Le monitorage de la transmission neuromusculaire consiste à évaluer la contraction d’un muscle en réponse à des trains d’impulsions électriques délivrés sur son nerf moteur. Le curare ayant pour effet de bloquer la communication entre le nerf et le muscle, les réponses musculaires seront maximales avant injection de la drogue et s’atténueront au fur et à mesure du blocage neuromusculaire, jusqu’à atteindre une paralysie complète. Au regard des principales limitations des moniteurs de curare actuels et des avantages qu'apporte le monitoring sur une variété de muscles, le monitorage par EMG semble être la meilleure alternative. Ce sont essentiellement les insuffisances dans la détection et la gestion des artefacts et des perturbations électriques qui rendent les moniteurs EMG actuels insuffisamment fiables et mal adaptés à l’usage clinique. L'objectif de ce travail est dès lors d'identifier les causes de perturabations et apporter les remèdes nécessaires pour faire de l'EMG une méthode de confiance à la fois pour la recherche et la pratique quotidienne.

The analysis of electromyographic (EMG) signals detected during muscle contraction provides important information to aid in the diagnosis and characterization of neuromuscular disorders. One important analysis measures neuromuscular jitter, which is the variability of the time intervals between two muscle fibre potentials (MFPs) belonging to the same motor unit over a set of discharges. Conventionally, neuromuscular jitter is measured using single fibre (SF) EMG techniques, which can identify individual MFPs by using a SF needle electrode. However, SF electrodes are expensive, very sensitive to needle movement and not easy to operate in practise. <br /><br /> A method is studied in this thesis for automatically measuring neuromuscular jitter in motor unit potentials (MUP), it measures jitter using routine EMG techniques, which detect MUPs using a concentric needle (CN) electrode. The method is based on the detection of near MFP contributions, which correspond to individual muscle fibre contributions to MUPs, and the identification of individual MFP pairs. The method was evaluated using simulated EMG data. After an EMG signal is decomposed into MUP trains, a second-order differentiator, McGill filter, is applied to detect near MFP contributions to MUPs. Then, using nearest neighbour clustering and minimum spanning tree algorithms, the sets of available filtered MUPs can be selected and individual MFPs can be identified according to the features of their shapes. Finally, individual MFP pairs are selected and neuromuscular jitter is measured. <br /><br /> Using the McGill filter, near MFP contributions to detected CN MUPs can be consistently detected across an ensemble of successive firings of a motor unit. The method is an extension of the work Sheng Ma, compared to previous works, more efficient algorithms are used which have demonstrated acceptable performance, and which can consistently measure neuromuscular jitter in a variety of EMG signals.

The Strain Index was originally designed to analyze mono-task jobs. An experiment using a grip dynamometer was used to simulate six multiple task jobs to study the effect of complex tasks on localized muscle fatigue and to evaluate six different models used to calcula te a Complex Strain Index score. These models included average Strain Index score, unadjusted summation, duration adjusted summation, complex equation, minimum intensity, and peak intensity. Two methods of calculating a continuous Strain Index score were also analyzed. Ratings of perceived exertion, hand and forearm fatigue and discomfort, Difficulty Rating, maximum voluntary contraction (MVC), and percent strength loss were recorded for each of the six treatments. Electromyography (EMG) was also recorded for the 24 subjects (12 males and females) who completed the experiment. The EMG signal was analyzed using root mean square (RMS), initial mean power frequency (IMnPF), and slope of the mean power frequency (MnPF). Each treatment, lasting one hour each, contained a primary exertion (Task 1) of either 10% or 40% MVC for three seconds and a secondary exertion (Task 2) of either 10% or 40% MVC for one or three seconds. Subjective variables linearly increased (R2 > 0.88) over the duration of the treatments and significantly differed between treatments (p < 0.05). Percent strength loss was the only variable with a gender effect (p < 0.05). RMS values did not indicate fatigue and were constant over each treatment, but were highly correlated with percent MVC. A significant difference was not found in IMnPF between pre and post treatment values or between treatments (p > 0.05). A significant difference was found for MnPF slope pre and post treatment, but no treatment effect was found (p > 0.05). The complex equation method of calculating a Strain Index score was the only model of the six evaluated that met all criteria for being an acceptable method of calculating a Complex Strain Index score. The two continuous methods presented for calculating a Strain Index score should not be used for job analysis until further research evaluates their reliability, validity, and critical scores for Hazard Classification.

Background. The bench press is a commonly used resistance training exercise for targeting the chest musculature. During hypertrophy training, different variations of bench press are often used to isolate different segments (pars clavicularis, pars sternocostalis and pars abdominals) of the chest muscle m.pectoralis major. Commonly used variations of the bench press are decline bench press (less than 0° from horizontal) and incline bench press (more than  0° from horizontal). Some research has been done into these variations of bench angle and their effect on muscle activation; however other commonly used bench angles is yet to be investigated. Aim. The aim of this study was to examine if there were any difference in muscle activity in the three segments of m.pectoralis majors while performing three different barbell bench press variations with different bench angles to obtain a greater understanding of m.pectoralis major activation and possibly optimize hypertrophy training in above mentioned muscles segments.  Method. 13 healthy male (age: 23± 3.8 year and BMI: 24.3 ±1.8 kg/m2) participated in this single group study. EMG was used to measure muscle activity in m.pectoralis major's three segments. Test subjects performed 1 set of 6 repetitions on each bench press variation at a relative load of 6RM. An maximal voluntary isometric contraction (MVIC) test was performed and set as 100 percent reference value for comparison muscle activity in various angles. Results. While performing the decline bench press and the incline bench press, the muscle activity in pars clavicularis displayed a strong trend of a lower muscle activity (decline: p= 0.055 and incline: p=0.052) in comparison to the flat bench press. Muscle activity in pars sternocostalis while performing the incline bench press was significantly lower in comparison to the flat bench press (flat: p&lt;0.001 and decline: p&lt;0.001). Muscle activity in pars abdominals while performing the decline bench press was significantly higher (p=0.013) in comparison to the flat bench press. Muscle activity in pars abdominals while performing the incline bench press were significantly lower than both the flat and decline bench press (incline: p&lt;0.001 and decline: p&lt;0.001). Conclusion. For a better isolation of the pars abdominals segment, the decline bench press should be used. Muscle activity in pars sternocostalis did not show any significant difference between flat and decline bench press and could be isolated with either of these two exercises.  The muscle activity in pars clavicularis showed a strong trend of higher activity while performing the flat bench press compared to the decline and incline bench press, however findings regarding the pars clavicularis differs between studies.

To get the maximal output of your exercise in gym machines, there are different factors to be considered. For example the strength of the muscle varies dependent on the position of the muscles. To get the best results of the exercise the load has to reduce and increase at specific positions. This study was made in cooperation with Caretaker Scandinavia AB, a company for sales, marketing and development in health care. They are general agent for Nordic Gym who works with manufacturing of equipment and machines for gym and fitness. The aim of this study was to generate a method of measurement to evaluate and control the biomechanics of Nordic Gym´s workout equipment. A protocol for an ergonomic analysis on the equipment has also been elaborated. One of the methods to measure the biomechanics was to measure the torque through the whole movement. The other method was electromyography (EMG). The EMGequipment registers electric signals that are generated in a working muscle, and makes it possible to see when the maximum muscle activity achieves. The results of those measurements will be compared to the muscles strengthprofile which describes how the muscle generates power in different positions throughout the movement. To measure the ergonomics an ergonomic protocol where produced, which was based on ergonomics aspect, adapted to gym machines. The method of measurement where tested on Nordic Gym´s training machine 101SE leg extension and Free Motion´s machine Leg Extension GZF18013 and this machines where controlled and evaluated. Two test persons tried out the machines and the machines where analysed in an ergonomic and a biomechanical perspective. The result shows that the biomechanics of Nordic Gym´s machine where a bit better than the biomechanics of FreeMotion´s machine. But in the both case the difference between the values of torque is marginal, to improve the biomechanics insistence a bigger different should be necessary to use. The ergonomic analyse of the machines showed that the ergonomics where good and well planed. Both machines had some small ergonomic lacks, which can be improved.

The Ergonomics Research Group at Queen’s University, supported by the Workplace and Safety Insurance Board, has been developing an on-line system to estimate peak and cumulative joint loading in the workplace. This study will aid the project by examining the muscle activation levels (MALs) in upper extremity and trunk muscles during a manual lifting task using both hands. It was hypothesized that MAL’s are correlated with the magnitude of the load in the hands and thus could be used to predict the load which in turn will be used to predict the lower back moments. Alterations in the muscle activation patterns due to lifting different loads were examined. Electromyographic signals (EMG) and kinematic data were recorded from different sites on the trunk and upper limb as subjects lifted a load from the floor to a shelf using squat, stoop and freestyle lift techniques. All raw EMG data were processed to obtain the linear envelopes (LE) which provides estimates of the MAL’s. The peak, mean and area of the linear envelopes were calculated. Using regression analysis, a relationship between the parameters and load lifted was found to exist. A non-linear parallel cascade type architecture was used to develop a model to predict the load in the hands. The model uses the EMG parameters as inputs and fits the data via linear and non-linear cascades to the output, i.e. the load in the hands. A model was successfully developed for the squat lift posture using the area, peak and mean of the zero-normalized EMG LE recorded from the erector spinae (L4 level), with a prediction error of ± 1.03kg and for the stoop posture, a prediction error of ± 2.34kg. Given the predicted loads, moments in the lower back were computed using the method of Hof (1992). / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2007-09-28 16:15:23.077

The purpose of this study was to investigate the reliability of three different electromyography (EMG) detection systems commonly used to acquire EMG data from the pelvic floor muscles (PFM) at rest, during maximum voluntary contractions (MVCs) and during a coughing task. Twelve nulliparous women between the ages of 24 and 40 participated in the study. EMG data were recorded from each side of the pelvic floor using surface (Femiscan™ and Periform™ vaginal probes), and fine-wire electrodes while subjects performed three repetitions of each task in supine and in standing. RMS amplitudes of baseline and peak PFM activity were computed from the data acquired during the MVC and the coughing tasks. The peak RMS amplitudes from the cough data were also normalized to each subject’s MVC and report as a percent of their maximum voluntary electrical activation (% MVE). Signal to noise ratio (SNR) was calculated for each task. Comparisons were made between the RMS amplitudes and SNR recorded from each side of the PFM. Between-trial and between-day reliability was determined using a variety of measures including intraclass correlation coefficients (ICC), coefficients of variation (CV) and mean absolute difference (MAD). The reliability of the different devices was compared using the MAD normalized to average signal amplitude (nMAD). The results indicated that the EMG data recorded from the right and left sides of the PFM were different, therefore the EMG data acquired from each side of the pelvic floor were analyzed separately. Between-trial reliability assessed by ICC was good for all the devices (left and right average ICC(3,1) = 0.80 – 0.96); the CVs supported these findings (average CV = 12.4 – 17.1%) Between-day reliability was poor and inconsistent across all devices as tasks. When the cough data were normalized however, the between-day RMS amplitudes were very consistent (79.5 – 90.2% MVE). Each device recorded consistent activation amplitudes within a given day. Between-day reliability results indicate that EMG data recorded on separate days with these instruments should not be compared unless data can be normalized. Clinicians and researchers are cautioned to normalize their data if day-to-day comparisons in EMG amplitude are to be made using data recorded with these devices. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2007-12-14 17:31:34.552

Monitoring electromyography signals (EMG) leads to a greater understanding of muscle properties hives insight into how muscles work together to coordinate tasks, and yields information about neuromuscular disorders. In this project we developed a PC based EMG data acquisition and analysis system to record and analysis EMG signals. We tested this system by recording EMG signals from the biceps brachii of a single normal subject. The acquired data was analyzed in both time and frequency domains to determine the behavior of the EMG signal during different experiment conditions. Fast Fourier Transform (FFT) and Short Time Fourier Transform (STFT) were applied during digital signal processing. The FFT only provides the information in frequency domain. STFT is a modification of the Fourier transform in an attempt to retain both time and frequency information during signal analysis. The STFT produces a two dimensional function with time and frequency as variables. Thus the STFT gives information about when in time a given frequency component occurs. The extracted features of EMG are RMS value, mean absolute value, mean power frequency, and median power frequency. The raw EMG signal is collected for 10 seconds. The sampling rate is set to 1000 Hz. The emphases of this project were software development, data collection, and simple signal analysis. / Thesis / Master of Engineering (ME)

Title: EMG analysis of the influence of the water environment on walking in the elderly Objectives: The main objective of this master thesis is to determine the degree of activation of selected muscles during walking on land and in water environment by using surface electromyography. The next component objective is to determine and compare dynamic co-contraction level of low extremity muscles during walking on land and in water. Methods: It is a pilot study which was attended by 5 participants. The average age of the research group was 67,2 years and was represented 3 men and 2 women. Activity of m. tibialis anterior, m. gastrocnemius, m. rectus femoris, m. biceps femoris and mm. erectores spinae in the level of ThL transition was recorded during walking on land and in water environment. EMG signal has been adjusted, analyzed and after that normalized EMG signal to MVC was compared in both environments. The records were compared both intraindividually and interindividually. At the end dynamic co-contraction level of selected muscles was evaluated and compared during gait in both environments. Results: Electromyographic analysis revealed that during walking in aquatic environment were analyzed muscles involved with less extent than during walking on land. Co-contraction level was lower in low...

A number of studies have investigated the relationship between surface electromyogram (EMG) and torque exerted about a joint. The standard deviation of the recorded EMG signal is defined as the EMG amplitude. The EMG amplitude estimation technique varies with the study from conventional type of processing (i.e. rectification followed by low pass filtering) to further addition of different noise rejection and signal-to-noise ratio improvement stages. Advanced EMG amplitude processors developed recently that incorporate signal whitening and multiple-channel combination have been shown to significantly improve amplitude estimation. The main contribution of this research is a comparison of the performance of EMG-torque estimators with and without these advanced EMG amplitude processors. The experimental data are taken from fifteen subjects that produced constant-posture, non-fatiguing, force-varying contractions about the elbow while torque and biceps/triceps EMG were recorded. Utilizing system identification techniques, EMG amplitude was related to torque through a zeros-only (finite impulse response, FIR) model. The incorporation of whitening and multiple-channel combination separately reduced EMG-torque errors and their combination provided a cumulative improvement. A 15th-order linear FIR model provided an average estimation error of 6% of maximum voluntary contraction (or 90% of variance accounted for) when EMG amplitudes were obtained using a four-channel, whitened processor. The equivalent single-channel, unwhitened (conventional) processor produced an average error of 8% of maximum voluntary contraction (variance accounted for of 68%). This study also describes the occurrence of spurious peaks in estimated torque when the torque model is created from data with a sampling rate well above the bandwidth of the torque. This problem is anticipated when the torque data are sampled at the same rate as the EMG data. The problem is resolved by decimating the EMG amplitude prior to relating it to joint torque, in this case to an effective sampling rate of 40.96 Hz.