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Biomedical subjects

J Dul

Publications and source records attributed to J Dul.

11 recordsLinked to original sources
PubMed2005

Enhancing the impact of ergonomics interventions.

The aim of this paper was to provide recommendations for ergonomists involved in project design and evaluation. Twelve research and consultancy projects involving ergonomics interventions in a variety of settings in The Netherlands were analysed to identify factors important to success. Projects included participatory and non-participatory cases. Eight factors were identified for successful project design and for demonstrating project effectiveness.

Community Participation↗
PubMed2002

The influence of climatic factors on non-specific back and neck-shoulder disease.

An epidemiological study was carried out to explore the relationship between climatic factors and non-specific low-back and neck-shoulder symptoms in working populations. In a review of published literature, 27 studies were found which related climatic factors to musculoskeletal symptoms, but none of these studies specifically addressed the subject. It can be concluded that a relationship between climatic factors and musculoskeletal symptoms is considered at least plausible by both researchers, workers and patients, but that the epidemiological evidence appearing from literature is very weak. Questionnaire data which were collected on musculoskeletal symptoms, workload and perceptions of climatic conditions of 2030 workers in 24 different occupations were analysed multi-variately. About one-quarter of the workers related symptoms of the low back and neck-shoulders to climatic factors. They perceived climatic factors in most cases as aggravating factors for their symptoms. No seasonal influence on prevalence rates was reported. For low-back and neck-shoulder symptoms and for sick leave due to neck-shoulder symptoms, an association was found with climatic factors, and in particular with respect to draughts in relation to neck-shoulder symptoms. In addition, neck-shoulder symptoms were negatively related to frequent outdoor work. The findings suggest a relationship between climatic factors and musculoskeletal symptoms and call for further detailed investigations.

Adult↗
PubMed2001

Dutch Musculoskeletal Questionnaire: description and basic qualities.

A questionnaire ('Dutch Musculoskeletal Questionnaire', DMQ) for the analysis of musculoskeletal workload and associated potential hazardous working conditions as well as musculoskeletal symptoms in worker populations is described and its qualities are explored using a database of 1575 workers in various occupations who completed the questionnaire. The 63 questions on musculoskeletal workload and associated potentially hazardous working conditions can be categorized into seven indices (force, dynamic and static load, repetitive load, climatic factors, vibration and ergonomic environmental factors). Together with four separate questions on standing, sitting, walking and uncomfortable postures, the indices constitute a brief overview of the main findings on musculoskeletal workload and associated potentially hazardous working conditions. Homogeneity of the indices is satisfactory. The divergent validity of the indices is fair when compared with an index of psychosocial working conditions and discomfort during exposure to physical loads. Worker groups with contrasting musculoskeletal loads can be differentiated on the basis of the indices and other factors. With respect to the concurrent validity, it appears that most indices and factors show significant associations with low back and/or neck-shoulder symptoms. This questionnaire can be used as a simple and quick inventory for occupational health services to identify worker groups in which a more thorough ergonomic analysis is indicated.

Adult↗
PubMed2000

The relationship between leisure time, physical activities and musculoskeletal symptoms and disability in worker populations.

OBJECTIVES: To assess the association between leisure time physical activity and musculoskeletal morbidity, as well as possible interactions with physical activity at work. METHODS: A literature search was performed to collect all studies on musculoskeletal disorders in which physical activity was involved as a variable. Next, an analysis was made of questionnaire data on a group of 2,030 workers in various occupations, on self-reported physical activity in leisure time and at work, musculoskeletal symptoms (from low back, neck-shoulder and lower extremity) and sick leave due to these symptoms. A logistic regression analysis was carried out to estimate the association between musculoskeletal morbidity and four physical-activity indices (participation in sports and sedentary activities, active life style, sedentary life style), adjusted for age, gender, education and work load. Interaction of leisure activities with age and work load was tested too. RESULTS: Available literature data (39 studies) showed inconsistent results. Most studies did not show any effects. Some studies indicated favourable effects of physical activity, both on low back and neck pain. Participation in some vigorous sports seemed associated with unfavourable effects. The empirical data showed no association between participation in sports and/or other physical activities in leisure time and musculoskeletal symptoms. Sedentary activity in leisure time was associated with higher prevalence rates of low back symptoms and sick leave due to low back symptoms. CONCLUSIONS: Stimulation of leisure time physical activity may constitute one of the means of reducing musculoskeletal morbidity in the working population, in particular in sedentary workers.

Adult↗
PubMed1996

Identification of high-risk groups among maintenance workers in a steel company with respect to musculoskeletal symptoms and workload.

To determine priorities for ergonomic improvements in five maintenance departments of a steel company, a study was carried out to identify groups with a high prevalence of musculoskeletal problems or a high exposure to unfavourable musculoskeletal workload. All workers were asked to complete a standardized questionnaire on musculoskeletal symptoms and musculoskeletal workload. Response rate in the five departments varied between 60 and 80% (n = 436). Symptoms of low back and neck-shoulder (12-month prevalence rates of 53% and 36%, respectively) were most common, but not higher in comparison with a reference group of 396 non-sedentary workers. Self-reported exposure rates to physical and psychosocial loads as well as poor climatic conditions were comparable with the reference group; only exposure to vibration was higher. Significant differences were seen between the five departments as well as between task groups with the departments. Several task groups with relatively high symptom rates and high exposure levels could be identified. It is concluded that a questionnaire survey can constitute a valuable contribution to the selection of high-risk task groups that need ergonomic intervention.

Adult↗
PubMed1994

Ergonomic guidelines for the prevention of discomfort of static postures based on endurance data.

This communication aims to show why guidelines to prevent discomfort of static postures can be based on endurance data, and to give insight in the aim and scope of a recent 'work-rest model for static postures' (WR model). The paper is a response to a recent paper of Mathiassen and Winkel (1992) who questioned the usefulness of discomfort and endurance data, and of the WR model for developing guidelines for static postures. It is concluded that discomfort can be considered as an independent evaluation variable for working postures, anchored in European legislation. Discomfort can be predicted from the 'remaining endurance capacity' (REC) because of a known relationship between the REC and discomfort as measured with the Borg rating scale. The WR model estimates at group level the mean REC of a static posture with or without an external force during and immediately after a work-rest schedule. The WR model is meant to assist practitioners in the assessment and optimization of static postures (and external forces) and work-rest schedules in order to avoid high levels of discomfort.

Ergonomics↗
PubMed1985

A kinematic model of the human ankle.

The spatial gross motion of the foot with respect to the shank is modelled as rotations about two fixed ankle axes: the upper ankle rotation axis (plantar flexion/dorsiflexion) and the subtalar rotation axis (inversion/eversion). The positions of the axes are determined by externally visible bony landmarks of the lower leg, and are measured for a living subject. The model input data are the plantar flexion/dorsiflexion and inversion/eversion rotation angles; the model output is a 4 X 4 transformation matrix which quantitatively describes the relative position of a foot coordinate system with respect to a shank coordinate system.

Ankle Joint↗
PubMed1984

Muscular synergism--I. On criteria for load sharing between synergistic muscles.

The use of optimization techniques to predict individual muscle forces in redundant biomechanical systems implies the formulation of a criterion for load sharing between the muscles. In part I of this paper, the characteristics and performance of several linear and non-linear criteria reported in the literature have been compared for static-isometric knee flexion. The results show that linear criteria inherently predict discrete muscle action (orderly recruitment of muscles) whereas non-linear criteria can predict synergistic action. All criteria predict that relatively more force is allocated to muscles with large moment arms. When muscle stresses (or ratios of muscle force to maximum muscle force) are used as the decision variables in the objective function, then relatively more force is allocated to muscles with large maximum possible force as well. Future formulations of the optimization should consider the differences in fiber type composition among the muscles. Such an approach is presented in part II of the paper.

Biomechanical Phenomena↗
PubMed1984

Muscular synergism--II. A minimum-fatigue criterion for load sharing between synergistic muscles.

P6new physiological criterion for muscular load sharing is developed. The criterion is based on the assumption that the endurance time of muscular contractions is maximized, hence muscular fatigue is minimized. The optimization problem is cast in the form of a linearly constrained, non-linear MINIMAX optimization. The new method predicts that: (1) there is synergistic muscle action, (2) muscle force increases non-linearly with external force (load), (3) relatively more force is allocated to muscles that have a large maximum force (large muscles), (4) relatively more force is allocated to muscles with a high percentage of slow-twitch fibers (muscles that are fatigue-resistant), (5) the load sharing does not depend on the moment arm of the muscles (although the absolute force levels do depend on this variable). The predicted load sharing between two cat muscles during standing and walking is in good agreement with direct force measurement data from the literature.

Animals↗