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Biomedical subjects

R S Bridger

Publications and source records attributed to R S Bridger.

11 recordsLinked to original sources
PubMed2002

Task and postural factors are related to back pain in helicopter pilots.

BACKGROUND: A previous survey by Shear et al. revealed a high prevalence of back pain in Royal Navy helicopter aircrew, compared with controls. It was recommended that a second survey be undertaken, taking account of flying tasks and cockpit ergonomics. This was the purpose of the present investigation. METHOD: A questionnaire containing items on back pain and posture was circulated to all 246 acting pilots, with returns of 75%. The questionnaire sought information on pain in both the flying pilot and co-pilot/instructor roles. RESULTS: The 12-mo prevalence of back pain was 80%. Task-related back pain was greatest in instrument flying (72%) and least in the co-pilot and instructor roles (24%). Self-ratings of posture indicated that forward flexed trunk postures predominated in the flying roles and were most extreme in instrument flying. In non-flying roles, symmetrical, reclining postures were more often reported. No demographic or psychosocial variables were significantly related to back pain prevalence or disability. CONCLUSIONS: Much of the back pain experienced by helicopter pilots appears to be due to the posture needed to operate the cyclic and collective controls. In instrument flying, it is suggested that the visual demands of scanning the displays may exacerbate the pain by causing the pilot to lean further forward.

Aerospace Medicine↗
PubMed1998

Anthropometric variability, equipment usability and musculoskeletal pain in a group of nurses in the Western Cape.

This study examined the anthropometry and anthropometric fit of a group of nurses in Western Cape private hospitals. Anthropometric variables were measured using a sample of nurses and a correlation matrix generated. All nurses were given a questionnaire concerned with operational problems in the work environment and musculoskeletal pain. The nurses reported numerous problems in the working environment, including lumbar backache, inadequate space and equipment that caused bodily discomfort. There were consistent, statistically significant associations between the frequency of occurrence of these problems and the anthropometric data indicating that the problems were caused or amplified by body size variability and were not simply general usability problems which would affect all nurses irrespective of their body dimensions.

Adult↗
PubMed1997

Physiological and subjective measures of workload when shovelling with a conventional and two-handled ('levered') shovel.

Previous studies have suggested that the two-handled (levered) shovel is advantageous over the conventional spade from a biomechanical point of view. The aim of this experiment was to determine whether less energy was consumed while shovelling a load of sand with this shovel compared to a conventional tool. Accordingly, an experiment was designed in which subjects (n = 10) shovelled 1815 kg sand under laboratory conditions using either a conventional or a levered shovel. Heart rate and oxygen consumption were measured continuously during the trial and subjective data on perceived exertion, general fatigue and body discomfort were recorded after the trial. Although total energy expenditure was similar under both conditions (120 +/- 20 and 125 +/- 25 kcal; conventional versus two-handled spade), average heart rate was 4% higher when the two-handled shovel was used (p < 0.05). In addition, the mass of sand per scoop was 4% less with the two-handled shovel (p < 0.05). In conclusion, subjects used similar energy expenditure to shovel 1815 kg sand with the conventional shovel and the two-handled tool despite lower mass of sand per scoop with the latter. This can be explained by the fact that the increased mass of the additional handle compensated for the lower mass of sand per scoop. The higher average heart rate while shovelling with the two-handled shovel can be explained by the more erect posture.

Adult↗
PubMed1995

Postural adaptations to workbench modifications in standing workers.

Surveys have shown that many workers operate under conditions that require constrained standing. The aim of this study was to investigate postural adaptations in constrained standing to facilitate the development of design guidelines for standing workspaces. Standing postures were observed in six different workspaces that were designed using combinations of task distance (which was either constrained or unconstrained) and foot position (which was constrained, unconstrained or employed a footrest). Subjects at work were recorded stereophotogrammetrically and postural variables were obtained in three dimensions. Postural adaptation to increased task distance was found to be characterized by increased trunk flexion and increased hip flexion while adaptation to close work was found to be characterized by increased neck flexion and increased thoracic kyphosis. Constrained foot position resulted in increased hip flexion accompanied by increased plantar flexion. Although use of the footrest resulted in some reduced lumbar lordosis, it increased trunk flexion and was not associated with significantly less discomfort than any of the other workspaces.

Adaptation, Physiological↗
PubMed1995

Work related musculoskeletal disorders and ergonomic stressors in the South African workforce.

OBJECTIVES: The main objective of this study was to investigate exposure-response relations between adverse musculoskeletal outcomes and ergonomic exposure variables. METHODS: A cross sectional analytical study was conducted in 11 factories from seven sectors of manufacturing industry in South Africa. Exposure to workplace ergonomic stressors was assessed in factory floor jobs (n = 46) with a simple low technology observational model. Repetition, force, static posture, dynamic movement, and other job exposures were measured. Data of adverse musculoskeletal outcome and data on potential confounders and effect modifiers were obtained from subjects (n = 401) randomly sampled from each job category with a questionnaire given by interviewers. RESULTS: High prevalences of regional musculoskeletal pain were found with substantial variability between industries. Sex was the only individual risk factor (after adjustment for potential confounders and effect modifiers) that was significantly associated with regional pain. Ergonomic exposures in the workplace were significantly associated with musculoskeletal pain of the neck and shoulders odds ratio (OR) 5.38 (95% confidence interval (95% CI) 1.16 to 25.0) for repetition, and OR 3.91 (95% CI 1.11 to 13.7) for seated compared with standing work; pain of the wrists and hands OR 10.2 (95% CI 1.39 to 75.6) for high summed score of dynamic postures of the wrist). CONCLUSIONS: This study indicates good predictive ability to reduce ergonomic stress with the exposure model, simple surveillance methods, and educational programmes in the workplace. Further study on sampling strategies and refinement of dimensions of ergonomic stressors are needed.

Cross-Sectional Studies↗
PubMed1994

Development of observational methods for estimation of exposure to workplace postural stress.

Several recent studies have illustrated the need for a simple observational instrument for the estimation of exposure to postural stress in epidemiological studies of musculoskeletal disorders. Such an instrument is particularly necessary in developing countries. This paper describes the development of an observational instrument across a spectrum of industrial occupations in South Africa. The instrument was derived from adaptations to previously published observational methods and was specifically adapted to the measurement and application constraints identified during empirical development work in various industries. The final instrument fulfilled its aims of being applicable across a broad spectrum of jobs, including a broad spectrum of exposure variables and being reasonably cost- and time-effective. Some construct validity is indicated by the fact that two out of the three main exposure variables of interest showed significant associations with neck and shoulder pain in an epidemiological analysis. These variables were the score of summed estimates of the duration of time in sustained postures in a working day and the score of estimated overall repetitiveness based on cycle-time criteria. Further investigations are needed for pain at other anatomical sites. The measurement and scoring problems identified are discussed with reference to some aspects of these results.

Biomechanical Phenomena↗
PubMed1990

Effect of lumbar traction on stature.

Ten subjects were given lumbar traction for each of three time periods. Traction forces of one third of body weight were used. Stature was measured before and after traction and before and after three control periods of crook lying (lying supine with the knees flexed at 90 degrees and the feet resting on the traction table). ANOVA was used to test the hypotheses that traction and time in traction were significantly related to stature increase. Traction had significant effects on stature. The mean stature increase was 8.94 mm after 25 minutes traction compared with 3.33 mm after 25 minutes crook lying. Time in traction also had significant effects on stature increase which was most rapid during the first 15 minutes of traction. These findings can be related to the use of stature measurement as an index of spinal loading and the possible implications for treatment. However, since only healthy, young subjects were used and only one magnitude of traction was applied, the findings should be interpreted with caution. Further investigations would overcome these limitations.

Adult↗
PubMed1989

Hip joint mobility and spinal angles in standing and in different sitting postures.

The spinal angles of 25 female subjects were measured in standing and in four different sitting postures with various trunk-thigh angles. Additionally, measurements of hip and lumbar mobility were made in an attempt to relate mobility to spinal curvature in the different sitting postures. Lumbar curvature was observed to decrease as the trunk-thigh angle decreased across the different sitting postures, and reduction in curvature was associated with hip mobility. An exploratory analysis of interrelationships among hip mobility, spinal mobility, and spinal curvature was also carried out. A significant correlation between lumbar and thoracic angular deviations in standing and hip flexion/extension range was obtained. The findings are discussed with reference to theories of sitting posture and the influence of hip joint mobility on postural adaptations to furniture. Further investigations, including studies of male subjects, are indicated.

Adult↗
PubMed1989

Effects of seat slope and hip flexion on spinal angles in sitting.

Lumbar and thoracic spinal angles of 25 male and 25 female subjects were measured in four sitting postures, with standing angles used as reference. Subjects sat with either 90 deg or 65 deg of hip flexion on either flat or forward-sloping seats. Lumbar kyphosis was greatest when the flat seat/90-deg posture was adopted and least when the sloping seat/65-deg posture was adopted. The opposite was observed for the thoracic angles, and intermediate results were observed for the other two sitting postures. No statistically significant interactions were observed among seat slope, hip flexion, and subject sex. The findings are discussed with reference to the anatomy of sitting and factors influencing pelvic tilt and the implications for the ergonomic design of chairs.

Adult↗