Mechanomyographic Parameter Extraction Methods: An Appraisal for Clinical Applications

The research conducted in the last three decades has collectively demonstrated that the skeletal muscle performance can be alternatively assessed by mechanomyographic signal (MMG) parameters. Indices of muscle performance, not limited to force, power, work, endurance and the related physiological processes underlying muscle activities during contraction have been evaluated in the light of the signal features. As a non-stationary signal that reflects several distinctive patterns of muscle actions, the illustrations obtained from the literature support the reliability of MMG in the analysis of muscles under voluntary and stimulus evoked contractions. An appraisal of the standard practice including the measurement theories of the methods used to extract parameters of the signal is vital to the application of the signal during experimental and clinical practices, especially in areas where electromyograms are contraindicated or have limited application. As we highlight the underpinning technical guidelines and domains where each method is well-suited, the limitations of the methods are also presented to position the state of the art in MMG parameters extraction, thus providing the theoretical framework for improvement on the current practices to widen the opportunity for new insights and discoveries. Since the signal modality has not been widely deployed due partly to the limited information extractable from the signals when compared with other classical techniques used to assess muscle performance, this survey is particularly relevant to the projected future of MMG applications in the realm of musculoskeletal assessments and in the real time detection of muscle activity

Muscle Fatigue Analysis With Optimized Complementary Ensemble Empirical Mode Decomposition and Multi-Scale Envelope Spectral Entropy

The preprocessing of surface electromyography (sEMG) signals with complementary ensemble empirical mode decomposition (CEEMD) improves frequency identification precision and temporal resolution, and lays a good foundation for feature extraction. However, a mode-mixing problem often occurs when the CEEMD decomposes an sEMG signal that exhibits intermittency and contains components with a near-by spectrum into intrinsic mode functions (IMFs). This paper presents a method called optimized CEEMD (OCEEMD) to solve this problem. The method integrates the least-squares mutual information (LSMI) and the chaotic quantum particle swarm optimization (CQPSO) algorithm in signal decomposition. It uses the LSMI to calculate the correlation between IMFs so as to reduce mode mixing and uses the CQPSO to optimize the standard deviation of Gaussian white noise so as to improve iteration efficiency. Then, useful IMFs are selected and added to reconstruct a de-noised signal. Finally, considering that the IMFs contain abundant frequency and envelope information, this paper extracts the multi-scale envelope spectral entropy (MSESEn) from the reconstructed sEMG signal. Some original sEMG signals, which were collected from experiments, were used to validate the methods. Compared with the CEEMD and complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), the OCEEMD effectively suppresses mode mixing between IMFs with rapid iteration. Compared with approximate entropy (ApEn) and sample entropy (SampEn), the MSESEn clearly shows a declining tendency with time and is sensitive to muscle fatigue. This suggests a potential use of this approach for sEMG signal preprocessing and the analysis of muscle fatigue

Análise da fadiga dos atletas de Taekwondo por meio do Espectro de Hilbert

Trabalho de Conclusão de Curso (Graduação)A avaliação e estudo da biomecânica do movimento é uma técnica fundamental para o profissional analista do movimento, como educador físico, treinador, fisioterapeuta. Atualmente, a biomecânica esportiva fornece muitas contribuições como a análise e melhoria da técnica desportiva, prevenção de lesões e desenvolvimento de equipamentos esportivos. A identificação da fadiga é uma das técnicas utilizadas para melhorar o desempenho e prevenir lesões nos atletas. As manifestações da fadiga têm sido referenciadas ao decaimento da força muscular gerada durante e após exercícios de alta intensidade, podendo assim, ser detectada por meio da análise do sinal eletromiográfico. A Frequência instantânea média é um dos indicadores utilizados em métodos para a quantificação destas manifestações, no qual ocorre uma diminuição nos valores desta, durante a ocorrência da fadiga muscular. Este trabalho propõe a aplicação da transformada de Hilbert-Huang para identificar a fadiga em atletas de Taekwondo. Para isso, foram necessários adquirir sinais eletromiográficos dos atletas durante a realização do movimento de chute do esporte. Estes sinais foram decompostos em um conjunto de componentes ou funções (IMFs). Com a obtenção dos IMFs é possível gerar o espectro de Hilbert, que possibilita obter a amplitude e a frequência instantânea média. De acordo com os resultados, foi possível identificar que o voluntário 1 e 3 apresentaram ótimos desempenhos, visto que apenas o músculo que realiza o chute, apresentou decaimento na frequência instantânea. Os outros voluntários não apresentaram resultados satisfatórios em relação ao desempenho do atleta, pois em todos os casos, a fadiga foi identificada no músculo de apoio para a realização do chute. Portanto, concluiu-se que o método de Hilbert-Huang é capaz de realizar a avaliação do desempenho e melhorar a preparação física dos aletas de taekwondo por meio da análise da fadiga muscular

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

A neurophysiological examination of voluntary isometric contractions: modulations in sensorimotor oscillatory dynamics with contraction force and physical fatigue, and peripheral contributions to maximal force production

Human motor control is a complex process involving both central and peripheral components of the nervous system. Type Ia afferent input contributes to both motor unit recruitment and firing frequency, however, whether maximal force production is dependent on this input is unclear. Therefore, chapter 2 examined maximal and explosive force production of the knee extensors following prolonged infrapatellar tendon vibration; designed to attenuate the efficacy of the homonymous Ia afferent-α-motoneuron pathway. Despite a marked decrease in H-reflex amplitude, indicating an attenuated efficacy of the Ia afferent-α-motoneuron pathway, both maximal and explosive force production were unaffected after vibration. This suggested that maximal and explosive isometric quadriceps force production was not dependent upon Ia afferent input to the homonymous motor unit pool. Voluntary movements are linked with various modulations in ongoing neural oscillations within the supraspinal sensorimotor system. Despite considerable interest in the oscillatory responses to movements per se, the influence of the motor parameters that define these movements is poorly understood. Subsequently, chapters 3 and 4 investigated how the motor parameters of voluntary contractions modulated the oscillatory amplitude. Chapter 3 recorded electroencephalography from the leg area of the primary sensorimotor cortex in order to investigate the oscillatory responses to isometric unilateral contractions of the knee-extensors at four torque levels (15, 30, 45 and 60% max.). An increase in movement-related gamma (30-50 Hz) activity was observed with increments in knee-extension torque, whereas oscillatory power within the delta (0.5-3 Hz), theta (3-7 Hz), alpha (7-13 Hz) and beta (13-30 Hz) bands were unaffected. Chapter 4 examined the link between the motor parameters of voluntary contraction and modulations in beta (15-30 Hz) oscillations; specifically, movement-related beta decrease (MRBD) and post-movement beta rebound (PMBR). Magnetoencephalography (MEG) was recorded during isometric ramp and constant-force wrist-flexor contractions at distinct rates of force development (10.4, 28.9 and 86.7% max./s) and force output (5, 15, 35 and 60%max.), respectively. MRBD was unaffected by RFD or force output, whereas systematic modulation of PMBR by both contraction force and RFD was identified for the first time. Specifically, increments in isometric contraction force increased PMBR amplitude, and increments in RFD increased PMBR amplitude but decreased PMBR duration. Physical fatigue arises not only from peripheral processes within the active skeletal muscles but also from supraspinal mechanisms within the brain. However, exactly how cortical activity is modulated during fatigue has received a paucity of attention. Chapter 5 investigated whether oscillatory activity within the primary sensorimotor cortex was modulated when contractions were performed in a state of physical fatigue. MEG was recorded during submaximal isometric contractions of the wrist-flexors performed both before and after a fatiguing series of isometric wrist-flexions or a time matched control intervention. Physical fatigue offset the attenuation in MRBD observed during the control trial, whereas PMBR was increased when submaximal contractions were performed in a fatigued state

Biomedicinsko inženjerstvo – prošlost, sadašnjost, budućnost

Medicine and health care have changed dramatically in the past few decades and they depend on high technology for prevention, diagnosis and treatment of diseases, and for patient rehabilitation. Modern biomedical research and health care are provided by multidisciplinary teams in which biomedical engineers contribute to the advancement of knowledge equally as medical professions. Biomedical engineering represents one (out of two) the most rapidly growing branches of industry in the developed world [1] (the other are sustainable and renewable energy sources). The new knowledge gained by basic biomedical engineering research (at gene, molecular, cellular, organ and system level) has high impact on the growth of new medical products and boosts industries, including small and medium size enterprises (SMEs). SMEs are expected to bring to the market new products and services for health care delivery [2]. Health is the major theme of the specific Programme on Cooperation under the European Seventh Framework Programme, with a total budget of e6.1 billion over the duration of FP7. The objective of health research under FP7 is to improve the health of European citizens and stir up the competitiveness of health-related industries and businesses, while addressing global health issues, life improving and develop life saving technologies. Hospitals and other medical institutions have a commitment to take care of all kinds of high technology devices including the hospital information systems, networks and their safety and security. Growing technological participation in health services enforces the support of technologically specialized personnel, trained clinical engineers. Worldwide, the educational system has adopted the curricula of biomedical engineering and of clinical engineering. Professional organizations are building certification system for biomedical and clinical engineers and the continuous education (life long learning) structures. The development of biomedical engineering and its affirmation has mainly appeared in the last 50 years, first as a result of development in electronic industry while later it started developing at its own pace. In the first part of this paper, we address the development of biomedical engineering in that period and present our views on the development of biomedical engineering in the future. The second part is devoted to the International Federation for Medical and Biological Engineering (IFMBE), the largest organization of biomedical engineers in the world which celebrated its 50th anniversary in 2009. In the third part, we recall our memories to the founder of biomedical engineering in Croatia, prof. Ante Šantic and his achievements in biomedical engineering, and present the state of art of biomedical engineering research and education in Croatia.Medicina i zdravstvena zaštita su se dramatično promijenile u posljednjih nekoliko desetljeća, i ovise o visokoj tehnologiji za prevenciju, dijagnostiku i liječenje bolesti, i za rehabilitaciju pacijenata. Moderna biomedicinska istraživanja i zdravstvena zaštita osigurava se multidisciplinarnim timovima u kojima biomedicinski inženjeri doprinose unapređenju znanja jednako kao i medicinski stručnjaci. Biomedicinsko inženjerstvo predstavlja jedno (od dvije) najbrže rastuće grane industrije u razvijenom svijetu [1] (druga grana su održivi i obnovljivi izvori energije). Nova znanja stečena temeljnim istraživanjima u biomedicinskom inženjerstvu (na razini gena, molekula, stanice, organa i na razini sustava) imaju velik utjecaj na razvoj novih medicinskih proizvoda i jačanje industrije, uključujući i mala i srednja poduzeća (MSP). Očekuje se da mala i srednja poduzeća na tržište donesu nove proizvode i usluge za zdravstvenu skrb [2]. Zdravlje je glavna tema specifičnog programa o suradnji u okviru europskog sedmog okvirnog programa (FP7), s ukupnim proračunom od 6,1 milijarde eura tijekom trajanja FP7. Cilj istraživanja u području zdravstva u okviru FP7 je poboljšati zdravlje europskih građana i povećati konkurenciju u okviru zdravstvene djelatnosti i industrije, a istovremeno voditi računa o globalnim zdravstvenim problemima, poboljšanju života i razvoju tehnologija za spašavanje života. Bolnice i druge medicinske ustanove imaju obvezu voditi brigu o svim vrstama uređaja visoke tehnologije, uključujući bolničke informatičke sustave, mreže i te o njihovoj sigurnosti. Povećanje udjela tehnologije u zdravstvu proizvelo je potrebu za tehnološki specijaliziranim osobljem, kliničkim inženjerima. Diljem svijeta, obrazovni sustav je usvojio visokoškolske programe biomedicinskog inženjerstva i kliničkog inženjerstva. Profesionalne organizacije su izgradile sustav potvrđivanja za biomedicinske i kliničke inženjere i za njihovo kontinuirano obrazovanje (cjeloživotno učenje). Razvoj biomedicinskog inženjerstva i njegova afirmacija je započela u posljednjih 50 godina, kao rezultat razvoja elektroničke industrije, a kasnije se biomedicinsko inženjerstvo nastavilo razvijati vlastitim tempom. U prvom dijelu ovog rada, govorimo o razvoju biomedicinskog inženjerstva u početnom razdoblju i predstavljamo naše poglede na razvoj biomedicinskog inženjerstva u budućnosti. Drugi dio posvećen je Međunarodnoj federaciji za medicinsko i biološko inženjerstvo (IFMBE), najvećoj organizaciji biomedicinskih inženjera u svijetu koji je proslavila svoju 50. godišnjicu u 2009. godini. U trećem dijelu, podsjećamo se na utemeljitelja biomedicinskog inženjerstva u Hrvatskoj, prof. Antu Šantića i njegova dostignuca u području biomedicinskog inženjerstva. Konačno, predstavljamo sadašnje stanje istraživanja i obrazovanja u području biomedicinskog inženjerstva u Hrvatskoj