Muscle-fiber specific genetic manipulation of Drosophila sallimus severely impacts neuromuscular development, morphology, and physiology.

The ability of skeletal muscles to contract is derived from the unique genes and proteins expressed within muscles, most notably myofilaments and elastic proteins. Here we investigated the role of the sallimus (sls) gene, which encodes a structural homologue of titin, in regulating development, structure, and function of Drosophila melanogaster. Knockdown of sls using RNA interference (RNAi) in all body-wall muscle fibers resulted in embryonic lethality. A screen for muscle-specific drivers revealed a Gal4 line that expresses in a single larval body wall muscle in each abdominal hemisegment. Disrupting sls expression in single muscle fibers did not impact egg or larval viability nor gross larval morphology but did significantly alter the morphology of individual muscle fibers. Ultrastructural analysis of individual muscles revealed significant changes in organization. Surprisingly, muscle-cell specific disruption of sls also severely impacted neuromuscular junction (NMJ) formation. The extent of motor-neuron (MN) innervation along disrupted muscles was significantly reduced along with the number of glutamatergic boutons, in MN-Is and MN-Ib. Electrophysiological recordings revealed a 40% reduction in excitatory junctional potentials correlating with the extent of motor neuron loss. Analysis of active zone (AZ) composition revealed changes in presynaptic scaffolding protein (brp) abundance, but no changes in postsynaptic glutamate receptors. Ultrastructural changes in muscle and NMJ development at these single muscle fibers were sufficient to lead to observable changes in neuromuscular transduction and ultimately, locomotory behavior. Collectively, the data demonstrate that sls mediates critical aspects of muscle and NMJ development and function, illuminating greater roles for sls/titin.

Predictive Value of Diaphragm Muscle Ultrasound for Ventilator Weaning Outcomes After Cervical Spinal Cord Injury: A Retrospective Case Series.

OBJECTIVES: Neuromuscular respiratory failure after cervical spinal cord injury (cSCI) can lead to dependence on an invasive mechanical ventilator. Ventilator-free breathing after cSCI is associated with improved morbidity, mortality, and quality of life. We investigated the use of diaphragm muscle ultrasound to predict ventilator weaning outcomes after cSCI. METHODS: This is a retrospective case series conducted at a university-affiliated freestanding inpatient rehabilitation facility. We identified patients with cSCI who had a tracheostomy and were dependent on an invasive mechanical ventilator at the time of admission to inpatient rehabilitation. A diaphragm muscle ultrasound was performed, which included measurements of the thickness of the diaphragm and a calculation of the thickening ratio (TR), which reflects diaphragm muscle contraction. The primary outcome measure was the need for mechanical ventilation at time of discharge from the inpatient rehabilitation facility. Successful ventilator weaning was defined as either daytime or full 24-hour ventilator-free breathing. RESULTS: Of the 21 patients enrolled, 11 (52%) were able to wean successfully (partially or fully) from the ventilator. Of the ultrasound measurements that were taken, the TR was the optimal predictor for ventilator weaning outcomes. A threshold of TR ≥ 1.2 as the maximum hemidiaphragm measurement had a sensitivity of 1.0 and specificity of 0.90 for predicting ventilator weaning. CONCLUSION: Normal diaphragm contractility (TR ≥ 1.2) as determined by diaphragm muscle ultrasound is a strong positive predictor for successful ventilator weaning in patients with cSCI. Utilizing diaphragm ultrasound, rehabilitation physicians can set precision rehabilitation goals regarding ventilator weaning for inpatients with respiratory failure after cSCI, potentially improving both outcomes and quality of life.

An Experimental Study to Optimize Neuromuscular Blockade Protocols in Cynomolgus Macaques: Monitoring, Doses, and Antagonism.

BACKGROUND: Neuromuscular blocking agents (NMBAs) are a crucial component of anesthesia and intensive care through the relaxation of skeletal muscles. They can lead to adverse reactions such as postoperative residual neuromuscular block. Only one agent is capable of an instant block reversal in deep block situations, but is restricted to aminosteroid agents. Among animal models, non-human primates are an essential model for a great diversity of human disease models. The main objective of this study was to establish a model for NMBA monitoring with current available drugs before testing new reversal agents. METHODS: Seven healthy male cynomolgus macaques were randomly assigned to this study. Experiments using macaques were approved by the local ethical committee (CEtEA #44). All animals were anesthetized according to institutional guidelines, with ketamine and medetomidine, allowing IV line placement and tracheal intubation. Anesthesia was maintained with isoflurane. Either rocuronium bromine (with or without sugammadex reversal) or atracurium besylate was evaluated. Monitoring was performed with two devices, TOF-Watch and ToFscan, measuring the T4/T1 and the T4/Tref ratios, respectively. Nonparametric Mann-Whitney statistical analyses were done when indicated. RESULTS: NMBA monitoring required adaptation compared to humans, such as stimulus intensity and electrode placement, to be efficient and valid in cynomolgus macaques. When administered, both NMBAs induced deep and persistent neuro-muscular block at equivalent doses to clinical doses in humans. The rocuronium-induced profound neuromuscular block could be reversed using the cyclodextrin sugammadex as a reversal agent. We report no adverse effects in these models by clinical observation, blood chemistry, or complete blood count. CONCLUSION: These results support the use of non-human primate models for neuromuscular block monitoring. This represented the first step before the forthcoming testing of new NMBA-reversal agents.

An algorithm for discontinuing mechanical ventilation in boys with x-linked myotubular myopathy after positive response to gene therapy: the ASPIRO experience.

X-linked myotubular myopathy (XLMTM) is a rare, life-threatening congenital myopathy. Most (80%) children with XLMTM have profound muscle weakness and hypotonia at birth resulting in severe respiratory insufficiency, the inability to sit up, stand or walk, and early mortality. At birth, 85-90% of children with XLMTM require mechanical ventilation, with more than half requiring invasive ventilator support. Historically, ventilator-dependent children with neuromuscular-derived respiratory failure of this degree and nature, static or progressive, are not expected to achieve complete independence from mechanical ventilator support. In the ASPIRO clinical trial (NCT03199469), participants receiving a single intravenous dose of an investigational gene therapy (resamirigene bilparvovec) started showing significant improvements in daily hours of ventilation support compared with controls by 24 weeks post-dosing, and 16 of 24 dosed participants achieved ventilator independence between 14 and 97 weeks after dosing. At the time, there was no precedent or published guidance for weaning chronically ventilated children with congenital neuromuscular diseases off mechanical ventilation. When the first ASPIRO participants started showing dramatically improved respiratory function, the investigators initiated efforts to safely wean them off ventilator support, in parallel with primary protocol respiratory outcome measures. A group of experts in respiratory care and physiology and management of children with XLMTM developed an algorithm to safely wean children in the ASPIRO trial off mechanical ventilation as their respiratory muscle strength increased. The algorithm developed for this trial provides recommendations for assessing weaning readiness, a stepwise approach to weaning, and monitoring of children during and after the weaning process.

Implications of neuromuscular electrical stimulation on gait ability, balance and kinematic parameters after stroke: a systematic review and meta-analysis.

INTRODUCTIN: Improper gait patterns, impaired balance and foot drop consistently plague stroke survivors, preventing them from walking independently and safely. Neuromuscular electrical stimulation (NMES) technology can help patients reactivate their muscles and regain motor coordination. This study aims to systematically review and summarize the evidence for the potential benefits of NMES on the improvement of gait patterns after stroke. EVIDENCE ACQUISITION: PubMed, Cochrane Library, Embase, Science Direct and Web of Science were systematically searched until April 2024, to identify randomized controlled trials with the following criteria: stroke survivors as participants; NMES as intervention; conventional rehabilitation as a comparator; and gait assessment, through scales or quantitative parameters, as outcome measures. EVIDENCE SYNTHESIS: 29 publications involving 1711 patients met the inclusion criteria. Meta-analysis showed no significant differences in Ten-meter walk test, Fugl-Meyer assessment lower extremity, Modified Ashworth Assessment and asymmetry between the NMES group and the control group. Besides, NMES was associated with changes in outcome indicators such as quantitative gait analysis speed [SMD = 0.53, 95% CI (0.20, 0.85), P = 0.001], cadence [SMD = 0.76, 95% CI (0.32, 1.20), P = 0.0008], affected side step length [SMD = 0.73, 95% CI (0.16, 1.31), P = 0.01], angle of ankle dorsiflexion [WMD = 1.57, 95% CI (0.80, 2.33), P < 0.0001], Six-Minute Walk Test [WMD = 14.83, 95% CI (13.55, 16.11), P<0.00001]. According to the PEDro scale, 21 (72.4%) studies were of high quality and 8 were of moderate quality (27.6%). CONCLUSIONS: Taken together, the review synthesis indicated that NMES might play a potential role in stroke-induced walking dysfunction. And NMES may be superior for survivors in the chronic phase than the acute and subacute phases, and the efficacy of short sessions received by patients was greater than that of those who participated in a longer session. Additionally, further comparisons of the effects of NMES with different types or stimulation frequencies may provide unexpected benefits.

Interpretation of Sydney Swallow Questionnaire results using the oropharyngeal dysphagia risk matrix.

BACKGROUND: Oropharyngeal dysphagia (OD) commonly occurs in neuromuscular diseases (NMD). Appropriate management involves early detection, clinical evaluation, and tailored follow-up to minimize complications. Various assessment tools exist, including the Sydney Swallow Questionnaire (SSQ), a patient-reported outcome measure for assessing OD severity in adult patients. This paper proposes utilizing an innovative risk matrix (OD-Risk-Matrix) to enhance SSQ interpretation. This matrix categorizes OD risk for each SSQ question, offering valuable assistance to clinicians. METHODS: This study analyzes SSQ results from a cohort of individuals with NMD (n = 57). Patients filled in the SSQ during outpatient visits at our neuromuscular center. Subsequently, SSQ scores were grouped by NMD conditions and interpreted using the OD-Risk-Matrix categorizing each question's risk as low, moderate, or high. This matrix is based on the SSQ results by categorizing the risk of OD for each question, as well as the likelihood of occurrence of OD. KEY RESULTS: In light of the OD-Risk-Matrix, the interpretation of SSQ scores revealed various risk categories associated with each question, while also highlighting distinct OD characteristics and discrepancies among the different NMDs. CONCLUSION AND INFERENCES: In conclusion, the OD-Risk-Matrix offers a framework for interpreting the SSQ, revealing variations in the risks of OD among different questions in patients with NMD. This novel approach could be a valuable tool in SSQ interpretation to identify specific fields of OD and could lead to a tailored management plan, prioritizing interventions aimed at reducing the risk of aspiration, ensuring proper nutrition, and enhancing swallowing safety and efficiency.

Elevated serum levels of C-terminal agrin fragment in acetylcholine receptor antibody-positive myasthenia gravis.

Agrin is essential for neuromuscular junction (NMJ) formation and maintenance. The C-terminal agrin fragment (CAF), generated by neurotrypsin-mediated cleavage of agrin, has been gaining attention as a potential biomarker for sarcopenia. We investigated serum CAF levels in myasthenia gravis (MG), a NMJ disorder. Compared to healthy controls, serum CAF levels were significantly elevated in acetylcholine receptor antibody-positive MG (AChR-MG) patients, but not in muscle-specific kinase antibody-positive MG patients. In AChR-MG, baseline and post-treatment CAF levels inversely correlated with post-treatment MG activities of daily living scores, suggesting that elevated CAF levels may reflect protective mechanisms against AChR-MG pathogenesis, such as improved NMJ regeneration.

Sero-Positive Isolated Ocular Myasthenia Gravis.

Ocular myasthenia gravis (OMG) is a neuromuscular disease characterized by the production of autoantibodies against post-synaptic proteins at the neuromuscular junction (NMJ). An 18-year-old male who had symptoms of drooping eyelids and double vision was diagnosed with ocular myasthenia gravis on investigations and examinations. Treatment was initiated with a tablet of pyridostigmine 60 mg twice daily per oral for two weeks, followed by three times daily for four weeks. The patient demonstrated significant improvement in ptosis and diplopia. There are still a considerable number of challenges in the diagnosis and treatment of ocular myasthenia gravis, with the typical treatment involving acetylcholinesterase inhibitors and immunosuppressants.

Real-time artificial intelligence-based texture analysis of muscle ultrasound data for neuromuscular disorder assessment.

Objective: Many artificial intelligence approaches to muscle ultrasound image analysis have not been implemented on usable devices in clinical neuromuscular medicine practice, owing to high computational demands and lack of standardised testing protocols. This study evaluated the feasibility of using real-time texture analysis to differentiate between various pathological conditions. Methods: We analysed 17,021 cross-sectional ultrasound images of the biceps brachii of 75 participants, including 25 each with neurogenic disorders, myogenic disorders, and healthy controls. The size and location of the regions of interest were randomly selected to minimise bias. A random forest classifier utilising texture features such as Dissimilarity and Homogeneity was developed and deployed on a mobile PC, enabling real-time analysis. Results: The classifier distinguished patients with an accuracy of 81 %. Echogenicity and Contrast from the Co-Occurrence Matrix were significant predictive features. Validation on 15 patients achieved accuracies of 78 %/93 % per image/patient over 15-second videos, respectively. The use of a mobile PC facilitated real-time estimation of the underlying pathology during ultrasound examination, without influencing procedures. Conclusions: Real-time automatic texture analysis is feasible as an adjunct for the diagnosis of neuromuscular disorders. Significance: Artificial intelligence using texture analysis with a light computational load supports the semi-quantitative evaluation of neuromuscular ultrasound.

Case report: Second report of neuromuscular syndrome caused by biallelic variants in ASCC3.

Introduction: Activating Signal Cointegrator 1 Complex, Subunit 3 (ASCC3) has been implicated in the pathogenesis of neurodevelopmental disorders and neuromuscular diseases (MIM: 620700). This paper analyzes the clinical manifestations of three patients with developmental delay caused by ASCC3 genetic variation. Additionally, we discuss the previously reported clinical features of these patients along with our own findings, thereby enhancing our understanding of these genetic disorders and providing valuable insights into diagnosis, treatment, and potential interventions for affected individuals. Methods: In this study, we utilized trio-whole-exome sequencing (Trio-WES) and trio-copy number variations sequencing (Trio-CNV-seq) to analyze three unique families diagnosed with developmental delay caused by variation in ASCC3. Additionally, we retrospectively examined eleven previously reported ASCC3 genetic variations exhibiting similar clinical features. Results: Proband I (family 1) and Proband III (family 3) exhibited global developmental delays, characterized by intellectual disability, motor impairment, language retardation, lower muscle strength, and reduced muscle tone in their extremities. Proband II (family 2) presented poor response and dysphagia during feeding within 7 days after birth, clinical examination displayed short limbs, long trunk proportions, and clenched fists frequently observed alongside high muscle tone in his limbs -all indicative signs of developmental delay. Trio-WES revealed compound heterozygous variants in ASCC3 inherited from their parents. Proband I carried c. [489 dup]; [1897C>T], proband II carried c. [2314C>T]; [5002T>A], and proband III carried c. [5113G>T]; [718delG] variations, respectively. Conclusion: This study present the first report of Chinese children carrying compound heterozygous genetic variants in ASCC3 with LOF variants, elucidating the relationship between these variants and various aspects of intellectual disability. This novel finding expands the existing spectrum of ASCC3 variations.

Pressure control plus spontaneous ventilation versus volume assist-control ventilation in acute respiratory distress syndrome. A randomised clinical trial.

PURPOSE: The aim of this study was to compare the effect of a pressure-controlled strategy allowing non-synchronised unassisted spontaneous ventilation (PC-SV) to a conventional volume assist-control strategy (ACV) on the outcome of patients with acute respiratory distress syndrome (ARDS). METHODS: Open-label randomised clinical trial in 22 intensive care units (ICU) in France. Seven hundred adults with moderate or severe ARDS (PaO2/FiO2 < 200 mmHg) were enrolled from February 2013 to October 2018. Patients were randomly assigned to PC-SV (n = 348) or ACV (n = 352) with similar objectives of tidal volume (6 mL/kg predicted body weight) and positive end-expiratory pressure (PEEP). Paralysis was stopped after 24 h and sedation adapted to favour patients' spontaneous ventilation. The primary endpoint was in-hospital death from any cause at day 60. RESULTS: Hospital mortality [34.6% vs 33.5%, p = 0.77, risk ratio (RR) = 1.03 (95% confidence interval [CI] 0.84-1.27)], 28-day mortality, as well as the number of ventilator-free days and organ failure-free days at day 28 did not differ between PC-SV and ACV groups. Patients in the PC-SV group received significantly less sedation and neuro-muscular blocking agents than in the ACV group. A lower proportion of patients required adjunctive therapy of hypoxemia (including prone positioning) in the PC-SV group than in the ACV group [33.1% vs 41.3%, p = 0.03, RR = 0.80 (95% CI 0.66-0.98)]. The incidences of pneumothorax and refractory hypoxemia did not differ between the groups. CONCLUSIONS: A strategy based on PC-SV mode that favours spontaneous ventilation reduced the need for sedation and adjunctive therapies of hypoxemia but did not significantly reduce mortality compared to ACV with similar tidal volume and PEEP levels.

The effect of caffeine chewing gum on muscle performance and fatigue after severe-intensity exercise: isometric vs. dynamic assessments in trained cyclists.

This study investigated the effect of caffeinated chewing gum (GUMCAF) on muscle fatigue (isometric vs. dynamic) after severe-intensity cycling bouts. Fifteen trained male cyclists participated in four visits. Each visit involved two severe-intensity cycling bouts (Δ1 and Δ2) lasting 6 min, separated by a 5-min recovery period. Muscle fatigue was assessed by isometric maximal voluntary knee extension contraction (IMVC) with twitch interpolation technique and dynamically by 7 s all-out cycling sprints. Assessments were performed before GUMCAF (Pre-GUM) and after the cycling bouts (Post-Exercise). GUMCAF and placebo gum (GUMPLA) were administered in a randomized double-blind procedure with participants receiving each gum type (GUMCAF and GUMPLA) during two separate visits. The results showed no significant interaction between gum types and time for the isometric and dynamic measurements (p > 0.05). The percentage change in performance from Pre-GUM to Post-Exercise showed no significant difference between GUMCAF and GUMPLA for either the dynamic-derived TMAX (~ -17.8% and -15.1%, respectively; p = 0.551) or isometric IMVC (~ -12.3% and -17.7%, respectively; p = 0.091) measurements. Moderate to large correlations (r = 0.31-0.51) were found between changes in sprint maximal torque and maximal power output measurements and isometric force, for both gum conditions. GUMCAF was not effective in attenuating muscle force decline triggered by severe-intensity cycling exercises, as measured by both isometric and dynamic methods. The correlations between IMVC and cycling maximal torque and power output suggest caution when interpreting isometric force as a direct measure of fatigue during dynamic cycling exercises.

Tubular Aggregates as a Marker of Aging in Skeletal Muscle.

Tubular aggregates (TA) are skeletal muscle structures that arise from the progressive accumulation of sarcoplasmic reticulum proteins, mainly with aging. Muscle regeneration plays a role in TA formation. TA quantification may aid in the evaluation of muscle aging and genetic muscle degeneration. TA form over time, appears in aging in normal murine muscles. TA reduction in injured conditions may be due to the degeneration-regeneration process in muscles, with loss of damaged muscle fibers and formation of new fibers that do not present protein aggregation. These new regenerated fibers do not improve the function capacity of the aged muscle. Here, we present a methodology for labeling and identifying tubular aggregates in muscle fibers and also the standardization of its quantification.

Social provisions in patients with mitochondrial diseases.

Background: Mitochondrial diseases often follow a chronic, multimorbid disease course in adults. Like other chronic conditions, mitochondrial diseases present a challenge to public and community health models and patients are potentially at higher risk of social isolation and loneliness. However, there is lack of data on social provisions in mitochondrial diseases. Methods: We performed a cross-sectional observational study on patients with a confirmed genetic or clinical diagnosis of mitochondrial disease, recruited between September 2018 and December 2021. Participants completed the Social Provisions Scale (SPS) as a measure of social support. Designated carers similarly completed the SPS in carer-specific questionnaires. Results: 95 mitochondrial disease patients and 24 designated carers completed the SPS. Social provisions were met for all six subscales of SPS in the mitochondrial disease cohort: (1) guidance 90.5% (n=86), (2) reassurance of self-worth 82.8% (n=77), (3) social integration 88.4% (n=84), (4) attachment 83.2% (n=79), (5) opportunity of nurturance, 61.1% (n=58) and (6) reliable alliance 95.8% (n=91). All social provisions were also met in the carer cohort. Conclusion: Patients with mitochondrial diseases and their carers demonstrate a high perceived level of social support in the setting of a tertiary referral centre specialised in mitochondrial disease despite the burden of chronic disease.

Upper limb function changes over 12 months in untreated SMA II and III individuals: an item-level analysis using the Revised Upper Limb Module.

The Revised upper limb module (RULM) has been increasingly used in clinical trials and in clinical settings. The aim of this study was to use the 'shift analysis' to assess the patterns of lost or gained abilities for each item on the RULM in an untreated cohort, stratified by SMA type, age, SMN2 copy number, and motor functional status. The analysis was performed on 222 12-month paired assessments from 129 individuals (115 assessment from type II and 107 from type III) who had at least two assessments at yearly intervals. There was a loss of one or more activities in 54% in type II and in 29% type III. A gain of one or more activities was found in 42% type II and in 22% type III. There were concomitant gains and losses in 27% in SMA II and in 9% in SMA III. Our results, measuring the number of abilities that are lost or gained, provide an additional method of detecting changes that can be used for the interpretation of the longitudinal data collected in treated SMA individuals.

Fluoxetine antagonizes the acute response of LPS: Blocks K2P channels.

The channels responsible for maintaining resting membrane potential are known as K2P (two-P-domain K+ subunit) channels, a subset of which are known to be blocked by Fluoxetine. In this experiment, the compound's effects on the membrane potential were examined on muscles in larval Drosophila overexpressing a subtype of K2P channel (known in Drosophila as dORKA1 or ORKA1) and compared to larvae without overexpression. The compound was also observed in sequence and/or combination with a form of lipopolysaccharide (LPS) that transiently activates K2P channels. Different concentrations of Fluoxetine were tested, and it was also examined in cocktail with the LPS. At 25 µM Fluoxetine exposure, muscle in control larvae underwent depolarization, while muscles overexpressing K2P channels hyperpolarized; at 50 µM, however, much more variable responses were observed. The LPS caused hyperpolarization in both larval strains, but the effect was more transient in the Canton-S line than in the K2P overexpressors. Finally, LPS continued to cause hyperpolarization even in the presence of Fluoxetine, while Fluoxetine quickly depolarized the muscle during exposure to LPS. The cocktail showed a smaller effect on muscles overexpressing ORKA1 as compared to the controls, indicating that Fluoxetine does not block the ORKA1 subtype. This study is significant because it demonstrates how overexpression of K2P channels alters membrane response to LPS and Fluoxetine exposure.

Investigation of Neuromuscular Activation in Older Female Adults during a Dynamic and Challenging Virtual Reality Activity: A Cross-Sectional Study.

The use of virtual reality (VR) in older adults promotes improvements in mobility, strength, and balance. Changes in neuromuscular activation have been found to be associated with these improvements; however, during VR activities, this aspect has not been thoroughly investigated. The aim of this study was to investigate neuromuscular activation among older female adults during VR activities. Sixteen older female adults, with the use of VR, performed dynamic punching movements involving elbow flexion/extension for one minute, and the muscle activation of the bicep brachii was recorded with electromyography (EMG) and normalized to the maximal voluntary isometric contraction of elbow flexion. The one-minute activity was divided into three time phases: 0-10 s, 25-35 s, and 50-60 s. The five highest EMG amplitude values (%) in each phase were selected and averaged. Differences between phases were analyzed using repeated ANOVA (αadj = 0.017). The EMG amplitude for the first phase was 39.1 ± 2.6%, that for the second phase was 44.8 ± 3.0%, and that for the third phase was 49.6 ± 3.1%. Statistically significant differences were found in all phases, with the first phase demonstrating a lower EMG amplitude (%) compared to the second (p = 0.002) and third phases (p = 0.000). The third phase demonstrated a higher EMG amplitude (%) compared to the second phase (p = 0.025). Engagement in VR activities can have significant effects on neuromuscular activation in older female adults, with our findings revealing a significant increase in the EMG amplitude within one minute of commencing a dynamic and challenging activity such as virtual boxing.

Perceived Factors That Contributed to Task Termination during Fatiguing Tasks Anchored to Perceptual Intensities.

This study examined the effects of sustained, isometric forearm flexion tasks anchored to ratings of perceived exertion of 2 (RPE2FT) and 8 (RPE8FT) on the patterns of fatigue-induced changes in torque and neuromuscular responses, time to task failure (TTF), performance fatigability (% decline in maximal voluntary isometric contraction [MVIC]), and perceived factors that contributed to task termination. Twelve men (mean ± SD: age = 20.9 ± 2.2 yrs) performed MVICs before and after the tasks and completed post-test questionnaires (PTQ). Data were analyzed using polynomial regression analyses, dependent t-tests, Spearman's rank order correlations, and Wilcoxon signed rank tests. The RPE8FT had greater (p < 0.001) performance fatigability than the RPE2FT, despite no difference (p > 0.05) in TTF. During both tasks, there were significant (p ≤ 0.05) composite linear decreases for torque, electromyographic amplitude, and neuromuscular efficiency, and substantial individual variability in the neuromuscular responses. There were no significant (p > 0.05) associations among the perceived factors and TTF or performance fatigability. Thus, there were RPE-specific differences in performance fatigability, but not TTF or the composite patterns of changes in torque and neuromuscular responses. In addition, in most cases, the individual neuromuscular, but not torque, patterns of responses were RPE-specific. Furthermore, the perceived factors assessed by the PTQ were not related to TTF or performance fatigability.

Concurrent Validity and Reliability of a Free Smartphone Application for Evaluation of Jump Height.

Background/Objectives: Jump test assessment is commonly used for physical tests, with different type of devices used for its evaluation. The purpose of the present study was to examine the validity and reliability of a freely accessible mobile application (VertVision, version 2.0.5) for measuring jump performance. Methods: With that intent, thirty-eight college age recreationally active subjects underwent test assessment after a specific warm-up, performing countermovement jumps (CMJs) and squat jumps (SJs) on a contact platform while being recorded with a smartphone camera. Jump height was the criterion variable, with the same formula being used for both methods. Data analysis was performed by two experienced observers. Results: The results showed strong correlations with the contact platform (ICC > 0.9) for both jumps. Furthermore, between-observer reliability was also high (ICC > 0.9; CV ≤ 2.19), with lower values for smallest worthwhile change (≤0.23) and typical error of measurement (≤0.14). Estimation error varied when accounting for both observers, with the SJ accounting for bigger differences (4.1-6.03%), when compared to the CMJ (0.73-3.09%). Conclusions: The study suggests that VertVision is a suitable and handy method for evaluating jump performance. However, it presents a slight estimation error when compared to the contact platform.