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Research Agenda

In the course of its review, the panel identified several important gaps in the science base. The suggestions included in this research agenda are presented in two sections. The first section contains the recommended research for improving methodology—better tools for exposure and outcome assessment as well as further quantification of the relationship between exposures and outcomes. The second section contains research recommendations for specific topic areas, including tissue mechanobiology, biomechanics, psychosocial factors and stress, epidemiology, and workplace interventions.

METHODOLOGICAL RESEARCH

    1. Develop improved tools for exposure (dose) assessment.

    • Develop practical and consistent methods for objectively measuring physical stress (force, motion, vibration, and temperature) in the workplace and for quantifying occupational exposure (magnitude, repetition, and duration) with precision and accuracy. Use this method to understand the quantitative exposure- or dose-response relationships between (1) exposure to external loads in the workplace and the resultant three-dimensional internal loads and physiological responses and (2) exposure to external loads in the workplace and pain, discomfort, impairment, and disability. Explorations of these relationships must consider interactions and combinations of physical stress factors.

    • Develop valid measures of psychosocial exposures that can be used in epidemiologic research and conduct prospective studies on the effects of psychosocial variables on the occurrence, exacerbation, and persistence



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Page 370 12 Research Agenda In the course of its review, the panel identified several important gaps in the science base. The suggestions included in this research agenda are presented in two sections. The first section contains the recommended research for improving methodology—better tools for exposure and outcome assessment as well as further quantification of the relationship between exposures and outcomes. The second section contains research recommendations for specific topic areas, including tissue mechanobiology, biomechanics, psychosocial factors and stress, epidemiology, and workplace interventions. METHODOLOGICAL RESEARCH 1. Develop improved tools for exposure (dose) assessment. Develop practical and consistent methods for objectively measuring physical stress (force, motion, vibration, and temperature) in the workplace and for quantifying occupational exposure (magnitude, repetition, and duration) with precision and accuracy. Use this method to understand the quantitative exposure- or dose-response relationships between (1) exposure to external loads in the workplace and the resultant three-dimensional internal loads and physiological responses and (2) exposure to external loads in the workplace and pain, discomfort, impairment, and disability. Explorations of these relationships must consider interactions and combinations of physical stress factors. Develop valid measures of psychosocial exposures that can be used in epidemiologic research and conduct prospective studies on the effects of psychosocial variables on the occurrence, exacerbation, and persistence

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Page 371 of musculoskeletal disorders using these well-defined and validated measures of exposure. 2. Develop improved measures of outcomes and case definitions for use in epidemiologic and intervention studies. These should include but not be limited to: Develop prognostic tools to identify clinical cases at increased risk for poorer outcomes and to tailor interventions to identified risk factors (e.g., ergonomic stressors, job stress). Develop tools and measures that are capable of quantifying the extent of a musculoskeletal disorder with adequate precision so that they can be used as precise dependent measures for prospective epidemiologic studies involving the workplace. Further develop and refine standardized survey instruments to identify symptomatic musculoskeletal outcomes with adequate sensitivity and specificity for use in epidemiologic studies in work environments. Further develop and refine physical examination and sensory discrimination criteria to identify musculoskeletal outcomes with adequate specificity and sensitivity for use in epidemiologic studies in work environments. Develop and refine epidemiologic case definitions of musculoskeletal disorders with adequate sensitivity and specificity for epidemiologic study in work environments. Case definitions that rely solely on self-report information are particularly useful for large survey studies. Case definitions that use both self-report and physical examination data are needed for more detailed studies. As these criteria evolve, particular attention needs to be paid to nonspecific pain syndromes that are not congruent with established clinical syndromes. There is a need to develop an appropriate classification of subgroups of nonspecific pain syndromes in order to carry out more effective epidemiologic studies of these syndromes. Further develop and refine physiological measures appropriate for use in epidemiologic studies that measure relevant features of the various musculoskeletal disorders, including for example, nerve conduction testing. Develop and evaluate definitions of musculoskeletal disorders currently used in epidemiologic studies to identify the best symptom-based and physical exam-based criteria for musculoskeletal disorders that can be recommended as the standards for use in epidemiologic studies of the different syndromes in the work environment.

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Page 372 3. In studies of humans, further quantify the relationships between exposures and outcomes, including: Dose-response relationships across the full range of relevant exposures in the context of work. Host factors, such as age, sex, previous injury, comorbidity, smoking, and physical condition. Interaction of physical and psychosocial factors. TOPIC AREA RESEARCH 1. Conduct tissue mechanobiology studies directed toward: Characterizing ultrastructural and cellular responses to cyclical physical loading exposure for vertebrae/disc, upper extremity tendon and muscle, and peripheral nerve using in vivo (animal) models. This involves: — Determining time frame, capacity, and mechanisms of the repair and remodeling responses associated with cyclic loading and injury, including the effect of various patterns of rest and reuse after injury on the mechanisms and time course of recovery. — Developing quantitative dose-response models identifying dose-response relationships for injury for tendons, muscles, and nerves. — Determining the dose-response relationships between pattern of load (e.g., rate of loading, duty cycle) for repeated loading and functional and structural damage to discs, tendons, muscles, and nerves. — Developing an in vivo upper extremity loading model for neuromuscular disorders for the evaluation of mechanisms of injury associated with cyclical loading. Determining the missing steps of the injury pathways associated with repeated loading, especially for muscles, tendons, and nerves. Determining the role of conditioning and health on injury susceptibility. — Identifying injury thresholds for sustained and repeated loading (e.g., load duration or load repetition) for disc, tendon, and muscle. — Determining thresholds for critical pressure duration for chronic nerve injury. — Determining the earliest molecular changes that precede structural damage and inflammatory responses to muscles, tendons, ligaments, bones, and nerves during various types of repetitive loading. — Validating noninvasive measures of skeletal muscle functional changes and symptoms associated with repetitive use disorders by establishing their biological basis in controlled scientific studies, with

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Page 373 the goal of identifying a noninvasive means of detecting a skeletal muscle damage threshold. Determining whether the injury response of muscle, disc, tendon and nerve to repeated loading has more to do with the rate of loading, peak loads, duration, or some other factor. This involves: — Determining differences among tissues in response to loading. — Determining the role of conditioning and age in modifying this response. Identifying sources and mechanisms of discogenic, muscular, and tendon-related pain, especially as related to the ultrastructural injury and biochemical alterations associated with physical loading. 2. Biomechanical studies directed toward: Investigating the role of repetition, change in workshift, and variable repetition patterns (as experienced during work rotation) on changes in loading patterns and tolerance limits for joints and soft tissue. Quantifying the relationship between loading of a joint or tendon and the pain process. Exploring the influence of psychological stress (including psychosocial) on musculoskeletal response and the mechanical loading of joints. 3. Psychosocial studies directed toward: Investigating the mechanisms through which psychosocial stressors contribute to or impact work-related musculoskeletal disorders and the biological basis for such associations. 4. Epidemiologic studies directed toward: Taking advantage of existing and newly developed measures of exposure and outcome to undertake longitudinal studies of musculoskeletal disorders directed toward: — Clarifying the natural history of musculoskeletal disorders resulting from physical and psychosocial work exposures, focusing on both clinical and functional outcomes. — Examining the separate and interacting influence of physical and psychosocial work stressors in the etiology of musculoskeletal disorders.

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Page 374 — Developing prognostic indicators with the necessary predictive value to guide decisions about return-to-work. — Determining the length of latency periods between exposures sufficient to permit recovery or repair of tissue or cell damage. — Defining the effects of various interventions. — Defining the influence of worker factors, including comorbidity and obesity. Investigating the independent and combined contribution of individual psychosocial (e.g., coping styles, stress vulnerability, personal sources of support) and workplace psychosocial (i.e., supervisor support, control, workload, deadlines) variables on symptoms and functional outcomes. 5. Workplace interventions studies directed toward: Conducting rigorous evaluations of workplace interventions including but not limited to randomized controlled trials or other scientifically valid approaches. Promoting investigation of multifactorial interventions. Developing effective methods to measure the efficacy and cost-effectiveness of interventions on the reduction of workplace injuries. Coordinating studies of interventions between the research community and industry. Validating techniques, standards, and manuals for target industries.