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OBJECTIVE: To determine the association between several whole-body vibration (WBV) exposure estimates and back pain-related work absence. METHODS: Exposures (based on the weighted daily root mean square acceleration, A(8); the daily vibration dose value, VDV(8); and the daily equivalent static compression dose, Sed(8)) of 2302 workers during 4 years were estimated using each worker's monthly vehicle operation records and WBV measurements from 11 different types of heavy equipment vehicles in a large coal mine. Company payroll data provided work absence during the concurrent 4 years of exposure. Cox regression models estimated the associations between the different WBV metrics and time to first work absence related to back pain. An adjusted R2 statistic provided a measure of model fit. RESULTS: All estimated metrics of WBV exposures were positively and significantly associated with back pain-related absence. HRs varied from 2.03 to 12.39 for every 0.21 m/s2 increase in the A(8)-based exposures; from 1.03 to 1.18 for every 1.72 m/s1.75 increase in VDV(8)-based exposures; and from 1.04 to 1.07 for every 0.06 MPa increase in Sed(8)-based exposures. Models using the estimated VDV(8) metric for the z axis fit the data best as measured by the R2 statistic. CONCLUSION: Higher WBV exposures were associated with back pain-related absences in this population, which appears after a few years of follow-up. Introducing controls to lower exposure levels may help reduce back pain-related work absences.

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OBJECTIVE: Manual flower cutting imposes large biomechanical demands on workers' upper extremities. Solutions are required to reduce these demands. This study investigated the effect of time elapsed since the last pruner maintenance on the biomechanical demands of the upper extremities during flower-cutting operations. METHODS: Sixteen experienced workers were recruited. All workers performed flower cutting 1, 15, and 30 days after standard pruner maintenance, including cleaning, adjustment, and sharpening. The outcomes included kinematics of the wrist, elbow, and forearm; muscular activity of the extensor carpi radialis, extensor carpi ulnaris, flexor carpi radialis, flexor carpi ulnaris, biceps and medium deltoids of the dominant arm; and self-reported effort. RESULTS: On average across muscles, a 15-day delay (from 1 to 15 and from 15 to 30 days) in the execution of pruner maintenance increased over 8% the median recorded muscular activity as measured by the percentage of the maximum voluntary contraction of the root mean square signal. An increase in time since last pruner maintenance resulted in an increase in the 90th percentile pronation-supination posture (larger excursion toward pronation); the median and the 90th percentile velocity of the wrist and elbow; and the 90th percentile acceleration in the pronation-supination direction. There was an increase in perceived effort as measured by a Borg scale as time since last maintenance increased from 1 to 15 days. CONCLUSION: Increasing the frequency of pruner maintenance procedures can effectively reduce workers' mechanical exposures during manual flower-cutting operations. Companies should implement daily maintenance programs considering their implementation capacity and expected benefits.

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Objectives: Duration of tasks in a job is an essential interest in occupational epidemiology. Such duration is frequently measured using self-reports, which may, however, be associated with both bias and random errors. The present systematic literature review examines the correctness of self-reported durations of tasks, i.e. the extent to which they differ from more valid reference data due to either systematic or random errors, and factors influencing this correctness, with particular emphasis on the assessment of exposures of relevance to musculoskeletal disorders. Methods: The search for relevant studies included the databases ISI Web of Science, MEDLINE, EBSCO HOST, Proquest, and Psycnet. Results: Thirty-two articles were identified; of which, 23 examined occupational tasks and 9 examined non-occupational tasks. Agreement between self-reports and a more correct reference was reported for, in total, 182 tasks. Average proportional errors were, for most tasks, between -50% (i.e. underestimations) and +100%, with a dominance of overestimations; 22% of all results considered overestimations of 100% or more. For 15% of the 182 reported tasks, the mean difference between the self-reported and the reference duration value was <5%, and 20% of the 182 mean differences were between 5 and 20%. In general, respondents were able to correctly distinguish tasks of a longer duration from shorter tasks, even though the actual durations were not correct. A number of factors associated with the task per se appeared to influence agreement between self-reports and reference data, including type of task, true task duration, task pattern across time (continuous versus discontinuous), and whether the addressed task is composed of subtasks. The musculoskeletal health status of the respondent did not have a clear effect on the ability to correctly report task durations. Studies differed in key design characteristics and detail of information reported, which hampers a formal aggregation of results. Conclusions: The correctness of self-reported task durations is, at the best, moderate at the individual level, and this may present a significant problem when using self-reports in task-based assessment of individual job exposures. However, average self-reports at the group level appear reasonably correct and may thus be a viable method in studies addressing, for instance, the relative occurrence of tasks in a production system. Due to the disparity of studies, definite conclusions on the quantitative effect on agreement of different modifiers are not justified, and we encourage future studies specifically devoted to understanding and controlling sources of bias in self-reported task durations. We also encourage studies developing decision support for when to apply or avoid self-reports to measure task durations, depending on study purpose and occupational setting.

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Somatising tendency, defined as a predisposition to worry about common somatic symptoms, is importantly associated with various aspects of health and health-related behaviour, including musculoskeletal pain and associated disability. To explore its epidemiological characteristics, and how it can be specified most efficiently, we analysed data from an international longitudinal study. A baseline questionnaire, which included questions from the Brief Symptom Inventory about seven common symptoms, was completed by 12,072 participants aged 20-59 from 46 occupational groups in 18 countries (response rate 70%). The seven symptoms were all mutually associated (odds ratios for pairwise associations 3.4 to 9.3), and each contributed to a measure of somatising tendency that exhibited an exposure-response relationship both with multi-site pain (prevalence rate ratios up to six), and also with sickness absence for non-musculoskeletal reasons. In most participants, the level of somatising tendency was little changed when reassessed after a mean interval of 14 months (75% having a change of 0 or 1 in their symptom count), although the specific symptoms reported at follow-up often differed from those at baseline. Somatising tendency was more common in women than men, especially at older ages, and varied markedly across the 46 occupational groups studied, with higher rates in South and Central America. It was weakly associated with smoking, but not with level of education. Our study supports the use of questions from the Brief Symptom Inventory as a method for measuring somatising tendency, and suggests that in adults of working age, it is a fairly stable trait.

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La evidencia científica muestra que existe asociación entre dolor lumbar y postura sedente prolongada y que una de las poblaciones más propensa a esta enfermedad es la de conductores, con una alta prevalencia. De igual manera, los movimientos posturales en la silla son la respuesta natural del cuerpo debida a la incomodidad percibida por el dolor lumbar, pero esta difiere en función de la historia previa. Con base en esto se realizó una revisión de los estudios relacionados con el dolor lumbar y el movimiento en postura sedente prolongada, incluyendo la población de conductores, con el fin de comprender esta relación. Se recuperaron 6226 artículos, de los cuales 16 fueron publicados entre 1970 y 2010; estos proporcionaron la información necesaria para contestar la pregunta de revisión. Se pudo constatar que ninguno de los estudios fueron realizados en actividades de conducir y la mayoría involucró sujetos voluntarios sin considerar si la población era trabajadora. El movimiento con dolor lumbar en postura sedente prolongada solo se pudo explicar desde el rango de movimiento lumbar, debido a que solo se encontró un artículo con estas características. También se encontró que los sintomáticos se mueven más, pero que el dolor lumbar no disminuye en función del tiempo, es decir que conocemos muy poco acerca de la paradoja movimiento y dolor en postura sedente prolongada.

Scientific evidence shows an association between low back pain and prolonged sitting posture, also one of the most sensitive populations to this disorder are the drivers with a high prevalence. Postural movements in the chair are body's natural response to perceived discomfort caused by back pain but this is different depending on each individual's background of back pain. Based on this, we perform a review of studies related to low back pain and movement in prolonged sitting posture, including the driver population, in order to understand this relationship. We retrieved 6226 articles, of which 16 matched the established criteria and provided the information necessary to answer the review question. We found that none of the studies considered were conducted in driving activities and most of them were done with volunteer subjects regardless if they were workers or not. The movement with low back pain in prolonged sitting posture could only be explained from the range of lumbar motion because only one article matched these characteristics, finding that symptomatic people move more but low back pain does not decrease as a function of time, proving that we know very little about the paradoxical between movement and pain in prolonged sitting posture.

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Introducción: el sector floricultor ha sido afectado por años por la alta ocurrencia de enfermedades músculo-esqueléticas entre sus trabajadores. Diversos esfuerzos han sido puestos en marcha para comprender la magnitud del problema, sus causas y sus posibles soluciones. Este manuscrito expone desde la perspectiva académica las lecciones y logros del modelo de actuación industria-academia para mejorar las condiciones ergonómicas de la población trabajadora de este importante sector industrial. Materiales y métodos: se hizo una recopilación de actas, comunicaciones, reportes y publicaciones científicas de los trabajos llevados a cabo desde el año 2007 con la participación del Centro de Estudios de Ergonomía del Departamento de Ingeniería Industrial de la Pontificia Universidad Javeriana. Un análisis retrospectivo de esta información buscó responder a preguntas sobre el origen de los trabajos, objetivos perseguidos, resultados alcanzados, beneficios obtenidos y lecciones aprendidas. Resultados: el modelo de trabajo fue participativo. El motor iniciador de los trabajos son las empresas productoras de flores que hacen explícitas sus necesidades a las aseguradoras del trabajo. El diseño global del estudio no fue encargado a la academia, sino construido con la academia; y, posteriormente, refinado con la agremiación de productores. Aunque el objetivo global del trabajo es la prevención de enfermedades, este se lleva a cabo a partir de proyectos que en la medida en que fue pasando el tiempo fueron asegurando fondos para la consecución de objetivos específicos relacionados con: la evaluación de las condiciones ergonómicas del trabajo, la caracterización de la población trabajadora y el desarrollo, implementación y prueba de soluciones. Conclusiones: el modelo de colaboración industria-academia presentada evidencia importantes resultados tanto de mejoras a las condiciones laborales como académicos. Aunque es necesario validar la visión de la industria sobre este tipo de modelos de trabajo colaborativo, se considera que este caso fue exitoso y, por lo tanto, debería ser replicado en otras industrias.

Introduction: The flower industry has been affected for years by the high occurrence of musculoskeletal disorders among workers. Various efforts have been done to understand the magnitude of the problem, its causes and possible solutions. This manuscript presents from the academic perspective the lessons and achievements of an industry-academics model of action to improve the ergonomic conditions of the working population of this important industry. Materials and methods: a review of minutes, communications, reports and scientific publications related to the ergonomics work done since year 2007 with the participation of the Center for Ergonomics Studies (CEE) of the Department of Industrial Engineering at Pontificia Universidad Javeriana was conducted. A retrospective analysis of the information sought to answer questions about the origin of the work, objectives, results, lessons learned and benefits gained. Results: The working model was participatory. Flower producers were the starters of the work. They made explicit their needs to workers' insurance companies. The overall study design was not just given but built with academics, and subsequently reined with the association of producers. Although the overall objective of the work was the prevention of musculoskeletal disease among workers, the work was carried out in time as funds were secured through studies with specific objectives related to: Workplace ergonomics evaluations, characterization of the working population, and the development, implementation and testing of solutions. Conclusions: The presented industry-academics collaboration model resulted in important improvements to working conditions and academic results. Although it is necessary to validate the view of the industry regarding this type of collaborative models, it is considered that this case was successful and therefore should be replicated in other industries.

Introdução: o setor floricultor tem sido afetado por anos por a alta ocorrência de doenças musculoesqueléticas entre seus trabalhadores. Diversos esforços têm sido postos em funcionamento para compreender a magnitude do problema, suas causas e suas possíveis soluções. Este manuscrito expõe desde a perspectiva acadêmica as lições e resultados do modelo de atuação indústria-academia para melhorar as condições ergonômicas da população trabalhadora deste importante setor industrial. Materiais e métodos: Se fez uma recopilação de atas, comunicações, reportes e publicações cientíicas dos trabalhos levados a cabo desde o ano 2007 com a participação do Centro de Estudos de Ergonomia do Departamento de Engenharia Industrial da Pontiicia Universidad Javeriana. Uma análise retrospectiva desta informação buscou responder a perguntas sobre a origem dos trabalhos, objetivos perseguidos, resultados alcançados, benefícios obtidos e lições aprendidas. Resultados: o modelo de trabalho foi participativo. O motor iniciador dos trabalhos são as empresas produtoras de flores que fazem explícitas suas necessidades às seguradoras do trabalho. A criação global do estudo não foi encarregada à academia, senão construído com a academia; e posteriormente refinado com a agremiação de produtores. Ainda que o objetivo global do trabalho é a prevenção de doenças, o trabalho se leva a cabo a partir de projetos, que na medida que foi passando o tempo, foram segurando fundos para a consecução de objetivos especíicos relacionados com: a avaliação das condições ergonômicas do trabalho, a caracterização da população trabalhadora e o desenvolvimento, implementação e prova de soluções. Conclusãos: o modelo de colaboração indústria-academia apresentada evidencia importantes resultados tanto de melhoras às condições laborais quanto acadêmicas. Ainda que é necessário validar a visão da indústria sobre este tipo de modelos de trabalho colaborativo, considera-se que este caso foi de sucesso e portanto deveria ser replicado em outras indústrias.

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OBJECTIVES: To describe the relation of the measured validity of self-reported mechanical demands (self-reports) with the quality of validity assessments and the variability of the assessed exposure in the study population. METHODS: We searched for original articles, published between 1990 and 2008, reporting the validity of self-reports in three major databases: EBSCOhost, Web of Science and PubMed. Identified assessments were classified by methodological characteristics (eg, type of self-report and reference method) and exposure dimension was measured. We also classified assessments by the degree of comparability between the self-report and the employed reference method, and the variability of the assessed exposure in the study population. Finally, we examined the association of the published validity (r) with this degree of comparability, as well as with the variability of the exposure variable in the study population. RESULTS: Of the 490 assessments identified, 75% used observation-based reference measures and 55% tested self-reports of posture duration and movement frequency. Frequently, validity studies did not report demographic information (eg, education, age, and gender distribution). Among assessments reporting correlations as measure of validity, studies with a better match between the self-report and the reference method, and studies conducted in more heterogeneous populations tended to report higher correlations [odds ratio (OR) 2.03, 95% confidence interval (95% CI) 0.89-4.65 and OR 1.60, 95% CI 0.96-2.61, respectively]. CONCLUSIONS: The reported data support the hypothesis that validity depends on study-specific factors often not examined. Experimentally manipulating the testing setting could lead to a better understanding of the capabilities and limitations of self-reported information.

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