The construction industry, one of the largest employers of labor in the United States, has long suffered from health and safety issues relating to work-related musculoskeletal disorders. Back-related injuries are one of the most prevalent of all musculoskeletal disorders in the construction industry. Due to advancements in the field of wearable technologies, wearable robots such as passive back-support exoskeletons have emerged as a possible solution. Exoskeletons have the potential to augment human capacity, support non-neutral work positions, and reduce muscle fatigue and physical exertion. Current research efforts to evaluate the potential of exoskeletons in other industry sectors have been focused on outcome measures such as muscle activity, productivity, perceived discomfort and exertion, usability, and stakeholders' perspectives. However, there is scarce evidence regarding the efficacy of using exoskeletons for construction work. Furthermore, the risks and sociotechnical challenges of employing exoskeletons on construction sites are not well documented. Thus, through the lens of human-centric and socio-technical considerations, this study explores the prospects of adopting back-support exoskeletons in the construction industry. Firstly, a laboratory experiment was conducted to quantify the impact of using a passive exoskeleton for construction work in terms of muscle activity, perceived discomfort, and productivity. In order to investigate the acceptance of exoskeletons among construction workers and the challenges of adopting exoskeletons on construction sites, field explorations evaluating usability, perceived discomfort and exertion, social influence, and workers user perceptions were executed. Using sequential mixed methods approach, the stakeholders and factors (i.e., facilitators and barriers) critical for the adoption of exoskeletons on construction sites were investigated. Thereafter, by employing the factors and leveraging the constructs of the normalization process theory, an implementation plan to facilitate the adoption of passive exoskeletons was developed. The study contributes to the scarce body of knowledge regarding the extent to which exoskeletons can reduce ergonomic exposures associated with construction work. This study provides evidence of the perceptions of the contextual use of wearable robots, and workers' interaction with wearable robots on construction sites. The study contributes to the normalization process theory by showing its efficacy for the development and evaluation of implementation frameworks for construction industry. Furthermore, this study advances the socio-technical systems theory by incorporating all its subsystems (i.e., human, technology, organization and social) for investigating the potential of using a passive back support exoskeleton in the construction industry. / Doctor of Philosophy / Construction workers are often subjected to harsh working conditions and physically demanding work postures, which are ergonomics risks causing back-related musculoskeletal injuries. These injuries have the potential to cause permanent disabilities, lead to early retirement of experienced labor, and is one of the causes of the shortage of skilled workforce in construction. Wearable robots, such as passive back-support exoskeletons, are increasingly been looked upon as a potential solution to mitigate the problem. Exoskeletons are wearable technologies that can support and reinforce workers' body parts. Studies have shown that the use of exoskeletons could lead to reduced muscle fatigue thereby decreasing injuries in the long run. However, most of the research on the use of exoskeletons is focused on other industrial sectors. Scarce evidence regarding the use of exoskeletons in construction is documented in the literature. Furthermore, the use of exoskeletons on construction sites could have certain unintended consequences. Thus, the objective of this research was to understand the risks and challenges of using passive exoskeletons in the construction industry. A laboratory experiment was conducted to measure the impact of using exoskeletons on physical demand and productivity while performing construction tasks. An increase in productivity and a reduction in discomfort in the lower back were observed while using an exoskeleton. Thereafter, field studies were conducted where construction workers performed their usual tasks using an exoskeleton to understand their user experience and acceptance. To help construction companies in the adoption of exoskeletons, facilitators and barriers to the adoption of exoskeletons were identified. Thereafter a plan was developed to facilitate the implementation of passive exoskeletons in construction organizations. This plan can guide construction companies in the adoption of passive exoskeletons. The outcomes of this study will help other researchers to conduct similar studies with other wearable technologies.

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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

Work-related repetitive strain injury (RSI), one of the work-related musculoskeletal disorders, is the most commonly reported occupational illness, yet the pathophysiological mechanisms are not yet clear. Using our unique RSI animal model, pathophysiological tissue responses can be examined simultaneously with behavioral responses that serve as indicators of sensorimotor function. Studies in humans and with this animal model have shown that prolonged performance of repetitive tasks leads to declines in grip strength and increased of serum pro-inflammatory cytokines, both valuable biomarkers of underlying tissue injuries. Identification of biomarkers would help to elucidate the time course of the inflammatory stage of these disorders and disease progression. Sickness responses/behaviors, normal responses and behaviors occurring as a consequence of infection or illness, are responsible for re-organizing perceptions and actions to enable individuals to respond appropriately to the infection, injury and other illnesses. These behaviors can include malaise, fatigue, increased irritability and social withdrawal, behaviors that can be beneficial when ill for avoiding others and enhancing wellness. However, sickness behaviors can also include depression, sleep disorders and an enhanced perception of illness. Although recent studies have shown that circulating pro-inflammatory cytokines in serum may trigger sickness behaviors, only a few studies have examined if there is an association between work-related musculoskeletal disorders and subsets of sickness behavior; no one to date has elucidated any plausible biological cause of this association. Also, the combined effects of both aging and performance of repetitive tasks needs more evaluation since several epidemiological studies have shown a relationship between advancing age and susceptibility to musculoskeletal disorders. Therefore, using female Sprague-Dawley rats, the aims of this dissertation project are to: 1) To determine if a systemic inflammatory response is maintained long-term in rats exposed to a moderate demand lever-pulling task with high repetition, low force (HRLF) requirements; if aging enhances this systemic inflammatory response and if this response correlates with functional motor declines; 2) To determine if performance of repetitive upper extremity tasks leads to the development of sickness behaviors (weight loss, decreased social interaction and increased aggression); 3) To determine if a relationship between repetitive upper extremity tasks lead to the development of dose- and age-dependent sickness behaviors, and, to determine if increased serum or brain inflammatory cytokines are plausible mechanisms for the induction of sickness behaviors in this model; and, lastly, 4) To determine if prophylactic or secondary systemic treatments with anti-inflammatory drugs (anti--tumor necrosis factor alpha or ibuprofen) reduces sickness behaviors in rats performing a high demand high repetition high force (HRHF) reaching and handle pulling task. This finding would be in further support of an underlying task-induced inflammatory mechanism contributing to these sickness behaviors. In the first study, the relationship between serum and grip strength was examined in aged and young adult rats performing a HRLF task. Serum levels of interleukin 1-alpha (IL-1α), interferon-gamma (IFNγ) and IL-6 were higher in aged rats in general, compared to young adult rats. Each increased more in aged trained-only and 12-week HRLF rats than in young adult trained-only and 12-week HRLF rats. Serum IL-6 showed the greatest increases, with the highest levels observed in aged 12-week HRLF rats. Grip strength declined with task performance in both age groups; however, this decline correlated negatively and only moderately with serum IL-6 levels in aged rats. Thus, aging enhanced a serum cytokine response in general, a response that was even greater with repetitive task performance. Grip strength was adversely affected by task performance in both age groups, but was apparently influenced by factors other than serum cytokine levels in young rats. In the second study, the relationship between sickness behaviors (weight loss, duration of social interaction and aggression towards novel juvenile rats), serum cytokines and brain cytokines were examined in aged and young adult rats that trained to one of two task levels before performing a HRLF task. Decreased duration of social interaction and increased aggression was greater in both young adult and aged rats that trained for 10 min/day for 4-5 weeks to learn a high force (TRHF) task, compared to young adult and aged rats that learned a low force (TRLF) task. TRHF and TRLF rats of both age groups then performed a HRLF task for 6 to 24 weeks, rats termed TRHF-HRLF and TRLF-HRLF, respectively. Declines in social interaction resolved by week 3 in young adult TRHF-HRLF rats, but were still evident in 6-week aged TRHF-HRLF rats (the final endpoint for TRHF-HRLF rats). Significant increases in aggression were observed only in TRHF-HRLF rats, in both age groups. Declines in social interaction were also observed in aged rats performing a TRLF-HRLF task through week 9, but not in young adult TRLF-HRLF rats, even those performing the HRLF task for 24 weeks. These behaviors correlated moderately with increased serum IL-6 observed in the aged task rats (both TRHF-HRLF and TRLF-HRLF) and young adult TRHF-HRLF rats, although serum TNFalpha and IL-1beta also increased with task performance. Increased IL-6 and IL-6 receptor was detected immunohistochemically in brains of aged TRHF-HRLF rats, specifically in ependymal and endothelial cells, as well as glial cells and neurons of the anterior cingulate cortex and paraventricular nucleus. Thus, training to high force, even for a short time period, induced increased sickness behaviors. Aging contributed to increased sickness behaviors in repetitive task rats, and to increased expression of IL6 and IL-6 receptor in several brain regions. In the third study, the relationships between sickness behaviors (duration of social interaction and aggression towards novel juvenile rats), serum cytokines and brain cytokines were examined in young adult rats performing a high repetition high force (HRHF) task with or without anti-inflammatory medications. Rats that trained to high force (TRHF) had decreased duration of social interaction and increased aggression; these behaviors were prevented by prophylactic anti-TNFalpha or ibuprofen treatment. Untreated TRHF rats that went on to perform a HRHF task showed decreased social interaction and increased aggression through week 12; these behaviors were attenuated by secondary anti-TNFalpha and ibuprofen treatments. Untreated HRHF rats had increased serum GroKC, IFN-gamma, IL-1beta, MIP2, MIP3a and TNFalpha. These increases were attenuated after two weeks of anti-TNFalpha treatment in HRHF weeks 5-6, and after 8 weeks of ibuprofen (in HRHF weeks 5-12). The sickness behaviors correlated moderately with increased serum Gro-KC, MIP2 and TNFalpha, and were concomitant with increased IL-1beta immunoexpression in ependymal and endothelial cells in brains of untreated TRHF and HRHF rats. Both treatments reduced the increased brain IL-1beta expression. Thus, sickness behaviors induced by overuse are attenuated by anti-inflammatory interventions that reduce task-induced increases in systemic and brain inflammatory cytokines. In conclusion, both aging and task performance increased serum inflammatory cytokine responses, the latter in an exposure-dependent manner, with a greater serum cytokine response with performance of high force tasks than low force tasks. While grip strength was adversely affected by task performance in both young and aged rats, it was influenced by factors other than serum cytokine levels. In contrast, decreased duration of social interaction and increased incidence of aggression were influenced by task-induced increases in serum and brain inflammatory cytokines, responses attenuated to baseline levels with systemic anti-inflammatory treatments. Sickness behaviors were also dose- and age-dependent, with higher incidence with performance of high force tasks than with low force tasks, and higher incidence in aged rats. We postulate that the higher incidence in aged rats is due to aged-induced brain "inflamm-aging", as they also had increased immunoexpression of IL6 and IL6 receptor in blood brain barrier cells and in glial and neurons of the hypothalamic pituitary axis. / Physical Therapy

Syfte – Syftet med denna studie är att öka förståelsen för kopplingen mellan Lean och kraftergonomi inom tillverkningsindustrin samt undersöka varför de, inom viss forskning, anses oförenliga. För att uppfylla syftet har det gemensamma snittet mellan Lean och kraftergonomi undersökts samt vilka konflikter som kan uppstå mellan Lean och kraftergonomi vid arbete inom tillverkningsindustrin. Metod – Litteraturstudier, med fokus på samverkan mellan Lean och kraftergonomi, har utgjort ett teoretiskt ramverk. Litteraturstudier har kompletterats med en fallstudie på ett företag inom tillverkningsindustrin. Empirisk data, utgjord av genomförda intervjuer, observationer och en riskbedömning på fallföretaget, har analyserats gentemot det teoretiska ramverket och därmed genererat studiens resultat. Resultat – Studiens resultat visar på en stark koppling mellan Lean och kraftergonomi, då de samverkar till att stödja och förbättra varandra. Den vanliga uppfattningen, att Lean skulle orsaka repetitivt arbete, motbevisas genom att Leans principer, såsom arbetsrotation, arbetsutvidgning och arbetsberikning, istället bidrar till variation. Att Lean orsakar repetitivt arbete motbevisas även genom att arbetets takt baseras på kundefterfrågan, istället för kortast möjliga cykeltid. Ett annat bevis för att Lean och kraftergonomi stödjer varandra är att kvalitetsbrister oftast beror på kraftergonomiskt krävande rörelser. Dessa rörelser ses som icke-värdeadderande aktiviteter enligt Lean och minskar effektiviteten i arbetet. En konflikt mellan Lean och kraftergonomi har dock identifierats i studien, vilket är rörelse i form av gång. Gång ses enligt Lean som en icke-värdeadderande aktivitet, medan det enligt kraftergonomi är en viktig faktor för ett varierat arbete. Implikationer – Studien bidrar till den forskning som visar på att Leans principer och metoder ligger i ett gemensamt snitt med kraftergonomi. Anledningen till att många verksamheter upplevt en försämrad kraftergonomi på grund av Lean, tros därför bero på en ofullständig implementering utan helhetssyn över verksamhetsstrategin. Studiens resultat är behjälpligt för verksamheter i alla stadier av arbete med Lean. Resultatet kan användas som underlag för beslut före implementering, som stöd under implementering och vid fortsatt uppföljning och förbättringsarbete enligt Leans principer och metoder. Förhoppningen är att resultatet ska kunna hjälpa verksamheter att minska sjukfrånvaron, genom ökad förståelse för Lean som verksamhetsstrategi. Varje verksamhet behöver dock ha i åtanke att den identifierade konflikten mellan Lean och kraftergonomi kräver en avvägning för varje specifik arbetssituation. Begränsningar – Studerad litteratur har innefattat teori, där både Lean och kraftergonomi behandlas. Genom enskilda studier av både Lean och kraftergonomi, hade mer information troligtvis erhållits och medfört ett mer omfattande resultat om kopplingen mellan de två. / Purpose – The purpose of this study is to increase the understanding of the connection between lean and physical ergonomics in manufacturing industry, and to investigate reasons why they, in certain research, are considered to be inconsistent. To fulfil this purpose the intersection between lean and physical ergonomics has been studied, as well as possible conflicts that may arise between lean and physical ergonomics in manufacturing industry. Method – The theoretical framework is based on literature studies, focusing on the interaction between lean and physical ergonomics, supplemented by a case study at a company in manufacturing industry. Empirical data from completed interviews, from observations, and from a risk assessment of the case study company, have been analysed against the theoretical framework and generated the study's results. Findings – The results of the study show a strong link between the principles and methods of lean and physical ergonomics, as they work together to support and improve each other. The common perception, that lean should cause repetitive work, is disproved through the principles of lean, such as work rotation, work enlargement and work enhancement, which all contribute to variation. Also, according to lean principles, work rate should be based on customer demand and not on shortest possible cycle time. Another evidence of lean and physical ergonomics supporting each other is the fact that quality defects mostly occur due to ergonomically demanding movements. Such movements reduce work efficiency, and should be considered as waste according to lean. In the study, one conflict has been identified between lean and physical ergonomics, regarding movements through walking. In lean, walking is considered a non-value adding activity, while it in physical ergonomics is seen as a vital factor for work variation. Implications – The study contributes to research showing that lean principles and methods have a common intersection with physical ergonomics. The reason why many companies have experienced impaired physical ergonomics from lean, is supposed to be through incomplete implementations, lacking operational strategy overview. The results from the study will be useful for companies in all phases of lean implementation. The result may assist decisions when considering implementation, during implementation, and in continued monitoring and improvement efforts according to lean principles and methods. It is hoped that the results can help reduce sick leave through increased understanding of lean as an operational strategy. Each company must, however, bear in mind that the identified conflict between lean and physical ergonomics will have to be weighed up carefully by that particular company. Limitations – Studied literature has included theory where both lean and physical ergonomics have been discussed. Through individual studies of lean and of physical ergonomics more information would most likely have been acquired, resulting in a more extensive result on the connection between the two.

L'émergence Troubles Musculo-Squelettiques (TMS) en industrie constitue un véritable fléau ayant de lourdes conséquences socio-économique en France. Afin de réduire la pénibilité au travail et les risques TMS, les industriels s'engagent dans une politique de réaménagement des postes de travail par la mise en œuvre de moyens robotisés d'assistance aux opérateurs. Dans cette politique de prévention, le groupe PSA Peugeot Citroën aspire à utiliser des cobots et des exosquelettes comme dispositifs d'assistance pour améliorer les conditions de travail des opérateurs. Mais pour mettre en œuvre ces types de robot en usine, il est nécessaire de quantifier leurs apports ergonomiques. C'est dans ce contexte que s'inscrit cette thèse, dont l'objectif est de proposer une méthode d'évaluation de robots collaboratifs visant à être mis en œuvre dans les usines PSA Peugeot Citroën. Dans le cadre de ces travaux, nous avons utilisé l'exosquelette mono-bras droit ABLE, conçu par le CEA-LIST. A partir d'une analyse biomécanique d'une tâche de manipulation humaine, nous avons pu évaluer l'apport de l'exosquelette en termes de réduction de charge physique de l'utilisateur. Aussi avons-nous proposé dans ces travaux d'analyser les mécanismes neuromusculaires résultants du mouvement effectué en interaction avec l'exosquelette. Sur la base de la théorie du contrôle moteur humain et en utilisant une méthode d'optimisation inverse, les fonctions objectifs telles que jerk, le couple articulaire, ou l'énergie, caractérisant la tâche de manipulation humaine en termes d'efforts, de cinématique et de temps d'exécution, ont été identifiées. Cette meilleure compréhension du mouvement du membre supérieur humain a permis ensuite de revenir sur la conception de l'exosquelette afin de proposer une stratégie de commande optimisée à l'exécution de tâches de travail en environnement industriel. / The emergence of Musculo-Squelettal Disorders (MSD) in the industry is a real blight, having major socioeconomic consequences in France. In order to reduce work painfulness and MSD risks, some industries are committing to modifying workstations by assisting operators with robotic devices. Following this MSD prevention policy, PSA Peugeot Citroen aims to use cobots or exoskeletons as assistive devices to improve workers conditions. However, implementing this type of robot in factories requires quantifying their ergonomic benefit. In this context, the objective of this thesis is to develop a method to assess collaborative robot that are intended to be used in PSA Peugeot Citroen factories. In this framework, the right mono-arm ABLE exoskeleton, designed by the CEA-LIST has been used. With a biomechanical analysis of an industrial manipulation task, we have been able to assess the benefit of the exoskeleton in terms of physical load reduction. We also proposed in this work to assess neuromuscular mechanisms underlying the industrial task performed in interaction with the exoskeleton. On the basis of the human motor control theory and using an inverse optimisation method, objectives functions such as jerk, joint torque or energy that characterize the human manipulation task in terms of efforts, kinematics and execution time, have been identified. This improved understanding of human upper limb movements then allowed reviewing the exoskeleton design in order to propose an optimal command strategy adapted to the execution of industrial tasks.

Pilotos agrícolas atuam em condições de trabalho que podem acometê-los de doenças e contribuir para ocorrência de acidentes de trabalho. Nesse contexto, estudos têm direcionado seus esforços para compreender os efeitos de diversos fatores no desempenho do piloto, na saúde e/ou na segurança de voo. Exemplos típicos incluem, principalmente, a exposição aos defensivos agrícolas, seguido da exposição ao ruído ambiental e condições térmicas desfavoráveis, bem como a distribuição das responsabilidades entre os profissionais envolvidos. Outros problemas relacionados ao trabalho de pilotos agrícolas, como a operação em áreas improvisadas e o efeito dessa condição de trabalho na exposição às vibrações não é explorado. Além disso, observa-se que as queixas de dores na coluna são comuns entre os profissionais e, em função das condições de trabalho, é possível que estes tenham um risco aumentado de problemas na coluna vertebral. O objetivo dessa tese é de explorar a exposição dos pilotos agrícolas à Vibração de Corpo Inteiro (VCI) e identificar os efeitos desta na saúde, principalmente, no que diz respeito aos sintomas musculoesqueléticos da coluna vertebral. A metodologia compreendeu três etapas que incluem: uma pesquisa de campo orientada ao entendimento das condições de trabalho dos pilotos agrícolas, principalmente sobre os fatores capazes de influenciar na exposição ocupacional à VCI e na ocorrência de distúrbios musculoesqueléticos; a coleta e análise de dados sobre a exposição ocupacional dos pilotos agrícolas à VCI; e, a coleta e análise de dados sobre os sintomas musculoesqueléticos da coluna vertebral. Como resultados da pesquisa de campo, são apresentados dados sobre a rugosidade da superfície das áreas de pouso, perfil de exposição à VCI e prevalência de sintomas musculoesqueléticos em pilotos agrícolas. Os fatores significativos identificados como na exposição dos pilotos agrícolas à VCI foram o modelo de aeronave usada, as condições de rugosidade superficial das áreas de pouso, bem como as etapas do voo. Com relação à saúde da coluna vertebral dos pilotos, apenas a exposição ocupacional à VCI se apresentou como significativa. Dada a complexidade das relações de trabalho no contexto da aviação agrícola, com o envolvimento de diferentes tipos de trabalhadores, são incluídos três tipos de soluções para prevenir a ocorrência de distúrbios musculoesqueléticos em pilotos agrícolas: a manutenção frequente das áreas de pouso, de responsabilidade dos produtores rurais; a gestão do tempo de exposição diário, de responsabilidade dos gestores operacionais e de segurança operacional; e, alterações no projeto de aeronaves, seja na interface com o piloto, para atenuar a transmissibilidade das vibrações oriundas da aeronave, ou, nos sistemas de amortecimento, capazes de isolar a fonte das vibrações, impedindo sua propagação. / Agricultural pilots work in conditions that can affect them and contribute to the occurrence of work-related accidents. In this context, earlier studies have focused their efforts on the understanding of the effects of many factors on pilot performance, health and/or flight safety. Typical examples include exposure to pesticides, exposure to environmental noise and unfavorable thermal conditions, as well as the distribution of responsibilities among the professionals involved with the aerial application. Other problems related to the work of agricultural pilots, such as operation on improvised runways and the effect of this working condition on exposure to vibrations is not explored. In addition, it is noted that complaints of pain in the spine are common among professionals and, depending on working conditions, they may have an increased risk of spinal problems. The objective of this thesis is to explore the exposure of agricultural pilots to Whole-Body Vibrations (WBV) and to identify the effects of this on health, especially regarding to musculoskeletal symptoms of the spine. The methodology consisted of three stages: a field research aimed at understanding the working conditions of agricultural pilots, mainly on the factors capable of influencing the occupational exposure to WBV and the occurrence of musculoskeletal disorders; The data collection and analysis about occupational exposure of agricultural pilots to WBV; and, the data collection and analysis about musculoskeletal symptoms of the spine. As results of the field research, data are presented on surface roughness of landing fields, exposure to WBV and prevalence of musculoskeletal symptoms in agricultural pilots. The significant factors identified as in the exposure of the agricultural pilots to the WBV were the aircraft model used, the surface roughness conditions of the landing areas, as well as the flight stages. Regarding the health of the spine of the pilots, only the occupational exposure to the WBV was presented as significant. Given the complexity of labor relations in the context of agricultural aviation with the involvement of different types of workers, three types of solutions are included to prevent the occurrence of musculoskeletal disorders in agricultural pilots: frequent maintenance of landing areas, farmers; The management of the daily exposure time, the responsibility of the operational managers and operational safety; And changes in aircraft design, either at the interface with the pilot, to mitigate the transmissibility of vibrations from the aircraft, or, in damping systems, capable of isolating the source from vibrations, preventing their propagation.