Prevalence and risk factors of work-related musculoskeletal disorders among emerging manufacturing workers in Beijing, China.

Objective: The workers in emerging manufacturing are at decreased risk of traditional occupational diseases, while probably at increased risk of work-related musculoskeletal disorders (WMSDs). This study aimed to investigate the prevalence and risk factors of WMSDs among emerging manufacturing workers in Beijing. Methods: A total of 3,359 valid questionnaires were collected from 10 enterprises in the electronics, pharmaceutical, and motor manufacturing industries. The prevalence of WMSDs was assessed using the Nordic Musculoskeletal Questionnaire. The work posture load was evaluated through a questionnaire. Results: The results showed that the highest prevalence of WMSDs was observed in part of the neck (15.0%), followed by the lower back (12.5%), shoulders (11.2%), and upper back (7.1%). Female workers, workers aged older than 35 years, workers with a BMI of ≥28 kg/m2, longer working experience, never exercised had a higher prevalence of WMSDs. Logistic regression analysis showed that female workers, workers aged older than 35 years, with a middle school education and college degree, and workers who never exercised had a higher risk of WMSDs. In addition, workers who sat for long during work, worked hard with upper limbs or hands, worked in uncomfortable postures, and performed repetitive operations were positively related with the increased risk of WMSDs. Conclusion: These findings suggested that WMSDs were prevalent among emerging manufacturing workers in Beijing, China, while efforts should be made to reshape the risk factors associated with WMSDs, such as prolonged sitting, uncomfortable positions, and repetitive operations. Encouraging exercise and promoting ergonomic interventions probably be also benefit to induce the risk of WMSDs.

[Meta analysis of the prevalence and influencing factors of WMSDs among dentists in China].

Objective: To explore the relevant factors of work-related musculoskeletal disorders (WMSDs) among dentists through Meta analysis, providing a basis for the prevention and control of WMSDs among dentists. Methods: In April 2022, cross-sectional research literatures on the prevalence correlation of WMSDs among Chinese dentists were searched in databases such as China National Knowledge Infrastructure, Wanfang, VIP, PubMed, Web of Science, and Em Base database. The search was conducted from the establishment of the database until April 2022, literatures were selected using keywords such as musculoskeletal disorders and dentists. To extract gender, age, length of service, disease classification and other related influencing factors as indicator, and prevalence was selected as the outcome indicator. After evaluating the quality of the literatures, RevMan 5.3 software was used to calculate the combined RD (95%CI) values of the included literatures. Results: A total of 15 articles were included, with a total sample size of 3646 people. Meta analysis results showed that the prevalence of WMSDs among dentists in China was 80%, and the top three parts of the incidence rates were 65% of the waist, 58% of the neck, and 50% of the back. Gender, age, length of service, region and disease classification all increased the risk of WMSDs, and the combined effect size were 75%, 78%, 71%, 77% and 82% respectively (P<0.05) . Conclusion: The occurrence of WMSDs among dentists in China is related to multiple factors such as gender, age, length of service and disease classification. The above risk factors should be taken into account in the workplace and preventive measures should be actively implemented to prolong the working life of dentists.

Efficacy of passive upper-limb exoskeletons in reducing musculoskeletal load associated with overhead tasks.

Overhead work can pose substantial musculoskeletal stress in many industrial settings. This study aimed to evaluate the efficacy of passive upper-limb exoskeletons in reducing muscular activity and subjective discomfort ratings. In a repeated-measures laboratory experiment, 20 healthy male participants performed 10-min drilling tasks with and without two passive upper-limb exoskeletons (VEX and Airframe). During the tasks, muscle activity in eight muscles (upper limb - upper trapezius, middle deltoid, biceps brachii, triceps brachii; low back - erector spinae; lower limb - rectus femoris, biceps femoris, tibialis anterior) was collected using electromyography as a physical exertion measure. Subjective discomfort rating in six body parts was measured using the Borg's CR-10 scale. The results showed that muscle activity (especially in the upper-limb muscles) was significantly decreased by 29.3-58.1% with both exoskeletons compared to no exoskeleton condition. The subjective discomfort ratings showed limited differences between the conditions. These findings indicate that passive upper-limb exoskeletons may have potential as an effective intervention to reduce muscular loading and physical exertion during overhead work.

Meta analysis of the prevalence and influencing factors of WMSDs among dentists in China / 中华劳动卫生职业病杂志

Objective: To explore the relevant factors of work-related musculoskeletal disorders (WMSDs) among dentists through Meta analysis, providing a basis for the prevention and control of WMSDs among dentists. Methods: In April 2022, cross-sectional research literatures on the prevalence correlation of WMSDs among Chinese dentists were searched in databases such as China National Knowledge Infrastructure, Wanfang, VIP, PubMed, Web of Science, and Em Base database. The search was conducted from the establishment of the database until April 2022, literatures were selected using keywords such as musculoskeletal disorders and dentists. To extract gender, age, length of service, disease classification and other related influencing factors as indicator, and prevalence was selected as the outcome indicator. After evaluating the quality of the literatures, RevMan 5.3 software was used to calculate the combined RD (95%CI) values of the included literatures. Results: A total of 15 articles were included, with a total sample size of 3646 people. Meta analysis results showed that the prevalence of WMSDs among dentists in China was 80%, and the top three parts of the incidence rates were 65% of the waist, 58% of the neck, and 50% of the back. Gender, age, length of service, region and disease classification all increased the risk of WMSDs, and the combined effect size were 75%, 78%, 71%, 77% and 82% respectively (P<0.05) . Conclusion: The occurrence of WMSDs among dentists in China is related to multiple factors such as gender, age, length of service and disease classification. The above risk factors should be taken into account in the workplace and preventive measures should be actively implemented to prolong the working life of dentists.

Manipulating device-to-body forces in passive exosuit: An experimental investigation on the effect of moment arm orientation using passive back-assist exosuit emulator.

Passive exosuits have been vastly researched in the past decade for lifting tasks to alleviate the mechanical loading on the spine and reduce the lower back muscle activities in lifting tasks. Despite promising advantages of exosuits, factors such as comfort directly influence the user's acceptability of such body-worn devices. Exosuits' routing/anchoring points, which transmit device-to-body forces, remain the leading cause of discomfort among users. In the present study, we sought to investigate the effect of the routing element, that is, the "moment arm," in altering the device-to-body forces and perceived discomfort. We first presented a simplified human-exosuit model to establish insight into the effect of the moment arm on the device-to-body forces acting at the shoulder (FS) and waist (FW). Further, an experimental investigation was conducted on 10 participants with six different exosuit moment arm configurations (C1, C2, C3, C4, C5, and C6) to investigate their effect on the device-to-body forces, perceived discomfort, and muscle activity using a passive back-assist exosuit emulator in a lifting/lowering task. Configuration C4 was found to be most beneficial in reducing device-to-body forces at the shoulder and waist by up to 44.6 and 22.2%, respectively, during lifting. Subjective scores also comprehended with the device-to-body forces, indicating that C4 produces significantly less discomfort for participants. The outcome of the study illustrates the importance of selecting an appropriate moment arm configuration for passive back support exosuits in alleviating the device-to-body forces and perceived discomfort.

Course Design and Learning Outcomes of a Practical Online Ergonomics Course for Surgical Residents.

OBJECTIVE: Course content was designed and the learning outcomes assessed for an online ergonomics course for surgical residents. This course could fulfill an optional Surgical Council on Resident Education (SCORE) curriculum on Surgical Ergonomics. DESIGN: The online course included five 5-minute modules within the residents' learning system, each ending with an ungraded knowledge question, and a final 5-question multiple-choice retention quiz that allowed infinite attempts. The course was designed by ergonomists and surgeons at a quaternary academic hospital system. Participants were given two weeks to complete the modules. An electronic survey with questions assessing ergonomics knowledge and understanding on a 5-point Likert scale (strongly disagree - strongly agree) was distributed both before and after the course. The post-course survey included three additional questions to elicit feedback regarding learning experience and course design. Descriptive statistics and nonparametric paired comparisons were used to evaluate learning outcomes. SETTING: General surgery residency program at an academic medical center in the U.S. PARTICIPANTS: Twenty-two general surgery post graduate year 1 residents (PGY1s) were recruited to participate and completed the pre-course survey. Eight out of the 22 participants (36%) completed the online course and quiz; seven (32%) completed the course, quiz, and the post-course survey. RESULTS: Participants had high pre-course awareness of the importance of surgical ergonomics, benefits of work-related musculoskeletal disorder (WMSD) prevention, as well as awkward intraoperative postures being an WMSD risk factor. Participants' confidence increased significantly from pre- to post-course in ability to assess risk (p = 0.021), but not in ability or willingness to mitigate risky surgical postures. Participants who completed the quiz answered a median of 4 (IQR: [4, 5]) questions correctly. All participants indicated that they would recommend this course to other residents. CONCLUSIONS: These short practical ergonomics online learning modules increased surgical residents' confidence in assessing surgical WMSD risks.

[Comparative analysis of work-related musculoskeletal disorders catalogues].

Work-related musculoskeletal disorders (WMSDs) refer to musculoskeletal disorders caused by work or work as the main cause, which are characterized by high prevalence and heavy burden of disease as a global problem. The classification and catalog of occupational diseases is of great significance for guiding the prevention and control of occupational diseases and safeguarding the rights and interests of workers. The types of WMSDs included in the list of occupational diseases vary greatly from country to country, and the regulations on specific pathogenic factors are also inconsistent. By sorting out and analyzing the lists and characteristics of WMSDs at home and abroad, and using the International Statistical Classification of Diseases and Related Health Problems (ICD-10) in occupational health to standardize of WMSDs in various countries, which would lay the foundation for future multi-country WMSDs occupational health registration and disease burden research, and provide a reference for China to revise the WMSDs list.

Musculoskeletal symptoms and associated factors among manual porcelain workers at different workstations: a cross-sectional study.

OBJECTIVES: To investigate the prevalence of work-related musculoskeletal disorders (WMSDs) symptoms and to identify the associated factors (individual, and work-related) among manual porcelain workers at different workstations. The risk level of each workstation was also assessed based on the working postures for the purpose of improving occupational health. METHODS: In total, 349 workers were recruited for this cross-sectional study. The Nordic Musculoskeletal Questionnaire (NMQ) was used to collect data on WMSDs symptoms in nine body regions. The relationship between individual/occupational factors and WMSDs symptoms was determined using multiple logistic regression analysis. The Rapid Entire Body Assessment (REBA) method was applied to classify the risk level of working postures at the five workstations (shaping, trimming, glazing, painting, and burning). RESULTS: The prevalence of musculoskeletal discomfort in at least one body region within the past 12 months was 69.1% among the participants: the neck (49.3%), lower back (43.8%), and shoulders (27.5%). Sex, work experience, daily working hours, perceived work fatigue, and workstation, were significantly associated with WMSDs symptoms in different body regions. The REBA indicated that 57.8% and 32.5% of the working postures were in the medium- and above high-risk levels, respectively. CONCLUSION: The findings of this study showed a high occurrence of WMSDs symptoms among manual porcelain workers and suggested that both individual and work-related characteristics should be considered to improve occupational health. Furthermore, urgent ergonomic intervention is needed to avoid awkward working postures that cause WMSDs symptoms in porcelain workers, particularly at the shaping and burning workstations.

Modeling and Validation of Fatigue and Recovery of Muscles for Manual Demolition Tasks.

Manual demolition tasks are heavy, physically demanding tasks that could cause muscle fatigue accumulation and lead to work-related musculoskeletal disorders (WMSDs). Fatigue and recovery models of muscles are essential in understanding the accumulation and the reduction in muscle fatigue for forceful exertion tasks. This study aims to explore the onset of muscle fatigue under different work/rest arrangements during manual demolition tasks and the offset of fatigue over time after the tasks were performed. An experiment, including a muscle fatigue test and a muscle fatigue recovery test, was performed. Seventeen male adults without experience in demolition hammer operation were recruited as human participants. Two demolition hammers (large and small) were adopted. The push force was either 20 or 40 N. The posture mimicked that of a demolition task on a wall. In the muscle fatigue test, the muscle strength (MS) before and after the demolition task, maximum endurance time (MET), and the Borg category-ratio-10 (CR-10) ratings of perceived exertion after the demolition task were measured. In the muscle fatigue recovery test, MS and CR-10 at times 1, 2, 3, 4, 5, and 6 min were recorded. Statistical analyses were performed to explore the influence of push force and the weight of the tool on MS, MET, and CR-10. Both muscle fatigue models and muscle fatigue recovery models were established and validated. The results showed that push force affected MET significantly (p < 0.05). The weight of the tool was significant (p < 0.05) only on the CR-10 rating after the first pull. During the muscle fatigue recovery test, the MS increase and the CR-10 decrease were both significant (p < 0.05) after one or more breaks. Models of MET and MS prediction were established to assess muscle fatigue recovery, respectively. The absolute (AD) and relative (RD) deviations of the MET model were 1.83 (±1.94) min and 34.80 (±31.48)%, respectively. The AD and RD of the MS model were 1.39 (±0.81) N and 1.9 (±1.2)%, respectively. These models are capable of predicting the progress and recovery of muscle fatigue, respectively, and may be adopted in work/rest arrangements for novice workers performing demolition tasks.

Quantification of physical stress experienced by obstetrics and gynecology sonographers: A comparative study of two ultrasound devices.

This study aims to quantify the stresses of sonographers using two different ultrasound devices, one of conventional and one of ergonomic design. A total of 20 obstetricians and gynecologists participated in this study, and two types of tasks (scanning and positioning) were evaluated while using the two different devices. To quantify workload, four dependent variables (muscle activity, estimated grip force, subjective comfort rating, and task time) were measured. The muscular activity required while using the conventional device was 14.4% MVC (Maximum voluntary contraction) for the scanning task, which was significantly higher than that of the ergonomic device. The subjective comfort rating for the conventional design was lower than that of the ergonomic design. For the positioning task, the ergonomic device (33.2% MVC) resulted in significantly higher muscle activity in the extensor digitorum (ED) and flexor digitorum superficialis (FDS) than the conventional design (22.2% MVC), whereas the deltoid muscle showed significantly lower activity than in users of conventional design (4.5% MVC). Ergonomically-designed ultrasound devices improve ease of moving and the probe's supporters, reduce physical load and increase ease of use for sonographers. Our results may be used as guidelines for usability testing of ultrasound devices.

Comparative analysis of work-related musculoskeletal disorders catalogues / 中华劳动卫生职业病杂志

Work-related musculoskeletal disorders (WMSDs) refer to musculoskeletal disorders caused by work or work as the main cause, which are characterized by high prevalence and heavy burden of disease as a global problem. The classification and catalog of occupational diseases is of great significance for guiding the prevention and control of occupational diseases and safeguarding the rights and interests of workers. The types of WMSDs included in the list of occupational diseases vary greatly from country to country, and the regulations on specific pathogenic factors are also inconsistent. By sorting out and analyzing the lists and characteristics of WMSDs at home and abroad, and using the International Statistical Classification of Diseases and Related Health Problems (ICD-10) in occupational health to standardize of WMSDs in various countries, which would lay the foundation for future multi-country WMSDs occupational health registration and disease burden research, and provide a reference for China to revise the WMSDs list.

A study on musculoskeletal complaints and working postures in pathology specialists in Iran.

BACKGROUND: Musculoskeletal disorders (MSDs) are one of the most common causes of occupational injuries and disabilities among health care workers. This study investigates the relationship between musculoskeletal complaints and pathologist postures in laboratories. METHOD: In this cross-sectional study, 40 pathologists were evaluated. MSDs in different body segments of the participants were evaluated by Nordic questionnaire. For postural analysis, 20 min film was recorded while using a microscope by subjects. Posture analysis was done by the Rapid Upper Limb Assessment (RULA) method and their repetitive movements were scored. The data was analyzed by SPSS Version 11.5. RESULTS: The mean age and duration of employment of subjects was 36.57 ± 7.54 years and 6.50 ± 6.30 years, respectively. Most MSDs were found in neck (65%), wrist (57.5%), upper back (50%) and lower back (47.5%). The mean RULA grand score was higher in participants with upper back and shoulder pain. A statistically significant relationship was found between the mean RULA grand, the upper back pain (P = 0.02) and the wrist pain (P = 0.003), as well as between the mean RULA B, the neck pain (P = 0.02) and the lower back pain (P = 0.05). The results showed a significant relationship between mean weekly working hours and tight (P < 0.001), wrist (p = 0.01) and ankle (P = 0.008). CONCLUSION: This study revealed high prevalence of MSDs among the pathologists. Therefore, performing ergonomic corrective actions is essential in order to improve their physical conditions at work.

Predictors for Clinical Outcomes Related to Upper Extremity Musculoskeletal Disorders in a Healthy Working Population.

A wide range of endpoints and methods of analysis can be observed in occupational health studies in the context of work-related musculoskeletal disorders (WMSDs). Comparison of study results is therefore difficult. We investigated the association between different clinical endpoints and the presence of upper extremity WMSDs in a healthy working population. Furthermore, the influence of socio-demographic, work-related, and individual predictors on different endpoints was examined. Two self-administered questionnaires were distributed to 70 workers and employees. In addition, a standardized physical examination and an industry test were performed in this cross-sectional study. Correlations between WMSDs and clinical endpoints were analyzed with the Spearman method and prediction ellipses. Multiple regression models were used to study the strength of associations with a pre-defined set of potential influencing factors. The prevalence of WMSDs was 56% (39/70). Disabilities of Arm, Shoulder, and Hand (DASH) score/pain under strain showed the strongest correlations with WMSDs. When analyzing the correlation between WMSDs and pre-selected predictors, none of the predictors could be identified as a risk factor. The DASH score remains a close candidate for best surrogate endpoint for WMSDs detection. Standardized analysis methods could improve the methodological quality of future occupational health studies.

Prevalence and Factors Associated with Musculoskeletal Disorders among Secondary Schoolteachers in Hail, Saudi Arabia: A Cross-Sectional Survey.

Musculoskeletal disorders (MSDs) are one of the most common occupational health hazards and serious health concerns among teachers. About 39% to 95% of teachers suffer from musculoskeletal pain that can lead to a decline in their performance, frequent sick leaves and early retirement, and can have a negative impact on their quality of life. The aim of this study was to investigate the prevalence of and risk factors for MSDs among secondary schoolteachers in Hail, Saudi Arabia. A cross-sectional study was conducted through an electronic survey. A self-reported and validated Arabic version of the Nordic Musculoskeletal Questionnaire (NMQ) was used. Participants were recruited randomly through a two-stage sampling technique. A total of 251 respondents (57.8% males and 42.2% females) returned the questionnaire. The overall prevalence of MSDs was 87.3%. Female teachers (95.3%) suffered more than their male counterparts (81.4%). The most common site was the lower back (62.55%), followed by the shoulders (53.39%) and knees (41.04%). Most of the participants (72.7%) reported MSDs in multiple sites. Binomial logistic regression predicted that smoking is a significant risk factor for lower back disorders (p < 0.05). A high prevalence of MSDs can be due to a substantial lack of awareness and practice of ergonomics, which warrant the development of preventive strategies and educational programs.

E-worker postural comfort in the third-workplace: An ergonomic design assessment.

BACKGROUND: Biomechanical simulation is an important tool in human-centred design, allowing for the assessment of comfort interactions between user, product and space, to optimize design features from an ergonomics perspective. OBJECTIVE: The aim of this study was to develop a biomechanical model for the evaluation of postural comfort levels. METHODS: The study used the scenario-based method to focus on the electronic-worker (e-worker) sedentary tablet tasks at public workplace (third-workplace) configurations. An empirical method determined work-related musculoskeletal disorders (WMSDs) risk levels. The experimental method was based on a motion-capture marker-based laboratory protocol and biomechanical model. Body postures were analysed to determine the WMSDs risk to the joints, and were compared to subjective questionnaires. RESULTS: Posture was affected by the tablet target location and workplace setting. The findings confirmed our hypothesis, that neutral-position cost functions govern human motion. Almost half of the time, the e-workers' joints tended to remain in the neutral position range; of the three third-workplaces, high-risk variability was less significant between the 'restaurant' and 'lounge' settings, compared to the 'anywhere' configuration. CONCLUSIONS: This evaluation model can contribute to optimizing comfort level in design for third-workplace settings and other sedentary work activities; it can be used to develop guidelines for minimizing work-related strain and health hazards.

Is Repetitive Workload a Risk Factor for Upper Extremity Musculoskeletal Disorders in Surgical Device Mechanics? A Cross-Sectional Analysis.

To assess the prevalence of upper extremity work-related musculoskeletal disorders (WMSDs) among surgical device mechanics compared to a control group, a total of 70 employees were included and assigned to three occupational groups (grinders, packers, and control). Personal factors, work exposure, manual skill, and complaints were assessed by two self-administered questionnaires and an industry test. WMSDs were diagnosed in a standardised clinical examination. The two-one-sided t-tests (TOST) procedure was used to test the clinical equivalence of the respective grinding and packaging groups vs. the control group in terms of the Disabilities of the Arm, Shoulder and Hand (DASH) score. Thirty-nine study participants (56%) experienced at least one WMSD at the elbow, forearm, and/or wrist, mainly with signs of epicondylitis and nerve entrapment at the medial elbow. The risk of grinders developing upper extremity WMSD was about 2.5-times higher and packers had an 8.6-fold higher risk of a clinically relevant DASH > 29 compared to the control group. However, these differences were not statistically significant. The groups were also proven to be clinically equivalent in terms of DASH score. Surgical device mechanics do not seem to have worse DASH values or be at higher risk of upper limb WMSDs compared to a control group. This is the first study to analyse and compare different workplaces in this industry that are also common in other industries.

Forced treadmill running reduces systemic inflammation yet worsens upper limb discomfort in a rat model of work-related musculoskeletal disorders.

BACKGROUND: Musculoskeletal disorders can result from prolonged repetitive and/or forceful movements. Performance of an upper extremity high repetition high force task increases serum pro-inflammatory cytokines and upper extremity sensorimotor declines in a rat model of work-related musculoskeletal disorders. Since one of the most efficacious treatments for musculoskeletal pain is exercise, this study investigated the effectiveness of treadmill running in preventing these responses. METHODS: Twenty-nine young adult female Sprague-Dawley rats were used. Nineteen were trained for 5 weeks to pull a lever bar at high force (15 min/day). Thirteen went on to perform a high repetition high force reaching and lever-pulling task for 10 weeks (10-wk HRHF; 2 h/day, 3 days/wk). From this group, five were randomly selected to undergo forced treadmill running exercise (TM) during the last 6 weeks of task performance (10-wk HRHF+TM, 1 h/day, 5 days/wk). Results were compared to 10 control rats and 6 rats that underwent 6 weeks of treadmill running following training only (TR-then-TM). Voluntary task and reflexive sensorimotor behavioral outcomes were assessed. Serum was assayed for inflammatory cytokines and corticosterone, reach limb median nerves for CD68+ macrophages and extraneural thickening, and reach limb flexor digitorum muscles and tendons for pathological changes. RESULTS: 10-wk HRHF rats had higher serum levels of IL-1α, IL-1ß and TNFα, than control rats. In the 10-wk HRHF+TM group, IL-1ß and TNFα were lower, whereas IL-10 and corticosterone were higher, compared to 10-wk HRHF only rats. Unexpectedly, several voluntary task performance outcomes (grasp force, reach success, and participation) worsened in rats that underwent treadmill running, compared to untreated 10-wk HRHF rats. Examination of forelimb tissues revealed lower cellularity within the flexor digitorum epitendon but higher numbers of CD68+ macrophages within and extraneural fibrosis around median nerves in 10-wk HRHF+TM than 10-wk HRHF rats. CONCLUSIONS: Treadmill running was associated with lower systemic inflammation and moderate tendinosis, yet higher median nerve inflammation/fibrosis and worse task performance and sensorimotor behaviors. Continued loading of the injured tissues in addition to stress-related factors associated with forced running/exercise likely contributed to our findings.

Blocking substance P signaling reduces musculotendinous and dermal fibrosis and sensorimotor declines in a rat model of overuse injury.

Purpose/Aim: Substance P-NK-1R signaling has been implicated in fibrotic tendinopathies and myositis. Blocking this signaling with a neurokinin 1 receptor antagonist (NK1RA) has been proposed as a therapeutic target for their treatment.Materials and Methods: Using a rodent model of overuse injury, we pharmacologically blocked Substance P using a specific NK1RA with the hopes of reducing forelimb tendon, muscle and dermal fibrogenic changes and associated pain-related behaviors. Young adult rats learned to pull at high force levels across a 5-week period, before performing a high repetition high force (HRHF) task for 3 weeks (2 h/day, 3 days/week). HRHF rats were untreated or treated in task weeks 2 and 3 with the NK1RA, i.p. Control rats received vehicle or NK1RA treatments.Results: Grip strength declined in untreated HRHF rats, and mechanical sensitivity and temperature aversion increased compared to controls; these changes were improved by NK1RA treatment (L-732,138). NK1RA treatment also reduced HRHF-induced thickening in flexor digitorum epitendons, and HRHF-induced increases of TGFbeta1, CCN2/CTGF, and collagen type 1 in flexor digitorum muscles. In the forepaw upper dermis, task-induced increases in collagen deposition were reduced by NK1RA treatment.Conclusions: Our findings indicate that Substance P plays a role in the development of fibrogenic responses and subsequent discomfort in forelimb tissues involved in performing a high demand repetitive forceful task.

Blocking CCN2 Reduces Progression of Sensorimotor Declines and Fibrosis in a Rat Model of Chronic Repetitive Overuse.

Fibrosis may be a key factor in sensorimotor dysfunction in patients with chronic overuse-induced musculoskeletal disorders. Using a clinically relevant rodent model, in which performance of a high demand handle-pulling task induces tissue fibrosis and sensorimotor declines, we pharmacologically blocked cellular communication network factor 2 (CCN2; connective tissue growth factor) with the goal of reducing the progression of these changes. Young adult, female Sprague-Dawley rats were shaped to learn to pull at high force levels (10 min/day, 5 weeks), before performing a high repetition high force (HRHF) task for 3 weeks (2 h/day, 3 days/week). HRHF rats were untreated, or treated in task weeks 2 and 3 with a monoclonal antibody that blocks CCN2 (FG-3019), or a control immunoglobulin G (IgG). Control rats were untreated or received FG-3019, IgG, or vehicle (saline) injections. Mean task reach rate and grasp force were higher in 3-week HRHF + FG-3019 rats, compared with untreated HRHF rats. Grip strength declined while forepaw mechanical sensitivity increased in untreated HRHF rats, compared with controls; changes improved by FG-3019 treatment. The HRHF task increased collagen in multiple tissues (flexor digitorum muscles, nerves, and forepaw dermis), which was reduced with FG-3019 treatment. FG-3019 treatment also reduced HRHF-induced increases in CCN2 and transforming growth factor ß in muscles. In tendons, FG-3019 reduced HRHF-induced increases in CCN2, epitendon thickening, and cell proliferation. Our findings indicate that CCN2 is critical to the progression of chronic overuse-induced multi-tissue fibrosis and functional declines. FG-3019 treatment may be a novel therapeutic strategy for overuse-induced musculoskeletal disorders. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2004-2018, 2019.

The association between long working hours and work-related musculoskeletal symptoms of Korean wage workers: data from the fourth Korean working conditions survey (a cross-sectional study).

BACKGROUND: It has been reported that long working hours are hazardous to the workers' health. Especially, work-related musculoskeletal disorders (WMSDs) have been considered as one of the significant health issues in workplace. The objective of this study was to identify the association between long working hours and work-related musculoskeletal symptoms. METHODS: The analysis was conducted using data from the Fourth Korean Working Conditions Survey (KWCS). Subjects of this study were 24,783 wage workers and divided into three groups according to the weekly working hours, which were ≤ 40, 41-52 and > 52 h. The relationship between long working hours and work-related musculoskeletal symptoms was analyzed by multivariate logistic regression method after adjusting for general, occupational characteristics including specific working motions or postures and psychosocial factors. RESULTS: Approximately 18.4% of subjects worked more than 52 h per week and 26.4 and 16.4% of male subjects and 33.0 and 23.4% of female subjects experienced work-related upper and lower limb pains, respectively, over the last 12 months. Moreover, the prevalence of upper and lower limb pain was increased in both genders as the weekly working hours increased. The odds ratios (ORs) of upper limb pain for those working 41-52 h and more than 52 h per week when adjusted for general, occupational characteristics including specific motions or postures and psychosocial factors were 1.36 and 1.40 for male workers and 1.26 and 1.66 for female workers compared to the reference group, respectively. Furthermore, ORs of lower limb pain for the same weekly working hour groups were 1.26 and 1.47 for male workers and 1.20 and 1.47 for female workers, respectively. CONCLUSIONS: Long working hours were significantly related to work-related musculoskeletal symptoms in Korean wage workers and appropriate interventions should be implemented to reduce long working hours that can negatively affect workers' health.