Effect of training on mRNA content. The mRNA content of HSc70 (a) and HSP72 (b) decreased in the strength training group (SST, n=9) during the 10 wks intervention period (P<0.05). Similarly, a decrease in HSP72 mRNA content was observed with the GFT (n=10) intervention (P<0.1) (B). No changes were observed for REF ((a): n=2; (b): n=3). The figure illustrates the 5th and 95th percentile, outliers (black dot), the group median (solid line), and group mean (dotted line).

Effect of training on mRNA content. The mRNA content of HSc70 (a) and HSP72 (b) decreased in the strength training group (SST, n=9) during the 10 wks intervention period (P<0.05). Similarly, a decrease in HSP72 mRNA content was observed with the GFT (n=10) intervention (P<0.1) (B). No changes were observed for REF ((a): n=2; (b): n=3). The figure illustrates the 5th and 95th percentile, outliers (black dot), the group median (solid line), and group mean (dotted line).

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The aim was to assess mRNA and/or protein levels of heat shock proteins, cytokines, growth regulating, and metabolic proteins in myalgic muscle at rest and in response to work tasks and prolonged exercise training. A randomized controlled trial included 28 females with trapezius myalgia and 16 healthy controls. Those with myalgia performed ~7 hrs r...

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... Despite that oxidative stress is involved in NMDs, and exercise induces ROS production, some types of training increase mRNA levels and the expression of metabolic muscle proteins. In particular, a moderate and regular physical exercise has been suggested as non-pharmacological treatment for the NMDs (Sjøgaard et al., 2013). ...
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Neuromuscular diseases (NMDs) are a group of often severely disabling disorders characterized by dysfunction in one of the main constituents of the motor unit, the cardinal anatomic-functional structure behind force and movement production. Irrespective of the different pathogenic mechanisms specifically underlying these disease conditions genetically determined or acquired, and the related molecular pathways involved in doing that, oxidative stress has often been shown to play a relevant role within the chain of events that induce or at least modulate the clinical manifestations of these disorders. Due to such a putative relevance of the imbalance of redox status occurring in contractile machinery and/or its neural drive in NMDs, physical exercise appears as one of the most important conditions able to positively interfere along an ideal axis, going from a deranged metabolic cell homeostasis in motor unit components to the reduced motor performance profile exhibited by the patient in everyday life. If so, it comes out that it would be important to identify a proper training program, suitable for load and type of exercise that is able to improve motor performance in adaptation and response to such a homeostatic imbalance. This review therefore analyzes the role of different exercise trainings on oxidative stress mechanisms, both in healthy and in NMDs, also including preclinical studies, to elucidate at which extent these can be useful to counteract muscle impairment associated to the disease, with the final aim of improving physical functions and quality of life of NMD patients.
... As pain is a perception and always self-reported, an animal model can only observe and test motor and sensory behaviors as indications of fatigue and pain. We analyzed for voluntary motor behaviors suggestive of fatigue and sensory behaviors suggestive of pain or discomfort, as well as inflammatory cytokines and Hsp72 as injury markers [26,27]. All original data from behavioral and tissue analyses used to support the findings of this study are available from the corresponding author upon request. ...
... Regarding Hsp72 in the present rat study, we found a significant increase in Flex muscles of the HRHF-RL compared to the HRHF-SL and FRC-R, while in a human study, we did not find resting baseline differences in Hsp72 among workers with trapezius muscle myalgia compared to healthy controls. However, among the workers with trapezius muscle myalgia, Hsp72 increased ∼8 fold following a 7-hour workday with standardized repetitive work [27]. Interestingly, however, it was shown that Hsp72 decreased following a 10-week strength training period that in previous papers was reported to relieve trapezius muscle pain and improved muscle morphological and metabolic markers [72][73][74]. ...
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Introduction: Ca2+ regulatory excitation-contraction coupling properties are key topics of interest in the development of work-related muscle myalgia and may constitute an underlying cause of muscle pain and loss of force generating capacity. Method: A well-established rat model of high repetition high force (HRHF) work was used to investigate if such exposure leads to an increase in cytosolic Ca2+ concentration ([Ca2+]i) and changes in sarcoplasmic reticulum (SR) vesicle Ca2+ uptake and release rates. Result: Six weeks exposure of rats to HRHF increased indicators of fatigue, pain behaviors, and [Ca2+]i, the latter implied by around 50-100% increases in pCam, as well as in the Ca2+ handling proteins RyR1 and Casq1 accompanied by an ∼10% increased SR Ca2+ uptake rate in extensor and flexor muscles compared to those of control rats. This demonstrated a work-related altered myocellular Ca2+ regulation, SR Ca2+ handling, and SR protein expression. Discussion: These disturbances may mirror intracellular changes in early stages of human work-related myalgic muscle. Increased uptake of Ca2+ into the SR may reflect an early adaptation to avoid a sustained detrimental increase in [Ca2+]i similar to the previous findings of deteriorated Ca2+ regulation and impaired function in fatigued human muscle.
... The above results from animal studies are consistent with findings by Sjogaard and colleagues showing that repetitive stressful work increases inducible Hsp70 levels in myalgic trapezius muscles of female humans (Sjogaard et al. 2013). Twenty-eight females with trapezius myalgia and 16 healthy females were included in the study, with all subjects employed in jobs with monotonous and repetitive work tasks (e.g., assembly line or office work). ...
... Twenty-eight females with trapezius myalgia and 16 healthy females were included in the study, with all subjects employed in jobs with monotonous and repetitive work tasks (e.g., assembly line or office work). The diagnosis of myalgia was fulfilled when subjects had: 1) pain or discomfort for more than 30 days during the last year in the neck and shoulder region; 2) more than 30 days of pain or discomfort in maximally three of eight major body regions; and 3) intense and frequent pain, assayed using three different scales (Sjogaard et al. 2013), and 4) palpable tenderness and tightness in the trapezius muscle (Sjogaard et al. 2010). At baseline, all participants (Controls and Myalgic patients) had biopsies collected from the trapezius muscle. ...
... In contrast, decreased tendon levels of Hsp70, an absence of tendon pathology, and no increases in any repair cytokine were observed in rats that had performed a low repetition low force task for 12 weeks, compared to control rats, suggesting that their tendon tissues had adapted to the task (Fig. 11.2a-f). These findings combined support a fatigue failure theory in which only the highest demand tasks or loads result in tissue pathology M. F. Barbe et al. (Fung et al. 2010;Fung et al. 2009;Gallagher and Heberger 2013;Neviaser et al. 2012) followed by enhanced repair processes, and that prolonged activity at low force parameters may activate metabolic changes that allow tendon tissues to handle more efficiently any potentially damaging changes occurring with task performance (Sjogaard et al. 2013). Fig. 11.2 Histopathology and production of repair proteins in flexor digitorum tendons after performance of repetitive tasks for 12 weeks at one of four combinations of repetitive rates and force levels as defined in Fig. 11.1. ...
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The heat shock protein (Hsp) response is understudied with non-exercise overuse injuries. We focused on the Hsp response in muscles and tendons undergoing such injury or cyclical loading. Hsp25 mRNA and protein levels increase in muscles undergoing functional overload, and show greater increases in fast type muscles. In an operant rat model of reaching and grasping, the inducible form of Hsp70 increased in muscles and tendons showing injury, with the greatest increase in rats performing a high repetition high force for 12 weeks, compared to easier repetition/loading paradigms. These increases were paralleled by increases in several repair-associated proteins (osteoactivin, MMPs, and TGFB1). Trapezius biopsies from patients with myalgia show increased mRNA levels of Hsp72 and decreased levels of growth and metabolism regulators. Prolonged exercise interventions in general, when provided to subjects with trapezius myalgia, decreased Hsp72 mRNA levels, while specific strength training of shoulder and neck muscles increased mRNA levels of analytes related to carbohydrate oxidation. In a rat model of supraspinatus injury, the Hsp response appeared related to the cascade of stress-related programmed cell death in torn tendons. A mild mechanical stimulation of cultured tendon fibroblasts reduced apoptosis and increased cell proliferation and may be helpful for tissue regeneration.
... But we did not have information on physical factor and work load among the subjects. Physical stress and work load may have impact on 8-OHdG formation in humans (Huang et al. 2012;Sjogaard et al. 2013;Zheng and Ariizumi 2007). In future research, we will consider these confounders and control them. ...
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PurposeCoke oven emissions containing polycyclic aromatic hydrocarbons (PAHs) are predominant toxic constituents of particulate air pollution that have been linked to increased risk of lung cancer. Numerous epidemiological studies have suggested that oxidative DNA damage may play a pivotal role in the carcinogenic mechanism of lung cancer. Little is known about the effect of interaction between PAHs exposure and lifestyle on DNA oxidative damage. Methods The study population is composed by coke oven workers (365) and water treatment workers (144), and their urinary levels of four PAH metabolites and 8-hydroxydeoxyguanosine (8-OHdG) were determined. Airborne samples of exposed sites (4) and control sites (3) were collected, and eight carcinogenic PAHs were detected by high-performance liquid chromatography. ResultsThe median values of the sum of eight carcinogenic PAHs and BaP in exposed sites were significantly higher than control sites (P < 0.01). The study found that the urinary PAH metabolites were significantly elevated in coke oven workers (P < 0.01). Multivariate logistic regression analysis revealed that the risk of high levels of urinary 8-OHdG will increase with increasing age, cigarette consumption, and levels of urinary 1-hydroxypyrene, and P for trend were all <0.05. Smoking can significantly modify the effects of urinary 1-hydroxypyrene on high concentrations urinary 8-OHdG, during co-exposure to both light or heavy smoking and high 1-hydroxypyrene levels (OR 4.28, 95% CI 1.32–13.86 and OR 5.05, 95% CI 1.63–15.67, respectively). Conclusions Our findings quantitatively demonstrate that workers exposed to coke oven fumes and smoking will cause more serious DNA oxidative damage.
... E-mails and flyers were distributed among several workplaces with predominant computer-based tasks. Subjects were required (1) to perform at least 20 hrs of computer work a week, for at least 1 yr, (2) to suffer from neck pain for at least 30 days in the last year and for at least 1 day/wk, 30 (3) to report a pain score of 3 or higher on a 10-point numeric rating scale (NRS), and (4) to have work-related neck pain, which aggravates during the working day and week. Eligibility was assessed using an online questionnaire including demographic features, characteristics of current and previous episodes of neck pain, medical history (general health, injuries, surgery, medical imaging), medication use, and the Neck Disability Index. ...
... During a writing task, Leonard et al. (2010) 19 found a higher sEMG activity in the upper trapezius of subjects with work-related neck pain, compared with pain-free participants. Sjøgaard et al. (2010) 30 found a significantly larger sEMG activity of the upper trapezius, during a pegboard task, in patients with trapezius myalgia, compared with healthy controls. 45 found a linear relationship between the degree of self-reported pain and the changes in sEMG activity of postural neck muscles during a unilateral upper limb task. ...
Article
Objective: Myofascial pain can be accompanied by a disturbed surface electromyographic (sEMG) activity. Nevertheless, the effect of myofascial treatment techniques, such as dry needling (DN), on the sEMG activity is poorly investigated. Several DN studies also emphasize the importance of eliciting local twitch responses (LTRs) during treatment. However, studies investigating the added value of LTRs are scarce. Therefore, the aims of this study were first to evaluate the effect of DN on the sEMG activity of myalgic muscle tissue, compared with no intervention (rest), and secondly to identify whether this effect is dependent of eliciting LTRs during DN. Methods: Twenty-four female office workers with work-related trapezius myalgia were included. After completion of a typing task, changes in sEMG activity were evaluated after a DN treatment of the upper trapezius, compared with rest. Results: The sEMG activity increased after rest and after DN, but this increase was significantly smaller 10 minutes after DN, compared with rest. These differences were independent whether LTRs were elicited or not. Conclusions: Dry needling leads to a significantly lower increase in sEMG activity of the upper trapezius, compared with no intervention, after a typing task. This difference was independent of eliciting LTRs.
... Other beneficial effects were found to include a number of health-related factors such as lowered blood pressure. Direct measures on the muscle level using biopsy and microdialysis techniques showed an increase in metabolic capacity (84), demonstrated even at the gene level (80). ...
Article
Work-related physical activity (PA), in terms of peak loads, sustained and/or repetitive contractions presents risk factors for the development of muscular pain and disorders. However, PA as training tailored to the employee's work exposure, health, and physical capacity offers prevention and rehabilitation. We suggest the concept of "Intelligent Physical Exercise Training" relying on evidence-based sports science training principles.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
... 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.
... Exercise training increases the expression of HSP72 a few days after the onset of training [83][84][85] while prolonged exercise training, using intermittent high-intensity treadmill running for 8 weeks, induces long-term enhancement of HSP70 expression in skeletal muscle [86]. Interestingly, Sjogaard et al. showed in human subjects that performance of repetitive tasks increased HSP72 in muscles while prolonged exercise training decreased its basal levels [87], suggestive of a clear difference between these two activities. Activation of HSP72 may play a dual role in inflammation [88], inhibiting the release of inflammatory cytokines including IL-1beta [89][90][91][92][93]. ...
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BACKGROUND: Expression of the growth factor osteoactivin (OA) increases during tissue degeneration and regeneration, fracture repair and after denervation-induced disuse atrophy, concomitant with increased matrix metalloproteinases (MMPs). However, OA's expression with repetitive overuse injuries is unknown. The aim of this study was to evaluate: 1) OA expression in an operant rat model of repetitive overuse; 2) expression of MMPs; 3) inflammatory cytokines indicative of injury or inflammation; and 4) the inducible form of heat shock protein 70 (HSPA1A/HSP72) as the latter is known to increase during metabolic stress and to be involved in cellular repair. Young adult female rats performed a high repetition negligible force (HRNF) food retrieval task for up to 6 weeks and were compared to control rats. METHODS: Flexor digitorum muscles and tendons were collected from 22 young adult female rats performing a HRNF reaching task for 3 to 6 weeks, and 12 food restricted control (FRC) rats. OA mRNA levels were assessed by quantitative polymerase chain reaction (qPCR). OA, MMP-1, -2, -3, and -13 and HSP72 protein expression was assayed using Western blotting. Immunohistochemistry and image analysis was used to evaluate OA and HSP72 expression. ELISA was performed for HSP72 and inflammatory cytokines. RESULTS: Flexor digitorum muscles and tendons from 6-week HRNF rats showed increased OA mRNA and protein expression compared to FRC rats. MMP-1, -2 and -3 progressively increased in muscles whereas MMP-1 and -3 increased in tendons with HRNF task performance. HSP72 increased in 6-week HRNF muscles and tendons, compared to controls, and co-localized with OA in the myofiber sarcolemma. IL-1alpha and beta increased transiently in tendons or muscles in HRNF week 3 before resolving in week 6. CONCLUSION: The simultaneous increases of OA with factors involved in tissue repair (MMPs and HSP72) supports a role of OA in tissue regeneration after repetitive overuse.
... Hence, neural adaptations may only in part explain the present findings, and we cannot exclude the possible contribution from muscular adaptation to the training-induced increase in fatigue resistance. In support of this notion, musculoskeletal pain has previously been associated with impaired microcirculation in the painful muscles, reduced capillarization of muscle fibers, and lowered carbohydrate oxidation capacity [34][35][36]. Consequently, such local muscular factors may contribute to increasing anaerobic metabolism and thus influence fatigue development during various work tasks. In line with this notion, Andersen and coworkers reported that increased strength capacity during repetitive isometric shoulder contractions was paralleled by increased capillarization and myofiber hypertrophy following 10 weeks of strength training in women with trapezius myalgia [15]. ...
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Chronic musculoskeletal pain is widespread in the working population and leads to muscular fatigue, reduced work capacity, and fear of movement. While ergonomic intervention is the traditional approach to the problem, physical exercise may be an alternative strategy. This secondary analysis of a randomized controlled trial investigates the effect of strength training on muscular fatigue resistance and self-rated health among workers with chronic pain. Sixty-six slaughterhouse workers with chronic upper limb pain and work disability were randomly allocated to 10 weeks of strength training or usual care ergonomic training (control). At baseline and follow-up, participants performed a handgrip muscular fatigue test (time above 50% of maximal voluntary contraction force) with simultaneous recording of electromyography. Additionally, participants replied to a questionnaire regarding self-rated health and pain. Time to fatigue, muscle strength, hand/wrist pain, and self-rated health improved significantly more following strength training than usual care (all P<0.05 ). Time to fatigue increased by 97% following strength training and this change was correlated to the reduction in fear avoidance (Spearman’s rho =-0.40 ; P=0.01 ). In conclusion, specific strength training improves muscular fatigue resistance and self-rated health and reduces pain of the hand/wrist in manual workers with chronic upper limb pain. This trial is registered with ClinicalTrials.gov NCT01671267 .
... 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 . Importantly, with exercise training functional capacity improved (Andersen et al., 2014), metabolic capacity increased (Søgaard et al., 2012), as demonstrated even at the gene level (Sjøgaard et al., 2013). Morphological recovery was also documented using advanced immuno-histochemical stainings; for example, satellite cells (Mackey et al., 2011) and neuronal nitric oxide synthase (Jensen et al., 2015). ...
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.