Altered neuromuscular control mechanisms of the trapezius muscle in fibromyalgia

Effect of physical activity education on shoulder girdle pain and muscle strength in participants with fibromyalgia: a pilot experimental study

Background

In patients with fibromyalgia, exercise and education are recommended to decrease pain level and improve pain management. The latest scientific evidence recommends to focus interventions on the upper limb. The aim of this pilot study was to compare the immediate effect of physical activity education vs. a control group on pain and muscle capacity in fibromyalgia patients.

Method

Fifty-six participants with fibromyalgia were randomized into an experimental group and a control group. The intervention consisted in watching a five-minute video that provided information about fibromyalgia, pain, kinesiophobia and physical activity. The control group watched a neutral five-minute video about beavers in Quebec. Following the video, participants performed a muscular fatigue task consisting of a repeated unilateral shoulder abduction task. At baseline and following the muscular fatigue task, maximal voluntary contraction (MVC) in shoulder abduction was assessed as well as pain level and pressure pain threshold (PPT) in the upper limb. Electromyographic activity was also assessed for upper trapezius and middle deltoid muscles. Two-way repeated measures analysis of variance was used to compare the MVC, PPT, and pain level before and after the muscular fatigue task between groups.

Results

The experimental group showed a significantly lower increase in pain than the control group in the middle deltoid muscle (p = 0.002) when assessed by verbal pain rating scale. No significant interaction or main effect of Group and Time were observed for the pain level at the upper trapezius and elbow extensor muscles nor for any of the PPT measures. According to electromyographic data, the median frequency values indicate that neither group experienced muscle fatigue during the repeated contraction task.

Conclusions

The preliminary results suggest that a short physical activity education video positively influenced middle deltoid pain following repeated abduction in participants with fibromyalgia. Electromyographic analysis showed no evidence of objective muscle fatigue, suggesting that there might be a partial disconnection between the perception of muscle fatigue and the physiological biomarkers associated with muscle fatigue.

Role of non-invasive objective markers for the rehabilitative diagnosis of central sensitization in patients with fibromyalgia: A systematic review

BACKGROUND

Central sensitization cannot be demonstrated directly in humans. Therefore, studies used different proxy markers (signs, symptoms and tools) to identify factors assumed to relate to central sensitization in humans, that is, Human Assumed Central Sensitization (HACS). The aims of this systematic review were to identify non-invasive objective markers of HACS and the instruments to assess these markers in patients with fibromyalgia (FM).

METHODS

A systematic review was conducted with the following inclusion criteria: (1) adults, (2) diagnosed with FM, and (3) markers and instruments for HACS had to be non-invasive. Data were subsequently extracted, and studies were assessed for risk of bias using the quality assessment tools developed by the National Institute of Health.

RESULTS

78 studies (n= 5234 participants) were included and the findings were categorized in markers identified to assess peripheral and central manifestations of HACS. The identified markers for peripheral manifestations of HACS, with at least moderate evidence, were pain after-sensation decline rates, mechanical pain thresholds, pressure pain threshold, sound 'pressure' pain threshold, cutaneous silent period, slowly repeated evoked pain sensitization and nociceptive flexion reflex threshold. The identified markers for central manifestations of HACS were efficacy of conditioned pain modulation with pressure pain conditioning and brain perfusion analysis. Instruments to assess these markers are: pin-prick stimulators, cuff-algometry, repetitive pressure stimulation using a pressure algometer, sound, electrodes and neuroimaging techniques.

CONCLUSIONS

This review provides an overview of non-invasive markers and instruments for the assessment of HACS in patients with FM. Implementing these findings into clinical settings may help to identify HACS in patients with FM.

Can intermittent changes in trunk extensor muscle length delay muscle fatigue development?

Muscle length changes may evoke alternating activity and consequently reduce local fatigue and pain during prolonged static bending. The aim of this study was to assess whether a postural intervention involving intermittent trunk extensor muscle length changes (INTERMITTENT) can delay muscle fatigue during prolonged static bending when compared to a near-isometric condition (ISOMETRIC) or when participants were allowed to voluntarily vary muscle length (VOLUNTARY). These three conditions were completed by 11 healthy fit male participants, in three separate sessions of standing with 30 ± 3 degrees trunk inclination until exhaustion. Conventional and high-density electromyography (convEMG and HDsEMG, respectively) were measured on the left and right side of the spine, respectively. The endurance time for INTERMITTENT was 33.6% greater than ISOMETRIC (95% CI: [3.8, 63.5]; p = 0.027) and 29.4% greater than VOLUNTARY (95% CI: [7.0, 51.7]; p = 0.010), but not different between ISOMETRIC and VOLUNTARY. The convEMG and HDsEMG amplitude coefficient of variation was significantly greater for INTERMITTENT versus ISOMETRIC. The rate of change in convEMG and HDsEMG spectral content did not reveal significant differences between conditions as found in endurance time. Additional regression analyses between endurance time and rate of change in convEMG (p > 0.05) and HDsEMG (R2 = 0.39-0.65, p = 0.005-0.039) spectral content indicated that HDsEMG better reflects fatigue development in low-level contractions. In conclusion, imposed intermittent trunk extensor muscle length changes delayed muscle fatigue development when compared to a near-isometric condition or when participants were allowed to voluntarily vary muscle length, possibly due to evoking alternating activity between/within trunk extensor muscles.

Feldenkrais awareness though movement intervention for fibromyalgia syndrome: A proof-of-concept study

INTRODUCTION

The Feldenkrais Method® is a form of awareness through movement (ATM) aimed at improving spatial and kinesthetic awareness through verbally guided movements, in order to learn more effective actions.

METHOD

The present study, a proof-of-concept, observational, non-controlled prospective study, aims at exploring the effectiveness of ATM for fibromyalgia syndrome (FM), measuring the effect by means of multi-dimensional questionnaires, administered at baseline and after 4 months of ATM activity.

RESULTS

One hundred twenty-eight FM patients (mean age 54 years old, 2% males) participated in the study. A statistically significant improvement was found in FM-specific measures (Polysymptomatic Distress Scale, PDS) (p = 0.003) and the Pain Catastrophization Scale (PCS) (p = 0.020); coherently, the Revised Fibromyalgia Impact Questionnaire (FIQR) showed a trend in improvement after the intervention, although this improvement was not statistically significant. The logistic regression analysis found a correlation between PDS, fatigue and anxiety measures; PCS, years from diagnosis and anxiety.

CONCLUSION

ATM could improve FM-specific measures and pain-related catastrophizing. Further studies are needed to identify FM subgroups in order to find personalized targets that can be used to guide treatments.

Effects of Vertical Lifting Distance on Upper-Body Muscle Fatigue

Manual material handling (MMH) is commonly demanded in the manufacturing industry. Occupational muscle fatigue of the arm, shoulder, and back, which arise from MMH tasks, can cause work absences and low efficiency. The available literature presents the lack of the fatigue comparison between targeted muscles, on the same part or on different parts. The main aim of the present study was to evaluate and compare the fatigue of upper-body muscles during repetitive bending tasks, an experiment involving 12 male subjects has been conducted to simulate material handling during furniture board drilling. The vertical lifting distance was chosen to be the single independent variable, and the three levels were 0, 250, and 500 mm. Surface electromyography (sEMG) was used to measure the muscle fatigue of the biceps brachii, upper trapezius, and multifidus, while the sEMG parameters, including the normalized electromyographic amplitude (Normalized EA) and mean power frequency (MPF), of the target muscles were analyzed. The experimental results reveal that during the manual handling tasks, the biceps brachii was the most relaxed muscle, contributing the least muscle tension, while the multifidus was the most easily fatigued muscle. Furthermore, the EMG MPF fatigue threshold (MPFFT) of multifidus muscle tension was tested to estimate its maximum workload in the long-term muscle contraction. In conclusion, bending angle should be maintained to a small range or bending should even be avoided during material-handling tasks.

Fatigue induces altered spatial myoelectric activation patterns in the medial gastrocnemius during locomotion

This research investigates the effects of muscle fatigue on spatial myoelectric patterns in the lower limb during locomotion. Both spatial and frequency aspects of neuromuscular recruitment in the medial gastrocnemius change in response to fatigue, resulting in altered myoelectric patterns during walking and running. These data may help us better understand the adaptations that occur in lower limb muscles to avoid overuse injuries caused by fatigue.

Human myoelectric spatial patterns differ among lower limb muscles and locomotion speeds

The spatial distribution of myoelectric activity within lower limb muscles is often nonuniform and can change during different stationary tasks. Recent studies using high-density electromyography (EMG) have suggested that spatial muscle activity may also differ among muscles during locomotion, but contrasting electrode array sizes and experimental designs have limited cross-study comparisons. Here, we sought to determine if spatial EMG patterns differ among lower limb muscles and locomotion speeds. We recorded high-density EMG from the vastus medialis, tibialis anterior, biceps femoris, medial gastrocnemius, and lateral gastrocnemius muscles of 11 healthy subjects while they walked (1.2 and 1.6 m/s) and ran (2.0, 3.0, 4.0, and 5.0 m/s) on a treadmill. To overcome the detrimental effects of cable, electrode, and soft tissue movements on high-density EMG signal quality during locomotion, we applied multivariate signal cleaning methods. From these data, we computed the spatial entropy and center of gravity from the total myoelectric activity within each recording array during the stance or swing phases of the gait cycle. We found heterogeneous spatial EMG patterns evidenced by contrasting spatial entropy among lower limb muscles. As locomotion speed increased, mean entropy values decreased in four of the five recorded muscles, indicating that EMG signal amplitudes were more spatially heterogeneous, or localized, at faster speeds. The EMG center of gravity location also shifted in multiple muscles as locomotion speed increased. Contrasting myoelectric spatial distributions among muscles likely reflect differences in muscle architecture, but increasingly localized activity and spatial shifts in the center of gravity location at faster locomotion speeds could be influenced by preferential recruitment of faster motor units under greater loads.

Evidence of Mitochondrial Dysfunction in Fibromyalgia: Deviating Muscle Energy Metabolism Detected Using Microdialysis and Magnetic Resonance

In fibromyalgia (FM) muscle metabolism, studies are sparse and conflicting associations have been found between muscle metabolism and pain aspects. This study compared alterations in metabolic substances and blood flow in erector spinae and trapezius of FM patients and healthy controls. FM patients (n = 33) and healthy controls (n = 31) underwent a clinical examination that included pressure pain thresholds and physical tests, completion of a health questionnaire, participation in microdialysis investigations of the etrapezius and erector spinae muscles, and also underwent phosphorus-31 magnetic resonance spectroscopy of the erector spinae muscle. At the baseline, FM had significantly higher levels of pyruvate in both muscles. Significantly lower concentrations of phosphocreatine (PCr) and nucleotide triphosphate (mainly adenosine triphosphate) in erector spinae were found in FM. Blood flow in erector spinae was significantly lower in FM. Significant associations between metabolic variables and pain aspects (pain intensity and pressure pain threshold PPT) were found in FM. Our results suggest that FM has mitochondrial dysfunction, although it is unclear whether inactivity, obesity, aging, and pain are causes of, the results of, or coincidental to the mitochondrial dysfunction. The significant regressions of pain intensity and PPT in FM agree with other studies reporting associations between peripheral biological factors and pain aspects.

Physical Condition Factors that Predict a Better Quality of Life in Women with Fibromyalgia

What physical qualities can predict the quality of life (QoL) in women with fibromyalgia (FM)? QoL is a very complex outcome affected by multiple comorbidities in people with fibromyalgia. This study aims to determine which physical qualities can predict the quality of life in women with FM. Also, a comparison between the physical qualities of women with FM and healthy counterparts was conducted. In total, 223 women participated in this cross-sectional study, 123 with FM, with ages ranging between 45 and 70 years. The study was conducted at several fibromyalgia associations and specialized medical units. QoL was measured as the main outcome. In addition, functional capacity, muscular strength, maintenance of thoracic posture, postural control, flexibility, pain threshold, and anxiety were measured. Prediction of the QoL was conducted with multiple linear regression analysis and comparison between groups, using the Mann–Whitney U test. There were significant differences between groups in all the variables measured (p < 0.01). The multiple linear regression model showed that factors influencing QoL in women with FM for all the variables measured were functional capacity, handgrip strength and bicep strength, maintenance of thoracic posture, pain threshold, and anxiety (R² = 0.53, p < 0.05). To conclude, women with FM show a significantly lower QoL than their healthy counterparts, and the factors that predict their perceived QoL are functional capacity, muscular strength, postural maintenance, pain threshold, and anxiety.

Hyperexcitability to Electrical Stimulation and Accelerated Muscle Fatiguability of Taut Bands in Rats

Objective

Myofascial trigger points contribute significantly to musculoskeletal pain and motor dysfunction and may be associated with accelerated muscle fatiguability. The aim of this study was to investigate the electrically induced force and fatigue characteristics of muscle taut bands in rats.

Methods

Muscle taut bands were dissected out and subjected to trains of electrical stimulation. The electrical threshold intensity for muscle contraction and maximum contraction force (MCF), electrical intensity dependent fatigue and electrical frequency dependent fatigue characteristics were assessed in three different sessions (n=10 each) and compared with non-taut bands in the biceps femoris muscle.

Results

The threshold intensity for muscle contraction and MCF at the 10th, 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those of non-taut bands (all p<0.05). The MCF at the 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those at the 1st and 5th stimuli (all p<0.01). The MCF in the frequency dependent fatigue test was significantly higher and the stimulus frequency that induced MCF was significantly lower for taut bands than for non-taut bands (both p<0.01).

Conclusions

The present study demonstrates that the muscle taut band itself was more excitable to electrical stimulation and significantly less fatigue resistant than normal muscle fibres.

The Relationship of Endocannabinoidome Lipid Mediators With Pain and Psychological Stress in Women With Fibromyalgia: A Case-Control Study

Characterized by chronic widespread pain, generalized hyperalgesia, and psychological stress, fibromyalgia (FM) is difficult to diagnose and lacks effective treatments. Endocannabinoids-arachidonoylethanolamide (AEA), 2-arachidonoylglycerol (2-AG), and the related oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and stearoylethanolamide (SEA)-are endogenous lipid mediators with analgesic and anti-inflammatory characteristics, in company with psychological modulating properties (eg, stress and anxiety), and are included in a new emerging "ome," the endocannabinoidome. This case-control study compared the concentration differences of AEA, OEA, PEA, SEA, and 2-AG in 104 women with FM and 116 healthy control subjects. All participants rated their pain, anxiety, depression, and current health status. The relationships between the lipid concentrations and the clinical assessments were investigated using powerful multivariate data analysis and traditional bivariate statistics. The concentrations of OEA, PEA, SEA, and 2-AG were significantly higher in women with FM than in healthy control subjects; significance remained for OEA and SEA after controlling for body mass index and age. 2-AG correlated positively with FM duration and body mass index, and to some extent negatively with pain, anxiety, depression, and health status. In FM, AEA correlated positively with depression ratings. The elevated circulating levels of endocannabinoidome lipids suggest that these lipids play a role in the complex pathophysiology of FM and might be signs of ongoing low-grade inflammation in FM. Although the investigated lipids are significantly altered in FM, their biological roles are uncertain with respect to the clinical manifestations of FM. Thus plasma lipids alone are not good biomarkers for FM. PERSPECTIVE: This study reports about elevated plasma levels of endocannabinoidome lipid mediators in FM. The lipids' suitability to work as biomarkers for FM in the clinic were low; however, their altered levels indicate that a metabolic asymmetry is ongoing in FM, which could serve as a baseline during explorative FM pain management.

Controlled, cross-sectional, multi-center study of physical capacity and associated factors in women with fibromyalgia

Background

Health and physical capacity are commonly associated with disease, age, and socioeconomic factors. The primary objective of this study was to investigate the degree to which physical capacity, defined as muscle strength and walking ability, is decreased in women with fibromyalgia (FM), as compared to healthy women, who are matched for age and level of education. The secondary aim was to investigate whether muscle strength and walking ability are associated with age, symptom duration, activity limitations and, Body Mass Index (BMI) in women with FM and control subjects.

Methods

This controlled, cross-sectional, multi-center study comprised 118 women with FM and 93 age- and education-level-matched healthy women. The outcome measures were isometric knee-extension force, isometric elbow-flexion force, isometric hand-grip force, and walking ability. Differences between the groups were calculated, and for the women with FM analyses of correlations between the measures of physical capacity and variables were performed.

Results

The women with FM showed 20% (p < 0.001) lower isometric knee-extension force, 36% (p < 0.001) lower isometric elbow-flexion force, 34% (p < 0.001) lower isometric hand-grip force, and 16% lower walking ability (p < 0.001), as compared to the healthy controls. All measures of muscle strength in women with FM showed significant weak to moderate relationship to symptom duration (r_s = − 0.23–0.32) and walking ability (r_s = 0.25–0.36). Isometric knee-extension force correlated with activity limitations, as measured using the SF-36 Physical function subscale (r_s=0.23, p = 0.011).

Conclusions

Physical capacity was considerably decreased in the women with FM, as compared to the age- and education-level-matched control group. All measures of physical capacity showed a significant association with symptom duration. Knee-extension force and walking ability were significantly associated with activity limitations, age, and BMI. It seems important to address this problem and to target interventions to prevent decline in muscle strength. Assessments of muscle strength and walking ability are easy to administer and should be routinely carried out in the clinical setting for women with FM.

Trial registration

ClinicalTrials.gov identification number: NCT01226784, Oct 21, 2010.

Alterations of anti-inflammatory lipids in plasma from women with chronic widespread pain - a case control study

Background

Chronic widespread pain conditions (CWP) such as the pain associated with fibromyalgia syndrome (FMS) are significant health problems with unclear aetiology. Although CWP and FMS can alter both central and peripheral pain mechanisms, there are no validated markers for such alterations. Pro- and anti-inflammatory components of the immune system such as cytokines and endogenous lipid mediators could serve as systemic markers of alterations in chronic pain. Lipid mediators associated with anti-inflammatory qualities – e.g., oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and stearoylethanolamide (SEA) – belong to N-acylethanolamines (NAEs). Previous studies have concluded that these lipid mediators may modulate pain and inflammation via the activation of peroxisome proliferator activating receptors (PPARs) and the activation of PPARs may regulate gene transcriptional factors that control the expression of distinct cytokines.

Methods

This study investigates NAEs and cytokines in 17 women with CWP and 21 healthy controls. Plasma levels of the anti-inflammatory lipids OEA, PEA, and SEA, the pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8, and the anti-inflammatory cytokine IL-10 were investigated. T-test of independent samples was used for group comparisons. Bivariate correlation analyses, and multivariate regression analysis were performed between lipids, cytokines, and pain intensity of the participants.

Results

Significantly higher levels of OEA and PEA in plasma were found in CWP. No alterations in the levels of cytokines existed and no correlations between levels of lipids and cytokines were found.

Conclusions

We conclude that altered levels of OEA and PEA might indicate the presence of systemic inflammation in CWP. In addition, we believe our findings contribute to the understanding of the biochemical mechanisms involved in chronic musculoskeletal pain.

Work Ability in Fibromyalgia: An Update in the 21st Century

BACKGROUND

Fibromyalgia (FM) is characterized by persistent widespread pain, increased pain sensitivity and tenderness. People with FM also report activity limitations and impaired work ability.

OBJECTIVE

This article aims to compile the findings of recently published research on work ability in people with fibromyalgia, and to present how work ability is influenced by various aspects.

METHODS

A systematic search of the literature published from the year 2000 and onwards was conducted. Thirtyfour articles were included in the review.

RESULT

Symptom severity was found to influence work ability in people with FM. Physically demanding jobs and work tasks were especially troublesome and were reported to constitute higher risks pof work disability. Working people with FM seemed to hold a careful balancing act to manage the risk of overload where well-functioning strategies such as making a career change, working part-time, and developing personal skills were necessary for managing work, in the short- and long term. The support of management and colleagues enabled people with FM to manage the risk of overload at work. Treatment studies evaluating work disability as outcome in FM are scarce. None of the included studies presented any effects on measures of sick-leave or work disability compared with a control group.

CONCLUSION

More studies of treatment effects on outcomes related to work ability in people with FM, and more longitudinal studies to explore long-term effects of symptoms on work ability and sick leave, are needed in order to be able to plan evidence based rehabilitation to improve or maintain work ability in people with FM.

Increased Interstitial Concentrations of Glutamate and Pyruvate in Vastus Lateralis of Women with Fibromyalgia Syndrome Are Normalized after an Exercise Intervention - A Case-Control Study

BACKGROUND

Fibromyalgia syndrome (FMS) is associated with central alterations, but controversies exist regarding the presence and role of peripheral factors. Microdialysis (MD) can be used in vivo to study muscle alterations in FMS. Furthermore for chronic pain conditions such as FMS, the mechanisms for the positive effects of exercise are unclear. This study investigates the interstitial concentrations of algesics and metabolites in the vastus lateralis muscle of 29 women with FMS and 28 healthy women before and after an exercise intervention.

METHODS

All the participants went through a clinical examination and completed a questionnaire. In addition, their pressure pain thresholds (PPTs) in their upper and lower extremities were determined. For both groups, MD was conducted in the vastus lateralis muscle before and after a 15-week exercise intervention of mainly resistance training of the lower limbs. Muscle blood flow and interstitial muscle concentrations of lactate, pyruvate, glutamate, glucose, and glycerol were determined.

RESULTS

FMS was associated with significantly increased interstitial concentrations of glutamate, pyruvate, and lactate. After the exercise intervention, the FMS group exhibited significant decreases in pain intensity and in mean interstitial concentrations of glutamate, pyruvate, and glucose. The decrease in pain intensity in FMS correlated significantly with the decreases in pyruvate and glucose. In addition, the FMS group increased their strength and endurance.

CONCLUSION

This study supports the suggestion that peripheral metabolic and algesic muscle alterations are present in FMS patients and that these alterations contribute to pain. After an exercise intervention, alterations normalized, pain intensity decreased (but not abolished), and strength and endurance improved, all findings that suggest the effects of exercise are partially peripheral.

Fibromyalgia: A Critical and Comprehensive Review

Fibromyalgia is a disorder that is part of a spectrum of syndromes that lack precise classification. It is often considered as part of the global overview of functional somatic syndromes that are otherwise medically unexplained or part of a somatization disorder. Patients with fibromyalgia share symptoms with other functional somatic problems, including issues of myalgias, arthralgias, fatigue and sleep disturbances. Indeed, there is often diagnostic and classification overlap for the case definitions of a variety of somatization disorders. Fibromyalgia, however, is a critically important syndrome for physicians and scientists to be aware of. Patients should be taken very seriously and provided optimal care. Although inflammatory, infectious, and autoimmune disorders have all been ascribed to be etiological events in the development of fibromyalgia, there is very little data to support such a thesis. Many of these disorders are associated with depression and anxiety and may even be part of what has been sometimes called affected spectrum disorders. There is no evidence that physical trauma, i.e., automobile accidents, is associated with the development or exacerbation of fibromyalgia. Treatment should be placed on education, patient support, physical therapy, nutrition, and exercise, including the use of drugs that are approved for the treatment of fibromyalgia. Treatment should not include opiates and patients should not become poly pharmacies in which the treatment itself can lead to significant morbidities. Patients with fibromyalgia are living and not dying of this disorder and positive outlooks and family support are key elements in the management of patients.

A pilot study of biomechanical assessment before and after an integrative training program for adolescents with juvenile fibromyalgia

BACKGROUND

Adolescents with juvenile fibromyalgia (JFM) tend to be very sedentary and avoid participation in physical activity. A prior study suggested that JFM patients show altered biomechanics compared to healthy adolescents which may make them more prone to pain/injury during exercise. A new intervention combining well established cognitive behavioral therapy (CBT) techniques with specialized neuromuscular exercise -Fibromyalgia Integrative Training for Teens (FIT Teens) was developed and shown to be promising in improving functioning in adolescents with JFM. In contrast to traditional exercise programs such as aerobic or resistance training, neuromuscular training is a tailored approach which targets gait, posture, balance and movement mechanics which form the foundation for safe exercise participation with reduced risk for injury or pain (and hence more tolerable by JFM patients). The aim of this pilot feasibility study was to establish whether objective biomechanical assessment including sophisticated 3-D motion analysis would be useful in measuring improvements in strength, balance, gait, and functional performance after participation in the 8-week FIT Teens program.

METHODS

Eleven female participants with JFM (ages 12-18 years) completed pre- and post-treatment assessments of biomechanics, including walking gait analysis, lower extremity strength assessment, functional performance, and dynamic postural stability.

RESULTS

Descriptive data indicated that mechanics of walking gait and functional performance appeared to improve after treatment. Hip abduction strength and dynamic postural control also demonstrated improvements bilaterally.

CONCLUSIONS

Overall, the results of this pilot study offer initial evidence for the utility of biomechanical assessment to objectively demonstrate observable changes in biomechanical performance after an integrated training intervention for youth with JFM. If replicated in larger controlled studies, findings would suggest that through the FIT Teens intervention, adolescents with JFM can progress towards normalized strength and biomechanics, which may enhance their ability to engage in physical exercise.

Specific proteins of the trapezius muscle correlate with pain intensity and sensitivity - an explorative multivariate proteomic study of the trapezius muscle in women with chronic widespread pain

Chronic widespread pain (CWP) including fibromyalgia syndrome (FMS) has a high prevalence and is associated with prominent negative consequences. CWP/FMS exhibits morphological and functional alterations in the central nervous system. The importance of peripheral factors for maintaining the central alterations are under debate. In this study, the proteins from biopsies of the trapezius muscle from 18 female CWP/FMS patients and 19 healthy female controls were analyzed. Pain intensity and pressure pain thresholds (PPT) over the trapezius muscles were registered. Twelve proteins representing five different groups of proteins were important regressors of pain intensity in CWP/FMS (R²=0.99; P<0.001). In the regression of PPT in CWP/FMS, it was found that 16 proteins representing six groups of proteins were significant regressors (R²=0.95, P<0.05). Many of the important proteins were stress and inflammation proteins, enzymes involved in metabolic pathways, and proteins associated with muscle damage, myopathies, and muscle recovery. The altered expression of these proteins may reflect both direct and indirect nociceptive/inflammatory processes as well as secondary changes. The relative importance of the identified proteins and central alterations in CWP need to be investigated in future research. Data from this and the previous study concerning the same cohorts give support to the suggestion that peripheral factors are of importance for maintaining pain aspects in CWP/FMS.

Protein alterations in women with chronic widespread pain--An explorative proteomic study of the trapezius muscle

Chronic widespread pain (CWP) has a high prevalence in the population and is associated with prominent negative individual and societal consequences. There is no clear consensus concerning the etiology behind CWP although alterations in the central processing of nociception maintained by peripheral nociceptive input has been suggested. Here, we use proteomics to study protein changes in trapezius muscle from 18 female patients diagnosed with CWP compared to 19 healthy female subjects. The 2-dimensional gel electrophoresis (2-DE) in combination with multivariate statistical analyses revealed 17 proteins to be differently expressed between the two groups. Proteins were identified by mass spectrometry. Many of the proteins are important enzymes in metabolic pathways like the glycolysis and gluconeogenesis. Other proteins are associated with muscle damage, muscle recovery, stress and inflammation. The altered expressed levels of these proteins suggest abnormalities and metabolic changes in the myalgic trapezius muscle in CWP. Taken together, this study gives further support that peripheral factors may be of importance in maintaining CWP.

Resistance exercise improves muscle strength, health status and pain intensity in fibromyalgia--a randomized controlled trial

Introduction

Fibromyalgia (FM) is characterized by persistent widespread pain, increased pain sensitivity and tenderness. Muscle strength in women with FM is reduced compared to healthy women. The aim of this study was to examine the effects of a progressive resistance exercise program on muscle strength, health status, and current pain intensity in women with FM.

Methods

A total of 130 women with FM (age 22–64 years, symptom duration 0–35 years) were included in this assessor-blinded randomized controlled multi-center trial examining the effects of progressive resistance group exercise compared with an active control group. A person-centred model of exercise was used to support the participants’ self-confidence for management of exercise because of known risks of activity-induced pain in FM. The intervention was performed twice a week for 15 weeks and was supervised by experienced physiotherapists. Primary outcome measure was isometric knee-extension force (Steve Strong®), secondary outcome measures were health status (FIQ total score), current pain intensity (VAS), 6MWT, isometric elbow-flexion force, hand-grip force, health related quality of life, pain disability, pain acceptance, fear avoidance beliefs, and patient global impression of change (PGIC). Outcomes were assessed at baseline and immediately after the intervention. Long-term follow up comprised the self-reported questionnaires only and was conducted after 13–18 months. Between-group and within-group differences were calculated using non-parametric statistics.

Results

Significant improvements were found for isometric knee-extension force (p = 0.010), health status (p = 0.038), current pain intensity (p = 0.033), 6MWT (p = 0.003), isometric elbow flexion force (p = 0.02), pain disability (p = 0.005), and pain acceptance (p = 0.043) in the resistance exercise group (n = 56) when compared to the control group (n = 49). PGIC differed significantly (p = 0.001) in favor of the resistance exercise group at post-treatment examinations. No significant differences between the resistance exercise group and the active control group were found regarding change in self-reported questionnaires from baseline to 13–18 months.

Conclusions

Person-centered progressive resistance exercise was found to be a feasible mode of exercise for women with FM, improving muscle strength, health status, and current pain intensity when assessed immediately after the intervention.

Trial registration

ClinicalTrials.gov identification number: NCT01226784, Oct 21, 2010.

Three-dimensional scapular motion during arm elevation is altered in women with fibromyalgia

BACKGROUND

The core feature of fibromyalgia is pain, which may play a role in various mechanisms that might lead to alterations in shoulder kinematics. Alterations in muscle activity and presence of tender points in the shoulder girdle have already been described in this population; however there is lack of evidence on three-dimensional scapular motion in women with fibromyalgia.

METHODS

Forty women with fibromyalgia and 25 healthy women (control group) matched in terms of age, weight and height, took part in this study. Three-dimensional scapular kinematics of the dominant arm were collected during elevation and lowering of the arm in the sagittal and scapular planes. Pain was evaluated by the Visual Analogue Scale and the Numerical Pain Rating Scale. Group comparisons were performed with one-way ANOVA for pain and two-way ANOVA for the kinematic variables (scapular internal/external rotation, upward/downward rotation and anterior/posterior tilt), with group and humeral elevation angle as categorical factors. Significance level was set at P<0.05.

FINDINGS

Fibromyalgia women presented higher pain scores (P<0.001) than the control group. Fibromyalgia women also presented greater scapular upward rotation (P<0.001, both planes) and greater scapular posterior tilt (P<0.001, both planes) than the control group.

INTERPRETATION

Women with fibromyalgia present greater scapular upward rotation and posterior tilt in the resting position and during arm elevation and lowering of the arm in sagittal and scapular planes. These alterations may be a compensatory mechanism to reduce pain during arm movement.

Pain severity is associated with muscle strength and peak oxygen uptake in adults with fibromyalgia

Background

The associations between pain, lower extremity strength, and aerobic conditioning have not been widely investigated in adults with fibromyalgia (FM). The principle objective of this study was to investigate the relationship between pain severity and knee strength in patients seeking treatment for FM. A secondary objective was to investigate the relationship between pain scores and aerobic conditioning.

Methods

Three measures of knee strength (isokinetic extensor, isokinetic flexor, isometric extensor) were quantified in the dominant leg of 69 adults with FM using a dynamometer at speeds of 60 degrees per second (60°/s) and 180°/s. Peak oxygen uptake (VO₂) was assessed using a cycle ergometer, and pain was assessed using the pain severity subscale of the Multidimensional Pain Inventory.

Results

In univariable linear regression analyses using pain severity as the dependent variable, lesser values of isokinetic knee extensor strength at 60°/s (P=0.041) and 180°/s (P=0.010), isokinetic knee flexor strength at 60°/s (P=0.028) and 180°/s (P=0.003), and peak VO₂ uptake (P=0.031) were predictive of greater pain severity scores. In multiple variable linear regression models adjusted for age, sex, body mass index, and opioid use, the following associations retained statistical significance; isokinetic knee extensor strength at 60°/s (P=0.020) and 180°/s (P=0.003), isokinetic knee flexor strength at 60°/s (P=0.015) and 180°/s (P=0.001), and peak VO₂ uptake (P=0.014). However, no significant associations were found between pain severity and isometric knee extensor strength.

Conclusion

The main findings from this study were that lesser values of isokinetic knee strength and peak VO₂ uptake were predictive of greater pain severity scores. These results build on the findings of previous investigations, but ongoing research is needed to further characterize the effects of strength and peak VO₂ uptake on the pathophysiology of FM.

Pain characteristics associated with the onset of disability in older adults: the maintenance of balance, independent living, intellect, and zest in the Elderly Boston Study

OBJECTIVES

To determine the effects of chronic pain on the development of disability and decline in physical performance over time in older adults.

DESIGN

Longitudinal cohort study with 18 months of follow-up.

SETTING

Urban and suburban communities.

PARTICIPANTS

Community-dwelling older adults aged 65 and older (N = 634).

MEASUREMENTS

Chronic pain assessment consisted of musculoskeletal pain locations and pain severity and pain interference according to the subscales of the Brief Pain Inventory. Disability was self-reported as any difficulty in mobility and basic and instrumental activities of daily living (ADLs, IADLs). Mobility performance was measured using the Short Physical Performance Battery (SPPB). Relationships between baseline pain and incident disability in 18 months were determined using risk ratios (RRs) from multivariable Poisson regression models.

RESULTS

Almost 65% of participants reported chronic musculoskeletal pain at baseline. New onset of mobility difficulty at 18 months was strongly associated with baseline pain distribution: 7% (no sites), 18% (1 site), 24% (multisite), and 39% (widespread pain, P-value for trend < .001). Similar graded effects were found for other disability measures. Elderly adults with multisite or widespread pain had at a risk of onset of mobility difficulty at least three times as great as that of their peers without pain after adjusting for disability risk factors (multisite pain: risk ratio (RR) = 2.95, 95% confidence interval (CI) 1.58-5.50; widespread pain: RR = 3.57, 95% CI = 1.71-7.48). Widespread pain contributed to decline in mobility performance (1-point decline in SPPB, RR = 1.47, 95% CI = 1.08-2.01). Similar associations were found for baseline pain interference predicting subsequent mobility decline and ADL and IADL disability. Weaker and less-consistent associations were observed with pain severity.

CONCLUSION

Older community-dwelling adults living with chronic pain in multiple musculoskeletal locations have a substantially greater risk for developing disability over time and for clinically meaningful decline in mobility performance than those without pain.

Forelimb brachial muscle activation patterns using surface electromyography and their relationship to kinematics in normal dogs walking and trotting

The objective of this study was to determine activity of the elbow flexor and elbow extensor groups of muscles relative to shoulder and elbow joint kinematics in normal walking and trotting dogs using surface electromyography (EMG), and to determine if muscle activity varies with gait or limb. Ten healthy mixed-breed dogs were walked and trotted across embedded force plates in a 6 m walkway while simultaneously recording muscle activation using surface EMG positioned over the biceps brachii (elbow flexor group) and triceps brachii (elbow extensor group); peak shoulder, elbow, and carpal joint angles from motion capture, and ground reaction forces. EMG magnitude, timing, and power spectral density (PSD) were used to analyse muscle activity. The effects of gait type and limb side on EMG measures and joint angles were assessed using an analysis of variance. Results showed that the elbow flexor group was maximally active at end of stance. The elbow extensor group was maximally active at the beginning of stance. Muscle activity occurred earlier in the gait phase (stance or swing) in the trot compared to the walk. The amplitude, frequency at maximum PSD (elbow flexor group only) and the median frequency were larger on the right side than on the left side. The maximum PSD and integrated PSD were larger on the left side than the right side. These data provide a reference for identifying abnormalities associated with orthopaedic, neurological, or rehabilitative changes. Limb asymmetry observed in muscle activation in clinically normal dogs should be further evaluated.

Psychological processing in chronic pain: a neural systems approach

Our understanding of chronic pain involves complex brain circuits that include sensory, emotional, cognitive and interoceptive processing. The feed-forward interactions between physical (e.g., trauma) and emotional pain and the consequences of altered psychological status on the expression of pain have made the evaluation and treatment of chronic pain a challenge in the clinic. By understanding the neural circuits involved in psychological processes, a mechanistic approach to the implementation of psychology-based treatments may be better understood. In this review we evaluate some of the principle processes that may be altered as a consequence of chronic pain in the context of localized and integrated neural networks. These changes are ongoing, vary in their magnitude, and their hierarchical manifestations, and may be temporally and sequentially altered by treatments, and all contribute to an overall pain phenotype. Furthermore, we link altered psychological processes to specific evidence-based treatments to put forth a model of pain neuroscience psychology.

Facial pain associated with fibromyalgia can be marked by abnormal neuromuscular control: a cross-sectional study

BACKGROUND

Temporomandibular disorder (TMD) development in fibromyalgia syndrome (FMS) is not yet fully understood, but altered neuromuscular control in FMS may play a role in triggering TMD.

OBJECTIVE

The purpose of this study was to verify the association between neuromuscular control and chronic facial pain in groups of patients with FMS and TMD.

DESIGN

A cross-sectional study was conducted.

METHODS

This study involved an analysis of facial pain and electromyographic activity of the masticatory muscles in patients with FMS (n=27) and TMD (n=28). All participants were evaluated according to Research Diagnostic Criteria for Temporomandibular Disorders and surface electromyography (SEMG). Myoelectric signal calculations were performed using the root mean square and median frequency of signals.

RESULTS

The data revealed premature interruption of masticatory muscle contraction in both patient groups, but a significant correlation also was found between higher median frequency values and increased facial pain. This correlation probably was related to FMS because it was not found in patients with TMD only. Facial pain and increased SEMG activity during mandibular rest also were positively correlated.

LIMITATIONS

Temporal conclusions cannot be drawn from the study. Also, the study lacked a comparison group of patients with FMS without TMD as well as a control group of individuals who were healthy.

CONCLUSIONS

Altered neuromuscular control in masticatory muscles may be correlated with perceived facial pain in patients with FMS.

Decreased muscle concentrations of ATP and PCR in the quadriceps muscle of fibromyalgia patients--a 31P-MRS study

BACKGROUND AND METHODS

Fibromyalgia (FMS) has a prevalence of approximately 2% in the population. Central alterations have been described in FMS, but there is not consensus with respect to the role of peripheral factors for the maintenance of FMS. 31P magnetic resonance spectroscopy (31P-MRS) has been used to investigate the metabolism of phosphagens in muscles of FMS patients, but the results in the literature are not in consensus. The aim was to investigate the quantitative content of phosphagens and pH in resting quadriceps muscle of patients with FMS (n = 19) and in healthy controls (CONTROLS; n = 14) using (31) P-MRS. It was also investigated whether the concentrations of these substances correlated with measures of pain and/or physical capacity.

RESULTS

Significantly lower concentrations of adenosine triphosphate (ATP) and phosphocreatinine (PCr; 28-29% lower) were found in FMS. No significant group differences existed with respect to inorganic phosphate (Pi), Pi/PCr and pH. The quadriceps muscle fat content was significantly higher in FMS than in CONTROLS [FMS: 9.0 ± 0.5% vs.

CONTROLS

6.6 ± 0.6%; (mean ± standard error); P = 0.005]. FMS had significantly lower hand and leg capacity according to specific physical test, but there were no group differences in body mass index, subjective activity level and in aerobic fitness. In FMS, the specific physical capacity in the leg and the hand correlated positively with the concentrations of ATP and PCr; no significant correlations were found with pain intensities.

CONCLUSIONS

Alterations in intramuscular ATP, PCr and fat content in FMS probably reflect a combination of inactivity related to pain and dysfunction of muscle mitochondria.

Upper limb position control in fibromyalgia

BACKGROUND

Motor problems are reported by patients with fibromyalgia (FM). However, the mechanisms leading to alterations in motor performance are not well understood. In this study, upper limb position control during sustained isometric contractions was investigated in patients with FM and in healthy controls (HCs).

METHODS

Fifteen female FM patients and 13 HCs were asked to keep a constant upper limb position during sustained elbow flexion and shoulder abduction, respectively. Subjects received real-time visual feedback on limb position and both tasks were performed unloaded and while supporting loads (1, 2, and 3 kg). Accelerations of the dominant upper limb were recorded, with variance (SD of mean position) and power spectrum analysis used to characterize limb position control. Normalized power of the acceleration signal was extracted for three frequency bands: 1-3 Hz, 4-7 Hz, and 8-12 Hz.

RESULTS

Variance increased with load in both tasks (P < 0.001) but did not differ significantly between patients and HCs (P > 0.17). Power spectrum analysis showed that the FM patients had a higher proportion of normalized power in the 1-3 Hz band, and a lower proportion of normalized power in the 8-12 Hz band compared to HCs (P < 0.05). The results were consistent for all load conditions and for both elbow flexion and shoulder abduction.

CONCLUSION

FM patients exhibit an altered neuromuscular strategy for upper limb position control compared to HCs. The predominance of low-frequency limb oscillations among FM patients may indicate a sensory deficit.

Accelerated muscle fatigability of latent myofascial trigger points in humans

OBJECTIVE

Muscle fatigue is prevalent in acute and chronic musculoskeletal pain conditions in which myofascial trigger points (MTPs) are involved. The aim of this study was to investigate the association of latent MTPs with muscle fatigue.

DESIGN

Intramuscular electromyographic (EMG) recordings were obtained from latent MTPs and non-MTPs together with surface EMG recordings from the upper trapezius muscles during sustained isometric muscle contractions in 12 healthy subjects.

OUTCOME MEASURES

Normalized root mean square (RMS) EMG amplitude and mean power frequency (MNF) were analyzed. The rate of perceived exertion and pain intensity from MTP side and non-MTP side were recorded.

RESULTS

Pain intensity on the MTP side was significantly higher than the non-MTP side (P < 0.05). Intramuscular EMG from latent MTPs showed an early onset of decrease in MNF and a significant decrease at the end of fatiguing contraction as compared with non-MTPs (P < 0.05). Surface EMG from muscle fibers close to latent MTPs presented with an early onset of the increase in RMS amplitude and the increase was significantly higher than that from non-MTPs at the end of sustained isometric contraction (P < 0.05).

CONCLUSIONS

A latent MTP is associated with an accelerated development of muscle fatigue and simultaneously overloading active motor units close to an MTP. Elimination of latent MTPs and inactivation of active MTPs may effectively reduce accelerated muscle fatigue and prevent overload spreading within a muscle.

Latent myofascial trigger points

A latent myofascial trigger point (MTP) is defined as a focus of hyperirritability in a muscle taut band that is clinically associated with local twitch response and tenderness and/or referred pain upon manual examination. Current evidence suggests that the temporal profile of the spontaneous electrical activity at an MTP is similar to focal muscle fiber contraction and/or muscle cramp potentials, which contribute significantly to the induction of local tenderness and pain and motor dysfunctions. This review highlights the potential mechanisms underlying the sensory-motor dysfunctions associated with latent MTPs and discusses the contribution of central sensitization associated with latent MTPs and the MTP network to the spatial propagation of pain and motor dysfunctions. Treating latent MTPs in patients with musculoskeletal pain may not only decrease pain sensitivity and improve motor functions, but also prevent latent MTPs from transforming into active MTPs, and hence, prevent the development of myofascial pain syndrome.

Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagation

Active myofascial trigger points are one of the major peripheral pain generators for regional and generalized musculoskeletal pain conditions. Myofascial trigger points are also the targets for acupuncture and/or dry needling therapies. Recent evidence in the understanding of the pathophysiology of myofascial trigger points supports The Integrated Hypothesis for the trigger point formation; however unanswered questions remain. Current evidence shows that spontaneous electrical activity at myofascial trigger point originates from the extrafusal motor endplate. The spontaneous electrical activity represents focal muscle fiber contraction and/or muscle cramp potentials depending on trigger point sensitivity. Local pain and tenderness at myofascial trigger points are largely due to nociceptor sensitization with a lesser contribution from non-nociceptor sensitization. Nociceptor and non-nociceptor sensitization at myofascial trigger points may be part of the process of muscle ischemia associated with sustained focal muscle contraction and/or muscle cramps. Referred pain is dependent on the sensitivity of myofascial trigger points. Active myofascial trigger points may play an important role in the transition from localized pain to generalized pain conditions via the enhanced central sensitization, decreased descending inhibition and dysfunctional motor control strategy.

Comparative muscle study fatigue with sEMG signals during the isotonic and isometric tasks for diagnostics purposes

The study of fatigue is an important tool for diagnostics of disease, sports, ergonomics and robotics areas. This work deals with the analysis of sEMG most important fatigue muscle indicators with use of signal processing in isometric and isotonic tasks with the propose of standardizing fatigue protocol to select the data acquisition and processing with diagnostic proposes. As a result, the slope of the RMS, ARV and MNF indicators were successful to describe the fatigue behavior expected. Whereas that, MDF and AIF indicators failed in the description of fatigue. Similarly, the use of a constant load for sEMG data acquisition was the best strategy in both tasks.