Advances and perspectives of mechanomyography

INTRODUCTION: The evaluation of muscular tissue condition can be accomplished with mechanomyography (MMG), a technique that registers intramuscular mechanical waves produced during a fiber's contraction and stretching that are sensed or interfaced on the skin surface. OBJECTIVE: Considering the scope of MMG measurements and recent advances involving the technique, the goal of this paper is to discuss mechanomyography updates and discuss its applications and potential future applications. METHODS: Forty-three MMG studies were published between the years of 1987 and 2013. RESULTS: MMG sensors are developed with different technologies such as condenser microphones, accelerometers, laser-based instruments, etc. Experimental protocols that are described in scientific publications typically investigated the condition of the vastus lateralis muscle and used sensors built with accelerometers, third and fourth order Butterworth filters, 5-100Hz frequency bandpass, signal analysis using Root Mean Square (RMS) (temporal), Median Frequency (MDF) and Mean Power Frequency (MPF) (spectral) features, with epochs of 1 s. CONCLUSION: Mechanomyographic responses obtained in isometric contractions differ from those observed during dynamic contractions in both passive and functional electrical stimulation evoked movements. In the near future, MMG features applied to biofeedback closed-loop systems will help people with disabilities, such as spinal cord injury or limb amputation because they may improve both neural and myoelectric prosthetic control. Muscular tissue assessment is a new application area enabled by MMG; it can be useful in evaluating the muscular tonus in anesthetic blockade or in pathologies such as myotonic dystrophy, chronic obstructive pulmonary disease, and disorders including dysphagia, myalgia and spastic hypertonia. New research becomes necessary to improve the efficiency of MMG systems and increase their application in rehabilitation, clinical and other health areas304384401CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFINANCIADORA DE ESTUDOS E PROJETOS - FINEPsem informaçã

Evaluación no invasiva de la función muscular respiratoria mediante el análisis de la señal mecanomiográfica en pacientes con enfermedad pulmonar obstructiva crónica

El estudio y evaluación de la función muscular respiratoria en enfermedades respiratorias a través de técnicas no invasivas representa un tema de gran interés, dado que hasta la fecha no existen métodos satisfactorios aplicables en situaciones clínicas. En la enfermedad pulmonar obstructiva crónica (EPOC), el trabajo mecánico de los músculos respiratorios aumenta dando lugar a la fatiga, disminución de los movimientos de la caja torácica, y por tanto una disminución de la eficiencia muscular respiratoria. Es conocido que el músculo diafragma, principal responsable de la actividad mecánica respiratoria, al igual que otros músculos esqueléticos vibra lateralmente durante su contracción. De ahí, que estas vibraciones puedan ser registradas mediante micrófonos, sensores piezoeléctricos o acelerómetros posicionados encima de la pared inferior del pecho en la zona de aposición del diafragma con la caja torácica. El registro de estas vibraciones da lugar a la señal mecanomiográfica del diafragma (MMGdi). El principal objetivo de esta tesis ha sido el estudio y caracterización no invasiva de la función muscular respiratoria en pacientes con EPOC a través de la señal MMGdi registrada mediante acelerómetros posicionados entre el séptimo y octavo espacios intercostales, en la línea axilar izquierda y derecha del cuerpo durante la realización de los protocolos respiratorios de carga incremental progresiva y de flujo incremental progresivo. Para mejorar la estimación de la amplitud de la señal MMGdi se han propuesto tres nuevos índices, que tienen en cuenta la naturaleza aleatoria y el ruido asociado en las señales MMGdi, y están basados en: el algoritmo de Lempel-Ziv (LZM), la entropía aproximada (fApEn), y la entropía muestral (fSampEn). Todos ellos son calculados con intervalos de cuantificación fijos y empleando ventanas móviles. Los resultados obtenidos con éstos índices han permitido estimar con mayor fiabilidad y robustez la amplitud de las señales MMGdi, en relación a los métodos clásicos utilizados en el estudio de señales miográficas. El estudio del valor medio de los parámetros analizados ha mostrado, que existe una tendencia incremental de éste en los parámetros de amplitud, y una tendencia decreciente en los parámetros frecuenciales (frecuencias media y máxima), con el incremento de la carga y/o flujo. En este sentido, se ha observado que el valor medio es mayor cuanto mayor es la severidad del paciente con EPOC. Por otra parte, se ha observado que existe una fuerte correlación entre los parámetros de amplitud y la presión inspiratoria máxima en el protocolo de flujo incremental progresivo, con una tendencia decreciente con la severidad. Del mismo modo la eficiencia muscular respiratoria, evaluada como la relación entre la fuerza que producen los músculos respiratorios (la presión inspiratoria en boca) y lo que gastan o necesitan para producir esta presión (la vibración de los músculos respiratorios evaluada mediante las señales MMGdi), ha mostrado en general una tendencia decreciente con el aumento de la severidad. Finalmente, los resultados que se desprenden de esta tesis indican que el estudio de la señal MMGdi representa una herramienta útil con un gran potencial para evaluar el grado de la severidad presente en sujetos con EPOC y su relación con la debilidad de la musculatura respiratoria, y por tanto su aplicación en estudios clínicos podría ser de gran ayuda para evaluar el desarrollo de la EPOC.The study and evaluation of the respiratory muscles function in people who suffer from respiratory diseases can be evaluated through the use of noninvasive techniques. This is a topic of great interest considering there are currently no existing methods that can be successfully applied in clinical situations. In chronic obstructive pulmonary disease (COPD), the mechanical work of the respiratory muscles increases, which could lead to muscular fatigue, decreased movement of the ribcage, and, therefore, a decrease in the respiratory muscle efficiency. The diaphragm muscle is the principal muscle of inspiration and the main mechanical responsible for the ventilation. Similar to other skeletal muscles the diaphragm laterally vibrates during its contraction. These vibrations can be recorded by microphones, piezoelectric sensors or accelerometers, which are placed above the lower chest wall in the area of apposition of the diaphragm to the ribcage. The record of these vibrations is known as mechanomyographic signal of the diaphragm muscle (MMGdi). The main objective of this thesis has been the study and noninvasive characterization of the respiratory muscles function in patients with COPD. This characterization has been made possible through the use of MMGdi signals recorded by accelerometers placed between the seventh and eighth intercostals spaces on the left and right anterior axillary lines of the body during two respiratory protocols. The first protocol is called progressive incremental load protocol and the second one progressive incremental flow protocol. In this thesis three new indices have been proposed to improve the MMGdi amplitude estimation. These indices take into account the random nature and the associated noise in the MMGdi signals, and are based on the: Lempel-Ziv algorithm (MLZ), approximate entropy (fApEn), and sample entropy (fSampEn). All of them are calculated with fixed quantization intervals and using moving windows. The obtained results with these new indices have shown improved reliability and robustness in the MMGdi amplitude estimation in comparison with classic methods used to study myographic signals. The study of the mean value of the analyzed parameters has shown an increasing trend of the amplitude parameters and a decreasing trend of the frequency parameters (mean and maximum frequencies) with increasing load and/or flow. Furthermore, we found that there was a direct relationship between these mean values and the severity of COPD; hence, the greater the mean value, the greater the severity of COPD. Moreover, we have seen that there is a strong correlation between the amplitude parameters and the maximum inspiratory pressure in the progressive incremental flow protocol with a decreasing trend as the severity of the patients increases. Likewise, the respiratory muscle efficiency, evaluated as the ratio between the force produced by the respiratory muscles (mouth inspiratory pressure) and what they need to produce this pressure (the vibration of respiratory muscles assessed by MMGdi signals), has also shown a generally decreasing trend as the severity of patients increases. Finally, the results of this thesis suggest that the study of the MMGdi signal is a useful tool with great potential to assess the relationship between respiratory muscle weakness and the degree of severity in patients with COPD. Therefore, the application of this innovative tool in clinical studies may be helpful to assess the development of COPD

Detecção de fadiga neuromuscular em pessoas com lesão medular completa utilizando transformada wavelet

Introduction: People with spinal cord injury (SCI) may have the paralyzed muscles activated through functional electrical stimulation (FES) on neural pathways present below the skin. These electrical stimulations are important to restore the neuromuscular trophism or during the movement control using neural prostheses. However, prolonged FES application causes fatigue, which decreases the contraction strength, mainly due the neuromuscular hypotrophy in this population. The acquisition of myofibers’ vibration is recognized by mechanomyography (MMG) system and does not suffer electrical interference from the FES system. Objective: To characterize the rectus femoris muscle vibration during electrically evoked neuromuscular fatigue protocol in complete spinal cord injury subjects. Methods: As sample, 24 limbs (right and left) from 15 male participants (age: 27±5 y.o.) and ranked as A and B according to American Spinal Injury Impairment Scale) were selected. An electrical stimulator operating as voltage source, specially developed for research, was configured as: pulse frequency set to 1 kHz (20% duty cycle) and burst (modulating) frequency set to 70 Hz (20% active period). The triaxial [X (transverse), Y (longitudinal) and Z (perpendicular)] MMG signal of rectus femoris muscle was processed with a third-order 5-50 Hz bandpass Butterworth filter. A load cell was used to register the force. The stimulator output voltage was increased (~3 V/s to avoid motoneuron adaptation/habituation) until the maximal electrically-evoked extension (MEEE) of the knee joint. After the load cell placement, the stimuli magnitude required to reach MEEE was applied and registered by the load cell as muscular F100% response. Stimuli intensity was increased during the control to keep the force in F100%. Four instants (I - IV) were selected from F100% up to the inability to keep the FES response force above 30% (F30%). The signal was processed in temporal (energy), spectral (median frequency) and wavelet (temporal-spectral with twelve band frequencies between 5 and 53 Hz) domains. All data were normalized by initial instant, creating arbitrary units (a.u.), and non-parametric tests were applied. Results: The median frequency did not show statistical significance. Regarding the MMG axes, the transverse axis showed most statistical differences. The MMG energy (temporal domain) indicates the decrease between the instants I (unfatigued) and II (pre-fatigue), as well as instants I and IV (fatigued). The wavelet domain focused on the transverse axis, especially on 13, 16, 20, 25 and 35 Hz frequency bands, for having shown significant reduction proven during neuromuscular fatigue. In focus on 25 Hz band frequency that showed a constant decrease between instants I (median value from data de 0.53 a.u.) with subsequent instants [II (0.30 a.u.), III (0.28 a.u.) and IV (0.24 a.u.). Conclusion: Neuromuscular fatigue is characterized by energy decrease in MMG X-axis (transverse) signal of vibration on the rectus femoris muscle for complete spinal cord injured subjects, in the temporal domain but mainly in the wavelet domain. The 25 Hz is the most important band frequency because its energy decreases with neuromuscular fatigue. These findings open the possibility of application in closed-loop systems during physical rehabilitation procedures using FES or in the control of neural prostheses.CNPqIntrodução: As pessoas com lesão medular (LM) podem ter seus músculos paralisados ativados por meio da estimulação elétrica funcional (FES) sobre vias neurais presentes próximas à pele. Estas estimulações elétricas são importantes para a recuperação do trofismo neuromuscular ou durante o controle de movimento por próteses neurais. No entanto, ao longo da aplicação da FES, a fadiga ocorre, diminuindo a eficiência da contração, principalmente devido à hipotrofia neuromuscular presente nessa população. A aquisição da vibração das fibras musculares como indicador de fadiga é registrada por meio da técnica de mecanomiografia (MMG), que não sofre interferências elétricas decorrentes da aplicação da FES. Objetivo: Caracterizar a vibração do músculo reto femoral durante protocolo de fadiga neuromuscular eletricamente evocada em pessoas com lesão medular completa. Método: 24 membros (direito e esquerdo) de 15 participantes (idade: 27±5 anos) do sexo masculino (A e B na American Spinal Injury Impairment Scale) foram selecionados. Um estimulador elétrico operando como fonte de tensão, desenvolvido especialmente para pesquisa, foi configurado com: freqüência de pulso em 1 kHz (20% de ciclo de trabalho) e trem de pulsos (modulação) em 70 Hz (20% período ativo). O sinal triaxial [X (transversal), Y (longitudinal) e Z (perpendicular)] da MMG foi processado com filtro Butterworth de terceira ordem e banda passante entre 5 e 50 Hz. Previamente ao protocolo, a tensão de saída do estimulador foi incrementada (~3 V/s evitando-se a adaptação/habituação dos motoneurônios) até alcançar a extensão máxima eletricamente estimulada (EMEE) da articulação do joelho. Uma célula de carga foi usada para registrar a resposta de força, onde após a sua colocação, a intensidade da FES necessária para alcançar a EMEE foi aplicada e registrada pela célula de carga como 100% da força (F100%). Durante o protocolo de fadiga neuromuscular, a intensidade do estímulo foi incrementada durante o controle para manter a força em F100%. Quatro instantes (I - IV) foram selecionados entre F100% e a incapacidade da FES manter a resposta de força acima de 30% (F30%). O sinal foi processado nos domínios temporal (energia), espectral (frequência mediana) e wavelet (temporal-espectral com doze bandas de frequência entre 5 e 53 Hz). Os dados extraídos foram normalizados pelo instante inicial (I) gerando unidades arbitrárias (u.a.), e testados com estatística não paramétrica. Resultados: A frequência mediana não apresentou significância estatística. Em relação aos eixos de deslocamento da MMG, o eixo transversal mostrou o maior número de resultados estatisticamente significantivos. A energia da vibração das fibras musculares (domínio temporal) indicou diminuição entre os instantes I (músculo fresco) e II (pré-fadiga), como também entre os instantes I e IV (fadigado) com redução significativa. O domínio wavelet teve como foco o eixo transversal, especialmente as bandas de frequência de 13, 16, 20, 25 e 35 Hz, por terem indicado redução significativa durante a fadiga neuromuscular; principalmente, a banda de 25 Hz, que indicou redução significativa entre o instante I (valor da mediana dos dados de 0,53 u.a.) e os demais instantes [II (0,30 u.a), III (0,28 u.a.) e IV (0,24 u.a.)]. Conclusão: A fadiga neuromuscular é caracterizada pela redução da energia do sinal no eixo de deslocamento transversal (X) da vibração do músculo reto femoral, em pessoas com lesão medular completa, tanto no domínio temporal quanto principalmente no domínio wavelet, sendo a banda de frequência de 25 Hz a mais relevante, porque sua energia diminui com a ocorrência da fadiga neuromuscular. Estes achados abrem a possibilidade de aplicação em sistemas de malha fechada durante procedimentos de reabilitação física utilizando FES ou no controle de próteses neurais

Computational Intelligence in Electromyography Analysis

Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG may be used clinically for the diagnosis of neuromuscular problems and for assessing biomechanical and motor control deficits and other functional disorders. Furthermore, it can be used as a control signal for interfacing with orthotic and/or prosthetic devices or other rehabilitation assists. This book presents an updated overview of signal processing applications and recent developments in EMG from a number of diverse aspects and various applications in clinical and experimental research. It will provide readers with a detailed introduction to EMG signal processing techniques and applications, while presenting several new results and explanation of existing algorithms. This book is organized into 18 chapters, covering the current theoretical and practical approaches of EMG research

Fatigue at the Workplace: Measurement and Temporal Development

Fatigue at the workplace has been described as a multidimensional construct, affecting the overall state of the whole organism, which may be a consequence of prolonged work and various psychological, socioeconomic, and environmental factors. In the short term, fatigue may lead to discomfort, diminished motor control, reduced proprioception, increased force variability, and reduced strength capability, resulting in reduced performance, lowered productivity, deficits in work quality, and increased incidence of accidents and human errors. Fatigue may also lead to longer-term adverse health outcomes such as chronic fatigue syndrome, myalgia, and burnout syndromes, and may be a precursor to WMSDs – work-related musculoskeletal disorders. If indeed fatigue is a precursor to WMSDs and other long-term health outcomes, it may then be a relevant biomarker for cumulative exposure to repetitive and/or sustained work, and thus a useful risk indicator and/or a design and evaluation tool. However, little is known of the temporal pattern of fatigue development and its relationships with disorder risks and work performance. The objective of this thesis was to identify and evaluate a battery of fatigue measures for both laboratory and field-based research, and provide insight into fatigue development in work-relevant task conditions. Six studies were designed to address these objectives. In the first study, measures and analysis methods that detect fatigue-related changes were identified by a group of expert fatigue researchers. The second was an exploratory study focused on the responsiveness of a select number of measures during a workday and multiple workdays in realistic physically demanding residential plumbing work. In the third study, a selected number of conventional and novel measures were evaluated for their reliability and sensitivity in a controlled laboratory setting. This study also addressed the responsiveness of measures during a test battery or during the fatiguing activity (i.e., continuously), and the time between cessation of activity and test battery in which measures remain responsive. The fourth study reported on whether circadian effects were detectable by selected measures, providing insight towards the daylong reliability of these measures. In the fifth study, measures were evaluated in four fatiguing conditions, representing changes in type of contraction, intensity, and body segment. Furthermore, the pattern of fatigue development and the temporal responsiveness of measures were described. Finally, measures were assessed over an 8-hour light precision micropipetting task to investigate temporal responsiveness of measures and fatigue development. Errors were quantified and the effects of scheduled work breaks were reported. In study 1, fifty-seven measures were identified based on outcomes and/or effects of fatigue in the workplace. Based on the perceived validity, reliability, and practicality in laboratory and field investigations, four measures were recommended for both settings: maximum voluntary contractions, questionnaires and fatigue scales, Borg’s rating of perceived exercise or discomfort, and visual analog scales. On the other hand, twenty-five measures were not recommended for field studies, including methods traditionally recognized as “gold standard” in measuring cellular and metabolic changes. In study 2, fatigue was documented in realistic physically demanding work while employing a set of measures to provide a comprehensive picture of fatigue development. Not all measures revealed increasing fatigue over the workday or over the workweek, which may be a result of measures reflecting different fatigue processes. Thus, the study reinforced the need of a complementary set of measures, reflecting multiple domains, to measure and interpret the temporal development of fatigue. Two measures, rating of perceived discomfort and grip strength, indicated significant differences within a work day, notably an increase at the beginning and end of the shift (perceived discomfort) and a decrease between mid-shift and end of shift (grip strength). It was speculated that within-day trends were consistent with central fatigue mechanisms. Over multiple workdays, both central and peripheral components displayed a significant day effect. Fatigue accumulation over the workweek was observed with grip strength, physiological resting tremor, and postural tremor measures, particularly between day 1 (Tuesday) and day 4 (Friday). In study 3, test-retest reliability ranged between “poor agreement” and “almost perfect agreement”. In terms of sensitivity, action tremor, MMG RMS amplitude, postural tremor, and rating of perceived fatigue were highly responsive. Perceived fatigue remained elevated, relative to baseline, until 11 minutes post-exercise. Postural and physiological tremor persisted from baseline until the third minute of recovery. Action tremor, however, quickly recovered within the first minute of recovery. This current study found that for most of the measures, there were no statistical differences between test battery and continuous measurement, but a few measures were approaching statistical significance. Action tremor and mechanomyography collected during a test contraction, and perceived fatigue assessed by a visual analog scale, were found to be most reliable, most responsive, comparable to continuous measures, and sensitive after the fatiguing activity, and should be considered with other measures of interest, as part of a test battery. In study 4, only two measures revealed a statistically significant time-of-day effect: mechanomyography of a flexor forearm muscle and action tremor at 30% MVC. These two measures exhibited rhythmicity based on cosinor analysis. Therefore a degree of caution might be required when interpreting daylong fatigue with these two measures, whereas the other measures may not be susceptible to, or detect, significant diurnal effects. Although the remaining measures did not reveal statistically significant time effects, most measures were characterized with similar patterns to those found in previous literature. In study 5, there was no one universal measure that was common, in terms of responsiveness, in all exercise conditions. Although no single measure was found to be most responsive in all conditions, there were measures responsive in most exercise conditions as either a continuous or test battery measure. This was the case with action tremor. A maximum voluntary contraction, which is dependent on processes in both central and peripheral domains, was similarly responsive. Rating of perceived fatigue, which has been cited as a centrally mediated indicator, was also found to increase with exercise progression in hand conditions. Therefore fatigue measures, reflecting changes to both central and peripheral processes, may be useful in measuring tasks and exercises of varying parameters. In this study, we support earlier investigations on the pattern of fatigue development in isometric and time-varying (e.g., intermittent isometric, concentric) contractions. The temporal responsiveness of central and peripheral measures, on the other hand, may be a better reflection of the intensity of the task. The shoulder intermittent condition was not consistent with the expected pattern for an intermittent isometric contraction. However, the study protocol may have inadvertently generated lower muscle activity, and therefore the extent of fatigue may have been minimal. There remains a need to understand complex combinations of task-dependent factors in both fatigue development and temporal responsiveness. In study 6, nine measurement parameters revealed significant increases in fatigue over the work period. Traditional field measures (i.e., MVC and EMG) did not lead to extraordinary time effects. Error rates followed similar trends to the 9 significant measurements: an increase from baseline towards mid-morning, a slight decrease prior to the lunch break, a nadir after lunch, and increasing fatigue effects over the course of the afternoon. Error rates, however, might not be a sole consequence of fatigue – cognitive and physical; but might also reflect changes in arousal level. Over the pipetting task, there was interplay between peripheral and central fatigue mechanisms in three body segments: thumb, hand, and shoulder. Fatigue developed at a “local” level (i.e., at the three body segments) and was consistent with expected patterns observed in study 5, particularly if thumb and shoulder actions were considered concentric actions and the grip force was a sustained isometric contraction. Overall, the collective assessments suggested that rating of perceived fatigue and action tremor, on average, were highly repeatable and responsive in multiple task conditions. Postural tremor or steadiness and maximum voluntary contractions were moderately reliable and responsive. Different forms of tremor may be responsive to different task conditions. Postural tremor amplitude was found to increase over the course of an 8-hour workday in a light precision work task, and over multiple days in physically demanding work. Action tremor, on the other hand, appeared to be responsive at higher work intensities performed at a shorter duration of time. Possibly, action tremor may be more indicative of changes in the periphery, whereas postural tremor reflects changes more central in nature. Consequently, these measures should be considered for inclusion into a test battery for field use. For the ergonomist or health and safety practitioner, this body of work provides some insight into the utility of a test battery of fatigue measures to complement current task analysis techniques. For workplace researchers, this dissertation provides insight into the temporal development of fatigue in various task conditions and the reliability and responsiveness of select measures in both short and longer-term work-studies. This research might subsequently elicit future investigations in the relationship between work exposure, fatigue development, and performance and longer-term health outcomes

Feasibility of a surface electromyography-based compression garment for monitoring internal player load in professional basketball

The psychophysiological demands placed on professional athletes nowadays is greater than ever. In fact, professional basketball players can compete up to three time per week in addition to frequent and regular training sessions. Thus, adequately prescribing and monitoring athletes’ loads is important to maintain player well-being, reduce fatigue while optimising performance. Therefore, sport science research is saturated with different internal and external load monitoring approaches to help teams achieve these goals. Expansion of the global wearable technology market in sport is ever growing as practitioners seek a competitive advantage to their competitors. One such technology which has clinically and extensively been used for decades but has entered a new era into the wearable technology field in sport is surface electromyography (sEMG). However, little research reports on this technology in sport and the internal load metrics which representative companies claim it can report. The purpose of this doctoral thesis was to comprehensively examine internal load experienced by professional basketball players in the British Basketball League (BBL), while investigating a wearable sEMG technology for reporting a novel sEMG-based internal load metric (“Training Load”) during controlled lab-based exercise protocols, as well as determine the feasibility of the wearable sEMG-based internal load monitoring system in the professional basketball environment. The first observational study assessed the internal load experienced by professional basketball players during an entire season in the BBL. The research used the session-rating of perceived exertion (sRPE) method for quantifying load in professional basketball players following training sessions and competition. Results show that players experience greater Weekly Load (training only) during preseason compared to the in-season phase. Weekly Load is greater in 1-game weeks compared to 2-game weeks, while Total Weekly Load (training and competition) is higher during 2-game weeks compared to 1-game weeks. In addition, starting players experience a moderately higher Total Weekly Load compared to bench players, yet playing status did not result in differences in Weekly Load. The results show variances in internal load depending on weekly game fixtures, training schedules and phases of the season. While the sRPE method provides a valid global measurement of the training session or competition, the nature of retrieving RPE’s from players by asking a question prevents deeper investigation of internal load from specific phases of play. The second investigative study explores the possibility of using a novel wearable sEMG garment for capturing internal load (Training Load). The research investigated the sEMG derived Training Load during a 3-speed treadmill test and its relationship with oxygen consumption (V̇O2) during an exhaustive ramp incremental running treadmill test to determine maximal oxygen uptake (V̇O2max). Findings demonstrate sEMG-derived Training Load is a sensitive measure in detecting small changes in work rate during dynamic exercise, and while a moderate positive correlation between %V̇O2 max is shown, 80% of participants’ Training Loads show a very strong positive correlation at the individual level. The findings conclude that wearable sEMG technology may provide an alternative and new approach to capturing players internal load during sport and dynamic, whole-body exercise. The third study investigates the feasibility, practicality, and acceptability of wearable sEMG technology in the professional basketball environment. Results show a high acceptance rate (seventy-five percent) of the sEMG technology amongst professional basketball players, who report they would use the wearable sEMG technology again during team basketball training. A minority of players (twenty-five percent) report they would not use the wearable sEMG technology again due to negative experiences such as, comfortability issues and perceived negative effects on performance. While the wearable sEMG technology is relatively feasible in the environment, a few practical implications are considered important for coaches to understand before use. In particular, the time taken for downloading data to report to coaching staff or players takes longer than other load monitoring systems, such as GPS. In addition, the technology is more suited to the professional environment where a kit manager takes care of the handling procedures associated with the shorts. Lastly, the Core unit attached to the shorts can interrupt training practice. The current thesis contributes original research to the field of wearable sEMG for monitoring internal load. Findings provide important implications for practitioners endeavouring to use wearable sEMG in a professional sport context or research to further extent. Most research in basketball is conducted internationally, within Europe and America. The thesis is one of the first studies to identify internal loads in professional male basketball players within the United Kingdom. The thesis was the first to investigate an sEMG-derived Training Load during specific running tests. Lastly, the thesis was the first to assess professional athletes’ perceptions on wearable sEMG technology, highlighting reasons for and against using the technology

A Systematic Review and Meta-Analysis of the Incidence of Injury in Professional Female Soccer

The epidemiology of injury in male professional football is well documented and has been used as a basis to monitor injury trends and implement injury prevention strategies. There are no systematic reviews that have investigated injury incidence in women’s professional football. Therefore, the extent of injury burden in women’s professional football remains unknown. PURPOSE: The primary aim of this study was to calculate an overall incidence rate of injury in senior female professional soccer. The secondary aims were to provide an incidence rate for training and match play. METHODS: PubMed, Discover, EBSCO, Embase and ScienceDirect electronic databases were searched from inception to September 2018. Two reviewers independently assessed study quality using the Strengthening the Reporting of Observational Studies in Epidemiology statement using a 22-item STROBE checklist. Seven prospective studies (n=1137 professional players) were combined in a pooled analysis of injury incidence using a mixed effects model. Heterogeneity was evaluated using the Cochrane Q statistic and I2. RESULTS: The epidemiological incidence proportion over one season was 0.62 (95% CI 0.59 - 0.64). Mean total incidence of injury was 3.15 (95% CI 1.54 - 4.75) injuries per 1000 hours. The mean incidence of injury during match play was 10.72 (95% CI 9.11 - 12.33) and during training was 2.21 (95% CI 0.96 - 3.45). Data analysis found a significant level of heterogeneity (total Incidence, X2 = 16.57 P < 0.05; I2 = 63.8%) and during subsequent sub group analyses in those studies reviewed (match incidence, X2 = 76.4 (d.f. = 7), P <0.05; I2 = 90.8%, training incidence, X2 = 16.97 (d.f. = 7), P < 0.05; I2 = 58.8%). Appraisal of the study methodologies revealed inconsistency in the use of injury terminology, data collection procedures and calculation of exposure by researchers. Such inconsistencies likely contribute to the large variance in the incidence and prevalence of injury reported. CONCLUSIONS: The estimated risk of sustaining at least one injury over one football season is 62%. Continued reporting of heterogeneous results in population samples limits meaningful comparison of studies. Standardising the criteria used to attribute injury and activity coupled with more accurate methods of calculating exposure will overcome such limitations

Evaluation and adaptive attenuation of the cardiac vibration interference in mechanomyographic signals

The study of the mechanomyographic signal of the diaphragm muscle (MMGdi) is a promising technique in order to evaluate the respiratory muscles effort. The relationship between amplitude and frequency parameters of this signal with the respiratory effort performed during respiration is of great interest for researchers and physicians due to its diagnostic potentials. However, MMGdi signals are frequently contaminated by a cardiac vibration or mechanocardiographic (MCG) signal. An adaptive noise cancellation (ANC) can be used to reduce the MCG interference in the recorded MMGdi activity. In this paper, it is evaluated the proposed ANC scheme by means of a synthetic MMGdi signal with a controlled MCG interference. The Pearson’s correlation coefficient (PCC) between both root mean square (RMS) and mean frequency (fm) of the synthetic MMGdi signal are considerably reduced with the presence of cardiac vibration noise (from 0.95 to 0.87, and from 0.97 to 0.76, respectively). With the ANC algorithm proposed the effect of the MCG noise on the amplitude and frequency of MMG parameters is reduced considerably (PCC of 0.93 and 0.97 for the RMS and fm, respectively). The ANC method proposed in this work is an interesting technique to attenuate the cardiac interference in respiratory MMG signals. Further investigation should be carried out to evaluate the performance of the ANC algorithm in real MMGdi signals.Peer Reviewe