Abdominal / adductor strength imbalance in soccer players with osteitis pubis

Background and Objective: The muscle imbalance between abdominal and hip adductor muscles as an etiology for osteitis pubis is not well understood. The concept of a relationship between eccentric/concentric ratios at the pelvis and osteitis pubis in athletes is limited. This study aimed to compare the eccentric/concentric ratios for abdominal/ adductor, abdominal/back, and hip adductor muscles as well as eccentric abdominal/eccentric adductor muscles in soccer players suffering from osteitis pubis with those in healthy athletes. Material and Methods: Twenty male soccer athletes with osteitis pubis were recruited to participate and 20 healthy male soccer athletes were recruited to participate. Peak torque/body weight (PT/BW) for the hip adductor, abdominal, and back muscles during isokinetic concentric and eccentric contraction modes at a speed of 180°/s was recorded for healthy players and soccer athletes with osteitis pubis. Eccentric/concentric ratios for the abdominal/adductor, abdominal/back, and hip adductor muscles and the eccentric abdominal/eccentric adductor muscles were measured for both groups. Results: There was a significant decrease in the eccentric abdominal/concentric hip adductor muscles ratio (p = 0.000) and in the eccentric/concentric hip adductor muscles ratio (p = 0.016) between the osteitis pubis group and the healthy control group. Conclusion: Soccer players with osteitis pubis present with strength imbalance. The osteitis pubis group displayed eccentric weakness of the abdominal and adductor muscles, resulting in imbalances in the normal eccentric abdominal/concentric adductor and eccentric/concentric adductor ratios. Therefore, exercises that increase the eccentric strength of abdominal and hip adductor muscles may be beneficial to include in rehabilitation programs of patients with osteitis pubis

EMG measurement of the adductor muscles during walking and running

Introduction Increased pelvic drop has been linked to a range of musculoskeletal running injuries and may be linked to atypical activation pattern of the muscles surrounding the pelvis. However, to date, previous research investigating pelvic drop has focused on the abductor group, with minimal focus on the adductor group. Importantly, the over-activation of the adductor muscles could increase the adduction movement at the hip and therefore increase pelvic drop. However, this has not yet been investigated. Therefore, the studies within this thesis aimed to develop a valid and reliable protocol for measuring the activity of the adductor muscles and to investigate the association between adductor activation patterns and pelvic drop. Methods Ethical approvals were obtained from the University of Salford. Study 1 quantified the relative movement of the adductor muscles under the skin at different hip joint angles and during incremental isometric contraction. In addition, it explored the relationship between adductor torque and the corresponding EMG amplitudes during ramped isometric contraction in 10 participants. Study 2 investigated the between-day reliability for EMG measurements for the adductor muscles collected during both walking and running in 10 healthy runners. Study 3 described the EMG profile and the inter-subject variability for the adductor muscles during running in 25 runners. Study 4 investigated the association between the frontal pelvic plane movement and the adductor activation pattern during the early stance phase of running in 25 runners. Results The results of Study 1 suggested that placing the surface electrodes centrally over the adductor muscles ensure that the adductor muscles remain within the EMG electrode detection volume. Study 2 showed good to high between days reliability in both walking and running for the EMG that was developed for measuring adductor muscles activity. Study 3 suggested that the adductor magnus and gracilis muscles activate at the foot strike while the adductor longus activates at toe off. Study 4 showed that there was a significant strong positive correlation between the degree of adductor magnus activity and the pelvic drop angle. Conclusions The thesis establishes a robust and reliable method for measuring the activity of the adductor muscles using surface EMG electrodes in walking and running. Importantly, runners who exhibit increased pelvic drop also appear to demonstrate increased activity of adductor magnus during early stance phase. This finding motivates future clinical trials which could focus on muscle coordination retraining in order to improve kinematic patterns which have been linked to running-related injuries

Fatigue in myasthenia gravis: is it more than muscular weakness?

BACKGROUND: Few studies have focused on fatigue in myasthenia gravis (MG), and fatigue in relation to the autonomic system has never been systematically explored in these patients. The study aimed to document the prevalence of MG-related fatigue in ethnic Norwegians and to examine whether MG severity is associated with symptoms of autonomic disturbance, which in turn is associated with fatigue and functional disability. METHODS: Eighty two of the 97 who fulfilled the study inclusion criteria participated in the study. Controls were 410 age- and sex-matched subjects drawn from a normative sample (n = 2136) representative of the Norwegian population. Bivariate analyses and multivariate linear regression analyses were used to assess associations between questionnaire-reported MG severity, symptoms of autonomic disturbance, fatigue (mental and physical) and functional disability. RESULTS: Forty-four per cent (36/82) of patients fulfilled the criteria for fatigue compared with 22% (90/410) of controls (odds ratio 2.0; p = 0.003). Twenty-one per cent of patients (17/82) met the criteria for chronic fatigue versus 12% (48/410) of controls (odds ratio 1.96; p = 0.03). MG patients had higher total fatigue scores than controls (p < 0.001) and a high prevalence of autonomic symptoms, especially poor thermoregulation and sleep disturbance. According to multivariate analyses controlled for MG score, symptoms of autonomic disturbances were independently positively associated with fatigue (p < 0.001), and fatigue was independently negatively associated with functional level (p < 0.001). CONCLUSION: Norwegian ethnic patients with MG have higher levels of fatigue and a higher prevalence of chronic fatigue than controls, even in patients in full remission. MG severity is highly suggestive to be associated with symptoms of autonomic disturbance, which in turn is associated with fatigue and the level of functional disability

Validation of mDurance, A Wearable Surface Electromyography System for Muscle Activity Assessment

The authors wish to thank all participants for their assistance and to Irene Cantarero-Villanueva Ph.D. and Paula Postigo-Martín, of the Department of Physiotherapy (University of Granada, Spain), for providing us with their laboratories and materials so that this study could be carried out.The mDurance® system is an innovative digital tool that combines wearable surface electromyography (sEMG), mobile computing and cloud analysis to streamline and automatize the assessment of muscle activity. The tool is particularly devised to support clinicians and sport professionals in their daily routines, as an assessment tool in the prevention, monitoring rehabilitation and training field. This study aimed at determining the validity of the mDurance system for measuring muscle activity by comparing sEMG output with a reference sEMG system, the Delsys® system. Fifteen participants were tested during isokinetic knee extensions at three different speeds (60, 180, and 300 deg/s), for two muscles (rectus femoris [RF] and vastus lateralis [VL]) and two different electrodes locations (proximal and distal placement). The maximum voluntary isometric contraction was carried out for the normalization of the signal, followed by dynamic isokinetic knee extensions for each speed. The sEMG output for both systems was obtained from the raw sEMG signal following mDurance's processing and filtering. Mean, median, first quartile, third quartile and 90th percentile was calculated from the sEMG amplitude signals for each system. The results show an almost perfect ICC relationship for the VL (ICC > 0.81) and substantial to almost perfect for the RF (ICC > 0.762) for all variables and speeds. The Bland-Altman plots revealed heteroscedasticity of error for mean, quartile 3 and 90th percentile (60 and 300 deg/s) for RF and at mean and 90th percentile for VL (300 deg/s). In conclusion, the results indicate that the mDurance® sEMG system is a valid tool to measure muscle activity during dynamic contractions over a range of speeds. This innovative system provides more time for clinicians (e.g., interpretation patients' pathologies) and sport trainers (e.g., advising athletes), thanks to automatic processing and filtering of the raw sEMG signal and generation of muscle activity reports in real-time

Between-day repeatability of lower limb EMG measurement during running and walking

There are minimal data describing the between-day repeatability of EMG measurements during running. Furthermore, there are no data characterising the repeatability of surface EMG measurement from the adductor muscles, during running or walking. The purpose of this study was to report on the consistency of EMG measurement for both running and walking across a comprehensive set of lower limb muscles, including adductor magnus, longus and gracilis. Data were collected from 12 lower limb muscles during overground running and walking on two separate days. The coefficient of multiple correlation (CMC) was used to quantify waveform similarity across the two sessions for signals normalised to either maximal voluntary isometric contraction (MVIC) or mean/peak signal magnitude. For running, the data showed good or excellent repeatability (CMC=0.87-0.96) for all muscles apart from gracilis and biceps femoris using the MVIC method. Similar levels of repeatability were observed for walking. Importantly, using the peak/mean method as an alternative to the MVIC method, resulted in only marginal improvements in repeatability. The proposed protocol facilitated the collection of repeatable EMG data during running and walking and therefore could be used in future studies investigating muscle patterns during gait

Late Onset Myasthenia Gravis Is Associated with HLA DRB1*15:01 in the Norwegian Population

BACKGROUND: Acquired myasthenia gravis (MG) is a rare antibody-mediated autoimmune disease caused by impaired neuromuscular transmission, leading to abnormal muscle fatigability. The aetiology is complex, including genetic risk factors of the human leukocyte antigen (HLA) complex and unknown environmental factors. Although associations between the HLA complex and MG are well established, not all involved components of the HLA predisposition to this heterogeneous disease have been revealed. Well-powered and comprehensive HLA analyses of subgroups in MG are warranted, especially in late onset MG. METHODOLOGY/PRINCIPAL FINDINGS: This case-control association study is of a large population-based Norwegian cohort of 369 MG patients and 651 healthy controls. We performed comprehensive genotyping of four classical HLA loci (HLA-A, -B, -C and -DRB1) and showed that the DRB1*15:01 allele conferred the strongest risk in late onset MG (LOMG; onset ≥ 60 years) (OR 2.38, p(c)7.4 × 10(-5)). DRB1*13:01 was found to be a protective allele for both early onset MG (EOMG) and LOMG (OR 0.31, p(c) 4.71 × 10(-4)), a finding not previously described. No significant association was found to the DRB1*07:01 allele (p(nc) = 0.18) in a subset of nonthymomatous anti-titin antibody positive LOMG as reported by others. HLA-B*08 was mapped to give the strongest contribution to EOMG, supporting previous studies. CONCLUSION: The results from this study provide important new information concerning the susceptibility of HLA alleles in Caucasian MG, with highlights on DRB1*15:01 as being a major risk allele in LOMG

Late Onset Myasthenia Gravis Is Associated with HLA DRB1*15:01 in the Norwegian Population

Background: Acquired myasthenia gravis (MG) is a rare antibody-mediated autoimmune disease caused by impaired neuromuscular transmission, leading to abnormal muscle fatigability. The aetiology is complex, including genetic risk factors of the human leukocyte antigen (HLA) complex and unknown environmental factors. Although associations between the HLA complex and MG are well established, not all involved components of the HLA predisposition to this heterogeneous disease have been revealed. Well-powered and comprehensive HLA analyses of subgroups in MG are warranted, especially in late onset MG. Methodology/Principal Findings: This case-control association study is of a large population-based Norwegian cohort of 369 MG patients and 651 healthy controls. We performed comprehensive genotyping of four classical HLA loci (HLA-A, -B, -C and -DRB1) and showed that the DRB1*15:01 allele conferred the strongest risk in late onset MG (LOMG; onset ≥60years) (OR 2.38, pc7.4×10−5). DRB1*13:01 was found to be a protective allele for both early onset MG (EOMG) and LOMG (OR 0.31, pc 4.71×10−4), a finding not previously described. No significant association was found to the DRB1*07:01 allele (pnc = 0.18) in a subset of nonthymomatous anti-titin antibody positive LOMG as reported by others. HLA-B*08 was mapped to give the strongest contribution to EOMG, supporting previous studies. Conclusion: The results from this study provide important new information concerning the susceptibility of HLA alleles in Caucasian MG, with highlights on DRB1*15:01 as being a major risk allele in LOMG