Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

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Up to 85% of cyclists experience repetitive strain injuries (RSI's). During long bouts of repetitive tasks, muscle fatigue may cause mal-alignments in kinematics, having cumulative effects, leading to an RSI. Purpose: The study's purpose was to examine how changes in localized muscle fatigue relate to changes in movement kinematics in highly trained cyclists throughout a full fatigue protocol. Methods: Seven highly trained cyclists participated in a 2 session experiment. Session 1 included a VO2 max test and familiarization trial and Session 2 was the fatigue protocol. Kinematic angles measured were trunk lean, hip, knee, ankle, and knee splay angle. Mean angle (MA) and range of motion (ROM) was calculated for each revolution thought the trial. Muscles monitored were the quadriceps, hamstring, gastrocnemius, and tibialis anterior. EMG median frequency (MDF) for each muscle was calculated for each revolution by averaging MDF for the two halves of each revolution. Cross-correlation analysis was done on MDF and MA data and MDF and ROM data. Results: All subjects exhibited increases in trunk lean and decreases in ankle angle. Non-monotonic changes were observed in trunk lean, ankle, knee splay angle, and among ROM results for all 5 angles. A 1-tailed T-tests for all subjects, revealed that HAM (p = 0.020) and GAS (p = 0.018) exhibited significant muscle fatigue. One-tailed T-tests yielded significantly negative cross-correlation time lags [Greek small letter tau] for trunk lean MA, ROM, and hip MA. Conclusions: Non-monotonic changes are present in kinematics and MDF. Therefore pre vs. post experimental designs cannot quantify fatigue processes. Shifts in trunk lean MA, ROM and hip MA are significantly correlated with preceding decreasing shifts of MDF (indicative of onset of fatigue). / text

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Employee turnover is a complex problem with many intertwining contributors. In general newly hired employees at an organization have a higher risk of injury. However, few studies have explored occupational injury as a predictor of employment duration. In this study we hypothesized that employees who sustained an injury during the early stages of employment were prone to higher turnover rates. All employees hired from 2012-2016 were identified using a large Midwestern manufacturing facilities human resources database (n=3765). Corresponding occupational injury information from the same time period was extracted from the onsite occupational health center. Employment duration was the dependent variable which was dichotomized as (i) working < 60 days or (ii) working ≥60 days. The 60-day threshold was based on the employer’s internal estimation of the duration of employment required to recover training costs. The primary independent variable was a first-time visit to the occupational health center within the first 60 days of employment, categorized as (i) no visit, (ii) a visit within 1-20 days, or (iii) a visit within 21-60 days. A secondary independent variable incorporated the nature of injury, classified as repetitive strain, acute sprain/strain, or other occupational injury types. Covariates included demographics (e.g., age, gender, and race/ethnicity), shift placement (e.g. first, second, third), and nature of assigned job (e.g., assembly, fabrication, maintenance). Incidence rates of first-time visits were calculated (i) across the full study period and (ii) for a reduced period that included only the first 60 days of employment. Logistic regression was used to estimate adjusted associations between the primary/secondary independent variables and the dependent variable. Of the 3765 employees, 1184 (31.5%) worked less than 60 days. About two-thirds were male, about half were white/Caucasian, and the overall mean age was 33.8±10.8 years. Between 2012 and 2016, 1105 first-time visits to the occupational health center were recorded for all new hires with an overall incidence rate (IR) of 47/100 person-years (PY). The IR for repetitive strain was 18/100PY. Of the 1105 first-time visits, 408 occurred within the first 60 days of employment with an overall IR of 85/100PY and an IR for repetitive strain of 36/100PY. Employees who visited the occupational health center in the first 20 days of employment were more likely to terminate prior to the 60-day threshold (adjusted odds ratio: 1.7; 95% confidence interval: 1.3-2.4). Elevated associations were seen for all nature of injury categories which occurred within 20 days when compared to non-injured employees. Overall, the results suggest that experiencing an occupational injury (in particular, a repetitive strain injury) within the first 20 days of employment is associated with termination before 60 days. Our results may not be generalizable to all manufacturing enterprises, and we do not make a distinction between voluntary and involuntary termination. However, the results indicate that employers should examine policies and practices to minimize the burden of injury among new employees and reduce turnover. In the case of the study facility, an extended or modified work hardening program could maximize new employees’ adaptation to the physical demands of manufacturing work.

MSc (Occupational Therapy), Faculty of Health Sciences, University of the Witwatersrand / Ergonomic interventions, addressing work and lifestyle factors, seem more effective in reducing computer related upper limb repetitive strain injury (RSI).This study considered the efficacy of such a programme on the resolution of RSI symptoms. A cross sectional survey, of 325 computer workers in a medical aid company call centres, in Gauteng, South Africa was used to establish a point prevalence of 30.23% for RSI symptoms, which correlates with those found elsewhere. An occupational therapy ergonomic intervention was then designed and piloted for efficacy. A randomised control trial conducted on 37 participants with RSI used the programme and computer generated “Break Software”. The six week intervention included the assessment of: three physical outcome measures and lifestyle factors for, the experimental and control groups. Results indicated positive effects on pain, grip strength, and lifestyle factors including feelings of inefficiency, pressure at the end of the day, depression and work capacity, but little extrapolation of ergonomic knowledge to the workplace.

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-12T17:14:11Z No. of bitstreams: 1 JESSICA FERREIRA DA SILVA – DISSERTAÇÃO (PPGEM) 2017.pdf: 3580915 bytes, checksum: 875b1175aef9908cbe030d48f0048870 (MD5) / Made available in DSpace on 2018-04-12T17:14:11Z (GMT). No. of bitstreams: 1 JESSICA FERREIRA DA SILVA – DISSERTAÇÃO (PPGEM) 2017.pdf: 3580915 bytes, checksum: 875b1175aef9908cbe030d48f0048870 (MD5) Previous issue date: 2017-11-28 / Capes / A lesão por esforço repetitivo (LER) configura uns dos maiores desafios enfrentados pela classe trabalhadora ao redor do mundo por causarem dor, dificuldade para realizar tarefas relacionadas ao trabalho, longos períodos de afastamento e invalidez da força de trabalho. As estruturas das extremidades superiores são particularmente vulneráveis a este tipo de lesão. Desse modo, o objetivo geral desse trabalho foi realizar um estudo térmico da região das mãos utilizando a técnica da termografia com vistas a auxiliar no diagnóstico da LER/DORT. A amostra foi composta por 21 voluntários, sendo 11 do gênero masculino e 10 do gênero feminino, acadêmicos da graduação e da pós-graduação da Universidade Federal de Campina Grande. Foi construída uma bancada de testes com o intuito de isolar a região de estudo e minimizar o efeito da temperatura ambiente refletida sobre o resultado dos termogramas. Os voluntários foram previamente orientados sobre os procedimentos a serem seguidos do dia do teste. No momento do teste, os voluntários foram instruídos a retirar qualquer adorno na região de estudo, não friccionar e/ou encostar as mãos umas nas outras ou em qualquer superfície e permanecerem por um tempo determinado por protocolo em repouso na posição sentada em uma sala com ambiente controlado. Foram coletadas imagens térmicas da vista anterior e posterior das mãos. As imagens foram analisadas qualitativa e quantitativamente. A análise quantitativa mostrou um estado marcante de equilíbrio térmico para as regiões de interesse contralaterais. O membro dominante possuiu maior temperatura média em relação ao seu correspondente lateral. O gênero não foi um fator determinante para avaliação dos padrões térmicos das mãos. Conclui-se que a medição da temperatura superficial da pele da região das mãos utilizando a técnica da termografia mostrou-se viável e reprodutível, recomendando-se a criação de tabelas de referência específicas para estabelecer as condições normais para cada segmento corporal. / The repetitive strain injury (RSI) is one of the greatest challenges faced by the working class around the world because it causes pain, difficulty in carrying out work-related tasks, long periods of absence and disability of the workforce. The structures of the upper extremities are particularly vulnerable to this type of injury. Thus, the general objective of this work was to perform a thermal study of the hands using thermography to assist in the RSI’s diagnosis. The sample consisted of 21 volunteers, 11 male and 10 female, undergraduate and graduate students from the Federal University of Campina Grande. A test bench was built in order to isolate the region of study and minimize the effect of the ambient radiation on the result of the thermograms. The volunteers were previously advised on the procedures to be followed on the day of the test. At the time of the test, volunteers were instructed to remove any adornment in the study region, not rub or touch their hands on each other or on any surface, and remain in a sitting position for a time set by protocol at rest in a room with controlled environment. Thermal images were collected from the anterior and posterior views of the hands. The images were analyzed qualitatively and quantitatively. Quantitative analysis showed a marked state of thermal equilibrium for the contralateral regions of interest. The dominant limb had a higher average temperature than its corresponding side. The gender was not a determining factor for evaluation of the thermal patterns of the hands. It is concluded that the measurement of the skin surface temperature of the hands using the thermography technique was feasible and reproducible, and it is recommended to create specific reference tables to establish the normal conditions for each body segment.

Este trabalho teve por principal objetivo o desenvolvimento e implantação de melhorias de um processo industrial para fabricação de preservativos, utilizando automação industrial por meio da metodologia Seis Sigma. A motivação foi o crescente número de funcionários afastados ou readaptados devido a Lesão por Esforço Repetitivo (LER), pois além dos danos pessoais permanentes, existem ainda os gastos com substituição de trabalhadores, treinamentos, horas extras, recuperação de empregados e salários pagos a trabalhadores afastados. A metodologia foi aplicada a duas partes do processo: no teste elétrico dos preservativos para verificação de existência de não conformidades no produto, e, no processo manual de desenrolamento, para quando um determinado lote não aprovado em testes de laboratório é rejeitado e submetido novamente ao teste elétrico. Por meio da ferramenta DMAIC, reconhecida em todo o mundo como o meio de se estruturar os projetos de melhoria na busca do padrão Seis Sigma, são definidos objetivos de melhoria, medição do sistema existente, análise do sistema medido, melhoria do sistema e controle do novo sistema. A solução emprega automação com apoio de dispositivos eletropneumáticos que se mostram eficientes do ponto de vista operacional, de custo e energético. A automatização do processo eliminou por completo o surgimento de novos casos de Lesão por Esforço Repetitivo e, ainda, proporcionou aumento de produtividade, diminuiu a área de estocagem e reduziu a quantidade de horas extras. / The main objective of this work was the development and implantation of improvements in industrial process to manufacture preservatives using the Six-Sigma methodology. The motivation was the increasing number of employees that were withdrawn and reallocated due to Repetitive Strain Injury (RSI), because, further permanent damages caused to the employees, there are existing costs associated with the substitution of workers, training, overtime, employee recovery, and salaries paid to withdrawn workers. The methodology was applied to two parts of the process: the electric test of the preservatives for verification of non-compliances in the product, and, in the manual unbind process, when a certain package unapproved in lab tests, is rejected and required to have another electrical test. Using the DMAIC methodology, recognized in the whole world as the way of structure the projects of improvement according to Six-Sigma, are defined the improvements objectives, measuring of the existing system, analysis of the measured system, improvement of the system and control of the new system. The solution uses automation with support of electro pneumatics devices that are operational, cost and energetic efficiency. The automation of this process completely eliminated the appearance of new Repetitive Strain Injury cases, and, still provided increased productivity, reduced storage area and reduced overtime.

Key clinical features of cumulative trauma disorders include pain, muscle weakness, and tissue fibrosis, although the etiology is still under investigation. Therefore, we first sought to characterize the temporal pattern of altered sensorimotor behaviors and inflammatory and fibrogenic processes occurring in forearm muscles and serum of young adult, female rats performing an operant, high repetition high force (HRHF) reaching and grasping task for 6, 12, or 18 weeks. Palmar mechanical sensitivity, cold temperature avoidance and spontaneous behavioral changes increased, while grip strength declined, in 18-week HRHF rats, compared to controls. Flexor digitorum muscles had increased MCP-1 levels after training and increased TNFα in 6-week HRHF rats. Serum had increased IL-1β, IL-10 and IP-10 after training. Yet both muscle and serum inflammation resolved by week 18. In contrast, IFNg increased at week 18 in both muscle and serum. Given the anti-fibrotic role of IFNg, and to identify a mechanism for the continued grip strength losses and behavioral sensitivities, we evaluated the fibrogenic proteins CCN2, collagen type I and TGFß-1, as well as the nociceptive/fibrogenic peptide substance P. Each increased in and around flexor digitorum muscles and extracellular matrix in the mid-forearm, and in nerves of the forepaw at 18 weeks. CCN2 was also increased in serum at week 18. At a time when inflammation had subsided, increases in fibrogenic proteins correlated with sensorimotor declines. Thus, muscle and nerve fibrosis may be critical components of chronic work-related musculoskeletal disorders. CCN2 and substance P may serve as potential targets for therapeutic intervention, and CCN2 as a serum biomarker of fibrosis progression. TGFß-1 and CCN2 are important mediators of tissue fibrosis by their stimulatory effect on extracellular matrix deposition, with CCN2 functions as a downstream mediator of TGFß-1. Substance P (SubP), a nociceptor-related neuropeptide, has also been linked to tissue fibrosis, although little work has been done to understand whether SubP directly causes fibrotic responses in tenocytes. Therefore, we sought to determine if SubP induces fibroblast proliferation and collagen production via CCN2 signaling directly or through the TGFß-1/CCN2 signaling pathway. We hypothesized that SubP may act directly through CCN2, independently from the TGFß-1/CCN2 signaling pathway, to increase fibroblast proliferation and fibrogenic and extracellular matrix protein production in vitro. To examine this question, we assayed cell proliferation and production of CCN2, TGFB1 and collagen type 1 in vitro using primary tendon fibroblasts (tenocytes) isolated from flexor digitorum tendons, and using rat dermal fibroblasts (RDF). We observed that cells isolated from flexor digitorum tendons that express proteins characteristic of tenocytes (vimentin and tenomodulin) underwent increased proliferation in a dose dependent manner after TGFß-1 treatment, but not SubP treatment, as did RDF cells. TGFß-1 treatment increased CCN2 production in both tenocytes and RDF cells, while SubP induced CCN2 production only in rat tenocytes. Expectedly, TGFß-1 treatment increased collagen expression in each cell type, as did SubP treatment alone using In-cell Western analysis. Interestingly, preliminary data that needs to be repeated showed that SubP treatment of each cell type enhanced TGFß-1 expression, assayed using In-cell Western and traditional western blot analyses. Our findings suggest that both SubP and TGFß-1 have distinct fibrogenic actions on tenocytes and dermal fibroblast and that both may be involved in tendinosis observed in animal models and patients with fibrosis. Inflammatory pain, muscle weakness, and tissue fibrosis are key clinical features of work-related musculoskeletal disorders. So, lastly, we evaluated the effects of therapeutic interventions on behavioral and cytokine changes in muscle, tendon and serum of HRHF rats that performed the reaching and grasping task for 11 weeks. We compared sensorimotor behavioral changes, and flexor digitorum tissue inflammation and fibrosis in rats receiving anti-TNFα therapy prophylactically during the initial training, or anti-TNFα therapy with or without rest as secondary interventions during the HRHF work task. Untreated or saline only treated animals at the end of the initial training period had decreased grip strength, increased mechanical sensitivity, and increased serum and tissue inflammatory cytokines (TNFα, IL-1ß, IL-6 and VEGF), changes prevented by prophylactic anti-TNFα treatment. Regarding the secondary interventions, four weeks of anti-TNFα therapy with or without rest, provided in HRHF task weeks 4-7, was more effective than rest alone for restoring grip strength; no treatments rescued forepaw mechanical sensitivity. Effectiveness of the 4-week anti-TNFα therapy extended to week 11, despite no further drug treatment after week 7, for maintenance of grip strength. Tissue cytokine analysis in week 11 showed that HRHF rats treated with saline had increased IL-18 in serum, muscle and tendon, and trends for increased muscle CCN2. Each treatment, particularly anti-TNF with or without rest, decreased serum and tendon IL-18 and IL-1alpha. Rats receiving combined rest and anti-TNFα therapy also had increased serum IL-10. Thus, similar short-term anti-TNFα therapy may be a potential intervention in WMSDs. These results demonstrate that both Substance P and CCN2 play important roles in the development of fibrosis in muscle and tendon in WMSDs based on our model of repetition reaching and grasping. Using in vitro methods, it was demonstrated that substance P is capable of inducing CCN2 in isolated tenocytes and rat dermal fibroblasts, independent of TGFß-1 signaling, a novel discovery that make suggest new treatments for fibrotic disorders. Finally, anti-TNFalpha treatment successfully prevented behavioral declines and increases in IL-18 in serum and tissues in our rat model when provided during the course of HRHF task performance. Key clinical features of cumulative trauma disorders include pain, muscle weakness, and tissue fibrosis, although the etiology is still under investigation. Therefore, we first sought to characterize the temporal pattern of altered sensorimotor behaviors and inflammatory and fibrogenic processes occurring in forearm muscles and serum of young adult, female rats performing an operant, high repetition high force (HRHF) reaching and grasping task for 6, 12, or 18 weeks. Palmar mechanical sensitivity, cold temperature avoidance and spontaneous behavioral changes increased, while grip strength declined, in 18-week HRHF rats, compared to controls. Flexor digitorum muscles had increased MCP-1 levels after training and increased TNFα in 6-week HRHF rats. Serum had increased IL-1β, IL-10 and IP-10 after training. Yet both muscle and serum inflammation resolved by week 18. In contrast, IFNg increased at week 18 in both muscle and serum. Given the anti-fibrotic role of IFNg, and to identify a mechanism for the continued grip strength losses and behavioral sensitivities, we evaluated the fibrogenic proteins CCN2, collagen type I and TGFß-1, as well as the nociceptive/fibrogenic peptide substance P. Each increased in and around flexor digitorum muscles and extracellular matrix in the mid-forearm, and in nerves of the forepaw at 18 weeks. CCN2 was also increased in serum at week 18. At a time when inflammation had subsided, increases in fibrogenic proteins correlated with sensorimotor declines. Thus, muscle and nerve fibrosis may be critical components of chronic work-related musculoskeletal disorders. CCN2 and substance P may serve as potential targets for therapeutic intervention, and CCN2 as a serum biomarker of fibrosis progression. TGFß-1 and CCN2 are important mediators of tissue fibrosis by their stimulatory effect on extracellular matrix deposition, with CCN2 functions as a downstream mediator of TGFß-1. Substance P (SubP), a nociceptor-related neuropeptide, has also been linked to tissue fibrosis, although little work has been done to understand whether SubP directly causes fibrotic responses in tenocytes. Therefore, we sought to determine if SubP induces fibroblast proliferation and collagen production via CCN2 signaling directly or through the TGFß-1/CCN2 signaling pathway. We hypothesized that SubP may act directly through CCN2, independently from the TGFß-1/CCN2 signaling pathway, to increase fibroblast proliferation and fibrogenic and extracellular matrix protein production in vitro. To examine this question, we assayed cell proliferation and production of CCN2, TGFB1 and collagen type 1 in vitro using primary tendon fibroblasts (tenocytes) isolated from flexor digitorum tendons, and using rat dermal fibroblasts (RDF). We observed that cells isolated from flexor digitorum tendons that express proteins characteristic of tenocytes (vimentin and tenomodulin) underwent increased proliferation in a dose dependent manner after TGFß-1 treatment, but not SubP treatment, as did RDF cells. TGFß-1 treatment increased CCN2 production in both tenocytes and RDF cells, while SubP induced CCN2 production only in rat tenocytes. Expectedly, TGFß-1 treatment increased collagen expression in each cell type, as did SubP treatment alone using In-cell Western analysis. Interestingly, preliminary data that needs to be repeated showed that SubP treatment of each cell type enhanced TGFß-1 expression, assayed using In-cell Western and traditional western blot analyses. Our findings suggest that both SubP and TGFß-1 have distinct fibrogenic actions on tenocytes and dermal fibroblast and that both may be involved in tendinosis observed in animal models and patients with fibrosis. Inflammatory pain, muscle weakness, and tissue fibrosis are key clinical features of work-related musculoskeletal disorders. So, lastly, we evaluated the effects of therapeutic interventions on behavioral and cytokine changes in muscle, tendon and serum of HRHF rats that performed the reaching and grasping task for 11 weeks. We compared sensorimotor behavioral changes, and flexor digitorum tissue inflammation and fibrosis in rats receiving anti-TNFα therapy prophylactically during the initial training, or anti-TNFα therapy with or without rest as secondary interventions during the HRHF work task. Untreated or saline only treated animals at the end of the initial training period had decreased grip strength, increased mechanical sensitivity, and increased serum and tissue inflammatory cytokines (TNFα, IL-1ß, IL-6 and VEGF), changes prevented by prophylactic anti-TNFα treatment. Regarding the secondary interventions, four weeks of anti-TNFα therapy with or without rest, provided in HRHF task weeks 4-7, was more effective than rest alone for restoring grip strength; no treatments rescued forepaw mechanical sensitivity. Effectiveness of the 4-week anti-TNFα therapy extended to week 11, despite no further drug treatment after week 7, for maintenance of grip strength. Tissue cytokine analysis in week 11 showed that HRHF rats treated with saline had increased IL-18 in serum, muscle and tendon, and trends for increased muscle CCN2. Each treatment, particularly anti-TNF with or without rest, decreased serum and tendon IL-18 and IL-1alpha. Rats receiving combined rest and anti-TNFα therapy also had increased serum IL-10. Thus, similar short-term anti-TNFα therapy may be a potential intervention in WMSDs. These results demonstrate that both Substance P and CCN2 play important roles in the development of fibrosis in muscle and tendon in WMSDs based on our model of repetition reaching and grasping. Using in vitro methods, it was demonstrated that substance P is capable of inducing CCN2 in isolated tenocytes and rat dermal fibroblasts, independent of TGFß-1 signaling, a novel discovery that make suggest new treatments for fibrotic disorders. Finally, anti-TNFalpha treatment successfully prevented behavioral declines and increases in IL-18 in serum and tissues in our rat model when provided during the course of HRHF task performance. / Cell Biology

We examined the relationship between grip strength declines and muscle-tendon responses induced by long-term performance of a high-repetition, low-force (HRLF) reaching task in rats. We hypothesized that grip strength declines would correlate with inflammation, fibrosis and degradation in flexor digitorum muscles and tendons. Grip strength declined after training, and further in weeks 18 and 24, in reach limbs of HRLF rats. Flexor digitorum tissues of reach limbs showed low-grade increases in inflammatory cytokines: IL-1beta after training and in week 18, IL-1alpha in week 18, TNF-alpha and IL-6 after training and in week 24, and IL-10 in week 24, with greater increases in tendons than muscles. Similar cytokine increases were detected in serum with HRLF: IL-1alpha and IL-10 in week 18, and TNF-alpha and IL-6 in week 24. Grip strength correlated inversely with IL-6 in muscles, tendons and serum, and TNF-alpha in muscles and serum. Four fibrogenic proteins, TGFB1, CTGF, PDGFab and PDGFbb, and hydroxyproline, a marker of collagen synthesis, increased in serum in HRLF weeks 18 or 24, concomitant with epitendon thickening, increased muscle and tendon TGFB1 and CTGF. A collagenolytic gelatinase, MMP2, increased by week 18 in serum, tendons and muscles of HRLF rats. Grip strength correlated inversely with TGFB1 in muscles, tendons and serum; with CTGF-immunoreactive fibroblasts in tendons; and with MMP2 in tendons and serum. Thus, motor declines correlated with low-grade systemic and musculotendinous inflammation throughout task performance, and increased fibrogenic and degradative proteins with prolonged task performance. Serum TNF-alpha, IL-6, TGFB1, CTGF and MMP2 may serve as serum biomarkers of work-related musculoskeletal disorders, although further studies in humans are needed. / Biomedical Sciences