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

Muscle contracture in cerebral palsy and stroke : an MRI investigation

Muscle contracture is a loss in joint range of motion caused by changes in the passive mechanical properties of muscle. Contractures are prevalent in cerebral palsy and stroke and are often debilitating. The mechanisms of contracture are poorly understood, partly due to limitations of previous techniques used to measure muscle architecture. This thesis used novel imaging techniques to investigate muscle adaptations in contracture following cerebral palsy and stroke. Anatomically-constrained diffusion tensor imaging and mDixon scans were used to measure fascicle lengths, muscle volumes, physiological cross-sectional areas, pennation angles and intramuscular fat fractions in the medial gastrocnemius muscles of children with hemiplegic cerebral palsy, adults who have had a stroke, and age-matched control participants. In children with cerebral palsy, reduced dorsiflexion range on the more-affected side compared to the less-affected side (13 degrees) was accompanied by medial gastrocnemius muscles with shorter fascicles (13%), smaller volumes (35%), smaller physiological cross-sectional areas (26%) and higher fat fractions. Compared to typically developing children, dorsiflexion range was also reduced (10 degrees), and more-affected muscles had shorter fascicles (11%), smaller volumes (33%), smaller physiological cross-sectional areas (7%) and higher fat fractions. Muscles on the less-affected side of children with cerebral palsy were architecturally similar to typically developing muscles but had elevated fat fractions. In people who have had a stroke, reduced dorsiflexion range on the paretic side compared to the non-paretic side (11 degrees) was accompanied by medial gastrocnemius muscles with smaller muscle volumes (15%). Compared to control participants, dorsiflexion range was reduced (6 degrees) and paretic muscles had smaller volumes (16%) and higher fat fractions. Muscles on the non-paretic side were architecturally similar to control muscles but had elevated fat fractions. In cerebral palsy and stroke, reduced dorsiflexion range was accompanied by reduced muscle volume and elevated intramuscular fat fractions. Intramuscular fat did not correlate with range of motion, suggesting (but not proving) that intramuscular fat does not cause contracture. In cerebral palsy, range of motion may be limited by short muscle fascicles. In contrast, muscle fascicle lengths appear to be unchanged following stroke, suggesting that mechanisms of contracture may be different in cerebral palsy and stroke. Muscle contracture in the medial gastrocnemius muscles of children with cerebral palsy may be explained by relatively short fascicles. If short muscle fascicles cause contracture, therapy should be designed to lengthen muscle fascicles. This thesis presents a series of cross-sectional studies. Cross-sectional studies cannot explain how contractures develop over time. Longitudinal studies are needed to understand better the progression of contracture. The MRI techniques used here are likely to be useful for future muscle architecture and intramuscular fat measurements, because these techniques overcome many of the limitations faced by conventional techniques used to make muscle architecture and intramuscular fat measurements

A two-sling mechanism of hyolaryngeal elevation in the pharyngeal phase of swallowing

Thesis (Ph.D.)--Boston UniversityThe pharyngeal phase of swallowing is a complex function that transfers a bolus from the oral cavity through the hypopharynx into the esophagus. A critical event in this process is the elevation of the hyolaryngeal complex, which opens the upper esophageal sphincter and relocates the airway away from an oncoming bolus. The suprahyoid group of muscles (mylohyoid, geniohyoid, digastric, and stylohyoid) and thyrohyoid are thought to underlie this function. The role of a deeper posterior sling of muscles that is comprised of stylopharyngeus, salpingopharyngeus and palatopharyngeus has not been determined. This project aims to investigate a hypothesized two-sling mechanism for hyolaryngeal elevation in the pharyngeal phase of swallowing. The thesis begins with background information of the functional anatomy thought to underlie hyolaryngeal elevation followed by an outline of studies that validate the structure, function, and clinical relevance of the two-sling mechanism. A cadaver model is first used to calculate potential force vectors of the muscular slings. The function of the two-sling apparatus is then investigated in vivo by using muscle functional MRI to evaluate muscles active in swallowing and dynamic MRI to perform kinematic analysis on key anatomical landmarks that represent attachment sites of the two-sling mechanism. Finally, the clinical significance of the two-sling mechanism is demonstrated by comparing spatial and temporal measurements collected from fluoroscopic imaging studies of patients with normal swallowing ability and swallowing difficulty

Investigating the reprogramming of the hypertrophic Myostatin null muscle with Estrogen-related receptor gamma; implications for muscle structure and function

Skeletal muscle is a highly compliant organ system that is composed of muscle fibres, nerves, sensory cells, blood vessels and connective tissue. A central concept of skeletal muscle biology is the existence of an inverse relationship between muscle fibre size and its oxidative capacity which has been used to explain why small fibres are oxidative and large fibres glycolytic. However, sturdiness of this relationship is unknown. In order to investigate the rigour of this relationship we made use of a genetic model that enhances oxidative metabolism, mediated by estrogen-related receptor gamma (Errγ) (a constitutively active orphan nuclear receptor belongs to the ERR subfamily), and the hypertrophic background of Myostatin (a member of the Transforming Growth Factor beta (TGF-β) superfamily that is negatively regulating skeletal muscle mass development) null (Mtn‐/‐) mice. We show that superimposition of Errγ on the Mtn‐/‐ background results in hypertrophic muscle that displays a high oxidative capacity (Mtn‐/‐/ErrγTg/+), thus violating the inverse relationship between muscle fibre cross-sectional area and its oxidative capacity. Thereafter, we examined the canonical view that there is a high number of satellite cells (skeletal muscle resident stem cells) in oxidative muscles. Surprisingly, I found that hypertrophic oxidative muscle fibres from Mtn‐/‐/ErrγTg/+ mice showed a deficit in the number of satellite cells. Unexpectedly, the lower population of satellite cells in the hypertrophic oxidative model is not associated with a lower regenerative capacity. We also examined the relationship between muscle fibre phenotype (size and metabolism) and components of its force transducer apparatus that consists of both extracellular matrix (ECM) and dystrophinglycoprotein complex (DGC). Interestingly, I showed that levels of ECM and DGC entities can be influenced by muscle fibre phenotype. Observations of this work firstly, challenge the notion of a constraint between skeletal muscle fiber size and oxidative capacity, secondly, indicate the important role of the microcirculation in the regenerative capacity of a muscle even with low population of satellite cells, and thirdly, show that the metabolic properties of a muscle fibre are a critical factor to regulate the levels of ECM and DGC proteins

Muscle activation patterns in shoulder impingement patients

Introduction: Shoulder impingement is one of the most common presentations of shoulder joint problems 1. It appears to be caused by a reduction in the sub-acromial space as the humerus abducts between 60o -120o – the 'painful arc'. Structures between the humeral head and the acromion are thus pinched causing pain and further pathology 2. Shoulder muscle activity can influence this joint space but it is unclear whether this is a cause or effect in impingement patients. This study aimed to observe muscle activation patterns in normal and impingement shoulder patients and determine if there were any significant differences. Method: 19 adult subjects were asked to perform shoulder abduction in their symptomatic arm and non-symptomatic. 10 of these subjects (age 47.9 ± 11.2) were screened for shoulder impingement, and 9 subjects (age 38.9 ± 14.3) had no history of shoulder pathology. Surface EMG was used to collect data for 6 shoulder muscles (Upper, middle and lower trapezius, serratus anterior, infraspinatus, middle deltoids) which was then filtered and fully rectified. Subjects performed 3 smooth unilateral abduction movements at a cadence of 16 beats of a metronome set at 60bpm, and the mean of their results was recorded. T-tests were used to indicate any statistical significance in the data sets. Significance was set at P<0.05. Results: There was a significant difference in muscle activation with serratus anterior in particular showing a very low level of activation throughout the range when compared to normal shoulder activation patterns (<30%). Middle deltoid recruitment was significantly reduced between 60-90o in the impingement group (30:58%).Trends were noted in other muscles with upper trapezius and infraspinatus activating more rapidly and erratically (63:25%; 60:27% respectively), and lower trapezius with less recruitment (13:30%) in the patient group, although these did not quite reach significance. Conclusion: There appears to be some interesting alterations in muscle recruitment patterns in impingement shoulder patients when compared against their own unaffected shoulders and the control group. In particular changes in scapula control (serratus anterior and trapezius) and lateral rotation (infraspinatus), which have direct influence on the sub-acromial space, should be noted. It is still not clear whether these alterations are causative or reactionary, but this finding gives a clear indication to the importance of addressing muscle reeducation as part of a rehabilitation programme in shoulder impingement patients

Epidemiology of Injury in English Women's Super league Football: A Cohort Study

INTRODUCTION: The epidemiology of injury in male professional football has been well documented (Ekstrand, Hägglund, & Waldén, 2011) and used as a basis to understand injury trends for a number of years. The prevalence and incidence of injuries occurring in womens super league football is unknown. The aim of this study is to estimate the prevalence and incidence of injury in an English Super League Women’s Football squad. METHODS: Following ethical approval from Leeds Beckett University, players (n = 25) signed to a Women’s Super League Football club provided written informed consent to complete a self-administered injury survey. Measures of exposure, injury and performance over a 12-month period was gathered. Participants were classified as injured if they reported a football injury that required medical attention or withdrawal from participation for one day or more. Injuries were categorised as either traumatic or overuse and whether the injury was a new injury and/or re-injury of the same anatomical site RESULTS: 43 injuries, including re-injury were reported by the 25 participants providing a clinical incidence of 1.72 injuries per player. Total incidence of injury was 10.8/1000 h (95% CI: 7.5 to 14.03). Participants were at higher risk of injury during a match compared with training (32.4 (95% CI: 15.6 to 48.4) vs 8.0 (95% CI: 5.0 to 10.85)/1000 hours, p 28 days) of which there were three non-contact anterior cruciate ligament (ACL) injuries. The epidemiological incidence proportion was 0.80 (95% CI: 0.64 to 0.95) and the average probability that any player on this team will sustain at least one injury was 80.0% (95% CI: 64.3% to 95.6%) CONCLUSION: This is the first report capturing exposure and injury incidence by anatomical site from a cohort of English players and is comparable to that found in Europe (6.3/1000 h (95% CI 5.4 to 7.36) Larruskain et al 2017). The number of ACL injuries highlights a potential injury burden for a squad of this size. Multi-site prospective investigations into the incidence and prevalence of injury in women’s football are require