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This study compares the levels of algesic substances between subjects with trapezius myalgia (TM) and healthy controls (CON) and explores the multivariate correlation pattern between these substances, pain, and metabolic status together with relative blood flow changes reported in our previous paper (Eur J Appl Physiol 108:657–669, 2010). 43 female...

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... inversely with the local blood flow in the tissue [40,41]. Microdialysates were collected continuously into MD vials that were changed every 20 min starting at t = 20 min until t = 320 min, and thereafter every 10 min up to t = 360 min ( Figure 1). The samples col- lected from t = 20-100 min were not used in this study. ...
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... group differences were found for the concentrations of glutamate, IL-6, LDH and BKN (Table 2). All sub- stances showed time effects (Table 2 and Figure 1). Simi- lar results and without group differences were obtained when the PEG and STR parts were analysed separately for each of these substances (data not shown). ...
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... had (See figure on previous page.) Figure 1 Mean interstitial concentrations of glutamate (panel a), interleukin 6 (IL-6; panel b), lactate dehydrogenase (LDH; panel c), and bradykinin (BKN; panel d) throughout the microdialysis experiment in women with trapezius myalgia (TM) and in healthy controls (CON). X-axis gives min after insertion of the catheters and samples are plotted at midpoint of the sampling period. ...
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... extended analysis of group membership (Table 3) showed that [IL-6] at two time points were significant and lower in TM. Interestingly, [IL-6] tended to be higher at recovery and at baseline after PEG in CON than in TM (Figure 1), which may in- dicate an effect of exercise [83,84]. Thus, a protective re- sponse may be lacking for TM. ...
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... was only important at one time point (at 150 min) according to the comprehensive analysis of group (Table 3) and TM was associated with low [BKN] (Figure 1). This result concerning a classical algesic might be related to other muscle alterations e.g., in blood flow [85][86][87]. ...

Citations

... [12,13] Elevated lactate and pyruvate levels have also been detected during microdialysis of painful muscles in other musculoskeletal pain conditions. [14,15] Elevated lactate levels have also been measured in the ventricular cerebrospinal fluid (CSF) of FM and chronic fatigue syndrome patients, compared with controls. [16] Pyruvate and lactate levels in the circulating blood of FM patients have been less studied. ...
Article
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Objectives: Fibromyalgia (FM) patients have an increased risk for glucose metabolism disturbances, and impaired glucose tolerance may be associated with symptom severity. Elevated levels of plasma lactate have been detected in FM patients. Both pyruvate and lactate are produced in glucose metabolism and reflect oxidative metabolism. The objective of our study was to analyse disturbances in glucose, pyruvate, or lactate metabolism in FM patients. Methods: We measured plasma levels of glucose, pyruvate, and lactate during an oral glucose tolerance test in 40 non-diabetic, female FM patients and 30 age- and gender-matched healthy controls. Results: FM patients showed a higher glycaemic response to the glucose load at 1 hour (F [1,68] = 10.4, P = .006) and 2 hours (F [1,68] = 7.80, P = .02), and higher glucose area under the curve (13.8 [SD 2.92] vs 11.6 [SD 2.31], P < .01), than healthy controls. Group differences were explained by higher body mass index and percentage of smokers among the FM patients. Pyruvate and lactate levels were similar in both groups. Discussion: Impaired glucose regulation in FM patients is likely not due to FM itself, but to associated lifestyle factors. Our results highlight the importance of assessing the glucose regulation status and the lifestyle factors affecting glucose regulation in FM patients for prevention or early treatment of diabetes and associated complications. Trial registration: ClinicalTrials.gov (NCT03300635).
... The exclusion criteria for office workers were: medical history of cardiovascular, cerebrovascular events; major chronic diseases; neurologic diseases; metabolic diseases; pregnancy; rheumatologic diseases; fibromyalgia; whiplash disorders; cervical disc herniation or severe disorders of the cervical spine such severe osteoarthritis; and past neck fractures. The symptomatic office workers were excluded if reported more than 30 days of pain in more than three out of eight major body regions (neck/shoulder, low back, and left or right arm/ hand, hip, knee, foot) to exclude widespread musculoskeletal diseases [37,38]. ...
Article
Objectives: Office workers with chronic neck pain demonstrates signs of widespread hyperalgesia, less efficient descending pain modulation, which could indicate sensitization of central pain pathways. No studies have assessed a wide variety of office workers with different chronic neck pain disorders and assessed the impact of pain intensity on assessments of central pain pathways. This study aimed to assessed pressure pain thresholds (PPTs), temporal summation of pain (TSP) and conditioned pain modulation (CPM) and to associate these with pain intensity and disability in subgroups of office workers. Methods: One hundred-and-seventy-one office workers were distributed into groups of asymptomatic and chronic neck pain subjects. Chronic neck pain was categorized as chronic trapezius myalgia and chronic non-specific neck pain and as 'mild-pain' (Visual Analog Scale [VAS]≤3) and 'moderate-pain' (VAS>3) groups. PPTs, TSP, CPM, and Copenhagen Psychosocial Questionnaire II were assessed in all subjects. Neck Disability Index and Pain Catastrophizing Scale were assessed in all the symptomatic office workers. Results: PPTs were lower in moderate pain (n=49) and chronic trapezius myalgia (n=56) compared with asymptomatic subjects (n=62, p<0.05). TSP was facilitated in moderate pain group compared with mild pain (n=60, p<0.0001) group and asymptomatic subjects (p<0.0001). No differences were found in CPM comparing the different groups (p<0.05). Multiple regression analysis identified Neck Disability Index and TSP as independent factors for prediction of pain intensity in chronic trapezius myalgia (R2=0.319) and chronic non-specific neck pain (R2=0.208). Somatic stress, stress and sleep as independent factors in chronic non-specific neck pain (R2=0.525), and stress in moderate pain group (R2=0.494) for the prediction of disability. Conclusions: Office workers with chronic trapezius myalgia and moderate pain intensity showed significant signs of widespread pressure hyperalgesia. Moreover, the moderate pain group demonstrated facilitated TSP indicating sensitization of central pain pathways. Neck Disability Index and TSP were independent predictors for pain intensity in pain groups. Sleep and stress were independent predictors for disability.
... The association between TBF and neck pain in the present study indicates that muscle microcirculation and alternations in TBF may be involved in the pathogenesis of neck pain development, which is also consistent with previous studies (Gerdle et al. 2014;Knardahl 2002;Larsson et al. 2008;Larsson et al. 1999;Näslund et al. 2007;Rosendal et al. 2004;Sjogaard et al. 2010;Strøm et al. 2009b;Thorud et al. 2012). Strom et al. (2009b) showed significant correlations between neck pain and TBF during computer work for both subjects with chronic neck and shoulder pain and a healthy reference group; however, the associations were in opposite directions in the two groups. ...
... The mechanisms behind the link between TBF and pain development are unclear and need further elucidation. However, muscle microcirculation is correlated with muscle metabolism, and different levels of metabolites involved in both pain sensation and vasodilation may explain the correlation between symptoms and circulation in both the present study and in previous research (Gerdle et al. 2014;Knardahl 2002;Sjøgaard et al. 2000;Strøm et al. 2009a, b). ...
Article
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Purpose Exposure to additional environmental stress during computer work, such as visual and psychological demands, is associated with increased eye and neck discomfort, altered moods, and reduced well-being. The aim of this study is to elucidate further how subjective responses in healthy, young females with normal binocular vision are affected by glare and psychological stress during computer work, and to investigate possible associations between trapezius muscle blood flow and neck pain development. Methods 43 females participated in a laboratory experiment with a within-subject design. Four 10-min computer work conditions with exposure to different stressors were performed at an ergonomically optimal workstation, under the following series of conditions: no additional stress, visual stress (induced as direct glare from a large glare source), psychological stress, and combined visual and psychological stress. Before and immediately after each computer work condition, questionnaires regarding different visual and eye symptoms, neck and shoulder symptoms, positive and negative state moods, perceived task difficulty, and perceived ambient lighting were completed. Associations between neck pain and trapezius muscle blood flow were also investigated. Results Exposure to direct glare induced greater development of visual/eye symptoms and discomfort, while psychological stress exposure made participants feel more negative and stressed. The perception of work lighting during glare exposure was closely related to perceived stress, and associations between visual discomfort and eyestrain, and neck pain were observed in all conditions. Furthermore, participants with high trapezius muscle blood flow overall reported more neck pain, independent of exposure. Conclusions Exposure to visual and psychological stresses during computer work affects the development of symptoms and negative moods in healthy, young females with normal binocular vision, but in different ways. The results also demonstrate the complex interactions involved in symptom development and lighting appraisal during computer work. When optimizing computer workstations, the complexity of the field must be taken into account, and several factors, including visual conditions, must be considered carefully.
... There may of course be some false positives among our findings, but all in all it does not seem sensible to dismiss all our results as a gigantic type I error. The MVDA methodology used in the present study is the same as used by the Linköping group in a number of recent peer-reviewed publications in different journals, 22,29,[62][63][64][65][66] and it is congruent with the principles argued for by Wheelock and Wheelock. 28 Finally, in order to ensure the robustness of our statistical methodology, the CSF data of the present study were recomputed using the statistical methodology described by Moen et al 32 (with use of false discovery rate); the result of this recomputation was exactly the same as the list presented in Table 1 (TG being the last author of both articles). ...
... There may of course be some false positives among our findings, but all in all it does not seem sensible to dismiss all our results as a gigantic type I error. The MVDA methodology used in the present study is the same as used by the Linköping group in a number of recent peer-reviewed publications in different journals, 22,29,[62][63][64][65][66] and it is congruent with the principles argued for by Wheelock and Wheelock. 28 Finally, in order to ensure the robustness of our statistical methodology, the CSF data of the present study were recomputed using the statistical methodology described by Moen et al 32 (with use of false discovery rate); the result of this recomputation was exactly the same as the list presented in Table 1 (TG being the last author of both articles). ...
Article
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In addition to central hyperexcitability and impaired top–down modulation, chronic inflammation probably plays a role in the pathophysiology of fibromyalgia (FM). Indeed, on the basis of both animal experiments and human studies involving the analysis of cytokines and other inflammation-related proteins in different body fluids, neuroinflammatory mechanisms are considered to be central to the pathophysiology of many chronic pain conditions. However, concerning FM, previous human plasma/serum and/or cerebrospinal fluid (CSF) cytokine studies have looked only at a few predetermined cytokine candidates. Instead of analyzing only a few substances at a time, we used a new multiplex protein panel enabling simultaneous analysis of 92 inflammation-related proteins. Hence, we investigated the CSF and plasma inflammatory profiles of 40 FM patients compared with CSF from healthy controls (n=10) and plasma from blood donor controls (n=46). Using multivariate data analysis by projection, we found evidence of both neuroinflammation (as assessed in CSF) and chronic systemic inflammation (as assessed in plasma). Two groups of proteins (one for CSF and one for plasma) highly discriminating between patients and controls are presented. Notably, we found high levels of CSF chemokine CX3CL1 (also known as fractalkine). In addition, previous findings concerning IL-8 in FM were replicated, in both CSF and plasma. This is the first time that such an extensive inflammatory profile has been described for FM patients. Hence, FM seems to be characterized by objective biochemical alterations, and the lingering characterization of its mechanisms as essentially idiopathic or even psychogenic should be seen as definitively outdated.
... This reduction was particularly large among those with high adherence, as pain reduction related to training volume in a dose-response relationship with the highest pain reduction being up to 80% over a 12-week period (14). In office workers the painful muscles showed adverse functional, morphological, hormonal, as well as metabolic characteristics (27)(28)(29)(30)(31). Metabolic muscular capacity increased (32) as demonstrated even at the gene level (33), and muscle morphological recovery was documented using advanced immunohistochemical stainings for satellite cells (34) and neuronal nitric oxide synthase (27). ...
Article
Background: Physical activity (PA) includes muscle activity during exercise, manual work, and leisure time activities including sport. Conflicting results exist regarding health effects of PA that may deteriorate with manual work and elite sports, but improve when performed in moderation in accordance with international guidelines and may additionally enhance well-being and productivity. Methods: In Denmark 15 randomized controlled trials have been conducted, introducing exercise at the workplace enrolling >3500 workers. The interventions lasted from 10 to 52 weeks and offered ~1 h weekly supervised exercise during working hours according to the concept of intelligent physical exercise training (IPET) that is based on evidenced sports sciences training principles and tailored to work exposure, employee health status, and physical capacity. Questionnaire surveys and health checks including blood and muscle sampling were performed at baseline and follow-up. The job groups included: office and computer workers, dentists, industrial technicians, cleaning personnel, health care workers, construction workers, and fighter/helicopter pilots. Results: In all job groups significant improvements were documented regarding health outcomes. These were job group specific: neck pain was reduced among office and computer workers, dentists, industrial laboratory technicians, health care workers as well as fighter pilots. Cardio-respiratory fitness—a health risk indicator for cardio-metabolic diseases—was improved among office and computer workers, health care workers, and construction workers. Additionally, other improvements were evidenced such as increased muscle strength and balance control. Importantly, productivity increased with improved muscle strength and decreased body mass index. Conclusion: IPET does enhance health if an exercise program with evidenced efficacy is implemented by expert trainees with support of the employer. Accordingly, in every study group outcomes of improved health were documented and the effect sizes were of clinical relevance. Cost effectiveness estimates indicate acceptable cost relative to savings on health expenses and lost productivity.
... Interestingly, the raised interstitial concentrations of glutamate and lactate seen in muscle dialysates from CWP patients were also seen in plasma from the same individuals [5]. In another microdialysis study investigating controls and individuals with trapezius myalgia, a positive correlation was seen between baseline pain and the interstitial levels of serotonin, an important painsignalling molecule [6]. ...
Article
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Background Chronic musculoskeletal pain may be associated with changes in the balance of algogenic and anti-nociceptive compounds, and such changes may be visible in plasma samples. We have undertaken an exploratory study to measure the levels of endocannabinoids, related N-acylethanolamines and oxylipins (primarily those derived from linoleic acid) in plasma samples from women with chronic neck pain (NP) and chronic widespread pain (CWP), and to investigate whether the observed levels are associated with the pain experienced by these women. Methods Blood samples from 35 women with NP, 15 with CWP and 27 age-matched controls were analysed for the lipids using ultra performance liquid chromatography coupled to tandem mass spectrometry. Current pain (“NRSday”) and the average pain during the last week (“NRSweek”) were rated by the participants using a numerical rating scale. Results There were no significant differences in the plasma concentrations of the fifteen lipids investigated between the women with pain and the controls. However, significant correlations were seen for the NP group between the NRSday scores and the plasma concentrations of the linoleic acid derivatives 9- and 13-hydroxy-octadecadienoic acid (Spearman’s rho values 0.51 [P = 0.0016]) and 0.53 [P = 0.0011], respectively). Conclusions The data obtained in this exploratory study indicate that although no group differences are seen in plasma lipid concentrations, there is an association between the NRSday scores and the 9- and 13-hydroxy-octadecadienoic acid levels. Whether or not the association reflects a causality (i.e. that the circulating lipids contribute to the perceived pain of the pain participants), requires further investigation.
... Muscle mechanics and metabolism improved as evidenced based on analysis of muscle biopsies from the myalgic trapezius muscle. Compared with healthy control trapezius muscle, the myalgic trapezius muscle had the same mean number of capillaries around fibers (Nielsen et al., 2010;Gerdle et al., 2014). However, more detailed morphological analysis showed a number of morphological impairments (Mackey et al., 2010), particularly an excess number of mega fibers with a ∼40% decrease in capillaries around the fiber area (Andersen et al., 2008b) and impaired oxidative metabolism at rest and with repetitive work . ...
Article
Bengt Saltin knew very well the history and work of the giants whose shoulders he was standing upon, such as August Krogh and Johannes Lindhard. He was basically a physiologist interested in physical activity and exercise, particularly in the cardiovascular and muscular responses. Some of his major original contributions were (a) the human muscle model in terms of the one-legged, knee extensor quantifying work by the high-precision Krogh ergometer and, using this, challenging Krogh's proposed autoregulation of capillary blood flow during exercise; (b) the electrolyte fluxes quantification on an intra- and extra-cellular level in human muscle during exercise to reveal such changes as possible fatigue mechanisms; and (c) the evidence presented that underlined the health-enhancing effect of physical exercise training from bedside to workplace.
... Our results indicate that poor cervical extensor endurance increases the risk of developing chronic, nonspecific neck pain among office workers. This finding suggests that sensitization of peripheral nociceptors by algesic metabolites 21,23 produced during postural muscle fatigue may play an important role in the transition to chronic pain in susceptible individuals. Depressed mood and DNIC were also found to significantly increase the risk of chronic neck pain. ...
Article
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Unlabelled: The purpose of this investigation was to identify modifiable risk factors for the development of first-onset chronic neck pain among an inception cohort of healthy individuals working in a high-risk occupation. Candidate risk factors identified from previous studies were categorized into psychosocial, physical, and neurophysiological domains, which were assessed concurrently in a baseline evaluation of 171 office workers within the first 3 months of hire. Participants completed monthly online surveys over the subsequent year to identify the presence of chronic interfering neck pain, defined as a Neck Disability Index score ≥5 points for 3 or more months. Data were analyzed using backward logistic regression to identify significant predictors within each domain, which were then entered into a multivariate regression model adjusted for age, sex, and body mass index. Development of chronic interfering neck pain was predicted by depressed mood (odds ratio [OR] = 3.36, 95% confidence interval [CI] = 1.10-10.31, P = .03), cervical extensor endurance (OR = .92, 95% CI, .87-.97, P = .001), and diffuse noxious inhibitory control (OR = .90, 95% CI, .83-.98, P = .02) at baseline. These findings provide the first evidence that individuals with preexisting impairments in mood and descending pain modulation may be at greater risk for developing chronic neck pain when exposed to peripheral nociceptive stimuli such as that produced during muscle fatigue. Perspective: Depressed mood, poor muscle endurance, and impaired endogenous pain inhibition are predisposing factors for the development of new-onset chronic neck pain of nonspecific origin in office workers. These findings may assist with primary prevention by allowing clinicians to screen for individuals at risk of developing chronic neck pain.
Chapter
Musculoskeletal disorders (MSDs) account for a large societal and economic burden throughout the world. In this chapter, the authors begin by providing a brief review of some of the more common MSDs, providing descriptions and characteristic features of the disorders, prevalence and incidence data, relevant anatomy and pathology, and the risk factors or activities associated with the development of the disorders. The common MSDs include low back pain, hand & wrist tendinopathy, lateral tendinopathy of the elbow, medial tendinopathy of the elbow, shoulder tendons, muscle fatigue, myalgia, muscle fibrosis, carpal tunnel syndrome, ulnar tunnel syndrome, and hand‐arm vibration syndrome. The authors also discuss some of the more common upper extremity disorders, their characteristics, prevalence and incidence, anatomy and pathology, and risk factors.