Moreover, there were significant differences in speed and distance at all time points (p ≤ 0.05) between PwMS and HCs.

CONCLUSIONS

PwMS have significant walking deficits as reflected by greater fatigability in both perceived and performance measures. These methods can enhance therapeutic strategies that improve the walking performances of PwMS.

The effects of sustained, low- and high-intensity isometric tasks on performance fatigability and the perceived responses that contributed to task termination

PURPOSE

The present study examined the effects of sustained, isometric low- versus high-intensity tasks on time to task failure (TTF), performance fatigability (PF), ratings of perceived exertion (RPE), and the perceived causes of task termination from a post-test questionnaire (PTQ).

METHODS

Ten men (mean ± SD: age = 21.1 ± 2.3 years; height = 180.2 ± 5.7 cm; body mass = 79.5 ± 8.8 kg) performed maximal voluntary isometric contractions (MVICs) before and after fatiguing, isometric forearm flexion tasks anchored to the torque corresponding to RPE values of 2 (TRQ2FT = 23.8 ± 7.1 N·m) and 8 (TRQ8FT = 60.9 ± 11.4 N·m). In addition, the subjects completed a PTQ which surveyed whether the perceived sensations of fatigue or pain, and/or the psychological factors of loss of focus and motivation contributed to the decision to terminate the task. Repeated measures ANOVAs, Wilcoxon-Signed Rank tests, and Spearman's Rank-Order Correlations were used to analyze the data.

RESULTS

Across the fatiguing tasks, there were similar decreases in MVIC torque (95.2 ± 20.3 vs. 68.9 ± 15.6 N·m; p < 0.001) and RPE values (p = 0.122) at task failure for TRQ2FT (7.4 ± 2.7) and TRQ8FT (8.9 ± 1.0), but a longer (p = 0.005) TTF for the TRQ2FT (245.0 ± 177.0 s) than TRQ8FT (36.8 ± 11.1 s).

CONCLUSIONS

Despite reaching task failure, the subjects were able to perform MVICs that were 100-300% greater than the target torque values within seconds of terminating the tasks. Thus, we hypothesized that task failure was not caused by an inability to produce sufficient torque to sustain the tasks, but rather an unwillingness to continue the task.

Electromyography Analysis of the Masseter Muscle's Activity in the Management of Oral Submucous Fibrosis

Introduction Oral submucous fibrosis (OSMF) is a persistent, collagen metabolic disorder distinguished by the presence of fibrosis of the connective tissue stroma in the oral mucosa with a higher malignant potential rate for oral cancer. This study aimed to analyze the utility of electromyography (EMG) as the prognostic assessment tool in the management of OSMF with conventional intralesional corticosteroid therapy. Materials and methods This study included 20 OSMF cases of age range 20 to 80 years without systemic comorbidities to assess pre-treatment and post-treatment changes with intralesional corticosteroid therapy as an intervention and to determine if it could be assessed using electromyographic study. Clinical and histopathological grading of OSMF was done. The five clinical parameters were evaluated for measuring treatment prognosis. Among them, mouth opening, tongue protrusion, and burning sensation assessments were quantitative parameters, and palpable fibrotic bands and mucosa colour were qualitative parameters. As OSMF involves changes in muscle plane in moderately advanced and advanced cases, EMG was used as an assessment tool for measuring muscle activity. Among the muscles of mastication, the masseter and temporalis were selected for evaluation. Twenty age and gender-matched healthy controls were required for this study as there are no standardized normal values for amplitude and onset of activity in muscle analysis. The EMG activity of the right and left temporalis and masseter muscles were recorded using surface electrodes and were correlated with five clinical assessment parameters. Results In the right masseter, the rest amplitude of 1.6010 µV of the OSMF was statistically significant (p-value: 0.050) when compared with 4.1275 µV of the control. The clench amplitude of 133.370 µV of the OSMF was statistically significant (p-value: 0.062) when compared with 94.310 µV of the control. In the left masseter, the rest amplitude of 1.6695 µV of the OSMF was statistically significant (p-value 0.066) when compared with 2.5735 µV of the control. In the left masseter, the onset of muscle action of 62.670 ms of the OSMF was statistically significant (p-value: 0.017) when compared with 131.835 ms of the control. The clench amplitude differences in the right masseter of 133.370 µV pre-treatment, and 102.775 µV post-treatment were statistically significant (p-value: 0.007). The clench amplitude in the left masseter of 102.535 µV pre-treatment, and 92.090 µV post-treatment were statistically significant (p-value: 0.036). The correlation was seen between tongue protrusion and rest amplitude in the right masseter in OSMF (r = 0.376, p-value: 0.023). Conclusion There was a correlation between tongue protrusion and rest amplitude in the right masseter muscle in OSMF patients before treatment. In the right and left masseter, during rest, the amplitude of the OSMF group was lesser than that of the control group. During clench, in the right masseter, the amplitude of the OSMF group was higher than that of the control group. During clench in the left masseter, the onset of muscle action was lesser in the OSMF group than in the control group. After treatment, there was a reduction in clench amplitude in OSMF patients from their pretreatment values signifying muscle relaxation and a better onset of muscle action.

Clinical evaluation of a patient participation assessment system for upper extremity rehabilitation exercises

In conventional and robotic rehabilitation, the patient's active participation in exercises is essential for the maximum functional output to be received from therapy. In rehabilitation exercises performed with robotic devices, the difficulty levels of therapy tasks and the device assistance are adjusted based on the patient's therapy performance to improve active participation. However, the existing therapy performance evaluation methods are based on either some specific device designs or certain therapy tasks, which limits their widespread use. In this paper, the effectiveness of a participation assessment system, which can evaluate patients' therapy performance, tiredness, and slacking independent of any device design and therapy exercise, was clinically tested on ten patients diagnosed with frozen shoulder syndrome. The patients performed exercises using the system once a week throughout their 4-week treatment period. Multiple clinical measurements and scales were employed during the clinical study to assess patients' progress and status, such as tiredness throughout the therapy process. The clinical data, along with the patient findings obtained from the participation assessment system, were statistically analyzed and compared. The findings revealed that the patients' improvements and progress during the therapy process clinically coincide with the variations in the performance evaluation results of the system, and the implemented method successfully assesses the patients' participation during the rehabilitation exercises.

Metabolome and microbiome analyses of the anti-fatigue mechanism of Acanthopanax senticosus leaves

Acanthopanax senticosus leaves, widely used as a vegetable and tea, are reported to be beneficial in treating neurological disorders. At present, their anti-fatigue effect remains to be established. In this study, we analyzed the composition of the extracts from A. senticosus leaves and confirmed their antioxidant and anti-inflammatory properties at the cellular level. In mice subjected to exhaustive running on a treadmill, supplementation with A. senticosus leaf extracts enhanced exercise performance and alleviated fatigue via the reversal of exercise-induced 5-HT elevation, metabolic waste accumulation, organ damage, and glucose metabolism-related gene expression. The collective findings from microbiome and metabolomic analyses indicate that A. senticosus leaf extracts increase α-diversity, regulate microbial composition, and reverse exercise-mediated disruption of carbohydrate, creatine, amino acid, and trimethylamine metabolism. This study provides preliminary evidence for the utility of A. senticosus leaves as a promising anti-fatigue food and offers insights into the underlying mechanism.

Establishment of a 3D esthetic analysis workflow on 3D virtual patient and preliminary evaluation

BACKGROUND

In esthetic dentistry, a thorough esthetic analysis holds significant role in both diagnosing diseases and designing treatment plans. This study established a 3D esthetic analysis workflow based on 3D facial and dental models, and aimed to provide an imperative foundation for the artificial intelligent 3D analysis in future esthetic dentistry.

METHODS

The established 3D esthetic analysis workflow includes the following steps: 1) key point detection, 2) coordinate system redetermination and 3) esthetic parameter calculation. The accuracy and reproducibility of this established workflow were evaluated by a self-controlled experiment (n = 15) in which 2D esthetic analysis and direct measurement were taken as control. Measurement differences between 3D and 2D analysis were evaluated with paired t-tests.

RESULTS

3D esthetic analysis demonstrated high consistency and reliability (0.973 < ICC < 1.000). Compared with 2D measurements, the results from 3D esthetic measurements were closer to direct measurements regarding tooth-related esthetic parameters (P<0.05).

CONCLUSIONS

The 3D esthetic analysis workflow established for 3D virtual patients demonstrated a high level of consistency and reliability, better than 2D measurements in the precision of tooth-related parameter analysis. These findings indicate a highly promising outlook for achieving an objective, precise, and efficient esthetic analysis in the future, which is expected to result in a more streamlined and user-friendly digital design process. This study was registered with the Ethics Committee of Peking University School of Stomatology in September 2021 with the registration number PKUSSIRB-202168136.

Comparison of psoas major activation during standing hip flexion between chronic low back pain and healthy populations

BACKGROUND

The psoas major (PM) has been identified as a potential contributor to chronic low back pain (LBP). However, few studies have investigated the effects of upright functional movement on PM activation in cLBP individuals.

OBJECTIVE

This cross-sectional study aims to compare PM muscle activation characteristics in chronic LBP (cLBP) and healthy subjects during the transition from quiet double-leg standing to standing hip flexion.

METHODS

Ultrasound Imaging was used to assess PM thickness at the lumbar vertebral level of L4-5 in 12 healthy and 12 cLBP participants. The changes in thickness between the test positions were utilized as a proxy for PM activation.

RESULTS

The cLBP group exhibited greater thickness changes on the non-dominant side PM during contralateral hip flexion but not ipsilateral hip flexion (p= 0.369) compared to their healthy counterparts (p= 0.011; cLBP: resting 27.85 mm, activated 34.63 mm; healthy: resting 29.51 mm, activated 29.00 mm). There were no significant differences in dominant side PM thickness changes between the two groups during either contralateral or ipsilateral hip flexion (p= 0.306 and p= 0.077).

CONCLUSION

Our findings suggest a potential overactivation of the PM in the cLBP population. This insight may aid in the development of tailored rehabilitation programs.

The Effect of Exercise-Induced Central Fatigue on Cervical Spine Joint Position Error, Strength, and Endurance

Background

Fatigue is common in sports, impairing performance and increasing injury risk, yet little is known regarding fatigue and concussion. Impaired neck neuromuscular function may contribute to concussion at baseline, where central fatigue may further impair neck function resulting in increased concussion risk. These effects may be magnified in athletes with a history of concussion.

Purpose

To determine the effect of exercise induced central fatigue on neck joint position error, strength, and endurance in healthy subjects and those with a history of concussion. The investigators hypothesized that EICF would have a negative effect on all variables.

Study Design

Healthy subjects were examined using a single factor, within-subjects repeated measures design. Concussion history subjects were examined using a single-subject design.

Methods

Nineteen healthy subjects and five subjects with a history of concussion were recruited for the study. Cervical joint position error, muscle strength, and neck flexor endurance were tested before and after exercise induced fatigue.

Results

There was a significant increase in constant (p = 0.0027) and absolute joint position error (JPE) (p < 0.001); decrease in neck flexor endurance (p < 0.001); and decrease neck strength into cervical flexion (p = 0.01) in healthy subjects following fatigue. Among concussion history subjects, five demonstrated a significant increase in absolute and constant JPE (p < 0.05); four demonstrated a significant decrease in neck flexor endurance (p < 0.05); one in neck flexion muscle strength (p < 0.05); and three in neck extension and rotation muscle strength (p < 0.05) following fatigue.

Conclusions

Cervical neuromuscular function deteriorated following fatigue in healthy subjects. Resulting impairments may affect force alterations in cervical control, potentially increasing concussion risk. Concussion history subjects descriptively demonstrated similar results, however further research should examine formal comparisons involving subjects with and without concussion history.

Level of Evidence

3b.

Facial electromyography during exercise using soft electrode array: A feasibility study

The use of wearable sensors for real-time monitoring of exercise-related measures has been extensively studied in recent years (e.g., performance enhancement, optimizing athlete's training, and preventing injuries). Surface electromyography (sEMG), which measures muscle activity, is a widely researched technology in exercise monitoring. However, due to their cumbersome nature, traditional sEMG electrodes are limited. In particular, facial EMG (fEMG) studies in physical training have been limited, with some scarce evidence suggesting that fEMG may be used to monitor exercise-related measurements. Altogether, sEMG recordings from facial muscles in the context of exercise have been examined relatively inadequately. In this feasibility study, we assessed the ability of a new wearable sEMG technology to measure facial muscle activity during exercise. Six young, healthy, and recreationally active participants (5 females), performed an incremental cycling exercise test until exhaustion, while facial sEMG and vastus lateralis (VL) EMG were measured. Facial sEMG signals from both natural expressions and voluntary smiles were successfully recorded. Stable recordings and high-resolution facial muscle activity mapping were achieved during different exercise intensities until exhaustion. Strong correlations were found between VL and multiple facial muscles' activity during voluntary smiles during exercise, with statistically significant coefficients ranging from 0.80 to 0.95 (p<0.05). This study demonstrates the feasibility of monitoring facial muscle activity during exercise, with potential implications for sports medicine and exercise physiology, particularly in monitoring exercise intensity and fatigue.

Assessment of Self-report, Palpation, and Surface Electromyography Dataset During Isometric Muscle Contraction

Measuring muscle fatigue involves assessing various components within the motor system. While subjective and sensor-based measures have been proposed, a comprehensive comparison of these assessment measures is currently lacking. This study aims to bridge this gap by utilizing three commonly used measures: participant self-reported perceived muscle fatigue scores, a sports physiotherapist's manual palpation-based muscle tightness scores, and surface electromyography sensors. Compensatory muscle fatigue occurs when one muscle group becomes fatigued, leading to the involvement and subsequent fatigue of other muscles as they compensate for the workload. The evaluation of compensatory muscle fatigue focuses on nine different upper body muscles selected by the sports physiotherapist. With a cohort of 30 male subjects, this study provides a valuable dataset for researchers and healthcare practitioners in sports science, rehabilitation, and human performance. It enables the exploration and comparison of diverse methods for evaluating different muscles in isometric contraction.

Recovery markers in elite climbers after the national boulder climbing championship

This study aimed to investigate recovery markers among elite climbers following the National Boulder Championship. We assessed maximum isometric hand grip strength (HS), forearm swelling (circumference), delayed soreness in forearm muscles, tiredness, and exercise readiness at several time points: pre-competition, immediately post-competition (within 4 min after their last effort), and 12, 24, 48, and 60 h post-competition. Maximum isometric hand grip strength decreased by 6.38 ± 1.32% (p = 0.006) post-12 h, returning to pre-competition values post-24 h (all p > 0.05). Forearm circumference (FC) increased 1.78 ± 1.77% (p < 0.001) post-competition, returning to pre-competition values post-12 h (all p > 0.05). Forearm pain (FP) increased post-competition (p = 0.002) and post-12 h (p < 0.001), returning to pre-competition values post-24 h (all p > 0.05). Tiredness increased post-competition (p < 0.001), post-12 h (p < 0.001), and post-24 h (p < 0.001), returning to pre-competition values post-48 h (all p > 0.05). Climbing readiness was reduced post-competition (p < 0.001), post-12 h (p < 0.001), post-24 h (p < 0.001), and post-48 h (p = 0.005), only returning to pre-competition values post-60 h (p = 0.189). Visual analysis of individual data pointed out a relatively small variability in the HS and FC markers, while FP, tiredness, and readiness exhibited larger individual variations. These findings indicate that different recovery patterns exist for the analyzed markers, suggesting that athletes may require up to 60 h after a competition to fully recover and regain their ability to face new competitive challenges.

Electromyography-driven musculoskeletal models with time-varying fatigue dynamics improve lumbosacral joint moments during lifting

Muscle fatigue is prevalent across different aspects of daily life. Tracking muscle fatigue is useful to understand muscle overuse and possible risk of injury leading to musculoskeletal disorders. Current fatigue models are not suitable for real-world settings as they are either validated using simulations or non-functional tasks. Moreover, models that capture the changes to muscle activity due to fatigue either assume a linear relationship between muscle activity and muscle force or utilize a simple muscle model. Personalised electromygraphy (EMG)-driven musculoskeletal models (pEMS) offer person-specific approaches to model muscle and joint kinetics during a wide repertoire of daily life tasks. These models utilize EMG, thus capturing central fatigue-dependent changes in multi-muscle bio-electrical activity. However, the peripheral muscle force decay is missing in these models. Thus, we studied the influence of fatigue on a large scale pEMS of the trunk. Eleven healthy participants performed functional asymmetric lifting task. Average peak body-weight normalized lumbosacral moments (BW-LM) were estimated to be 2.55 ± 0.26 Nm/kg by reference inverse dynamics. After complete exhaustion of the lower back, the pEMS overestimated the peak BW-LM by 0.64 ± 0.37 Nm/kg. Then, we developed a time-varying muscle force decay model resulting in a time-varying pEMS (t-pEMS). This reduced the difference between BW-LM estimated by the t-pEMS and reference to 0.49 ± 0.14 Nm/kg. We also showed that five fatiguing contractions are sufficient to calibrate the t-pEMS. Thus, this study presents a person and muscle specific model to track fatigue during functional tasks.

Effects of exhaustive whole-body exercise and caffeine ingestion on muscle contractile properties in healthy men

BACKGROUND

The influence of exhaustive whole-body exercise and caffeine ingestion on electromechanical delay (EMD) has been underexplored. This study investigated the effect of exhaustive cycling exercise on EMD and other parameters of muscle contractile properties and the potential ability of caffeine to attenuate the exercise-induced impairments in EMD and muscle contractile properties.

METHODS

Ten healthy men cycled until exhaustion (88±2% of V̇O2max) on two separate days after ingesting caffeine (5 mg.kg-1 of body mass) or cellulose (placebo). Parameters of muscle contractile properties of the quadriceps muscles were assessed via volitional and electrically evoked isometric contractions, performed before and 50 minutes after ingestion of the capsules, and after exercise. Muscle recruitment during volitional contractions was determined via surface electromyography.

RESULTS

Exhaustive cycling exercise did not affect volitional and relaxation EMD (P>0.05) but increased evoked EMD. In addition, the exhaustive cycling exercise also increased muscle recruitment at the beginning of volitional isometric muscle contraction (P<0.05). The peak twitch force, maximal rate of twitch force development, and twitch contraction time were all compromised after exhaustive cycling exercise (P<0.05). Acute caffeine ingestion had no effect on muscle contractile properties (P>0.05), except that caffeine increased twitch contraction time at postexercise (P<0.05).

CONCLUSIONS

Exercise-induced decline in peripheral components of the EMD might be compensated by an increase in the muscle recruitment. In addition, acute caffeine ingestion had minimal influence on exercise-induced changes in muscle contractile proprieties.

Fatigue as hallmark of Fabry disease: role of bioenergetic alterations

Fabry disease (FD) is a lysosomal storage disorder due to the impaired activity of the α-galactosidase A (GLA) enzyme which induces Gb3 deposition and multiorgan dysfunction. Exercise intolerance and fatigue are frequent and early findings in FD patients, representing a self-standing clinical phenotype with a significant impact on the patient's quality of life. Several determinants can trigger fatigability in Fabry patients, including psychological factors, cardiopulmonary dysfunctions, and primary alterations of skeletal muscle. The "metabolic hypothesis" to explain skeletal muscle symptoms and fatigability in Fabry patients is growing acknowledged. In this report, we will focus on the primary alterations of the motor system emphasizing the role of skeletal muscle metabolic disarrangement in determining the altered exercise tolerance in Fabry patients. We will discuss the most recent findings about the metabolic profile associated with Fabry disease offering new insights for diagnosis, management, and therapy.

Real-Time Monitoring of Underground Miners' Status Based on Mine IoT System

Real-time monitoring and timely risk warnings for the safety, health, and fatigue of underground miners are essential for establishing intelligent mines, enhancing the safety of production, and safeguarding the well-being of miners. This concerns the collection, transmission, and processing of relevant data. To minimize physical strain on miners, data collection functions are consolidated into two wearable terminals: an electronic bracelet equipped with reliable, low-power components for gathering vital sign data and transmitting them via Bluetooth and a miner lamp that integrates multi-gas detection, personnel positioning, and wireless communication capabilities. The gas sensors within the miner lamp undergo regular calibration to maintain accuracy, while the positioning tag supports round-trip polling to ensure a deviation of less than 0.3 m. Data transmission is facilitated through the co-deployment of 5G communication and UWB positioning base stations, with distributed MIMO networking to minimize frequent cell handovers and ensure a low latency of no more than 20 ms. In terms of data processing, a backpropagation mapping model was developed to estimate miners' fatigue, leveraging the strong correlation between saliva pH and fatigue, with vital signs as the input layer and saliva pH as the output layer. Furthermore, a unified visualization platform was established to facilitate the management of all miners' states and enable prompt emergency response. Through these optimizations, a monitoring system for underground miners' status based on mine IoT technology can be constructed, meeting the requirements of practical operations.

Proprioceptive and Strength Exercise Guidelines to Prevent Falls in the Elderly Related to Biomechanical Movement Characteristics

Falls are a major concern in the elderly and walking is an important daily activity in which falls occur, with tripping and slipping being the most frequent causes. Gait biomechanical parameters have been related to the occurrence of falls in the elderly. Moreover, there is evidence that falls can be prevented through exercise programs, which have been shown to be also effective in improving gait biomechanical parameters. However, a question remains: "What types of exercises must be included in exercise programs to prevent falls?". The purpose of this manuscript was to present guidelines for a fall prevention exercise program for the elderly, which was created with the aim of improving the gait biomechanical parameters related to falls. The critical review performed during the preparation of this manuscript collected important evidence and knowledge in order to create a structural basis for the development of a fall prevention exercise program. This type of program should last 6 or more weeks and be prescribed based on four movement pillars (locomotion, level changes, pulling and pushing, and rotations); however, the locomotion pillar must be the focus of the program. Proprioceptive and functional strength exercises should be included in this program. Based on the theoretical rationale, a proposal for a fall prevention exercise program is presented.

The influence of symptom severity and fatigue on sleep quality in patients with myasthenia gravis

INTRODUCTION

Myasthenia gravis is a rare and chronic autoimmune disease. The study aimed to evaluate the influence of symptom severity and fatigue on sleep quality in patients with myasthenia gravis.

METHODS

This was a cross-sectional study, and the population consisted of patients with MG throughout Turkey. The study was completed with 163 patients on 1 April and 31 July 2022.

RESULTS

 It was found that the mean Myasthenia Gravis-Activities of Daily Living Scale score was 6.32 ± 3.9, the Fatigue Severity Scale score was 37.01 ± 23.26, and the total Pittsburgh Sleep Quality Index score was 9.04 ± 2.69. The variables affecting the Pittsburgh Sleep Quality Index scores were age, Body Mass Index, Fatigue Severity Scale ≥ 4, Myasthenia Gravis-Activities of Daily Living Scale ≥ 5.5, duration of diagnosis, and income level; a multiple regression model was created with these variables, and the variables in the resulting model explained 26.4% of the Pittsburgh Sleep Quality Index scores. In addition, those with clinically significant symptom severity (MG-ADL ≥5.5) in daily living and those with severe fatigue (FSS ≥4) explained 17.2% of the PSQI scores, and the model was statistically significant (p < 0.001).

CONCLUSION

The study determined that the participants had clinically significant symptom severity in daily living, severe fatigue, and poor sleep quality. The participants with clinically significant severe symptoms in daily living and fatigue had higher sleep disturbances, daytime dysfunction, and poor sleep quality.

Transcranial direct current stimulation for fatigue in neurological conditions: A systematic scoping review

BACKGROUND AND PURPOSE

Fatigue following neurological conditions negatively impacts daily activities, reducing overall quality of life. Transcranial direct current stimulation (tDCS) for fatigue management is still underexplored. This scoping review explores its use in managing fatigue among various neurological conditions.

METHODS

A thorough literature search was carried out using PubMed, Scopus, CINAHL, Web of Science, Embase, ProQuest, and the Cochrane Library. Google Scholar and clinicaltrials.gov were manually searched for gray literature and ongoing trials, respectively. Regardless of the study design, all studies utilizing tDCS for the management of fatigue in various neurological conditions were considered. Two reviewers independently screened all the studies, following which the data were retrieved.

RESULTS

Studies employing tDCS for fatigue management across neurological conditions is as follows: Multiple sclerosis (MS) (n = 28, 66%), stroke (n = 5, 12%), Parkinson's disease (PD) (n = 4, 10%), post-polio syndrome (PPS) (n = 2, 5%), traumatic brain injury (TBI) (n = 2, 5%), and amyotrophic lateral sclerosis (n = 1, 2%). All the studies used anodal stimulation, with the common stimulation site being the left dorsolateral prefrontal cortex for MS, stroke, and PD. A stimulation intensity of 1.0-4.0 mA with a duration ranging from 15 to 30 min in 1 to 24 sessions were commonly reported. The Fatigue Severity Scale (n = 21) and Modified Fatigue Impact Scale (n = 17) were frequently implemented outcome measures. Regardless of the study design, 36/42 (85.7%) studies reported an improvement in fatigue scores in the tDCS group. The common adverse events noted were tingling (n = 8, 35%), headache (n = 6, 26%), and itching (n = 6, 26%).

DISCUSSION

Application of tDCS for fatigue was explored in individuals with stroke, PD, PPS, and TBI after MS. Even though a wide range of treatment parameters and outcome measures were adopted to assess and target fatigue, tDCS proves to have a promising role in alleviating this symptom.

Polysaccharides from Brassica rapa root: Extraction, purification, structural features, and biological activities. A review

Brassica rapa (B. rapa) roots are attracting increased attention from nutritionists and health-conscious customers because of their remarkable performance in supplying necessary nutrients. Polysaccharides are major biologically active substances in B. rapa roots, which come in a variety of monosaccharides with different molar ratios and glycosidic bond types. Depending on the source, extraction, separation, and purification methods of B. rapa roots polysaccharides (BRP); different structural features, and pharmacological activities are elucidated. Polysaccharides from B. rapa roots possess a range of nutritional, biological, and health-enhancing characteristics, including anti-hypoxic, antifatigue, immunomodulatory, hypoglycemic, anti-tumor, and antioxidant activities. This paper reviewed extraction and purification methods, structural features, and biological activities as well as correlations between the structural and functional characteristics of polysaccharides from the B. rapa roots. Ultimately, this work will serve as useful reference for understanding the connections between polysaccharide structure and biological activity and developing novel BRP-based functional foods.

Effects of auriculotherapy on muscle fatigue: A randomized crossover trial

OBJECTIVE

This study aimed investigate the effect of auriculotherapy on exercise-induced muscle fatigue, isometric torque production, and surface electromyographic activity (EMG).

METHODS

Design: Randomized Crossover Trial. The sample consisted of 18 males' volunteers who exercised at least twice a week.

THE SAMPLE WAS RANDOMLY ASSIGNED TO TWO GROUPS

Placebo Group (n = 9) and Treated Group (n = 9), and after seven days, the groups were crossed. The data analysis included 18 participants in each group.

MAIN OUTCOME MEASURE

The muscle fatigue index, force production rate, and EMG of the quadriceps were used for evaluation. The evaluation moments included baseline pre-fatigue, baseline post-fatigue, 48 h post-intervention pre-fatigue, and 48 h post-intervention post-fatigue. Mixed two-way test ANOVA was used to compare times and groups.

RESULTS

The fatigue index for peak torque and work showed no significant effect on time, groups, or interaction (p > 0.05). However, for isometric torque, force production rate, and EMG median frequency and average, the results indicate a positive change in values over time (p < 0.05) (with little practical relevance), with no differences observed between the groups or interaction (p > 0.05).

CONCLUSIONS

In conclusion, auriculotherapy had no effect on exercise-induced muscle fatigue, isometric torque production, and surface electromyographic activity.

The Effect of Anthropometric Shoes on Lactic Acid Reduction in Nurses: A Mixed-Methods Study from Indonesia

Background

The mobilization characteristics of nurses' work, such as standing, walking, and transferring patients for a long time, can increase the risk of musculoskeletal disorders. Repetitive activities nurses perform can cause foot problems such as discomfort and insecurity, characterized by increased lactic acid levels. Anthropometric shoes are specifically designed to reduce complaints on nurses' feet.

Purpose

This study aimed to determine the effect of individual anthropometric shoes on lactic acid levels in nurses at the hospital.

Methods

This study used a mixed-method study design. This study involved 71 nurses in the quantitative study and 15 nurses in the qualitative study. Nurses in Emergency Room, Central Surgical Installation, Inpatient Room, Intensive Care Unit, and Outpatient Installation were randomly selected using a stratified random sampling technique. The instruments used were the Accutrend Lactacyd tool, demographic questionnaire and interview questionnaire. Bivariate data analysis was using Statistical Package for Social Sciences (SPSS) and qualitative data analysis using thematic analysis.

Results

This mixed-method study shows that anthropometric shoes can reduce nurses' lactic acid levels. In the quantitative study; there was a significant difference in lactic acid levels of nurses before and after using anthropometric shoes with the average results of measuring lactic acid levels, namely pre-test (22.48 mg/dL) and post-test (16.27 mg/dL), with a p-value (0.000). The qualitative study data revealed positive results related to increased nurse knowledge, positive views on the effect of shoes on nurse performance, and the impact of using anthropometric shoes in providing comfort and safety, such as decreased muscle fatigue and pain.

Conclusion

The findings of this study highlight the effect of individualized anthropometric shoes on lactic acid levels in nurses in Indonesian hospitals. It is essential to conduct further research and evaluate the results in a broader setting to ensure that anthropometric shoes can directly affect lactic acid levels.

Wrist Extensor Muscle Fatigue During a Dual Task With Two Muscular and Cognitive Load Levels in Younger and Older Adults

OBJECTIVE

To examine the effect of concurrent physical and cognitive demands as well as age on indicators of muscle fatigue at the wrist.

BACKGROUND

There are few studies examining risk indicators for musculoskeletal disorders associated with work-related physical and cognitive demands that often occur simultaneously in the workplace.

METHODS

Twenty-four gender-balanced older and 24 gender-balanced younger (mean age 60 and 23 years) participants performed four 30 min dual tasks. Tasks differed by the muscular load level during force tracking: 5% and 10% of maximum voluntary contraction force (MVC) and concurrent cognitive demands on the working memory: easy and difficult. Muscle fatigue was assessed by MVC decline and changes in surface electromyography (increased root mean square: RMS, decreased median frequency: MF) at the extensor digitorum (ED) and extensor carpi ulnaris (EU).

RESULTS

A decline in MVC was found in all participants when tracking was performed at 10% MVC (mean ± SD: 137.9 ± 49.2 - 123.0 ± 45.3 N). Irrespective of age, muscular, or cognitive load, RMS increased (ED 12.3 ± 6.5 - 14.1 ± 7.0% MVE, EU 15.4 ± 7.6 - 16.9 ± 8.6% MVE) and MF decreased (ED 85.4 ± 13.6 - 83.2 ± 12.8 Hz, EU 107.2 ± 17.1 - 104.3 ± 16.7 Hz) in both muscles. However, changes in MF of EU tended to be more pronounced in the older group at higher cognitive and lower muscular load, without reaching statistical significance.

CONCLUSION

Maximum voluntary contraction indicated no interaction between muscle fatigue, cognitive load, or age. However, the tendencies toward altered muscle activity due to an increase in cognitive load and older age suggest muscular adaptations while maintaining tracking performance during the onset of fatigue signs in the sEMG signal.

APPLICATION

If the tendencies in muscle activity are confirmed by further studies, ergonomic assessments in industrial workplaces should consider cognitive load and age when describing the risk of musculoskeletal disorders.

The influence of cadence on fatigue during maximal sprint cycling in world-class and elite sprint cyclists

Optimising cadence through appropriate gear selection is a key consideration for track sprint cycling performance, yet the influence of cadence on fatigue (i.e., decrement in power output) within a maximal sprint is not well understood. The aim of this study was to identify the influence of cadence on fatigue during maximal sprint cycling. Eleven world-class and elite track sprint cyclists (n = 6 men, maximal power output (Pmax) = 1894 ± 351 W, optimal cadence (Fopt) = 134 ± 8 rev∙min-1: n = 5 women, Pmax = 1114 ± 80 W, Fopt = 124 ± 8 rev∙min-1) completed two testing sessions where power-cadence profiles were constructed to determine the Fopt associated with Pmax. Cyclists also performed three maximal 15-s sprints (Fopt, ±15%Fopt) to identify fatigue per pedal stroke across these cadence ranges. There was no significant difference (p = 0.2) in the absolute fatigue per pedal stroke when cadence was fixed 15% above (16.7 ± 6.1 W∙stroke-1) and below (15.3 ± 5.1 W∙stroke-1) Fopt. Similarly, there was no significant difference in the relative fatigue per pedal stroke (% peak power∙stroke-1) across Fopt and ± 15%Fopt trials (p = 0.12). The relative decrement in power output is equivalent across the ± 15%Fopt cadence range. As such, a higher-geared, lower-cadence approach to maximal sprint cycling could be a viable method to minimise maximal pedal strokes and reduce the decrement in power output.

Hispidin-enriched Sanghuangporus sanghuang mycelia SS-MN4 ameliorate disuse atrophy while improving muscle endurance

BACKGROUND

Disuse atrophy is a frequent cause of muscle atrophy, which can occur in individuals of any age who have been inactive for a prolonged period or immobilization. Additionally, acute diseases such as COVID-19 can cause frequent sequelae and exacerbate muscle wasting, leading to additional fatigue symptoms. It is necessary to investigate potent functional nutrients for muscle reinforcement in both disuse atrophy and fatigue to ensure better physical performance.

METHODS

The effects of Sanghuangporus sanghuang SS-MN4 mycelia were tested on two groups of 6-week-old male mice-one with disuse atrophy and the other with fatigue. The disuse atrophy group was divided into three sub-groups: a control group, a group that underwent hind limb casting for 7 days and then recovered for 7 days and a group that was administered with SS-MN4 orally for 14 days, underwent hind limb casting for 7 days and then recovered for 7 days. The fatigue group was divided into two sub-groups: a control group that received no SS-MN4 intervention and an experimental group that was administered with SS-MN4 orally for 39 days and tested for exhaustive swimming and running on Day 31 and Day 33, respectively. RNA sequencing (RNA-seq) and western blot analysis were conducted on C2C12 cell lines to identify the therapeutic effects of SS-MN4 treatment.

RESULTS

In a disuse atrophy model induced by hind limb casting, supplementing with 250 mg/kg of SS-MN4 for 14 days led to 111.2% gastrocnemius muscle mass recovery and an 89.1% improvement in motor function on a treadmill (P < 0.05). In a fatigue animal model, equivalent SS-MN4 dosage improved swimming (178.7%) and running (162.4%) activities (P < 0.05) and reduced blood urea nitrogen levels by 18% (P < 0.05). SS-MN4 treatment also increased liver and muscle glycogen storage by 34.36% and 55.6%, respectively, suggesting a higher energy reserve for exercise. RNA-seq and western blot studies from the C2C12 myotube showed that SS-MN4 extract upregulates Myh4 and helps sustain myotube integrity against dexamethasone damage.

CONCLUSIONS

Supplementation of SS-MN4 (250-mg/kg body weight) with hispidin as active compound revealed a potential usage as a muscle nutritional supplement enhancing muscle recovery, fast-twitch fibre regrowth and fatigue resistance.

Development of a Low-Cost Portable EMG for Measuring the Muscular Activity of Workers in the Field

This study explores the development and validation of a low-cost electromyography (EMG) device for monitoring muscle activity and muscle fatigue by monitoring the key features in EMG time and frequency domains. The device consists of a Raspberry Pico microcontroller interfacing a Myoware EMG module. The experiment involved 34 volunteers (14 women, 20 men) who performed isometric and isotonic contractions using a hand dynamometer. The low-cost EMG device was compared to a research-grade EMG device, recording EMG signals simultaneously. Key features including root mean square (RMS), median power frequency (MDF), and mean power frequency (MNF) were extracted to evaluate muscle fatigue. During isometric contraction, a strong congruence between the two devices, with similar readings and behavior of the extracted features, was observed, and the Wilcoxon signed rank test confirmed no significant difference in the ability to detect muscle fatigue between the devices. For isotonic contractions, the low-cost device demonstrated behavior similar to the professional EMG device in 70.58% of cases, despite some susceptibility to noise and movement. This suggests the potential viability of the low-cost EMG device as a portable tool for assessing muscle fatigue, enabling accessible and cost-effective management of muscle health in various work scenarios.

Sweat analysis for urea sensing: trends and challenges

With increasing population there is a rise in pathological diseases that the healthcare facilities are grappling with. Sweat-based wearable technologies for continuous monitoring have overcome the demerits associated with sweat sampling and sensing. Hence, sweat as an alternative biofluid holds great promise for the quantification of a host of biomarkers and understanding the functioning of the body, thereby deducing ailments quickly and economically. This comprehensive review accounts for recent advances in sweat-based LOCs (Lab-On-Chips), which are a likely alternative to the existing blood-urea sample testing that is invasive and time-consuming. The present review is focused on the advancements in sweat-based Lab-On-Chips (LOCs) as an alternative to invasive and time-consuming blood-urea sample testing. In addition, different sweat collection methods (direct skin, near skin and microfluidic) and their mechanism for urea sensing are explained in detail. The mechanism of urea in biofluids in protein metabolism, balancing nitrogen levels and a crucial factor of kidney function is described. In the end, research and technological advancements are explained to address current challenges and enable its widespread implementation.

Acute outcomes of acupuncture and dry needling over peripheral acute fatigue in untrained healthy volunteers: A randomized controlled clinical trial

Peripheral acute fatigue (PAF) is defined as when the skeletal muscle is incapable of generating power. We aimed to investigate the acute effects of traditional Chinese acupuncture (TCA) and dry needling (DN) over PAF induced on the biceps brachii of untrained healthy volunteers. We conducted a randomized, single-blind controlled clinical trial. All volunteers (n = 45) underwent fatigue induction protocols repeated before and after treatment with TCA (TCA group; TCAg; n = 15), DN (DN group; DNg; n = 15), and rest (control group; Cg; n = 15). Assessments of PAF, skin temperature, and exercise time occur before and after each event: 1st fatigue induction (FI), treatment, and 2nd FI. We used repeated measures ANOVA adjusted with Bonferroni post hoc test to determine any change in tested variables (PAF-VAS, PAF-EMG, and skin temperature) at different time points compared to the baseline. Paired Samples t-test was used for the variable exercise times. All statistical tests considered' the significance level at p ≤ 0,05. There was no difference between groups in acute fatigue recovery (p = 0.19). All intragroup analyses were significant (p ≤ 0.05) and all volunteers show a reduction in fatigue perception after treatment (p ≤ 0,05), however, exercise time did not ameliorate after TCA or DN (p > 0.77). A single session of TCA and, DN can equally reduce fatigue, temperature, and exercise time over PAF induced on biceps brachii of untrained healthy volunteers.

Using Electronic Handgrip Dynamometry and Accelerometry to Examine Multiple Aspects of Handgrip Function in Master Endurance Athletes: A Pilot Study

ABSTRACT

Klawitter, LA, Hackney, KJ, Christensen, BK, Hamm, JM, Hanson, M, and McGrath, R. Using electronic handgrip dynamometry and accelerometry to examine multiple aspects of handgrip function in master endurance athletes: A Pilot Study. J Strength Cond Res 37(9): 1777-1782, 2023-Electronic handgrip dynamometry and accelerometry may provide novel opportunities to comprehensively measure muscle function for human performance, especially for master athletes. This investigation sought to determine the multivariate relationships between maximal strength, asymmetry, rate of force development, fatigability, submaximal force control, bimanual coordination, and neuromuscular steadiness to derive one or more handgrip principal components in master-aged endurance athletes. We included n = 31 cyclists and triathletes aged 35-70 years. Maximal strength, asymmetry, rate of force development, fatigability, submaximal force control, bimanual coordination, and neuromuscular steadiness were measured twice on each hand using electronic handgrip dynamometry and accelerometry. The highest performing measures were included in the analyses. A principal component analysis was conducted to derive a new collection of uncorrelated variables from the collected handgrip measurements. Principal components with eigenvalues >1.0 were kept, and individual measures with a factor loading of |>0.40| were retained in each principal component. There were 3 principal components retained with eigenvalues of 2.46, 1.31, and 1.17. The first principal component, "robust strength," contained maximal strength, rate of force development, submaximal force control, and neuromuscular steadiness. The second principal component, "bilateral synergy," contained asymmetry and bimanual coordination, whereas the third principal component, "muscle conditioning," contained fatigability. Principal components 1, 2, and 3 explained 44.0, 31.6, and 24.4% of the variance, respectively. Different dimensions of muscle function emerged from our findings, suggesting the potential of a muscle function battery. Further research examining how these measures are associated with appropriate human performance metrics and lower extremity correlates is warranted.

Invasive dynamic electrical impedance myography during 100 s of moderate contraction in rats' gastrocnemius muscle

GOAL

The present study aimed to investigate the behavior of dynamic electrical impedance myography (dEIM) signals during a 100-s period of the dynamic contraction of Wistar rats' gastrocnemius evoked by electrical stimulation and to link the variations in bioimpedance with muscular energy systems.

METHODS

Muscle contraction used 30% of the maximum muscular force and persisted for 100 s, along which dynamic bioimpedance signals were acquired. Based on the bioimpedance signals, two parameters, ΔZc and ΔZpc, were calculated to allow the analysis of their changes with the energy systems that supplied adenosine triphosphate (ATP) to the muscle. ΔZc indicated the variation of impedance of a twitch cycle compared to the values observed during the rest period preceding the cycle, and ΔZpc indicated slow bioimpedance variations compared to the values obtained during the rest period.

RESULTS

The results indicated that ΔZc followed the force behavior, achieving a change rate of ∼14%. This parameter was associated with instantaneous impedance changes owing to the occurrence of each twitch.

CONCLUSION

Although the findings of this study were linked to energy system processes, future studies are required for improving the understanding of the underlying mechanisms involved in dEIM.

SIGNIFICANCE

The results contributed to understanding the relation of energy systems that supply ATP to the muscles with dEIM variations that occurred during muscle activity.

β-Alanine Supplementation in Combat Sports: Evaluation of Sports Performance, Perception, and Anthropometric Parameters and Biochemical Markers-A Systematic Review of Clinical Trials

β-alanine does not have an ergogenic effect by itself, but it does as a precursor for the synthesis of carnosine in human skeletal muscle. β-alanine and carnosine together help improve the muscles' functionality, especially in high-intensity exercises such as combat sports. Therefore, β-alanine could be considered a nutritional ergogenic aid to improve sports performance in combat athletes. We aimed to critically review clinical trial evidence on the impact of β-alanine supplementation on sports performance, perception, and anthropometric parameters, as well as circulating biochemical markers in combat athletes. This systematic review was conducted following the specific methodological guidelines of the Preferred Report Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA), the PICOS question model, the Critical Review Form of McMaster, and the PEDro scale. Furthermore, the Cochrane risk-of-bias assessment tool was used. The search was carried out in the SCOPUS, Web of Science (WOS), and Medline (PubMed) databases for studies published from the beginning of the database until July 31, 2023. Of the 41 registers identified, only 7 met the established criteria and were included in this systematic review. Overall, performance parameters related to strength, power, total exercise work capacity, and combat-specific parameters were significantly improved (p < 0.05). Perception parameters increased non-significantly (p > 0.05). Regarding biochemical parameters, carnosine increased significantly (p < 0.05), pH decreased non-significantly (p > 0.05), and the results for blood bicarbonate and blood lactate were heterogeneous. Finally, there was a non-significant (p > 0.05) improvement in the anthropometric parameters of lean mass and fat mass. β-alanine supplementation appears to be safe and could be a suitable nutritional ergogenic aid for combat athletes.

Intermittent treatment with elamipretide preserves exercise tolerance in aged female mice

The pathology of aging impacts multiple organ systems, including the kidney and skeletal and cardiac muscles. Long-term treatment with the mitochondrial-targeted peptide elamipretide has previously been shown to improve in vivo mitochondrial function in aged mice, which is associated with increased fatigue resistance and treadmill performance, improved cardiovascular diastolic function, and glomerular architecture of the kidney. However, elamipretide is a short tetrameric peptide that is not orally bioavailable, limiting its routes of administration. This study tested whether twice weekly intermittent injections of elamipretide could recapitulate the same functional improvements as continuous long-term infusion. We found that intermittent treatment with elamipretide for 8 months preserved exercise tolerance and left ventricular mass in mice with modest protection of diastolic function and skeletal muscle force production but did not affect kidney function as previously reported using continuous treatment.

Baf155 regulates skeletal muscle metabolism via HIF-1a signaling

During exercise, skeletal muscle is exposed to a low oxygen condition, hypoxia. Under hypoxia, the transcription factor hypoxia-inducible factor-1α (HIF-1α) is stabilized and induces expressions of its target genes regulating glycolytic metabolism. Here, using a skeletal muscle-specific gene ablation mouse model, we show that Brg1/Brm-associated factor 155 (Baf155), a core subunit of the switch/sucrose non-fermentable (SWI/SNF) complex, is essential for HIF-1α signaling in skeletal muscle. Muscle-specific ablation of Baf155 increases oxidative metabolism by reducing HIF-1α function, which accompanies the decreased lactate production during exercise. Furthermore, the augmented oxidation leads to high intramuscular adenosine triphosphate (ATP) level and results in the enhancement of endurance exercise capacity. Mechanistically, our chromatin immunoprecipitation (ChIP) analysis reveals that Baf155 modulates DNA-binding activity of HIF-1α to the promoters of its target genes. In addition, for this regulatory function, Baf155 requires a phospho-signal transducer and activator of transcription 3 (pSTAT3), which forms a coactivator complex with HIF-1α, to activate HIF-1α signaling. Our findings reveal the crucial role of Baf155 in energy metabolism of skeletal muscle and the interaction between Baf155 and hypoxia signaling.

Prevalence and risk factors of work-related musculoskeletal disorders among cashiers in small-scale businesses: a cross-sectional study in Ethiopia

OBJECTIVE

This study aimed to investigate the prevalence and factors associated with work-related musculoskeletal disorders among cashiers in small-scale businesses in Northwestern Ethiopia.

DESIGN

A multicentre cross-sectional study was conducted from July to September 2022. The data were collected using a validated and standardised Nordic Musculoskeletal Questionnaire. The collected data were entered into EpiData V.4.6 and analysed using Stata V.14. A multivariable logistic regression analysis was used to ascertain the significance of associations at p<0.05 and the adjusted OR (AOR) with a 95% CI.

SETTING

The study was conducted in small-scale businesses in the North Gondar Zone.

PARTICIPANTS

A total of 618 cashiers participated in this study.

OUTCOME MEASURES

The primary outcome of the study is the prevalence of work-related musculoskeletal disorders, which was measured using the Nordic Musculoskeletal Questionnaire.

RESULTS

The response rate was 97.5% (N=618). The majority (373; 60.4%) of the study participants were female. The mean (±SD) age of the participants was 30 (±8.3) years. The prevalence of work-related musculoskeletal disorders during the last 12 months was found to be 75.4% (n=466) (95% CI 71.8%, 78.8%). Marital status (married) (AOR=2.12; 95% CI 1.26, 3.56), lack of physical exercise (AOR=2.07; 95% CI 1.32, 3.23), alcohol consumption (AOR=3.55; 95% CI 2.18, 5.78) and awkward work posture (AOR=2.40; 95% CI 1.43, 4.0) were significant factors associated with work-related musculoskeletal disorders among sampled cashiers.

CONCLUSION

This study concluded that the overall prevalence of work-related musculoskeletal disorders was high among cashiers in small-scale businesses. Being married, a lack of physical exercise, alcohol consumption and awkward work posture were significant factors of work-related musculoskeletal disorders. To reduce work-related musculoskeletal disorders, it is recommended taking part in physical activity, avoiding alcohol consumption and avoiding awkward work posture.

Personality Traits and Fatigue in Multiple Sclerosis: A Narrative Review

(1) Background: Multiple sclerosis (MS) is a chronic neurodegenerative autoimmune disease. Fatigue is a prevalent and debilitating symptom that significantly impacts the quality of life of these patients. A relationship between personality traits and fatigue in MS has been hypothesized but not clearly defined. (2) Methods: A literature search was carried out from databases up to April 2023 for studies correlating personality traits and fatigue in patients suffering from MS. (3) Results: A total of ten articles was included; most of the studies depict a neuroticism-fatigue correlation; however, they were not consistent in terms of the fatigue, personality, and covariate assessments. (4) Conclusions: The clinical and methodological heterogeneity of the included studies prevented us from drawing any firm conclusion on the link between personality traits and fatigue in MS. Several models of personality and different fatigue assessments have been found. Despite this, a common pathway shows that the neuroticism trait or similar personality patterns has a role in fatigue diagnosis. This may be a useful target to improve the quality of life and enhance the modification of the disease treatment results. Further homogeneous and longitudinal studies are needed.

Central and Peripheral Fatigue Evaluation during Physical Exercise in Athletic Horses by Means of Raman Spectroscopy

The evaluation of the performance levels in athletic horses is of major importance to prevent sports injuries. Raman spectroscopy is an innovative technique that allows for a rapid evaluation of biomolecules in biological fluids. It also permits qualitative and quantitative sample analyses, which lead to the simultaneous determination of the components of the examined biological fluids. On the basis of this, the Raman spectroscopy technique was applied on serum samples collected from five Italian Saddle horses subjected to a standardized obstacle course preceded by a warm-up to evaluate the applicability of this technique for the assessment of central and peripheral fatigue in athletic horses. Blood samples were collected via jugular venipuncture in a vacutainer tube with a clot activator before exercise, immediately after exercise, and 30 min and 1 h after the end of the obstacle course. Observing the obtained Raman spectra, the major changes due to the experimental conditions appeared in the (1300-1360) cm^-1 and (1385-1520) cm^-1 bands. In the (1300-1360) cm^-1 band, lipids and tryptophan were identified; in the (1385-1520) cm^-1 band, leucine, glycine, isoleucine, lactic acid, tripeptide, adenosine, and beta carotene were identified. A significant effect of exercise was recorded on all the sub-bands. In particular, a change immediately after exercise versus before exercise was found. Moreover, the mean lactic concentration was positively correlated with the Raman area of the sub-band assigned to lactic acid. In this context, the application of Raman spectroscopy on blood serum samples represents a useful technique for secondary-structure protein identification to investigate the metabolic changes that occur in athletic horses during physical exercise.

Physiological and clinical responses to cycling 7850 km over 85 days in a physically active middle-aged man with idiopathic Parkinson's disease

This case characterizes the clinical motor, perceived fatigue, gait and balance, cardiovascular, neuromuscular, and cardiopulmonary responses after cycling 7850 km over 85 days in a physically active 57-year-old male with idiopathic Parkinson's disease (PD). The participant cycled 73/85 days (86%); averaging 107.5 ± 48.9 km/day over 255.4 ± 108.8 min. Average cycling heart rate was 117 ± 11 bpm. The Unified Parkinson Disease Rating Scale (UPDRS) Part III motor score decreased from 46 to 26 (-44%), while the mean Parkinson Fatigue Scale (PFS-16) score decreased from 3.4 to 2.3 (-32%). Peak power output on a maximal aerobic exercise test increased from 326 to 357 W (+10%), while peak isotonic power of single-leg knee extension increased from 312 to 350 W (+12%). Maximal oxygen uptake following the trip was 53.1 mL/min/kg or 151% of predicted. Resting heart rate increased from 48 to 71 bpm (+48%). The systolic and diastolic blood pressure responses to a 2-min submaximal static handgrip exercise were near absent at baseline (∆2/∆2 mm Hg) but appeared normal post-trip (∆17/∆9 mm Hg). Gait and static balance measures were unchanged. This case report demonstrates the capacity for physiological and clinical adaptations to a high-volume, high-intensity cycling regiment in a physically active middle-aged male with PD.

Effect of core training on athletic and skill performance of basketball players: A systematic review

A limited number of studies focus on the effect of core training on basketball players' athletic performance and skills. This systematic reviewaimed to comprehensively and critically review the available studies in the literature that investigate the impact of core training on basketball players' physical and skill performance, and then offer valuable recommendations for both coaches and researchers. Thedata collection, selection, and analysis adhered to the PRISMA protocol. English databases, including Ebscohost, Scopus, PubMed, Web of Science, and Google Scholar,were searched until September 2022. A total of eight articles were included, with four studies comparing the effects of core training versus traditional strength training or usual basketball training. All studies investigated the impact of core training on athletic performance. The findings revealed that core training can help players improve their overall athletic and skill performance, particularly in the areas of strength, sprinting,jumping, balance, agility, shooting, dribbling, passing, rebounding, and stepping. In addition, core training, particularly on unstable surfaces,as well as combining static and dynamic core training,improvebasketball players' athletic and skill performance. Despite the relativelylittle evidence demonstrating the effect of core training on endurance, flexibility, and defensive skills, this review demonstrates that it should be incorporated into basketball training sessions.

Design guidelines for limiting and eliminating virtual reality-induced symptoms and effects at work: a comprehensive, factor-oriented review

Virtual reality (VR) can induce side effects known as virtual reality-induced symptoms and effects (VRISE). To address this concern, we identify a literature-based listing of these factors thought to influence VRISE with a focus on office work use. Using those, we recommend guidelines for VRISE amelioration intended for virtual environment creators and users. We identify five VRISE risks, focusing on short-term symptoms with their short-term effects. Three overall factor categories are considered: individual, hardware, and software. Over 90 factors may influence VRISE frequency and severity. We identify guidelines for each factor to help reduce VR side effects. To better reflect our confidence in those guidelines, we graded each with a level of evidence rating. Common factors occasionally influence different forms of VRISE. This can lead to confusion in the literature. General guidelines for using VR at work involve worker adaptation, such as limiting immersion times to between 20 and 30 min. These regimens involve taking regular breaks. Extra care is required for workers with special needs, neurodiversity, and gerontechnological concerns. In addition to following our guidelines, stakeholders should be aware that current head-mounted displays and virtual environments can continue to induce VRISE. While no single existing method fully alleviates VRISE, workers' health and safety must be monitored and safeguarded when VR is used at work.