Neuromuscular Assessment Research Articles

Neuromuscular ultrasound competency assessment: Consensus‐based survey

Neuromuscular ultrasound is a rapidly evolving specialty with direct application for patient care. Competency assessment is an essential standard needed to ensure quality for practitioners, particularly for those newly acquiring skills with the technique. Our aim was to survey experts' opinions regarding physician competency assessment of neuromuscular ultrasound and to identify minimal competency of knowledge and skills. The opinions of 18 experts were obtained through the Delphi method using two consecutive electronic surveys. A high degree of consensus was achieved on items regarding framework and the conduct of neuromuscular ultrasound assessment and the knowledge and skills that a candidate needs to attain minimal competency in neuromuscular ultrasound. In this study, a group of neuromuscular ultrasound experts developed a general framework for neuromuscular ultrasound competency assessment and recommended testable areas of knowledge and skills suitable for establishing minimal competency.

Neuromuscular and physiological assessment during a vertical jumping test in aerobic gymnastics

In executing aerobic gymnastics technical elements, a high level of explosive power is needed, especially at lower-body muscle groups. In addition, to maintain the specific effort during routine length (1 min 30 s - 1 min 45 s), an optimal development of specific endurance training and a high capacity of focusing is required, in order to execute the technical elements with accuracy. The purpose of this study was to elaborate a testing protocol to evaluate the physical effort capacity necessary to perform specific technical elements in aerobic gymnastics. The proposed testing protocol, is aimed at assessing neuromuscular behavior of lower-body muscle action and the physiological demands, in a maximal vertical jump test (MVJ). The neuromuscular assessment of the of lower-body was achieved by measuring the specific vertical jump parameters, respectively the power in the take-off phase (P) and the height of the jump (JH). The testing protocol consisted of three sets of maximum vertical jumps, lasting 30 s each, with a 15 s rest time between sets. For the physiological demands, as a result of test implementation, heart rate (HR) and the blood lactate concentration (La) were measured. The study was conducted on a group of 13 junior level gymnasts, 7 females and 6 males (aged 14-16 years, average height 163 SD 8.1 cm, average weight 50.69 SD 8.47 kg). The results of this study confirm the proposed methodology reflects an objective view of the physical training status necessary for specific effort accomplishment in aerobic performance gymnastics.

Survey of neuromuscular monitoring and assessment of postoperative residual neuromuscular block in a postoperative anaesthetic care unit.

The use of neuromuscular blocking agents (NMBAs) is common during general anaesthesia. Neuromuscular monitoring with a peripheral nerve stimulator (PNS) is essential to prevent postoperative residual neuromuscular block (PRNB), defined as a train-of-four (TOF) ratio < 0.9. PRNB remains a common complication and may contribute to morbidity in the postoperative anaesthetic care unit (PACU). An online survey was sent to anaesthesiologists in our department to assess their knowledge and clinical practices related to neuromuscular blockade. Next, a study was conducted on adult patients scheduled for elective surgery under general anaesthesia requiring NMBAs. Upon admission to the PACU, TOF monitoring was performed. A large proportion of anaesthesiologists showed a lack of knowledge of neuromuscular blockade or non-adherence to the best clinical practices associated with it. The majority (98.7%) stated that they did not routinely use PNS monitoring. In the clinical study, TOF monitoring was only used in 17.9% of the 335 patients who were assessed. The prevalence of PRNB was 33.4% and was associated with the elderly (age ≥ 65 years), a higher dose of NMBA used, a shorter duration of surgery, and a shorter duration between the last dose of NMBA and measurement of PRNB in the PACU. The incidence of adverse symptoms in the PACU was observed to be higher in patients with PRNB. PRNB remains a clinically significant problem, but routine PNS monitoring is rare in our institution. This is compounded by inadequate knowledge and poor adherence to best clinical guidelines related to neuromuscular blockade.

Adapted protocol of rate of force development and relaxation scaling factor for neuromuscular assessment in patients with knee osteoarthritis

BackgroundThe linear relationship between muscle torque and rate of torque rise/relaxation during rapid muscle contractions has been recently introduced as a novel measure of muscle quickness, termed rate of torque development/relaxation scaling factor (RTD-SF/RTR-SF). Because the standard assessment protocol includes potentially painful muscle contractions, the first purpose of this study was to validate an adapted RTD-SF/RTR-SF protocol for knee extensor muscles that utilizes lower submaximal intensities and can be used in knee osteoarthritis patients. MethodsA cross-sectional study was performed on a group of healthy controls (n = 24) who underwent the standard RTD-SF/RTR-SF protocol (20–80% of maximum) and the knee osteoarthritis group (n = 24) who underwent the adapted protocol (20–60% of maximum). We calculated the RTD-SF, RTR-SF and the linearity (r2) for both relationships, based on both protocols in controls. ResultsThe validity of the adapted protocol was acceptable (intraclass correlation coefficient = 0.77–0.93), with low within-participant variation (coefficient of variability <10%) for both outcome measures. Compared with the control group, the knee osteoarthritis group had similar RTD-SF, but lower linearity of RTD-SF (0.90 vs. 0.82). The RTR-SF (8.0/s vs. 6.7/s) and its linearity (0.87 vs. 0.73) were significantly reduced. Comparing the affected and the unaffected leg in the knee osteoarthritis group, the unaffected leg had greater maximal torque (96.2 vs. 84.1 Nm) and higher linearity for RTD-SF (0.86 vs. 0.80) and RTR-SF (0.82 vs. 0.73). ConclusionsWe confirmed the validity of the adapted RTD/RTR-SF protocol and its sensitivity to impairments associated with knee osteoarthritis.

SLEEP DISORDERED BREATHING FEATURES, EVOLUTION AND MANAGEMENT OF A PATIENT WITH ROHHAD SYNDROME

SESSION TITLE: Medical Student/Resident Sleep Disorders Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: ROHHAD syndrome (rapid-onset obesity, hypothalamic dysregulation, hypoventilation and autonomic dysregulation), is a condition of unknown etiology with only about 100 cases reported worldwide, and a high mortality from alveolar hypoventilation. CASE PRESENTATION: A male patient was diagnosed at age six with ROHHAD syndrome, with features of morbid obesity, diabetes insipidus, hyperprolactinemia, hypogonadism, neuroganglioma and multiple respiratory abnormalities including central alveolar hypoventilation, restrictive lung disease (RLD) and obstructive sleep apnea (OSA). At age ten his weight was 103 kg and neck circumference 41 cm. Spirometry showed mild restrictive pattern and polysomnography (PSG) revealed moderate sleep apnea. Direct laryngoscopy was unrevealing. He was started on nocturnal volume and pressure control ventilator with average volume assured pressure support (PC/AVAPS) at 20 breaths/minute (RR), AVPAS rate: 2, maximum inspiratory pressure (MaxIP): 24cmH2O, minimum inspiratory pressure (MinIP) 16cmH2O, tidal volume (TV): 580 cc and end-expiratory pressure (e-EP) 8cmH2O. He continued to gain weight and his functional status declined due to multiple hospitalizations and the nature of the disease. Most recently, at age 19, his weight was 193 kg and NC of 43 cm. His studies showed progression to moderate RLD and severe OSA. Neuromuscular assessment revealed Max IP at -93cmH20 and e-EP of 34cmH2O, suggestive of alveolar hypoventilation and ineffective cough. He has required multiple titrations of his NIV settings, currently: PC/AVAPS mode, RR 16, TV 1200 ml, AVAPS Rate 4, Max IP 36 cmH20, MinIP 18 cmH20, EPAP 14 cmH20, with Auto-Trak and a full-face mask. To date, he continues to be on this regimen for 10 hours at night along with levalbuterol nebulizations as needed. DISCUSSION: ROHHAD syndrome begins with rapid weight gain during early childhood followed by respiratory abnormalities. Endocrine and autonomic disturbances are required to make a diagnosis. Early diagnosis and treatment are imperative. Unfortunately, this remains a progressive, incurable condition with an average survival of 10 years from time from diagnosis. The novelty of this case is that the patient has survived 13 years thus far. We firmly believe that this is in part to the patient’s intense pulmonary and neuromuscular rehabilitation program and to the modality of NIV. By using AVAPS we have avoided the need for 24-hour NIV and tracheostomy (which up to 80% of patients require) as well as the development of pulmonary hypertension. CONCLUSIONS: ROHHAD syndrome requires a multidisciplinary approach along with an aggressive hypoventilation management. AVAPS improves ventilation and delays or may even prevent the need for surgical airway. Additionally, behavioral interventions, NIV titration, oxygen saturation above 95% and CO2 levels between 35-45 mmHg are measures that also seem to render a better prognosis. Reference #1: Reppucci, Diana; Hamilton, Jill; Yeh, E Ann; Katz, Sherri; Al-Saleh, Suhail; Narang, Indra (2016-07-30). “ROHHAD syndrome and evolution of sleep disordered breathing”. Orphanet Journal of Rare Diseases. 11 (1): 106 Reference #2: Kocaay, Pinar; Siklar, Zeynep; Çamtosun, Emine; Kendirli, Tanil; Berberoglu, Merih (December 2014). “ROHHAD Syndrome: Reasons for Diagnostic Difficulties in Obesity”. Journal of Clinical Research in Pediatric Endocrinology. 6 (4): 254–257 Reference #3: Carroll MS, Patwari PP, Kenny AS, Brogadir CD, Stewart TM, Weese-Mayer DA. Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD): response to ventilatory challenges. Pediatr Pulmonol. 2015; 50: 1336- 1345. DISCLOSURES: No relevant relationships by Maria De Lourdes Alegría Peña, source=Web Response No relevant relationships by Francisco Davila, source=Web Response No relevant relationships by Fernando Figueroa Rodriguez, source=Web Response No relevant relationships by Matthew Schloop, source=Web Response

AUTOIMMUNE MYOPATHIES: P.309 Immune mediated necrotising myopathy: a treatable condition missed in the Arab and African regions

There has been no report of immune–mediated necrotizing myopathy (IMNM) from Arab or African countries, including Egypt. To characterize IMNM cases identified in Egypt, clinical records of 18 IMNM cases diagnosed at Myo–Care Center, Cairo, Egypt (2–61 years, 12 females) were reviewed; neuromuscular assessment, CK level, EMG, MRI, muscle pathology, autoantibody testing and clinical course. No case had family history. All except 2 were previously diagnosed as muscular dystrophy at other medical institutes.

Use of the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) in X-Linked Myotubular Myopathy: Content Validity and Psychometric Performance

X-linked myotubular myopathy (XLMTM) is a life-threatening, congenital myopathy characterized by extreme hypotonia, weakness, delayed motor milestones, and respiratory failure, often resulting in pediatric mortality. This study evaluated the content validity and psychometric performance of the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders as a measure of neuromuscular functioning in children with X-linked myotubular myopathy. This study was conducted in two phases. Phase I assessed the content validity of the measure for use in an XLMTM pediatric population through: literature review, clinical expert interviews, caregiver interviews, and a modified-Delphi panel among clinicians. Phase II assessed psychometric performance based on the INCEPTUS observational clinical study and the ASPIRO interventional gene therapy study, including tests of reliability (internal consistency, test-retest, and interrater), validity (construct and criterion), and responsiveness based on observational and interventional clinical trial data analyses. Data established construct validity and reliability of the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders among XLMTM patients before administration of resamirigene bilparvovec, and sensitivity to study drug administration as evidenced by the significant post-administration response in ASPIRO. Findings support the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders as an appropriate neuromuscular functioning assessment in a pediatric X-linked myotubular myopathy patient population.

Time Course of Recovery after Cycling Repeated Sprints.

The present study investigated the recovery of performance and neuromuscular fatigue after cycling repeated sprints. Ten participants performed two sessions of repeated sprints (one session: 10 × 10-s sprints, 30-s recovery) separated by 24 h (R24-S1 and R24-S2) and two sessions separated by 48 h (R48-S1 and R48-S2). The recovery condition (i.e., 24 or 48 h) was randomized and separated by 1 wk. All sessions were performed on a recumbent bike, allowing minimal delay between sprints termination and neuromuscular measurements. Neuromuscular function of knee extensors (neuromuscular assessment [NMA]) was assessed before sessions (presession), after the fifth sprint (midsession), and immediately after (postsession). Before sessions, baseline NMA was also carried out on an isometric chair. The NMA (bike and chair) was composed of maximal voluntary contraction (MVC) of knee extension and peripheral neuromuscular stimulation during the MVC and on relaxed muscle. The sprints performance was not significantly different between sessions and did not presented significant interaction between recovery conditions. MVC was significantly lower at R24-S2 compared with R24-S1 (-6.5% ± 8.8%, P = 0.038) and R48-S2 (-5.6% ± 8.2%, P = 0.048), whereas resting potentiated high-frequency doublet (Db100) was lower at R24-S2 compared with R24-S1 (-10.4 ± 8.3, P = 0.01) (NMA on chair). There were significant reductions in MVC (>30%, P < 0.001) and Db100 (>38%, P < 0.001) from pre- to postsession in all sessions, without significant interactions between recovery conditions (NMA on bike). Cycling repeated sprints induce significant fatigue, particularly at the peripheral level, which is fully restored after 48 h, but not 24 h, of recovery. One versus two days of recovery does not affect neuromuscular fatigue appearance during cycling repeated-sprint sessions.

Novel Surface Mechanomyography Sensor Assessment Of Hamstrings Contraction During A Neuromuscular Control Screening Task

PURPOSE: Hamstring strain is a common injury among athletes. Asymmetries in muscle balance and activation are potential injury risk factors. Surface mechanomyography (sMMG) sensors are wearable devices that when applied across a muscle group provide a novel measurement of physical muscle output during a contraction. The purpose of this study is to assess 1) the relationship of sMMG’s muscle bulk displacement measurement to force generation and 2) sMMG detection of hamstrings contraction timing compared to the clinical standard method of electromyography (EMG). METHODS: Healthy, active individuals (mean age= 30.0 ±10.77 y, n=9, 6 males, 3 females) underwent hamstrings neuromuscular control assessment with simultaneous recording of EMG and sMMG by sensors applied to the right hamstrings. Subjects performed a series of 3 resisted “make-test” isometric hamstring curls against a hand-held dynamometer (HHD). Raw sMMG data and 6th order Butterworth filter and TKEO processed EMG data were used in timing analyses. Paired T-tests and a Pearson correlation assessed relationships between measurement modalities. RESULTS: Peak hamstrings muscle bulk displacement detected by sMMG (mean= 4.02 ±1.04 mm) positively correlated with HHD maximum force generation (mean= 28.84 ±12.13 lb), r2= 0.850. There was no significant difference in the timing duration of muscle contraction between EMG (mean= 4.443 ±0.573 s) and sMMG (mean= 4.469 ±0.623 s), p= 0.279. CONCLUSIONS: Results are consistent with physiologic expectations that increased physical muscle bulk displacement during a contraction is associated with greater force. Similarity in time signatures with EMG support findings of successful sMMG detection of hamstrings contraction (Figure 1). The sMMG sensor may be helpful for assessing hamstrings muscle performance of both force output and timing as part of neuromuscular control screening for injury prevention, rehabilitation monitoring, or return-to-sport readiness.

Dynamic transperineal ultrasonography correlates with prolonged pudendal nerve latency in female with fecal incontinence.

The pelvic floor is a complex anatomical entity and its neuromuscular assessment is evaluated through debated neurophysiological tests. An innovative approach is the study of pelvic floor through dynamic transperineal ultrasound (DTU). The aim of this study is to evaluate DTU sensitivity in recognizing patients with fecal incontinence and to evaluate its concordance with the results of the motor latency studied via pudendal nerve terminal motor latency (PNTML). Female patients affected by FI addressed to our center of coloproctology were prospectively assessed. After a coloproctological evaluation, comprising the PNTML assessment to identify pudendal neuropathy, patients were addressed to DTU to determine anterior and posterior displacement of puborectalis muscle by a blinded coloproctologist. In order to compare the data, a cohort of female healthy volunteers was enrolled. Sixty-eight subjects (34 patients and 34 healthy volunteers) were enrolled. The sensitivities of anterior displacement, posterior displacement and either anterior or posterior displacement in determining the fecal incontinence were 82%, 67% and 91%, respectively. A further high correlation of either anterior or posterior displacement with PTNML was also noted (88%). DTU is an indirect, painless and reproducible method for the identification of the pelvic floor neuromuscular integrity. Its findings seem to highly correlate with FI symptoms and with PNTML results. In the near future, after larger comparative studies, DTU would be considered a potential reliable non-invasive and feasible indirect procedure in the identification of fecal incontinence by pudendal neuropathy. Trial registration number is NCT03933683.

Feasibility of eccentric overloading and neuromuscular electrical stimulation to improve muscle strength and muscle mass after treatment for head and neck cancer.

Treatment of head and neck cancer (HNC) results in severe weight loss, mainly due to the loss of lean body mass. Consequently, decreases in muscular strength and health-related quality of life (HRQL) occur. This study investigated the feasibility of a 12-week novel strength training (NST) and conventional strength training (CST) intervention delivered after HNC treatment. Participants were randomized to a NST group (n = 11) involving eccentric overloaded strength training and neuromuscular electrical stimulation (NMES), or a CST group (n = 11) involving dynamic resistance exercises matched for training volume. Feasibility outcomes included recruitment, completion, adherence, and evidence of progression. A neuromuscular assessment involving maximal isometric voluntary contractions (MIVCs) in the knee extensors was evaluated prior to and during incremental cycling to volitional exhaustion at baseline and after the interventions. Anthropometrics and patient-reported outcomes (PROs) were also assessed. Although recruitment was challenging, completion was 100% in NST and 82% in CST. Adherence was 92% in NST and 81% in CST. Overall, MIVC increased by 19 ± 23%, muscle cross-sectional area improved 18 ± 22%, cycling exercise time improved by 18 ± 13%, and improvements in HRQL and fatigue were clinically relevant. Both interventions were found to be feasible for HNC patients after treatment. Strength training significantly improved maximal muscle strength, muscle cross-sectional area, and PROs after HNC treatment. Future research should include fully powered trials and consider the use of eccentric overloading and NMES during HNC treatment. Eccentric- and NMES-emphasized strength training may be useful alternatives to conventional strength training after HNC treatment.

Current Management of Paediatric Supracondylar Fractures of the Humerus.

Supracondylar fractures of the humerus in children are common and can be distressing injuries to the child, the parents and to the surgical team. Type 1 fractures are managed non-operatively, however displaced fractures (Types 2, 3 and 4) are usually managed surgically. Accurate and repetitive neuromuscular assessment is critical not just for medicolegal reasons but also to expedite management with different specialists if needed. The Rock, paper, scissor, OK technique is simple which is easily understood by most children. We discuss the current evidence with regards to pin diameter, number, pin configuration along with a simple algorithm on how to manage a child with a displaced supracondylar fracture with no pulse focussing mainly on the extension-type fracture.

Neuromuscular function and fatigability in people diagnosed with head and neck cancer before versus after treatment.

Treatment for headand neck canceris associated with multiple side effects, including loss of body mass, impaired physical function andreduced health-relatedquality of life. This study aimed to investigate the impact of treatment (radiation therapy ± concurrent chemotherapy) on (i) muscle strength, muscle cross-sectional area and patient-reported outcomes, and (ii) central and peripheral alterations during a whole-body exercise task. Ten people with head and neck cancer (4 female; 50 ± 9years) completed a lab visit before and after (56 ± 30days) completion of treatment. Participants performed a neuromuscular assessment (involving maximal isometric voluntary contractions in the knee extensorsandelectrical stimulation of the femoral nerve)before and duringintermittent cycling to volitional exhaustion. Anthropometrics and patient-reported outcomes were also assessed. From before to after treatment, maximal isometric muscle strength was reduced (P = 0.002, d = 0.73), as was potentiated twitch force (P < 0.001, d = 0.62), and muscle cross-sectional area (e.g., vastus lateralis: P = 0.010, d = 0.64). Exercise time was reduced (P = 0.008, d = 0.62) and peripheral processes contributed to a reduction in maximal force due to cycling. After treatment, the severity of self-reported fatigue increased (P = 0.041, r = - 0.65) and health-related quality of life decreased (P = 0.012, r = - 0.79). Neuromuscular function was impaired in patients with head and neck cancer after treatment. Whole-body exercise tolerance was reduced and resulted in predominantly peripheral, rather than central, disturbances to the neuromuscular system. Future research should evaluate strength training after treatment for head and neck cancer, with the overall aim of reducing fatigue and improving health-related quality of life.

Assessment of Quadriceps Contraction Using a Novel Surface Mechanomyography Sensor During a Neuromuscular Control Screening Task

PURPOSENeuromuscular control is an important factor for injury incidence and post‐surgical rehabilitation. Surface Mechanomyography (sMMG) sensors are novel wearable devices that are applied over a muscle group to measure the physical output of muscle deformation resulting from a muscle contraction. Electromyography (EMG) is the clinical standard for assessing the electrical signal identifying muscle activation. However, well‐established data collection and analysis challenges limit the utility of EMG for wide‐spread neuromuscular control screening in a clinic environment. The purpose of this study was to investigate the ability of sMMG sensors to detect timing patterns of muscle contraction and compare time events to those collected through traditional clinical EMG during a bilateral squat task.METHODSEleven healthy, active individuals (mean age= 30.0 ± 10.77 y, 7 males, 4 females) underwent a neuromuscular control assessment with EMG and sMMG sensors simultaneously applied to the right quadriceps. Subjects performed a series of 3 bilateral deep squats. EMG data processed with a low‐pass 6th order Butterworth filter and a TKEO function, and raw sMMG data were used for timing analyses. Statistical analyses included paired T‐test assessments between measurement modalities.RESULTSThere was no significant difference in the timing of total duration of quadriceps contraction between EMG (mean= 2.526 ± 0.553 s) and sMMG (mean= 2.527 ± 0.539 s), p= 0.985. The duration of quadriceps contraction during the descent phase of the squat (eccentric contraction, p= 0.773) and the ascent phase (concentric contraction, p= 0.298) did not differ significantly between modalities.CONCLUSIONSResults are consistent with physiologic expectations that myoelectrical activity (measured by EMG) and the physical muscle deformation of muscles (measured by sMMG) occur in extremely rapid succession. Successful sMMG detection of quadriceps contraction is supported by similarity to EMG time signatures. Findings also suggest the ability of sMMG sensors to detect timing of activation for different types of muscle contraction during a functional exercise without the need for complex signal processing (Figure 1). The sMMG sensor may be helpful for assessing quadriceps muscle performance and timing as part of quick, in‐the‐clinic neuromuscular control screenings for injury prevention, rehabilitation, and exercise training.Example of data analysis steps for comparison between electromyography (EMG) and surface mechanography (sMMG) timing during a bilateral squat taskFigure 1

Automated assessment of alcohol-induced impairment of balance in male and female social drinkers.

The acute administration of alcohol reliably impairs the ability to balance when standing. The standardized field sobriety test uses alcohol-induced impairment of body stability to indicate probable alcohol intoxication. Given that body sway is used in the detection of alcohol impairment and intoxication, it is surprising that little research with humans has incorporated new technology that provides automated neuromuscular control assessment. Therefore, the purpose of this study was to examine the dose response to the acute effects of alcohol below and at the legal limit for driving in the United States on balance impairments, as measured by the Biosway Portable Balance System (Biodex Medical Systems, Inc.). Fourteen social drinkers attended 3 separate sessions during which they received alcohol (0.0, 0.3, and 0.6 g/kg alcohol). Body sway with eyes open and eyes closed was assessed at 45 min after dose administration when breath alcohol concentration was peaking for both active alcohol doses (.04g% and .08g%). The results indicated that body sway was significantly increased in the 0.6 g/kg alcohol conditions when compared with the placebo and 0.3 g/kg alcohol conditions. Body sway was not significantly elevated in the 0.3 g/kg alcohol condition compared with placebo. The results from this study suggest that this new technology may be of interest to alcohol researchers and the police as a more precise assessment of balance. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Relationship of Surface Mechanomyography to Force Production in an Assessment of Gastrocnemius Muscle Contraction

PURPOSEEfficient gastrocnemii force production is essential for performance of functional activities such as stair ascent/descent and athletic activities involving jumping or running. Appropriate neuromuscular control and timing of gastrocnemius contraction is also important for fatigue and injury prevention. Hand Held Dynamometry (HHD) is the clinical standard for assessing force production during a muscle contraction. However, HHD is unable to provide precise timing data on the muscle activation responsible for force generation or monitor fatigue during an activity. Surface mechanomyography (sMMG) sensors are novel wearable devices that can be applied across a muscle group to provide a measurement of physical muscle output during a contraction. The purpose of this study is 1) to assess the relationship of sMMG’s muscle bulk displacement measurement to force generation and 2) to confirm sMMG detection of gastrocnemius contraction compared to the clinical timing standard of electromyography (EMG).METHODSHealthy, athletic individuals (mean age= 32.56 ±10.57 y, n= 9, 7 males, 2 females) underwent a neuromuscular control assessment of the gastrocnemius. Subjects performed a series of 3 resisted “make‐test” isometric holds with the right leg supported on an exam table and the ankle plantar flexed at 90 degrees against a hand‐held dynamometer with simultaneous EMG and sMMG recording. The third trial was selected for analysis when available. EMG data was processed with a 6th order low‐pass Butterworth filter and a Teager‐Kaiser energy operator function. A threshold for detecting the time points of gastrocnemius activation and deactivation was set at 3 standard deviations of a resting calibration trial above the minimum value for each measurement modality. The relationship of sMMG signal output for physical muscle displacement was compared to muscle contraction force output via HHD and timing measured via EMG using paired T‐tests and a Pearson correlation.RESULTSPeak gastrocnemius muscle bulk displacement detected by sMMG (mean= 7.65 ±2.68 mm) positively correlated with maximum force generation detected by HHD during isometric contraction (mean= 58.43 ±13.12 lb), r2= 0.669. The duration of gastrocnemius muscle contraction during the isometric hold activity did not differ significantly between SMG (mean= 4.71 ±1.17 s) and EMG (mean= 4.53 ±1.17 s), p= 0.273.CONCLUSIONSCorrelation between HHD and sMMG support the findings that increased physical muscle bulk displacement of the gastrocnemius was associated with greater force production during a contraction. The similarity to EMG timing reinforces the ability of the sMMG sensor to consistently detect active gastrocnemius contraction without complex signal processing (Figure 1). sMMG sensors may be a useful measurement tool for assessment of gastrocnemius functional performance during neuromuscular control screenings for injury prevention and rehabilitation.Example comparison of signal output during a resisted isometric gastrocnemius hold between a hand‐held dynamometer [HHD, (A)], surface mechanomyography [sMMG, (B)], and electromyography [EMG, (C)]. Greenand redXs indicate calculated muscle activation and deactivation time points based on 3 standard deviations of a resting calibration trial above the minimum for each modality (Solonik et al., 2010).Figure 1

Neuromuscular predictors of competition performance in advanced international female weightlifters: a cross-sectional and longitudinal analysis

ABSTRACTThe aim of this study was to investigate the physical determinants of weightlifting competition performance based on Isometric Mid-Thigh Pull (IMTP) and Countermovement Jump (CMJ) force-time variables, in a cross-sectional and longitudinal analysis. Ten British advanced international female weightlifters’ competition results and neuromuscular assessment data collected as part of the British Weight Lifting World Class Programme were utilised for the purpose of this study. All data were averaged for two consecutive 1-year periods. The cross-sectional analysis utilised the second year of data, whereas the longitudinal analysis assessed the mean change between the two years. The cross-sectional analysis results reveal IMTP Net Isometric Peak Force (PF) and CMJ Peak Power (PP) predict 94.2%, 95.1% and 91.8% of the variance in Total, Snatch and Clean & Jerk competition performance, respectively (p = <0.5). The longitudinal analysis results revealed that ∆IMTP PF was the only predicting factor of longitudinal change in weightlifting competition performance predicting 41.5%, 41.7% and 42.5% of ∆Total, ∆Snatch and ∆Clean & Jerk, respectively (p = <0.5). The assessments and equations may be utilised by coaches or sports scientists to inform the prescription of training and help predict competition performance.

Impact of Different Stimulation Patterns of Neuromuscular Blockade Monitoring and Clinical Assessment on Intubation Time and Intensity of Hemodynamic Response During Rocuronium Induced Endotracheal Intubation

Introduction and aims: Typical autonomic response to endotracheal intubation manifests itself by increasing blood pressure and heart rate. The aim of this study as to evaluate whether different stimulation patterns of neuromuscular blockade monitoring techniques may impact hemodynamic response. Materials and Methods: Randomized, prospective, double blind study involved 60 patients who underwent elective abdominal surgery. Patients were randomly allocated into 3 groups. Anesthesia was induced with propofol-remifentanil and acceleromyography at adductor pollicis was established before rocuronium (0.6 mg/kg) was given to facilitate endotracheal intubation. Endotracheal intubation was initiated after 95% suppression of 0.1 Hz single twitch (ST group), complete disappearance of responses to train-of-four stimulation (TOF group) or after clinical criteria (good relaxation of the masseter muscle and the lower jaw, easy mask ventilation and the fact that 60 secs had elapsed since rocuronium was administered) were met (control-CL group). Blood pressure and heart rate were measured in five time points: after positioning the patient (HDbas), 30 s after propofol-remifentanyl (HD1), 30 s after rocuronium (HD2), 30 s (HD3) and 2 minutes following initiation (HD4) of endotracheal intubation. Results: The interval between administration of rocuronium and initiation of endotracheal intubation was significantly shorter in CL group (66.5 s), compared to TOF group (75.44 s) and ST group (83.75 s), (p &lt; 0.001). There was statistically significant difference in systolic blood pressure at HD3 and HD4 time point between groups (p &lt; 0.01). Post hoc analysis shows that these values of systolic blood pressure in CL group were significantly higher compared to the other two groups (p &lt; 0.05). Also, systolic blood pressure after the fourth and fifth measurements were significantly higher compared to initial three measurements in CL group (p &lt; 0.01). By comparing the heart rate at HD3and HD4 time points, significant difference between the groups was noted (p &lt; 0.01). At HD3 time heart rate was significantly higher in CL group compared to other groups (p &lt; 0.01). Additionally, at HD4 heart rate was significantly higher in CL group than in TOF group (p &lt; 0.05) and ST group (p &lt; 0.01). Also, heart rate was significantly increased at HD3 time point. Conclusion: Even though objective NMB monitoring prolongs intubating time, its use prevents vacillation of the hemodynamic response associated with endotracheal intubation.

Creatine supplementation improves performance above critical power but does not influence the magnitude of neuromuscular fatigue at task failure.

What is the central question of this study? Does the magnitude of neuromuscular fatigue depend on the amount of work done (W') at task failure when cycling above critical power (CP)? What is the main finding and its importance? Creatine supplementation increases W' and enhances supra-CP performance, but induces similar magnitudes of neuromuscular fatigue at task failure compared to placebo. Increased W' does not lead to higher levels of neuromuscular fatigue. This supports the notion of a critical level of neuromuscular fatigue at task failure and challenges a direct causative link between W' depletion and neuromuscular fatigue. The present study examined the effect of creatine supplementation on neuromuscular fatigue and exercise tolerance when cycling above critical power (CP). Eleven males performed an incremental cycling test with four to five constant-load trials to task failure (TTF) to obtain asymptote (CP) and curvature constant (W') of the power-duration relationship, followed by three constant-load supra-CP trials: (1) one TTF following placebo supplementation (PLA); (2) one TTF following creatine supplementation (CRE); and (3) one trial of equal duration to PLA following creatine supplementation (ISO). Neuromuscular assessment of the right knee extensors was performed pre- and post-exercise to measure maximal voluntary contraction (MVC), twitch forces evoked by single (Qpot ) and paired high- (PS100) and low- (PS10) frequency stimulations and voluntary activation. Creatine supplementation increased TTF in CRE vs. PLA by ∼11% (P=0.017) and work done above CP by ∼10% (P=0.015), with no difference (P>0.05) in reductions in MVC (-24±8%vs. -20±9%), Qpot (-39±13%vs. -32±14%), PS10 (-42±14%vs. -36±13%), PS100 (-25±10%vs. -18±12%) and voluntary activation (-7±8%vs. -5±7%). No significant difference was found between ISO and either PLA or CRE (P>0.05). These findings suggest similar levels of neuromuscular fatigue can be found following supra-CP cycling despite increases in performance time and amount of work done above CP, supporting the notion of a critical level of neuromuscular fatigue and challenging a direct causative link between W' depletion and neuromuscular fatigue.

Exercise-Induced Fatigue in One Leg Does Not Impair the Neuromuscular Performance in the Contralateral Leg but Improves the Excitability of the Ipsilateral Corticospinal Pathway.

To investigate the influence of pre-induced fatigue in one leg on neuromuscular performance and corticospinal responses of the contralateral homologous muscles, three experiments were conducted with different exercise protocols; A (n = 12): a 60 s rest vs. time-matched sustained left leg knee extension maximum voluntary contraction (MVC), B (n = 12): a 60 s rest vs. time-matched left leg MVC immediately followed by 60 s right leg MVC, and C (n = 9): a similar protocol to experiment B, but with blood flow occluded in the left leg while the right leg was performing the 60 s MVC. The neuromuscular assessment included 5 s knee extensions at 100%, 75%, and 50% of MVC. At each force level, transcranial magnetic and peripheral nerve stimuli were elicited to investigate the influence of different protocols on the right (tested) knee extensors’ maximal force output, voluntary activation, corticospinal excitability, and inhibition. The pre-induced fatigue in the left leg did not alter the performance nor the neuromuscular responses recorded from the right leg in the three experiments (all p > 0.3). However, enhanced corticospinal pathway excitability was evident in the tested knee extensors (p = 0.002). These results suggest that the pre-induced fatigue and muscle ischemia in one leg did not compromise the central and peripheral components of the neuromuscular function in the tested contralateral leg.