Participatory ergonomics (PE) is a macroergonomics approach in which the end-users actively participate in developing and implementing the technology. PE can be an effective method for involving front-line workers in analyzing and redesigning their own jobs. PE can be used at the macro-level, the micro-level, or somewhere in between. At the macro-level, the focus of the PE program is across an entire organization or work system. At the micro-level, the focus of a PE approach is on a particular task, workstation, or product. A major benefit for using PE is that workers are more likely to accept changes to their job if they participate in the redesign. Furthermore, workers' motivation, job satisfaction, and knowledge are enhanced through the participatory process. There are many case studies that describe successful PE approaches. These studies, however, lack a control group or comparison group and so changes in the workplace (e.g., a reduction of musculoskeletal injury) cannot be attributed directly to the interventions resulting from the PE program with certainty. Quantifying the effects of PE is difficult because of problems in trying to isolate variables. Confounding variables are often difficult to contain. This study quantified some of the effects of PE by utilizing a controlled experimental design in the laboratory in which participants analyzed and redesigned a manual material handling job. The effects of this PE approach were quantified by measuring a reduction of risk factors associated with the job and by measuring a lift index of the lifting task that indicates a risk for injury. Many authors state or infer that some degree of ergonomics training should be given to the participants in a PE approach. However, the effects of providing ergonomics training to participants in these types of participatory approaches are unclear. This research evaluates the effects of providing the participants with basic ergonomics instruction relevant to the job being evaluated and redesigned. Also, this research suggests if the NIOSH lifting equation can be an effective tool in a participatory ergonomics approach in the redesign of a manual material handling job that involves lifting tasks. A 2-factor, between-subjects design was used. Participants consisted of 32 volunteers (16 males and 16 females). Only individuals that have had no prior ergonomics knowledge were considered for the subject pool. Participants performed a simulated manual material handling job in the laboratory. After performing the job, some subjects were given ergonomics training and/or instructed on how to use the NIOSH lifting equation for manual lifting tasks. The participants were then asked to redesign the original job. The participants' redesigns were compared to the redesigns of the control subjects (who received no ergonomics instruction and did not use the NIOSH lifting equation). The subjects who received the ergonomics instruction identified significantly more risk factors in the original job and eliminated significantly more risk factors in the redesign than the control subjects. The subjects who learned and used the NIOSH lifting equation also identified significantly more risk factors in the original job but did not eliminate significantly more risk factors in the redesign. The subjects who received the ergonomics instruction and who used the NIOSH lifting equation were not shown to have an advantage over the subjects who received the ergonomics instruction alone. The group that received the ergonomics training performed optimally with respect to the other experimental groups. Implications for participatory ergonomics approaches are discussed. / Master of Science

During field observations of professional movers, it was noticed that some experienced movers carried loads posterior to their pelvis. The purpose of this study was two-fold: (1) to assess the biomechanical differences between hand-held load carriage anterior (AC) and posterior (PC) to the pelvis; and, (2) to determine if an assistive load carriage device could reduce muscle effort while carrying loads either anterior or posterior to the pelvis. In the first laboratory study, an electromyographic (EMG) analysis was conducted while participants carried a load on a treadmill using AC and PC techniques. The subjects conducted three trials of AC and PC techniques while EMG data were being collected. All trial data were normalized to their respective iMVE values. An amplitude probability distribution function (APDF) was used to compare EMG amplitudes between carrying techniques. Results indicated that PC reduced EMG activity of the erector spinae (>50% reduction), trapezius, and anterior deltoid (p<0.05) as well as increasing EMG activity in the posterior deltoid (p<0.05). Eighty percent of the subjects reported that the PC method felt awkward. Due to its awkwardness, many individuals may not use the PC technique; thus, the second purpose of the study was to design an assistive movers’ pack to aid in AC and PC techniques and make the PC method easier to perform. In the second study, subjects were asked to walk unloaded while EMG was recorded. The subjects then performed the AC and PC methods with and without the assistive device. All EMG signals were normalized to unloaded gait followed by EMG APDF analyses. Findings from the first study were confirmed, in that PC, compared to AC significantly reduced erector spinae activity (p<0.05) and focused shoulder activity to the posterior deltoid. Secondly, the assistive device effectively reduced flexor digitorum activity (>40% reduction, p<0.03) and anterior deltoid activity (>75% reduction, p=0.5) in both AC and PC. Erector spinae EMG remained similar to their respective unassisted conditions. The assistive load carriage device may be an effective ergonomic tool in both AC and PC techniques. Subjective surveys indicate that the assistive device decreased the awkwardness in performing the PC technique. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2008-09-29 16:58:19.305

Work-related musculoskeletal disorders (WSMDs) are an important health concern in the workplace.  Accurately quantifying the level of physical exposures (i.e., kinematics and kinetics) is essential for risk assessments, developing and/or testing interventions, and improving estimates of exposure-response relationships.  Such exposures ideally should be quantified in situ, while workers interact with the actual work environment to complete their tasks.  However, in practice, relatively crude and/or time-consuming methods are often used, including self-reports, observational methods, and simple instrumentation, since directly assessing physical exposures is challenging in the workplace, and typically resource prohibitive. Inertial motion capture (IMC) and in-shoe pressure measurement (IPM) systems are emerging wearable technologies, and they can, respectively, facilitate monitoring of body kinematics and external forces on the body in the workplace.  Thus, this research examined the potential of such technologies in exposure assessments, and evaluated them in comparison to mature laboratory systems (i.e., optical motion capture system and force platform) or direct observation.  Performance of an IMC system was evaluated during several manual material handling (MMH) tasks, in terms of estimated body kinematics and kinetics at selected body parts.  A practical issue, regarding calibrating the IPM system in the field, was addressed by defining an ad hoc global coordinate system using a force platform.  Several regression models were developed for estimating center-of-pressure location and ground reaction forces.  Given that outputs from the IMC and the IPM systems are numerically fine-grained, but generally lack contextual information about a given job, task classification approaches were explored to automatically identify task types and their time proportions in a job. Overall, the outcomes from these studies demonstrated the potential of the IMC and the IPM systems for measuring physical exposures in the workplace.  However, estimation of physical exposures using these systems requires further improvements in some cases.  This research provided groundwork for future rapid and direct assessments of physical exposures in the workplace, and which needs to be expanded and validated in future efforts. / Ph. D.

Roll containers are widely used in transportation and delivery operations due to the high level of flexibility and agility they offer to supply chains. However, there is a negative side to the application of roll containers in industry which can be removed or minimized by proper ergonomic and technical considerations. In this thesis work, the safety problems, economic issues and environmental effects associated with roll containers being used in VGR-WESTMA organization are reviewed in order to come up with alternative solutions to the current way of using old roll containers in their supply chain. The analysis of the problem resulted in ergonomic, safety and technical recommendation on using roll containers within their associated supply chain. The appropriate technical design of roll containers that fits the organization facilities are introduced with the aim of streamlining the supply chain flow within the organization. However, cost is considered as a limiting factor for this organization. Hence, proper ergonomic awareness and use of appropriate accessories to the roll containers are considered as a contemporary alternative solution to replacing roll containers being used in this supply chain.

Slips, trips, and falls are a serious public health concern, particularly among older adults and within occupational settings, given that falls contribute to a large number of injuries and associate with high medical costs. To reduce the number of falls, there is a need to better understand risk factors contributing to falls, and to develop and evaluate improved balance training interventions to prevent falls. To address these needs, this work has two primary goals: first, to better understand risk factors contributing to falls, including fatigue and balance reactions after a large postural perturbation, and, second, to develop and evaluate improved reactive balance training (RBT) interventions to reduce risk of falls due to slipping and tripping. The first study investigated the effects of performing occupationally-relevant fatigue-inducing physical work on trip and fall risk. Healthy young adults performed a simulated manual material handling (MMH) task, using either heavy or light boxes, for two hours. Gait measures related to risk of tripping and slipping were assessed before and after the task. Reactive balance during one laboratory-induced trip was also assessed after the task. Results showed that performing the heavy MMH task did not affect risk of tripping or slipping, or reactive balance after tripping. These results may have resulted from insufficient fatigue due to the MMH task. The second study investigated the relationship between feet kinematics upon slipping while walking, and the outcome of the slip. Seventy-one laboratory-induced slips were analyzed, which included recoveries, feet-split falls, feet-forward falls, and lateral falls. Feet kinematics differed between these four slip outcomes, and a discriminant model including six measures of feet kinematics correctly predicted 87% of slip outcomes. Two potentially modifiable characteristics of feet kinematics upon slipping that can improve the likelihood of successfully averting a fall were identified: (1) quickly arresting the motion of the slipping foot; and (2) a recovery step that places the trailing toe approximately 0-10% body height anterior to the sacrum. This information may be used to guide the development of improved RBT interventions to reduce risk of slip-induced falls. The third study evaluated the efficacy of two low-cost, low-tech RBT methods for improving reactive balance after slipping. The two methods were: unexpected slip training (UST), which involved repeated unexpected slips while walking and volitional slip-recovery training (VST), which involved practicing balance reactions after volitionally inducing a slip-like perturbation. Young adults completed one session of an assigned intervention (UST, VST, or control), followed by one unexpected, laboratory-induced slip while walking. Compared to controls, UST and VST resulted in a higher proportion of successful balance recoveries from the laboratory-induced slips. UST improved both proactive control and reactive stepping after slipping, while VST primarily improved the ability to arrest slipping foot motion. These results support the use of UST and VST as practical, low-tech methods of slip training. The fourth study evaluated the efficacy of RBT that targets both slipping and tripping. Community-dwelling, healthy older adults (61-75 years) completed four sessions of either RBT (treadmill-based trip-recovery training and VST) or control training (general strength and balance exercises). Reactive balance during unexpected laboratory-induced slips and trips was assessed before and after RBT, and compared between subjects at baseline (before the intervention), after control training, and after RBT. The incidence of slip-induced falls differed between groups in that 80% fell at baseline, 60% fell after control training, and 18% fell after RBT. Post-RBT subjects also exhibited less severe slips, compared to baseline and post-control subjects. The incidence of trip-induced falls did not differ between groups, but margin of stability after tripping was greater for post-RBT subjects, compared to post-control subjects. These results show promise for the use of RBT applied to both slipping and tripping to reduce fall risk among older adults. / Doctor of Philosophy / Slips, trips, and falls are a serious public health concern, given that falls contribute to a large number of injuries and deaths. Falls are particularly concerning among older adults, who are reported to fall more frequently, and within occupational settings, where falls cause a larger number of injuries and a significant economic burden. To reduce the number of falls, there is a need to better understand risk factors contributing to falls, and to develop and evaluate improved balance training interventions to prevent falls. Four studies were conducted to address these needs: two studies aimed to better understand risk factors contributing to falls, including fatigue and balance reactions after slipping, and two studies aimed to develop and evaluate improved balance training interventions to reduce risk of falls due to slipping and tripping. This work focused on slipping and tripping, because slips and trips are reported to cause a large number of injuries and falls among both workers and older adults. The first study investigated the effect of performing occupationally-relevant fatigue-inducing physical work on trip and fall risk among healthy young adults, and results showed that performing a simulated manual material handling task (i.e. moving and stacking boxes using a two-wheeled dolly) did not affect risk of tripping and falling. The second study investigated the relationship between balance reactions after slipping and the outcome of the slip. Results showed that balance reactions of the feet predicted the outcome of the slip (i.e. recovering balance or one of three types of slip-induced falls) with 87% accuracy. We also identified characteristics of balance reactions that can improve the likelihood of successfully averting a fall. The third study evaluated the efficacy of two low-tech reactive balance training (RBT) methods for reducing slip-induced fall risk among young adults. These methods involved practicing balance reactions after slip-like perturbations, induced either unexpectedly or volitionally. Results showed that both RBT methods improved reactive balance after slipping, but through different mechanisms. The fourth study evaluated the efficacy of a RBT intervention targeting both slipping and tripping among older adults. Results showed that RBT improved reactive balance during both slipping and tripping, and reduced the incidence of slip-induced falls. In conclusion, these results help to better understand risk factors contributing to falls, and support the use of practical reactive balance training interventions targeting both slipping and tripping to reduce fall risk.

Made available in DSpace on 2016-06-02T20:18:11Z (GMT). No. of bitstreams: 1 2134.pdf: 6972689 bytes, checksum: 9585b0c3ed9c5691b7b4e49bea7a6eb7 (MD5) Previous issue date: 2008-11-27 / Universidade Federal de Minas Gerais / Despite the large tendency to task automation, manual material handling (MMH) is still performed in occupational settings. This activity has been widely studied but the focus has been kept on the low back. Besides the lower back, the incidence of musculoskeletal disorders also on upper limb, among workers who perform MMH, shows that there is a need to achieve a better understanding on the interaction between this segment and physical risk factors in the workplace. Besides physical factors, the musculoskeletal load during the MMH seems to be also influenced by the workers experience. In order to contribute with information on the effects of workplace factors on the upper limb behavior during MMH, two studies were developed. The objective of the first study was to evaluate the effects of height of the target surface and load mass on the muscular activity and movements during MMH performed by experienced and inexperienced subjects. Both muscular activity and movements were influenced by the variation of the load mass and height of the target surface. However, there was any difference for the comparison between experienced and inexperienced subjects. This fact was probably related to the homogeneity of the grip used by the subjects to carry out the handling, which has probably an association with the design of the box used in the experiment. In order to better understand the characteristics of the grip used by the subjects to perform the task, another study was conduced. The objectives were (1) to evaluate how experienced and inexperienced subjects would grasp a box when all sides were free to be approached; (2) to describe grip force and wrist movements according to each kind of hand grip, attempting to different heights of the destination surface; (3) to check for safe range of motion recorded for wrist movements in all conditions. Wrist movements and grip force were recorded during the task. Experienced and inexperienced subjects grasped the box by placing their hands on the lateral side and fingers on bottom side. This pattern was observed in all assessed conditions. It seems that when the box allows the free access to the bottom side, both experienced and inexperienced subjects prefer to use that side to position their hands/fingers. Data on movements and grip force has suggested that this grip can provide biomechanical advantage and should be available in occupational settings. In general, the results have shown that physical factors, like height of target surface and load mass, are determinants on the musculoskeletal load. Considering the demand required from the upper limbs, the high surface (around shoulder level) seems to produce higher risk to the development of disorders on this segment. To provide a better understanding on the upper limbs load, studies considering different layouts, as well as asymmetrical tasks and real occupational settings should be conduced. / Apesar da grande tendência à automação de tarefas, o manuseio de carga ainda é amplamente realizado em ambientes ocupacionais. Esta atividade tem sido bastante estudada, com o foco sendo quase sempre mantido na coluna lombar. O acometimento do membro superior de sujeitos que realizam tarefas de manuseio indica a necessidade de melhor entendimento a respeito da interação deste segmento com os fatores de risco físicos do ambiente de trabalho. Além dos fatores físicos, a sobrecarga musculoesquelética durante o manuseio parece ser também influenciada pela experiência dos trabalhadores. Para contribuir com o entendimento dos efeitos dos fatores do ambiente de trabalho no comportamento do membro superior durante o manuseio de cargas, dois estudos foram desenvolvidos. O primeiro estudo teve como objetivo avaliar o efeito da altura da superfície-alvo e massa da carga na atividade muscular e postura do segmento durante manuseio de carga, realizado por sujeitos experientes e inexperientes. Tanto a atividade muscular quanto os movimentos do ombro foram afetados pela variação da massa da carga e da altura da superfície-alvo. No entanto, não houve diferença para a comparação entre indivíduos experientes e inexperientes. Este fato foi associado à homogeneidade no tipo de preensão adotada pelos sujeitos para a realização da tarefa, o que foi atribuído ao desenho da caixa utilizada. Para melhor entender as características da preensão adotada por sujeitos experientes e inexperientes no manuseio de uma caixa que permite livre acesso às faces para posicionamento das mãos, o segundo estudo foi conduzido. Os objetivos foram (1) avaliar como sujeitos experientes e inexperientes manuseariam uma caixa quando todas as superfícies desta estavam livres para o contato; (2) descrever a força de preensão e movimentos do punho de acordo com a preensão realizada, considerando diferentes alturas de superfície-alvo; (3) avaliar as amplitudes de movimento do punho registradas de acordo com a amplitude de movimento segura proposta pela literatura. Movimentos do punho e força de preensão foram registrados durante a atividade. Sujeitos experientes e inexperientes pegaram a caixa a partir do posicionamento das mãos na face lateral e dedos na face inferior, em todas as condições avaliadas. Parece que quando a caixa permite livre acesso à face inferior, todos os sujeitos, independentemente do nível de experiência, preferem posicionar as mãos nesta superfície. Os dados de postura e força sugerem que este tipo de pega possa ser biomecanicamente mais vantajoso para o sistema musculoesquelético e deveria estar disponível nos manuseios. De maneira geral, os resultados dos estudos indicam que fatores físicos do ambiente de trabalho, como altura da superfíciealvo e massa da caixa manuseada, são determinantes da carga final imposta ao sistema musculoesquelético. Considerando a demanda imposta ao membro superior, a superfície alta (em torno da altura do ombro) parece fornecer maior risco para o desenvolvimento de lesão neste segmento. Para melhor entendimento da carga imposta ao membro superior, estudos envolvendo diferentes layouts, assim como manuseios assimétricos e ambientes ocupacionais reais devem ser conduzidos.

Wearable sensors and systems have become increasingly popular for diverse applications. An emerging technology for physical activity assessment is Smart Textile Systems (STSs), comprised of sensitive/actuating fiber, yarn, or fabric that can sense an external stimulus. All required components of an STS (sensors, electronics, energy supply, etc.) can be conveniently embedded into a garment, providing a fully textile-based system. Thus, STSs have clear potential utility for measuring health-relevant aspects of human activity, and to do so passively and continuously in diverse environments. For these reasons, STSs have received increasing interest in recent studies. Despite this, however, limited evidence exists to support the implementation of STSs during diverse applications. Our long-term goal was to assess the feasibility and accuracy of using an STS to monitor human activities. Our immediate objective was to investigate the accuracy of an STS in three representative applications with respect to occupational scenarios, healthcare, and activities of daily living. A particular STS was examined, consisting of a smart socks (SSs), using textile pressure sensors, and smart undershirt (SUS), using textile strain sensors. We also explored the relative merits of these two approaches, separately and in combination. Thus, five studies were completed to design and evaluate the usability of the smart undershirt, and investigate the accuracy of implementing an STS in the noted applications. Input from the SUS led to planar angle estimations with errors on the order of 1.3 and 9.4 degrees for the low-back and shoulder, respectively. Overall, individuals preferred wearing a smart textile system over an IMU system and indicated the former as superior in several aspects of usability. In particular, the short-sleeved T-shirt was the most preferred garments for an STS. Results also indicated that the smart shirt and smart socks, both individually and in combination, could detect occupational tasks, abnormal and normal gaits, and activities of daily living with greater than 97% accuracy. Based on our findings, we hope to facilitate future work that more effectively quantifies sedentary periods that may be deleterious to human health, as well as detect activity types that may be help or hinder health and fitness. Such information may be of use to individuals and workers, healthcare providers, and ergonomists. More specifically, further analyses from this investigation could provide strategies for: (a) modifying a sedentary lifestyle or work scenario to a more active one, and (b) helping to more accurately identify occupational injury risk factors associated with human movement. / PHD / The use of interactive or “smart” textiles that have sensing material(s) incorporated into them supports an emerging technology for physical activity assessment called Smart Textile Systems (STSs). STSs are an increasingly useful technology for researchers, athletes, patients, and others. Our aims in the current study were the development and assessment of a new smart undershirt (SUS) that was designed to monitor low-back and shoulder motions, and to evaluate the preferred placement and usability of two STSs. We also assessed the accuracy of two smart garments, smart socks (SSs) and the SUS, both individually and in combination. Accuracy was evaluated in terms of the ability of these systems to distinguish between diverse simulated occupational tasks, normal and abnormal walking patterns, and several typical daily activities. Our investigation indicated that STSs could discriminate between different human activities common in three domains: occupational scenarios, healthcare, and activities of daily life. We also found that both smart garments (i.e., SSs and SUS) provided similar accuracy for activity classification, typically exceeding 97%, and thus there was no clear superiority between these two smart garments. We conclude that, overall, smart garments represent a promising area of research and a potential alternative for discriminating and monitoring a range of human activities. Use of this technology in the future may have positive implications for health promotion.

The movement and handling of material are necessary activities, however, commonly regarded as waste. Moving and handling material more times and over longer distance than necessary is time consuming, costly and unproductive. Therefore, a suitable material handling (MH) system with appropriate facility layout is advocated. The purpose of this thesis is to explore options for material flow improvements and handling of material in production area. This comprises of a study of the material flow from storage to production areas and the handling of material in production section A. If necessary for improvements of material flow, a change in layout design will be recommended. The research approach for this thesis is a case study where data has been collected from documents, observations and interviews. The study shows that 9 % of the production time of one article is spent on manual material handling (MMH). These activities are classified as both waste and necessary, however not adding any value. The same applies for the material flow. Unnecessary distances of movements are caused by the current location of storage, operations and lack of proper structure for handling and moving material. The contribution of this study is a list of suggestions for improving the material flow and handling. Changes for improvements are, namely, availability of appropriate equipment, storing materials closer to the operations and investing in automation and vision systems with cameras of robots. The material flow and the way the material is handled can further beimproved by a change in the layout of the production area. Connecting and rearranging operations can shorter and ease the movement of material with ample space to handle the material.

Made available in DSpace on 2016-06-02T20:19:04Z (GMT). No. of bitstreams: 1 DissRLC.pdf: 4124701 bytes, checksum: 7ad00279ff99c72a1e55ee44b80f553a (MD5) Previous issue date: 2007-02-02 / Financiadora de Estudos e Projetos / Despite recent technological advances, occupational activities of manual nature are still essential in many sectors and industries. Such activities impose risky conditions, which are inherent to its nature and can be responsible for musculoskeletal injuries. In addiction, the complexity and the interaction of risk factors, many still not comprehended, that act together during the performance of manual material handlings confer challenges and stimulations to the preventive approach. In this way, two main studies (Studies I and II) and two unfolding studies had been carried through. The main studies contextualized the hamstrings flexibility and its influence on the performance of occupational tasks. The objectives of Study I had been to compare the results of two clinical tests used to evaluate hamstrings flexibility and to evaluate the reliability of the photogrammetric procedure adopted for the analysis. The fingertip-to-floor test and straight leg raise test were applied in 35 healthy male subjects. Based on tests results, subjects were divided into two groups: normal and reduced flexibility. Superficial anatomical landmarks were fixed on bony references by means of manual palpation in order to permit the tracing of the hip, thoracic-lumbar, leg, knee and tibio-tarsal angles. The student t test was applied to evaluate the differences between the two groups, for each variable. Findings showed that hip angle was significant lower at the reduced flexibility group and that the straight leg raise test was more sensible for detecting subjects with reduced flexibility. The aim of Study II was to evaluate the influence of hamstrings flexibility on the movement strategy of the trunk and pelvis adopted by healthy subjects during the performance of the manual handling. Subjects were divided into two groups, based on the straight leg raise test. A JVC digital camera with a sampling of 50 frames/second and positioned perpendicularly to the sagittal plane of the subjects was used to register the activity. The cross-correlation coefficient was used to quantify movement patterns relationship between groups, and the student t test applied to the movement variables in order to determine differences between groups. The results had demonstrated that subjects with reduced flexibility used a lesser pelvic amplitude and bigger amplitudes of the trunk during handling. Still, subjects with reduced flexibility adopted a retroverted movement of the pelvis, without great alterations during the activity. The unfolding studies contextualized the comparison of the strategies adopted by subjects with experience in load handling activities and inexperienced individuals. The Study III had as objective to evaluate the manual handling performed by 16 experienced subjects and 15 inexperienced ones. It was used a flexible electrogoniometer to measure trunk movements and the University of Michigan 3D software to estimate the intradiscal compression in L5/S1 during the handling. The normalized movement patterns were evaluated and the coefficient of variation was applied to quantify the variability of this movement. The student t test determined the differences between variables. Results pointed out to great variability of adopted postures. Smaller amplitudes of flexion had been found, but bigger amplitudes of trunk extension when the loads were deposited, respectively, in low and high surfaces for experienced individuals. Experienced subjects presented lower intradiscal compression during box deposition and the lowering task was characterized by the highest intradiscal compression. Study IV aimed to compare manual handling strategies adopted by experienced and inexperienced subjects with relation to the positioning of the feet and trunk during lowering and inclination of the box during lowering and lifting activities. Ten experienced workers and 10 subjects without professional experience with the handling activity had been selected. The manual handling carried out between different heights was filmed. By means of one edition software, the images referring to the instant of 50% of the task had been selected and used to classify the postures and to measure the inclination of the box. An ANOVA with 3 factors was used to evaluate the inclination of the box with relation to the experience, handled load and type of handling (lifting and lowering). The results had indicated that subjects with professional experience adopted strategies characterized by biggest inclination of the box and adoption of balanced postures of the trunk, with widening of the support base. Professional experience determined the adoption of different movement strategies, when compared to inexperienced ones, in response to task conditions. However, other studies are suggested in order to determine if such strategies were protective or risky ones. The results presented in this dissertation raise the hypothesis that hamstrings flexibility is a risk factor for the increase of trunk overload, during the performance of manual material handling. / Apesar dos recentes avanços tecnológicos, as atividades ocupacionais de natureza manual ainda são imprescindíveis e amplamente utilizadas em muitos setores e indústrias. Tais atividades impõem condições de risco, que são inerentes à sua natureza e podem ser responsáveis por lesões músculo-esqueléticas. Em adição, a complexidade e a interação de fatores de risco, muitos ainda não totalmente compreendidos, que atuam em conjunto durante a realização do manuseio de materiais conferem desafios e estímulos à abordagem preventiva. Deste modo, foram realizados dois estudos principais e dois estudos decorrentes das pesquisas direcionadas ao estudo do manuseio de carga. Os estudos principais (Estudos I e II) contextualizam a flexibilidade dos músculos isquiotibiais e sua influência na performance de tarefas ocupacionais. Os objetivos do Estudo I foram comparar os resultados de dois testes clínicos utilizados para avaliar a flexibilidade dos músculos isquiotibiais e avaliar a confiabilidade do procedimento fotogramétrico utilizado. Os testes de Dedos ao Chão e Elevação dos Membros Inferiores (MMII) em Extensão foram aplicados em 35 sujeitos sadios do gênero masculino. Com base nos resultados dos testes, os sujeitos foram divididos em dois grupos: flexibilidade normal e reduzida. Marcadores superficiais refletivos foram fixados em referências ósseas por meio da palpação para permitir o traçado dos ângulos do quadril, tóraco-lombar, perna, joelho e tíbio-tarsico. Aplicou-se o teste t de student para avaliar as diferenças de cada variável entre os dois grupos. Os achados demonstraram que o ângulo do quadril foi significativamente menor no grupo com flexibilidade reduzida e o teste de Elevação dos MMII foi mais sensível para detectar sujeitos com redução de flexibilidade. O objetivo do Estudo II foi avaliar a influência da flexibilidade dos músculos isquiotibiais na estratégia de movimento do tronco e pelve adotada por sujeitos sadios durante a realização do manuseio de carga. Os sujeitos foram divididos em dois grupos, com base na aplicação do teste de Elevação dos MMII. Uma câmera digital JVC com amostragem de 50 quadros/segundo e posicionada perpendicularmente ao plano sagital dos sujeitos foi utilizada para registrar a atividade. O coeficiente de correlação cruzada foi utilizado para quantificar a relação dos padrões de movimento entre os grupos, e o teste t de student aplicado nas variáveis de movimento para determinar as diferenças entre grupos. Os resultados indicaram que sujeitos com flexibilidade reduzida utilizaram uma menor amplitude pélvica e uma maior amplitude do tronco durante o manuseio. Ainda, sujeitos com flexibilidade reduzida adotam movimento em retroversão da pelve, sem grandes alterações ao longo da atividade. Os desdobramentos (Estudos III e IV) contextualizaram a comparação das estratégias adotadas por sujeitos com experiência no manuseio de cargas e por indivíduos inexperientes em tais atividades. O Estudo III teve como objetivo avaliar o manuseio realizado por 16 sujeitos experientes e 15 inexperientes. Utilizou-se um eletrogoniômetro flexível para mensurar o movimento da coluna e o programa 3D da Universidade de Michigan para estimar a compressão intradiscal em L5/S1 durante o manuseio. Foram avaliados os padrões de movimento normalizados e o coeficiente de variação foi aplicado para quantificar a variabilidade deste movimento. O teste t de student foi aplicado na determinação das diferenças para as variáveis em estudo. Os resultados apontam para uma grande variabilidade de posturas adotadas. Foram encontradas menores amplitudes de flexão, mas maiores amplitudes de extensão da coluna quando as cargas eram depositadas, respectivamente, em superfícies baixas e altas para indivíduos experientes. Sujeitos experientes apresentaram menores valores de compressão intradiscal durante a deposição da caixa e a atividade de abaixamento com 15kg foi caracterizada por maior sobrecarga intradiscal. O Estudo IV teve como objetivos comparar as estratégias de manuseio realizadas por sujeitos experientes e inexperientes com relação ao posicionamento dos pés e tronco durante atividade de abaixamento e de inclinação da carga no levantamento e abaixamento. Foram selecionados 10 trabalhadores experientes e 10 sujeitos sem experiência profissional com o manuseio de cargas. O manuseio realizado entre diferentes alturas foi filmado. Por meio de um programa de edição, as imagens referentes ao instante de 50% da tarefa foram selecionadas e utilizadas para classificar as posturas e mensurar a inclinação da caixa. Utilizou-se uma ANOVA com 3 fatores para avaliar a inclinação da carga com relação à experiência, carga manuseada e tipo de manuseio (levantamento e abaixamento). Os resultados indicaram que sujeitos com experiência profissional do manuseio adotaram estratégias caracterizadas pela maior inclinação da caixa e adoção de posturas mais equilibradas do tronco, com afastamento dos pés. A experiência profissional parece determinar a adoção de estratégias de movimento diferentes do grupo inexperiente, em resposta às condições da atividade. Entretanto, novos estudos são sugeridos com o intuito de determinar se tais estratégias foram protetoras ou de risco. Ainda, o conjunto de resultados apresentados na dissertação levanta a hipótese de que a flexibilidade dos isquiotibiais seja um fator de risco para o aumento de sobrecarga na coluna, durante a realização do manuseio de materiais.

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-04-24T17:31:20Z No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-25T14:19:24Z (GMT) No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-25T14:19:34Z (GMT) No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5) / Made available in DSpace on 2017-04-25T14:28:40Z (GMT). No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5) Previous issue date: 2016-11-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Bundesministerium für Bildung und Forschung (BMBF) / Musculoskeletal risks involving manual box handling can be minimized with the adoption of preventive approaches such as the inclusion of handles in boxes. However, the literature indicates the acquisition of motor skills over working time, can also be a protective factor in development of musculoskeletal disorders. Thus, the study 1 aimed to evaluate the physical load of the upper arms and upper back between 37 novice and 21 experienced subject during handling a new box design compared to commercial ones. The order of surfaces to handle (places to boxes depositions – floor and shoulder levels) and the type of box was randomized. In addition to direct measures (electrogoniometry, inclinometry and electromyography) subjective scales were used to assess the comfort and perceived effort. In general, both experienced and inexperienced subjects had lower biomechanics load handling non-commercial boxes compared to commercial ones. However, the inexperienced subjects demonstrated greater reductions in physical overload during the handling of non-commercial boxes, being more advantageous the recommendation of these boxes for this user profile. In the real work setting, handling boxes is highly rotating mainly in developing countries. Thus, interventions focus on boxes could help the workers, who may have different levels of experience with the job. However, the real work environment involves other tasks besides handling box, and tasks distribution over time could minimize the handling risks. In this way, the study 2 has been proposed to assess the physical exposure in real environment, where in addition to handling box workers perform other activities, aiming to identify the representative handling task in the total work exposure. The biomechanical exposure was assessed from muscular electrical activity of trapezius and upper limb movement recordings during a period of 4 hours to the work routine. The results showed that handling box task required the greater activation of the trapezius in relation to other activities, particularly in peak loads (percentiles 90 and 99 APDF - Amplitude Probability Distribution Function). Effect size calculations have identified the magnitude of the difference between the tasks is large, particularly in peak loads. In relation to the total job, handling box differed by greater amplitudes of upper back forward flexion and left arm elevation postures. Thus, the handling task requires interventions to decrease the physical load in a real work environment in order to promote occupational health, as identified in simulated environment by other studies. The conclusions of this thesis are related to the importance of considering the profile of workers' experience and the need to assessment work exposure involving all tasks performed, emphasizing the importance of studies involving workers in the real working environment. / Os riscos musculoesqueléticos do manuseio de caixas podem ser minimizados a partir da adoção de medidas preventivas, como a inserção de alças em caixas. No entanto, a literatura aponta que a aquisição de habilidades motoras, ao longo do tempo de trabalho, também pode ser um fator protetor no desencadeamento de lesões musculoesqueléticas. Dessa forma, o Estudo 1 teve como objetivo avaliar a carga física dos membros superiores e do tronco superior imposta à 37 sujeitos inexperientes e 21 experientes durante o manuseio de um novo design de caixa, comparado às caixas comerciais. A ordem do ajuste das superfícies onde as caixas foram depositadas (chão e ombro) e da utilização das caixas foi randomizada. Além de medidas diretas (eletrogoniometria, inclinometria e eletromiografia) foram utilizadas escalas para avaliação da agradabilidade e do esforço percebido. Em linhas gerais, tanto os sujeitos experientes como os não experientes apresentaram menor carga biomecânica durante o manuseio das caixas não comerciais comparadas às comerciais. No entanto, os inexperientes demonstraram maiores reduções da sobrecarga física durante o manuseio das caixas não comerciais, sendo mais vantajosa a recomendação dessas caixas para esse perfil de usuário. O contexto real de trabalho, o manuseio de caixas nos países em desenvolvimento é altamente rotativo. Dessa forma, intervenções na caixa poderiam favorecer os trabalhadores, que podem ter diferentes níveis de experiência com o trabalho. No entanto, o ambiente real de trabalho envolve outras tarefas além do manuseio de caixas, e a forma como as tarefas são distribuídas ao longo do tempo poderiam minimizar os riscos do manuseio. Dessa forma, o estudo 2 foi proposto para avaliar a exposição física em ambiente real, onde além do manuseio de caixas os trabalhadores realizam outras atividades, a fim de identificar a representatividade do manuseio na exposição total do trabalho. A exposição foi avaliada a partir do registro da atividade elétrica muscular do trapézio e dos movimentos do membro superior durante um período de 4h da jornada de trabalho. Os resultados demonstraram que o manuseio de caixas exigiu a maior ativação do trapézio em relação às demais atividades realizadas, particularmente nas cargas de pico (percentis 90 e 99 da APDF – Amplitude Probability Distribution Function). Cálculos do tamanho do efeito identificaram que a magnitude da diferença entre as tarefas é grande, principalmente nas cargas de pico. Já em relação ao trabalho total, o manuseio de caixas se diferiu pelas maiores amplitudes da postura de flexão anterior da coluna superior e de elevação do membro superior esquerdo. Dessa forma, o manuseio de caixas requer intervenções para diminuição da sobrecarga física em ambiente real de trabalho, a fim de promover saúde ocupacional, como identificado em ambiente simulado por outros estudos. As conclusões desta tese são referentes à importância de se considerar o perfil de tempo de experiência dos trabalhadores, bem como a necessidade de avaliações da exposição do trabalho envolvendo todas as tarefas realizadas, enfatizando a importância de estudos realizados com trabalhadores e no ambiente real de trabalho. / FAPESP: 2013/04839-5 / FAPESP: 2015/12493-7 / CNPq: 162324/2012-0