Work-related musculoskeletal disorders (WMSDs) due to overexertion and consequently the low back pain (LBP) are one of the most prevalent sources of nonfatal occupational injuries and illnesses in all over the world. In the past several years, the industrial exoskeletons especially the passive ones have been proposed as alternative intervention and assistive devices, which are capable of reducing the risk of WMSDs and LBP. However, more research is warranted to validate the applicability of these exoskeletons. In addition, because the majority of previous studies have been limited to specific lifting tasks using only one type of lift assistive exoskeleton, more research is needed to examine the effect of alteration of different lift-assistive exoskeletons on reducing the activity of back muscles and metabolic reduction. The main objective of this dissertation is to render an overview of three studies that attempt to improve the literature by providing comprehensive biomechanical evaluations and metabolic assessments of three passive lift-assistive exoskeletons (VT-Lowe's Exoskeleton (developed in ARLab at VT), Laevo and SuitX). This dissertation has been composed of three related studies. The first study aimed to investigate and examine the capability of a novel lift assistive exoskeleton, VT-Lowe's exoskeleton, in reducing the peak and mean activity of back and leg muscles. Findings revealed that the exoskeleton significantly decreased the peak and mean activity of back muscles (IL(iliocostalis lumborum) and LT(longissimus thoracis)) by 31.5% and 29.3% respectively for symmetric lifts, and by 28.2% and 29.5% respectively for asymmetric lifts. Furthermore, the peak and mean EMG of leg muscles were significantly reduced by 19.1% and 14.1% during symmetric lifts, and 17.4% and 14.6% during asymmetric lifts. Interestingly, the VT-Lowe's exoskeleton showed higher reduction in activity of back and leg muscles compared to other passive lift-assistive exoskeletons available in the literatures. In the second study, the metabolic cost reduction associated with the use of VT-Lowe's exoskeleton during freestyle lifting was theoretically modelled, validated and corresponding metabolic savings were reported. The metabolic cost and the oxygen consumption results supported the hypothesis that the VT-Lowe's exoskeleton could significantly reduce the metabolic demands (~7.9% on average) and oxygen uptake (~8.7% on average) during freestyle lifting. Additionally, we presented a prediction model for the metabolic cost of exoskeleton during repetitive freestyle lifting tasks. The prediction models were very accurate as the absolute prediction errors were small for both 0% (< 1.4%) and 20% (< 0.7%) of body weight. In the third study, the biomechanical evaluation, energy expenditure and subjective assessments of two passive back-support exoskeletons (Laevo and SuitX) were examined in the context of repetitive lifting tasks. The experimental lifting tasks in this study were simulated in a laboratory environment for two different levels of lifting symmetry (symmetric vs. asymmetric) and lifting posture (standing vs. kneeling). Results of this study demonstrated that using both exoskeletons during dynamic lifting tasks could significantly lower the peak activity of trunk extensor muscles by ~10-28%. In addition, using both exoskeletons could save the energy expenditure by ~4-13% in all conditions tested by partially offsetting the weight of the torso. Such reductions were, though, task-dependent and differed between the two tested exoskeletons. Overall, the results of all three studies in this dissertation showed the capability of passive lift-assistive exoskeletons in reducing the activity of back and leg muscles and providing metabolic savings during repetitive lifting tasks. / Doctor of Philosophy / Low back pain (LBP) due to overexertion is known as one of the most important sources of nonfatal occupational injuries especially for the workers or manual material handlers who are involved in frequent or repetitive lifting tasks. Every year, many workers are temporarily or permanently disabled due to overuse injuries at workplace. In the past several years, industrial exoskeletons have gained growing interest among biomechanist, roboticist, and other human factor researchers as potential assistive devices to reduce the risk of LBP. In general, the industrial exoskeletons are either “passive or “active”; Active exoskeletons are powered by mechanical/electrical motors and actuators, however, the passive exoskeletons often work using cheaper devices such as gas or metal springs, elastic elements, etc. The exoskeletons discussed in this dissertation are categorized as passive rigid lower-back exoskeletons and they function by storing energy in a spring when the wearer bends and returning the stored energy when the wearer lifts. This dissertation consists of three studies that attempt to provide comprehensive biomechanical evaluations and metabolic assessments of three passive lift-assistive exoskeletons (i.e., VT-Lowe’s Exoskeleton, Laevo and SuitX). The first study examined the efficacy of a novel lift-assistive exoskeleton, VT-Lowe’s exoskeleton, in reducing the peak and mean activity of back and leg muscles. The results of this study demonstrated that the exoskeleton reduced the peak and mean activity of back and leg muscles for symmetric and asymmetric lifting tasks. VT-Lowe’s exoskeleton also showed higher reduction in activity of back muscles compared to other passive lift-assistive exoskeletons available in the literature. In the second study, the metabolic cost reduction with VT-Lowe’s exoskeleton was theoretically modeled and the modeling outcomes were compared to metabolic costs measurements when the exoskeleton was worn. The experimental findings of this study supported the applicability of the exoskeleton by significantly reducing the metabolic cost and oxygen uptake during the freestyle repetitive lifting tasks. Moreover, the prediction metabolic cost model of the exoskeleton showed high accuracy as the absolute prediction errors were within 1.5%. In the third study, the biomechanical evaluation, energy expenditure and subjective assessments of two passive back-support exoskeletons (Laevo and SuitX) were examined in repetitive lifting tasks. The lifting tasks of this study were simulated in a laboratory environment for two different levels of lifting symmetry (symmetric vs. asymmetric) and lifting posture (standing vs. kneeling). Findings of this study showed that both exoskeleton significantly lowered the peak activity of back muscles during the dynamic lifting tasks. Moreover, using both exoskeletons provided metabolic cost savings in all of the studies conditions. Overall, results obtained from the three studies in this dissertation verified the capability of these passive lift- vi assistive exoskeleton in reducing the activity of back and leg muscles and providing the metabolic savings during repetitive lifting tasks.

Thesis (MScPhysio)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Aims: To assess the effect of a chair and computer screen height adjustment on the neck and upper back musculoskeletal symptoms in an office worker. Methods: An N=1 study was conducted using the ABC design. Ethics approval was obtained for the study and the participant provided informed written consent. The participant was assessed over three four week phases as she performed her habitual computer work. The outcome measures assessed during the three phases were the pain intensity and perceived sitting comfort. The three phases were named the baseline, intervention and wash-out phases. During the baseline phase, the outcome measures were obtained at the participant‟s habitual work station. The intervention phase involved a vertical adjustment of the chair and computer screen height. The wash-out phase allowed the participant to adjust the chair and computer screen height to their choice. A follow-up interview was conducted with the participant three months after completion of the study. The mean values and the ranges of the pain intensity and perceived comfort were obtained and compared. The data collected was captured on a Microsoft Excel 2010 spread sheet, where after the data was tabulated and presented graphically. Results: The mean pain intensity of the participant increased slightly during the intervention phase in comparison to the baseline phase, but remained stable during the wash-out phase. The mean perceived sitting comfort deteriorated initially during the intervention phase, but improved later during the intervention phase and showed greater improvement during the wash out phase. The perceived sitting comfort showed more improvement than the pain intensity during the washout phase. Both the pain intensity and perceived sitting comfort showed improvement at the three months follow up assessment, post completion of the study. Conclusion: The vertical height adjustment of the chair and the VDT did not improve the participant‟s pain intensity and perceived sitting comfort when compared to the participant‟s habitual workstation parameters. The findings do not favour the horizontal viewing angle. The findings of this study however support the use of „slightly below horizontal‟ viewing angle as being conducive to reduce the pain intensity and improve the sitting comfort of an office worker. / AFRIKAANSE OPSOMMING: Doelstelling: Om die effek te bepaal van die hoogte aanpassing van die stoel en rekenaarskerm op die nek en bo-rug muskuloskeletale simptome van 'n kantoorwerker. Metodes: „n N=1 studie was uitgevoer deur gebruik te maak van die ABC ontwerp. Etiese goedkeuring was verkry vir die studie en die deelnemer het ingeligte skriftelike toestemming verleen. Die deelnemer was ge-evalueer oor drie vier week-lange fases terwyl sy haar gewone rekenaarwerk verrig het. Die uitkomsmetings ge-evalueer tydens die drie fases was pyn intensiteit en waargenome sitgemak. Die drie fases was genoem die basislyn, intervensie en uitwas fases. Gedurende die basislyn fase was die uitkomsmetings by die deelnemer se gewone werkstasie ingevorder. Die intervensie fase het 'n vertikale aanpassing van die stoel en rekenaarskerm behels. Die uitwas fase het die deelnemer toegelaat om haar stoel en rekenaarskerm se hoogte aan te pas volgens haar keuse. 'n Opvolg onderhoud was gevoer met die deelnemer drie maande na die voltooiing van die studie. Die resultate was vasgelê op 'n Microsoft Excel 2010 data bladsy, waarna die data getabuleer en grafies uitgebeeld is. Resultate: Die gemiddelde pyn intensiteit van die deelnermer het effens toegeneem tydens die intervensie fase in vergelyking met die basislyn fase, maar het stabiel gebly tydens die uitwas fase. Die gemiddelde waargenome sitgemak het aanvanklik verswak tydens die intervensie fase, maar het later verbeter tydens die intervensie fase en het aangehou verbeter tydens die uitwas fase. Die waargenome sitgemak het groter verbetering getoon as die pyn intensiteit tydens die uitwas fase. Beide pyn intensiteit en waargenome sitgemak het verbetering getoon by die drie maande opvolg evaluasie, na voltooiing van die studie. Gevolgtrekking. Die vertikale hoogte aanpassing van die stoel en rekenaarskerm het nie die deelnemer se pyn intensiteit en waargenome sitgemak in vergelyking met die deelnemer se gewone werkstasie parameters verbeter nie. Hierdie bevindinge is nie ten voordeel van die horisontale kykhoek nie. Nietemin, ondersteun die bevindinge van hierdie studie die gebruik van die "effens onder die horisontale" kykhoek as bevorderend om die pyn intensiteit te verminder en die sitgemak van 'n kantoorwerker te verbeter.

A perspectiva dos fisioterapeutas que desenvolvem programas de educação postural com crianças bem jovens é que essas medidas de prevenção primária possam reduzir, a longo prazo a prevalência de dores nas costas.Esse estudo experimental, verificou os efeitos da educação postural comparando duas estratégias educacionais utilizando-se da pedagogia de uma história em quadrinhos (HQ) na retenção de informações desses hábitos posturais e de um circuito demonstrativo (CD), onde as crianças vivenciavam cada postura correta e incorreta. O programa de educação postural foi aplicado em três sessões educativas em escolares das 2ª e 3º séries, com idades entre 7-11 anos, de uma Escola Municipal, no Estado de São Paulo. A amostra consistiu de 80 crianças nos grupos HQ e CD. As sessões tiveram a duração de uma hora e serviram para transmitir noções básicas sobre: anatomia, biomecânica e fisiopatologia de dores na coluna vertebral e hábitos posturais corretos nas seguintes situações: postura sentada, postura em pé, postura deitada, transporte de mochila, técnica de levantamento e transferência de objetos. O conhecimento dos hábitos posturais foi verificado por intermédio de questionários aplicados antes do início do programa e após um período de 6 meses do término da pesquisa. Os resultados do estudo indicaram que para todas as variáveis estudadas não foram detectadas diferenças no aprendizado e memorização dos hábitos posturais corretos em ambos os sexos que se submeteram às duas metodologias de ensino, exceto no jeito de dormir, onde o índice de aumento das respostas corretas foi de 23% para o Circuito, enquanto o HQ apresentou apenas 7% / OBJECTIVE: This experimental study compared two educational strategies using the pedagogy of a comic book story (HQ) and a demonstration circuit (CD), to teach instructions for correct posture habits. METHOD: 80 students from the 2nd and 3rd grades of an elementary school in São Paulo city were studied using a questionnaire before and after the education program, and also six months after the end of the research, to assess the retention of the correct habits. RESULTS: The correct rates after the instructions increased 90% for both education strategies, except for the sleeping posture, which had more correct responses in the CD education practice. CONCLUSION: In the comparison between the comic book story and the demonstration circuit education strategies, both were effective in the memorization of correct postural habits

A perspectiva dos fisioterapeutas que desenvolvem programas de educação postural com crianças bem jovens é que essas medidas de prevenção primária possam reduzir, a longo prazo a prevalência de dores nas costas.Esse estudo experimental, verificou os efeitos da educação postural comparando duas estratégias educacionais utilizando-se da pedagogia de uma história em quadrinhos (HQ) na retenção de informações desses hábitos posturais e de um circuito demonstrativo (CD), onde as crianças vivenciavam cada postura correta e incorreta. O programa de educação postural foi aplicado em três sessões educativas em escolares das 2ª e 3º séries, com idades entre 7-11 anos, de uma Escola Municipal, no Estado de São Paulo. A amostra consistiu de 80 crianças nos grupos HQ e CD. As sessões tiveram a duração de uma hora e serviram para transmitir noções básicas sobre: anatomia, biomecânica e fisiopatologia de dores na coluna vertebral e hábitos posturais corretos nas seguintes situações: postura sentada, postura em pé, postura deitada, transporte de mochila, técnica de levantamento e transferência de objetos. O conhecimento dos hábitos posturais foi verificado por intermédio de questionários aplicados antes do início do programa e após um período de 6 meses do término da pesquisa. Os resultados do estudo indicaram que para todas as variáveis estudadas não foram detectadas diferenças no aprendizado e memorização dos hábitos posturais corretos em ambos os sexos que se submeteram às duas metodologias de ensino, exceto no jeito de dormir, onde o índice de aumento das respostas corretas foi de 23% para o Circuito, enquanto o HQ apresentou apenas 7% / OBJECTIVE: This experimental study compared two educational strategies using the pedagogy of a comic book story (HQ) and a demonstration circuit (CD), to teach instructions for correct posture habits. METHOD: 80 students from the 2nd and 3rd grades of an elementary school in São Paulo city were studied using a questionnaire before and after the education program, and also six months after the end of the research, to assess the retention of the correct habits. RESULTS: The correct rates after the instructions increased 90% for both education strategies, except for the sleeping posture, which had more correct responses in the CD education practice. CONCLUSION: In the comparison between the comic book story and the demonstration circuit education strategies, both were effective in the memorization of correct postural habits