Physiological responses to low-force work and psychosocial stress in women with chronic trapezius myalgia

Myofascial release for adults with chronic neck pain and depression

BACKGROUND

Depression affects a significant portion of the global adult population, with chronic pain patients being particularly susceptible to severe depression. Pain and mental illness contribute to an imbalance in the autonomic nervous system, affecting heart function. Myofascial release promises to improve mental and physical health by addressing fascial dysfunctions.

OBJECTIVE

This study aims to investigate the influence of myofascial release on emotional states and autonomic nervous system functioning in individuals with chronic neck pain and depression. Additionally, it seeks to evaluate the myofascial release effect on fascial properties, pain intensity and sensitivity, and cervical spine range of motion.

METHOD

Experimental Study.

RESULT

The study revealed significant enhancements in the myofascial release group, such as a substantial reduction in pain perception and stiffness, increased range of motion of the cervical spine, heart rate variability, positive affect, and pressure pain threshold. The effect sizes of these improvements ranged from small to large. No significant differences were observed in elasticity and tone.

CONCLUSION

The findings suggest that myofascial release has a positive impact on individuals with chronic neck pain and depression, particularly in reducing pain intensity. Integrating myofascial release into treatment approaches may be beneficial. However, further research is needed to confirm and expand upon these findings, explore long-term effects, and better understand the clinical significance of certain outcomes.

TRIAL REGISTRATION

http://www.osf.io, doi.org/10.17605/OSF.IO/6F5RS.

Happy Enough to Relax? How Positive and Negative Emotions Activate Different Muscular Regions in the Back - an Explorative Study

Embodiment theories have proposed a reciprocal relationship between emotional state and bodily reactions. Besides large body postures, recent studies have found emotions to affect rather subtle bodily expressions, such as slumped or upright sitting posture. This study investigated back muscle activity as an indication of an effect of positive and negative emotions on the sitting position. The electromyography (EMG) activity of six back muscles was recorded in 31 healthy subjects during exposure to positive and negative affective pictures. A resting period was used as a control condition. Increased muscle activity patterns in the back were found during the exposure to negative emotional stimuli, which was mainly measured in the lumbar and thorax regions. The positive emotion condition caused no elevated activity. The findings show that negative emotions lead to increased differential muscle activity in the back and thus corroborate those of previous research that emotion affects subtle bodily expressions.

The use of surface electromyography in rehabilitating rheumatic patients after knee arthroplasty (pilot study)

Objectives

The aim of the conducted research was to assess muscle performance in rheumatic patients qualified for knee arthroplasty before and after surgical treatment.

Material and methods

Patients with the diagnosis of rheumatoid arthritis or a degenerative joint disease qualified for surgical treatment were examined. Three groups were analysed: 1) a control group, 2) a group of patients qualified for knee arthroplasty (G1), 3) a group of patients with one knee joint endoprosthesis qualified for the second surgery (G2). The study was carried out through a portable surface electromyography system from Noraxon U.S.A. INC., Clinical DTS and using surface electrodes. The surface electromyography (sEMG) examination was conducted twice: before and on the 10th day after the surgery. The study concerned the quadriceps femoris muscle, i.e. its straight and medial head in both lower limbs during isometric tension and active movement.

Results

The comparison of the examined muscles’ activity in the control group revealed greatly increased activity during isometric tension than during active movement in both muscles. In the G1 group, the comparison of the average values of isometric tension of the examined muscles before the surgery showed slight differences between the healthy limb and the one qualified for the surgical treatment. After the surgery, significant asymmetry between the average values achieved by the healthy and the operated limb could be identified in both muscles. In the G2 group, muscle activity within the currently operated limb revealed only slight differences between the limbs before the surgery. After the surgery, there was an increase in muscle activity within the previously operated limb.

Conclusions

Considerably higher average values of muscle activity during the isometric tension, when compared to the active movement in a sitting position, indicate the necessity of more widespread use of isometric tension in rehabilitating patients after knee arthroplasty.

Differences in the Mitochondrial and Lipid Droplet Morphology in Female Office Workers With Trapezius Myalgia, Compared With Healthy Controls: A Muscle Biopsy Study

OBJECTIVE

Trapezius myalgia or, more specifically, myofascial dysfunction of the upper trapezius mainly affects women performing jobs requiring prolonged low level activation of the muscle. This continuous low muscle load can be accompanied by a shift to a more anaerobic energy metabolism, causing pain. The aim of the study was to investigate whether morphological signs of an impaired aerobic metabolism are present in female office workers with trapezius myalgia.

DESIGN

Muscle biopsy analysis, using electron and light microscopy, was performed to compare mitochondrial and fat droplet morphology, and irregular muscle fibers, between female office workers with (n = 17) and without (n = 15) work-related trapezius myalgia.

RESULTS

The patient group showed a significantly higher mean area (P = 0.023) and proportion (P = 0.029) for the subsarcolemmal and intermyofibrillar mitochondria respectively, compared with the control group. A significantly lower mean area of subsarcolemmal lipid droplets was found in the patient group (P = 0.015), which also displayed a significantly higher proportion of lipid droplets touching the mitochondria (P = 0.035). A significantly higher amount of muscle fibers with cytochrome c oxidase-deficient areas were found in the patient group (P = 0.030).

CONCLUSIONS

The results of the present study may be indicative for an impaired oxidative metabolism in work-related trapezius myalgia. However, additional research is necessary to confirm this hypothesis.

Could Alcohol Abuse Drive Intimate Partner Violence Perpetrators' Psychophysiological Response to Acute Stress?

Proactively aggressive individuals have been shown to present a different pattern of autonomic nervous system (ANS) dysregulation from that of individuals characterized by reactive violence. Although attempts have been made to classify intimate partner violence (IPV) perpetrators based on ANS reactivity to acute stress, subsequent studies have failed to replicate this classification. Notably, the proposed classification neglected the role of chronic alcohol abuse in ANS dysregulation and the fact that this dysregulation entails an abnormal stress response. The aim of the present study was to analyze the response profile (psychological state and ANS response) of groups of IPV perpetrators with high (n = 27) and low (n = 33)-risk alcohol use to an acute stressor, compared to controls (n = 35). All IPV perpetrators scored higher on executive dysfunctions and impulsivity and showed larger decreases in positive affect, less satisfaction, and a higher external locus of control after the stressor than controls. IPV perpetrators with low-risk alcohol use had higher skin conductance levels and breathing reactivity than controls, especially during preparatory, task, and recovery periods. This information could help to develop methods for increasing batterers’ behavioral self-regulation, thus decreasing IPV recidivism risk.

The association between neck and shoulder discomfort-Katakori-and high somatizing tendency

Objectives: 'Katakori', discomfort or dull pain around the neck and shoulder, is common in Japan. Somatizing tendency is important in the quality of daily living. This study aimed to examine the association between disability due to Katakori and high somatizing tendency.Methods: This internet study included 34,754 Japanese adults who reported Katakori in the past four weeks. Katakori was classified into four grades: 1) no Katakori, 2) Katakori without difficulty in activities for daily living (ADL), 3) Katakori with ADL difficulty but without absence from social activities, and 4) Katakori with absence from social activities. Somatizing tendency was assessed using the Somatic Symptom Scale-8 (SSS-8). The association between a very high (SSS-8 ≥ 16) somatizing tendency and Katakori grade was examined using logistic regression adjusting for age, sex, body mass index, marital status, smoking, regular exercise, low back pain, depression, and the number of chronic conditions.Results: Katakori grade was significantly associated with a very high somatizing tendency (Odds ratio (OR)= 5.36 [4.36-6.60] in grade 4 vs. 2, and OR= 2.57 [2.30-2.89] in grade 3 vs. 2).Conclusion: When treating severe Katakori with disability, somatizing tendency should be assessed to facilitate better management.

Changes in the bioelectric activity of the trapezius muscle following the thermal effect of red light and infrared radiation

BACKGROUND

The therapeutic effects of visible light and infrared is especially often used in physiotherapy.

OBJECTIVE

The purpose of this study was to determine the effect of exposure to radiation on the motor units activity.

METHODS

The study included 29 volunteers of whom the spontaneous and voluntary bioelectric activity of the trapezius muscle was evaluated using surface electromyography (value of average amplitude and frequency), before and immediately after a 15-minute irradiation. Additionally, the range of motion of the cervical spine and trigger points pain sensitivity to the pressure were assessed.

RESULTS

No statistically significant changes in the pain sensitivity threshold and the range of motion after the irradiation was applied. On the other hand, a 15-minute exposure to radiation induced an increase in the value of average amplitude of rest-related as well as exercise-related potentials and an increase in the average value of frequency of the right side biopotentials at rest and of both sides for active elevation.

CONCLUSIONS

Infrared radiation and visible red light have a stimulating effect on the muscle ability to develop active contraction. It is proposed that the observed changes are associated with the thermal effect of radiation as well as with the so-called extra-visual effects.

Influence of Regular Physical Activity and Fitness on Stress Reactivity as Measured with the Trier Social Stress Test Protocol: A Systematic Review

BACKGROUND

Psychosocial stress is associated with multiple health complaints. Research to date suggests that regular physical activity (PA) and higher cardiorespiratory fitness may reduce stress reactivity and therefore contribute to a reduction of stress-related risk factors. While previous reviews have not differentiated between stressors, we focus on psychosocial stress elicited with the Trier Social Stress Test (TSST).

OBJECTIVE

Our objective was to examine the effect of regular PA and cardiorespiratory fitness on stress reactivity, with a particular focus on the TSST. The TSST is the laboratory task most widely used to induce socio-evaluative stress and elicits stronger stress reactions than most other cognitive stressor tasks.

METHODS

A systematic search within various databases was performed in January 2018. The following outcomes were considered: cortisol, heart rate, psychological stress reactivity, and potential moderators (age, sex, exercise intensity, assessment mode, and psychological constructs).

RESULTS

In total, 14 eligible studies were identified. Cortisol and heart rate reactivity were attenuated by higher PA or better fitness in seven of twelve studies and four of nine studies, respectively. Two of four studies reported smaller increases in anxiety and smaller decreases in calmness in physically active/fitter participants. Three of four studies found that higher PA/fitness was associated with more favorable mood in response to the TSST.

CONCLUSION

About half of the studies suggested that higher PA/fitness levels were associated with an attenuated response to psychosocial stress. Currently, most evidence is based on cross-sectional analyses. Therefore, a great need for further studies with longitudinal or experimental designs exists.

Intrinsic Laryngeal Muscle Response to a Public Speech Preparation Stressor

PURPOSE

Research suggests that abnormal levels of intrinsic laryngeal muscle (ILM) contraction is a potential causal factor in stress-induced voice disorders. This study seeks to characterize the ILM stress response in a cohort of vocally healthy women.

METHOD

The authors used an unblinded, nonrandomized, repeated-measures design. Forty vocally healthy female adults were subjected to a stressful speech preparation task. Measurements of heart rate, blood pressure, trapezius muscle (positive control) activation, and tibialis muscle (negative control) activation were obtained from 37 participants before and during stressor exposure, in a nonvoice and nonspeaking task paradigm, to confirm physiological stress response compared to baseline. Fine wire electromyography of the ILMs (posterior cricoarytenoid, thyroarytenoid/lateral cricoarytenoid muscle complex, and cricothyroid) was performed simultaneously so that the activity of these muscles could be measured prior to and during stressor exposure.

RESULTS

The protocol successfully elicited the typical and expected physiological stress responses. Findings supported the hypothesis that, in some individuals, the ILMs significantly increase in activity during stress reactions compared to baseline, as do the control muscles.

CONCLUSIONS

This study characterizes ILM responses to psychological stress in vocally healthy participants. Some of the female adults in this study appeared to be "laryngeal stress responders," as evidenced by increased activity of the ILMs during a silent (i.e., nonvocal, nonspeech) speech preparation task that they considered to be stressful.

Normalization of the trapezius sEMG signal - a reliability study on women with and without neck-shoulder pain

Objective

To evaluate within- and between-days reliability of two normalization methods of surface electromyography (sEMG) recordings of the trapezius muscle.

Methods

Nineteen women were allocated into 2 groups (healthy and with neck-shoulder pain). The sEMG was recorded in two sessions with 7 days in between sessions. The four portions of the trapezius muscle (the clavicular and acromial fibers of the upper trapezius, the middle and the lower trapezius) were evaluated during maximal and submaximal isometric voluntary contractions. The within- and between-days reliability of both maximal and submaximal contractions were assessed through Intraclass Correlation Coefficient (ICC_(2,1) was used for within-day analyses of both maximal and submaximal contractions, and for between-days analyses of maximal contractions while ICC_(2,3) was used for between-days analyses of submaximal contractions), Coefficient of Variation, Standard Error of Measurement, and Bland–Altman analysis.

Results

In general, submaximal contractions presented higher within-day reliability, with higher ICC values (e.g., middle trapezius – mean of 0.97), smaller Coefficient of Variation and Standard Error of Measurement ranges compared to maximal contractions (ICC values, e.g. for middle trapezius – mean of 0.94) in both groups. The same pattern was observed for between-days analyses, with submaximal contractions presenting higher ICC values (e.g., middle trapezius – mean of 0.84), smaller Coefficient of Variation and Standard Error of Measurement ranges than maximal contractions (ICC values, e.g. for middle trapezius – mean of 0.73) in both groups.

Conclusion

Submaximal contractions are recommended for normalization procedures of trapezius sEMG, in both subjects with neck-shoulder pain and healthy individuals.

The coordination of shoulder girdle muscles during repetitive arm movements at either slow or fast pace among women with or without neck-shoulder pain

PURPOSE

The aim of this study was to evaluate the coordination of the shoulder girdle muscles among subjects with or without neck-shoulder pain performing repetitive arm movement at either a slow or fast pace.

METHODS

Thirty female adults were allocated to one of two groups-healthy controls or cases with neck-shoulder pain. Surface electromyography (sEMG) signals from the clavicular, acromial, middle and lower trapezius portions and the serratus anterior muscles were recorded during a task performed for 20min at a slow pace and 20min at a fast pace. The root mean square (RMS), relative rest time (RRT) and normalised mutual information (NMI, an index of functional connectivity between two muscles in a pair) were computed.

RESULTS

No significant differences on RMS, RRT and NMI were found between groups. For both groups, the fast movement pace resulted in increased levels of RMS, lower degrees of RRT and higher NMI compared to the slow pace. No interaction between group and movement pace was found.

CONCLUSIONS

This study highlights the change in sEMG activity of muscles to meet the demands of performing a task at fast movement pace. The fast pace imposed a higher muscle demand evidenced by increased sEMG amplitude, low degree of muscle rest and increased functional connectivity for subjects in both the case and control groups. No indication of impaired sEMG activity was found in individuals with neck-shoulder pain.

Morphological and physiological differences in the upper trapezius muscle in patients with work-related trapezius myalgia compared to healthy controls: A systematic review

BACKGROUND

Trapezius myalgia is a common musculoskeletal complaint, characterized by pain, stiffness and tightness of the upper trapezius muscle. It is often work-related and caused by prolonged static and repetitive work tasks. It is hypothesized that this leads to various morphological and physiological alterations in muscle tissue but the pathophysiology is poorly understood. These alterations can be investigated by analysing muscle biopsies in order to reveal the underlying cellular mechanisms.

OBJECTIVES

This systematic review aimed at providing a summary of the existing literature regarding morphological and physiological differences between people with work-related trapezius myalgia and healthy controls, obtained by analysing muscle biopsies.

DESIGN

Systematic review.

METHODS

A systematic literature search was performed in following databases: Pubmed, Web of Science and Embase by using different keyword combinations. This systematic review is reported following the PRISMA guidelines.

RESULTS

Generally, low to moderate evidence was found for the absence of differences in muscle morphology in people with trapezius myalgia, compared to healthy controls. However, significant differences were mainly found in comparison with the control group with another occupation than the myalgic group. It can thus be hypothesized that morphological alterations in muscle tissue are related to work load and not to pain. Low to moderate evidence was also found for the absence of differences at the physiological level.

CONCLUSIONS

Based on this systematic review, there are no clear differences in muscle morphology and physiology between subjects with trapezius myalgia and healthy controls.

Differences in the activation and co-activation ratios of the four subdivisions of trapezius between genders following a computer typing task

The aim of this study was to provide a description of gender differences of the activation patterns of the four subdivisions of the trapezius (clavicular, upper, middle, lower) following a 60min computer work task. Surface EMG was collected from these subdivisions from 21 healthy subjects during bilateral arm elevation pre-/post- task. Subjects completed a standardized 60min computer work task at a standard, ergonomic workstation. Normalized activation and activation ratios of each trapezius subdivision were compared between genders and condition with repeated measures ANOVAs. The interaction effect of Gender×Condition for upper trapezius% activation approached significance at p=0.051with males demonstrating greater activation post-task. The main effect of Condition was statistically significant for% activation of middle and lower trapezius (p<0.05), with both muscles demonstrating increase activation post-task. There was a statistically significant interaction effect of Gender×Condition for the Middle Trapezius/Upper Trapezius ratio and main effect of Condition for the Clavicular Trapezius/Upper Trapezius ratio, with a decreased ratio post-typing. Gender differences exist following 60min of a low force computer typing task. Imbalances in muscle activation and activation ratios following computer work may affect total shoulder kinematics and should be further explored.

Long-Term Monitoring of Physical Behavior Reveals Different Cardiac Responses to Physical Activity among Subjects with and without Chronic Neck Pain

Background. We determined the extent to which heart rate variability (HRV) responses to daily physical activity differ between subjects with and without chronic neck pain. Method. Twenty-nine subjects (13 women) with chronic neck pain and 27 age- and gender-matched healthy controls participated. Physical activity (accelerometry), HRV (heart rate monitor), and spatial location (Global Positioning System (GPS)) were recorded for 74 hours. GPS data were combined with a diary to identify periods of work and of leisure at home and elsewhere. Time- and frequency-domain HRV indices were calculated and stratified by period and activity type (lying/sitting, standing, or walking). ANCOVAs with multiple adjustments were used to disclose possible group differences in HRV. Results. The pain group showed a reduced HRV response to physical activity compared with controls (p = .001), according to the sympathetic-baroreceptor HRV index (LF/HF, ratio between low- and high-frequency power), even after adjustment for leisure time physical activity, work stress, sleep quality, mental health, and aerobic capacity (p = .02). The parasympathetic response to physical activity did not differ between groups. Conclusions. Relying on long-term monitoring of physical behavior and heart rate variability, we found an aberrant sympathetic-baroreceptor response to daily physical activity among subjects with chronic neck pain.

Task variation during simulated, repetitive, low-intensity work--influence on manifestation of shoulder muscle fatigue, perceived discomfort and upper-body postures

Work-related musculoskeletal disorders are increasing due to industrialisation of work processes. Task variation has been suggested as potential intervention. The objectives of this study were to investigate, first, the influence of task variation on electromyographic (EMG) manifestations of shoulder muscle fatigue and discomfort; second, noticeable postural shoulder changes over time; third, if the association between task variation and EMG might be biased by postural changes. Outcome parameters were recorded using multichannel EMG, Optotrak and the Borg scale. Fourteen participants performed a one-hour repetitive Pegboard task in one continuous and two interrupted conditions with rest and a pick-and-place task, respectively. Manifestations of shoulder muscle fatigue and discomfort feelings were observed throughout the conditions but these were not significantly influenced by task variation. After correction for joint angles, the relation between task variation and EMG was significantly biased but significant effects of task variation remained absent.

PRACTITIONER SUMMARY

Comparing a one-hour continuous, repetitive Pegboard task with two interrupted conditions revealed no significant influences of task variation. We did observe that the relation between task variation and EMG was biased by posture and therefore advise taking account for posture when investigating manifestations of muscle fatigue in assembly tasks.

Analysis of scapular muscle EMG activity in patients with idiopathic neck pain: a systematic review

It is proposed that altered scapular muscle function can contribute to abnormal loading of the cervical spine. However, it is not clear if patients with idiopathic neck pain show altered activity of the scapular muscles. The aim of this paper was to systematically review the literature regarding the differences or similarities in scapular muscle activity, measured by electromyography ( = EMG), between patients with chronic idiopathic neck pain compared to pain-free controls. Case-control (neck pain/healthy) studies investigating scapular muscle EMG activity (amplitude, timing and fatigue parameters) were searched in Pubmed and Web of Science. 25 articles were included in the systematic review. During rest and activities below shoulder height, no clear differences in mean Upper Trapezius ( = UT) EMG activity exist between patients with idiopathic neck pain and a healthy control group. During overhead activities, no conclusion for scapular EMG amplitude can be drawn as a large variation of results were reported. Adaptation strategies during overhead tasks are not the same between studies. Only one study investigated timing of the scapular muscles and found a delayed onset and shorter duration of the SA during elevation in patients with idiopathic neck pain. For scapular muscle fatigue, no definite conclusions can be made as a wide variation and conflicting results are reported. Further high quality EMG research on scapular muscles (broader than the UT) is necessary to understand/draw conclusions on how scapular muscles react in the presence of idiopathic neck pain.

Comparative metabolomics of muscle interstitium fluid in human trapezius myalgia: an in vivo microdialysis study

Purpose

The mechanisms behind trapezius myalgia are unclear. Many hypotheses have been presented suggesting an altered metabolism in the muscle. Here, muscle microdialysate from healthy and myalgic muscle is analysed using metabolomics. Metabolomics analyse a vast number of metabolites, enabling a comprehensive explorative screening of the cellular processes in the muscle.

Methods

Microdialysate samples were obtained from the shoulder muscle of healthy and myalgic subjects that performed a work and stress test. Samples from the baseline period and from the recovery period were analysed using gas chromatography—mass spectrometry (GC–MS) together with multivariate analysis to detect differences in extracellular content of metabolites between groups. Systematic differences in metabolites between groups were identified using multivariate analysis and orthogonal partial least square discriminate analysis (OPLS-DA). A complementary Mann–Whitney U test of group difference in individual metabolites was also performed.

Results

A large number of metabolites were detected and identified in this screening study. At baseline, no systematic differences between groups were observed according to the OPLS-DA. However, two metabolites, l-leucine and pyroglutamic acid, were significantly more abundant in the myalgic muscle compared to the healthy muscle. In the recovery period, systematic difference in metabolites between the groups was observed according to the OPLS-DA. The groups differed in amino acids, fatty acids and carbohydrates. Myristic acid and putrescine were significantly more abundant and beta-d-glucopyranose was significantly less abundant in the myalgic muscle.

Conclusion

This study provides important information regarding the metabolite content, thereby presenting new clues regarding the pathophysiology of the myalgic muscle.

Chronic pain and cardiovascular stress responses in a general population: the Tromsø Study

We tested whether cardiovascular stress responsiveness is elevated in individuals experiencing chronic pain in a large general population sample. Blood pressure (BP) and heart rate (HR) were assessed at rest, during the cold pressor test, and during subsequent recovery in 554 individuals reporting daily chronic pain and 3,082 individuals free of chronic pain. After correcting for potential confounds, differences as a function of chronic pain status were noted for only 5 of 23 cardiovascular outcomes despite very high statistical power. Compared to the pain-free group, the chronic pain group displayed higher baseline HR/mean arterial pressure (MAP) ratio (p = .03), greater systolic BP (SBP) reactivity during the cold pressor test (p = .04), and higher HR/MAP ratio (p = .047) and significantly less SBP (p = .017) and MAP (p = .041) return to baseline during recovery. Findings suggest that changes in cardiovascular stress responsiveness associated with chronic pain are of limited clinical significance and unlikely to contribute to increased cardiovascular risk in the chronic pain population.

Effect of brief daily resistance training on occupational neck/shoulder muscle activity in office workers with chronic pain: randomized controlled trial

Purpose. This study investigates the acute and longitudinal effects of resistance training on occupational muscle activity in office workers with chronic pain. Methods. 30 female office workers with chronic neck and shoulder pain participated for 10 weeks in high-intensity elastic resistance training for 2 minutes per day (n = 15) or in control receiving weekly email-based information on general health (n = 15). Electromyography (EMG) from the splenius and upper trapezius was recorded during a normal workday. Results. Adherence to training and control interventions were 86% and 89%, respectively. Compared with control, training increased isometric muscle strength 6% (P < 0.05) and decreased neck/shoulder pain intensity by 40% (P < 0.01). The frequency of periods with complete motor unit relaxation (EMG gaps) decreased acutely in the hours after training. By contrast, at 10-week follow-up, training increased average duration of EMG gaps by 71%, EMG gap frequency by 296% and percentage time below 0.5%, and 1.0% EMGmax by 578% and 242%, respectively, during the workday in m. splenius. Conclusion. While resistance training acutely generates a more tense muscle activity pattern, the longitudinal changes are beneficial in terms of longer and more frequent periods of complete muscular relaxation and reduced pain.

Autonomic regulation, physical activity and perceived stress in subjects with musculoskeletal pain: 24-hour ambulatory monitoring

The aim of the study was to investigate autonomic nervous system regulation, physical activity (PA) and perceived stress and energy during daily activities in subjects with chronic muscle pain in the neck-shoulders (trapezius myalgia) (n=23) and symptom-free controls (n=22). Subjects underwent 24-hour objective ambulatory monitoring of heart rate variability (HRV) and PA, and reported their perceived stress and energy in a diary. Standard HRV measures were extracted in time and frequency domains. The volume and pattern of different types of activities were quantified in terms of intensity and duration of walking, and time spent sitting, standing and lying during the 24-hour measurement. Results showed shortened inter-beat-intervals (higher heart rate) and reduced HRV in the pain group, most pronounced during sleep (p<0.05). For overall PA, the pain group showed increased lying time, compared to controls (p<0.05). A different activity pattern was found in the pain group, with reduced leisure time PA and increased PA during morning hours, in comparison with controls (p<0.05). Both groups demonstrated low levels of perceived stress, whereas reduced energy was observed in the pain group (p<0.05). In conclusion, monitoring of 24-hour HRV demonstrated diminished HRV among persons with chronic neck-shoulder pain. This reflected aberration in autonomic regulation, suggesting reduced parasympathetic activation and increased sympathetic tone as an element in maintenance of chronic muscle pain.

An increased response to experimental muscle pain is related to psychological status in women with chronic non-traumatic neck-shoulder pain

Background

Neck-shoulder pain conditions, e.g., chronic trapezius myalgia, have been associated with sensory disturbances such as increased sensitivity to experimentally induced pain. This study investigated pain sensitivity in terms of bilateral pressure pain thresholds over the trapezius and tibialis anterior muscles and pain responses after a unilateral hypertonic saline infusion into the right legs tibialis anterior muscle and related those parameters to intensity and area size of the clinical pain and to psychological factors (sleeping problems, depression, anxiety, catastrophizing and fear-avoidance).

Methods

Nineteen women with chronic non-traumatic neck-shoulder pain but without simultaneous anatomically widespread clinical pain (NSP) and 30 age-matched pain-free female control subjects (CON) participated in the study.

Results

NSP had lower pressure pain thresholds over the trapezius and over the tibialis anterior muscles and experienced hypertonic saline-evoked pain in the tibialis anterior muscle to be significantly more intense and locally more widespread than CON. More intense symptoms of anxiety and depression together with a higher disability level were associated with increased pain responses to experimental pain induction and a larger area size of the clinical neck-shoulder pain at its worst.

Conclusion

These results indicate that central mechanisms e.g., central sensitization and altered descending control, are involved in chronic neck-shoulder pain since sensory hypersensitivity was found in areas distant to the site of clinical pain. Psychological status was found to interact with the perception, intensity, duration and distribution of induced pain (hypertonic saline) together with the spreading of clinical pain. The duration and intensity of pain correlated negatively with pressure pain thresholds.

Effects of static contraction and cold stimulation on cardiovascular autonomic indices, trapezius blood flow and muscle activity in chronic neck-shoulder pain

The aim of the present study was to investigate reactions in trapezius muscle blood flow (MBF), muscle activity, heart rate variability (HRV) and systemic blood pressure (BP) to autonomic tests in subjects with chronic neck-shoulder pain and healthy controls. Changes in muscle activity and blood flow due to stress and unfavourable muscle loads are known underlying factors of work-related muscle pain. Aberration of the autonomic nervous system (ANS) is considered a possible mechanism. In the present study, participants (n = 23 Pain, n = 22 Control) performed autonomic tests which included a resting condition, static hand grip test (HGT) at 30% of maximal voluntary contraction, a cold pressor test (CPT) and a deep breathing test (DBT). HRV was analysed in time and frequency domains. MBF and muscle activity were recorded from the upper trapezius muscles using photoplethysmography and electromyography (EMG). The pain group showed reduced low frequency-HRV (LF) and SDNN during rest, as well as a blunted BP response and increased LF-HRV during HGT (∆systolic 22 mm Hg; ∆LF(nu) 27%) compared with controls (∆systolic 27; ∆LF(nu) 6%). Locally, the pain group had attenuated trapezius MBF in response to HGT (Pain 122% Control 140%) with elevated trapezius EMG following HGT and during CPT. In conclusion, only HGT showed differences between groups in systemic BP and HRV and alterations in local trapezius MBF and EMG in the pain group. Findings support the hypothesis of ANS involvement at systemic and local levels in chronic neck-shoulder pain.

Interstitial concentration of serotonin is increased in myalgic human trapezius muscle during rest, repetitive work and mental stress - an in vivo microdialysis study

OBJECTIVES

The pathophysiology of trapezius myalgia is not fully elucidated. Serotonin (5-HT) is involved in modulation of nociception and hyperalgesia. Our aim was to compare the interstitial 5-HT levels of the trapezius muscle in women with chronic trapezius myalgia and in pain-free controls.

MATERIALS AND METHODS

Microdialysate of the trapezius muscle collected every 20 minutes during rest, work (100 min) and stress (20 min) was used to study the dynamics of 5-HT in women with chronic trapezius myalgia (MYA; n=18) and in pain-free controls (CON; n=30).

RESULTS

MYA had higher levels of 5-HT than CON at baseline, during repetitive work, during mental stress and during recovery. There were no significant time effects on 5-HT levels.

CONCLUSION

5-HT has the potential of a biomarker of chronic myalgia. Elevated levels of 5-HT may be involved in maintenance of habitual chronic pain and might contribute to increased pain during exercise by facilitating the effect of released algesic substances linked to such muscle demands.

Salivary cortisol response to acute stress and its relation to psychological factors in women with chronic trapezius myalgia--a pilot study

This study investigated differences in HPA axis function, measured as salivary cortisol concentrations, between 18 women with chronic trapezius myalgia (MYA) and 30 healthy female controls (CON). In addition, the interactions between HPA axis reactions to psychosocial stress and aspects of pain, health and psychological symptoms were analyzed. Salivary cortisol was measured both in daily life, to assess the circadian profile, and in the laboratory during light repetitive work and standardized psychosocial stress (Trier Social Stress Test, TSST). MYA and CON exhibited similar circadian rhythms and comparable salivary cortisol response magnitudes after TSST. In subjects defined as responders to the TSST, the mean peak time point of the cortisol response after TSST differed significantly between MYA and CON. Furthermore, negative psychological states and higher pain intensity were related to a slower HPA axis response to TSST. Low circadian variations in cortisol and smaller cortisol responses to TSST were found among subjects scoring high on anxiety sensitivity. Thus, a relatively favorable sample of female chronic trapezius myalgia patients exhibited normal circadian rhythm and normal salivary cortisol response magnitudes after a psychosocial stress test. In the subgroup of responders, the MYA group showed indications of a slower salivary cortisol response to psychosocial stress. Further studies are needed to elucidate the possibility of altered HPA axis activity in terms of a slower salivary cortisol response.