Seating

Seating

Industrial safety proved to be a hornets nest of an area and resulted in a hectic discussion with numerous other points being debated. Costbenefits, p...

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Industrial safety proved to be a hornets nest of an area and resulted in a hectic discussion with numerous other points being debated. Costbenefits, politics, legal weaknesses and managerial attitudes were all discussed. It is difficult to say what the session concluded. One thing was clear there must be stronger links between ergonomics and industrial safety. How this can best be achieved would depend on whom you talk to, judging by the discussion. Seating

(Chairman: Prof E.N. Corlett (Nottingham University)) Human beings were never meant to sit down for extended periods but our society dictates that they must. In recent years there has been a renaissance of 'seating science' as the packed session suggested. The first paper by J. Eklund and E.N. Corlett (Nottingham University) investigated the most basic problem of all: " A method of evaluating the effectiveness of a work seat". The method involves measuring spinal compression which is linked to lumbar loading and pain. The paper briefly outlined how various aspects of the seat and back geometry of a chair influence the lumbar spinal load. The authors conclude that the method is suitable for laboratory and field use. In "Physiological and medical effects of improved seating" R. H. Westgaard (Institute of Work Physiology, Oslo) described parts of a longitudinal study of muscularskeletal problems at work. Using clinical examination of work absentees, the sites of disease could be identified amd the causes found. Ergonomic changes in the workplaces have shown reduction in muscular-skeletal disease incidence and labour turn-over. "An ergonomic approach to the design of car seating" by J.M. Porter and M.C. Steam (LUT) described a series of techniques that have been adopted to improve driver comfort. Using examples from studies carried out for Jaguar Cars and Austin Morris, the authors described how a combination of postal questionnaires (to the owners of the car under study), laboratory and field trials have resulted in improved seating design. The simply titled " A design for a sit-stand stool" by E.N. Corlett, J.A. Eklund, C.S. Houghton and R. Webb '(Nottingham University) took the Mandal concept of a forward sloping seat as its starting point. The Mandal design, whilst maintaining lumbar lordosis, introduced its own problems. Experimental results suggest that the new Nottingham design has overcome

the problem of forward slipping and increased load on the legs by introducing a small horizontal ridge which supports the ischial tuberosities. Changes in the front section of the seat pan have reduced the under thigh pressure. The design now looks set to be produced by a British seating company. A multi-disciplinary Norwegian team made up of E. Stranden (Aker Hospital), A. Aarhs, D. M. Anderson, K. Martinsen (Standard Telefon og Kilbelfabrik) and H.O. Myhre (Trondheim Hospital) investigated "The effects of working posture on muscular-skeletal load and circulatory condition" at a particular STK workstation. Sickness records, questionnaires and medical examinations revealed musculoskeletal disorders predominantly in the neck, shoulders and arms and significant swelling of the feet. They concluded that the cause was the predominantly static postures the employees were obliged to maintain for the task. Modifications in the workplace were made to reduce the muscular loads and interstitial fluid pressure which caused the swelling of the feet was alleviated by the provision of a dynamic footrest !

Cognitive ergonomics

(Chairman: Mr J. Long ( UCL )) The complexity of the area was amply illustrated by the three papers presented. The interaction of cognitive factors is unavoidable but at least studies such as these make them slightly more predictable. L.R. Hartley (Murdoch University, Australia) gave the first paper entitled "Cognitive strategy, alcohol and noise". Results from his experiments suggested that in verbal tasks, noise improved subjects' performance (measured as a reaction time) but impaired spatial tasks. Conversely, alcohol improved spatial strategies and had a detrimental effect on verbal strategies (as many of us know).These findings are not consistent with previous work on alcohol/noise and cognitive performance so be warned if you are designing for intoxicated fighter pilots! From Italy came a paper from S. Bagnara(CNR, Rome), F. Simion (Padova University) and C. Umilta (Parma University, entitled "Analytical and holistic comparison processes on internally generated visual patterns". The results showed that spotting similarities between visual cues was faster than perceiving ways in which they differed. A holistic model of processing the images was suggested since, as the presentation of the

visual cues became very short (100 m/s), performance dropped to the much slower "difference spotting" times. R.H. Logic and A.D. Baddeley (APU, Cambridge) presented the results of "Simulated deep-sea diving in trimix, oxyhelium and oxynitrogen studies of cognitive performance, sleep quality and m o o d " , The studies investigated the claim that trimix (a three gas mixture) caused less cognitive decrement and allowed faster decompression time. The former claim was not upheld by the studies' results. Furthermore, the authors were unable to attribute the fluctuations in performance to either sleep quality or mood.

Training

(Chairman." Dr R. Stammers (Aston University)) In the last session of the conference two quite different aspects of training were presented. The first paper claimed that the US Army had no structured programme for training maintenance supervisors. W.R. Harper's (Anacapa Sciences, USA) paper entitled "Assessment of behavioural characteristics of effective supervisors" described how a training schedule was developed. He explained how"different levels of Army personnel were asked to rank 100 items relating to supervisor effectiveness. Based on these results a model for effective training will be developed. In complete contrast, the second paper dealt with "Recreation marathon running". T. Reilly and T.K. Foreman (Liverpool Polytechnic) concluded that over 60% of runners' injuries are associated with training error. Improper footwear, exclusive training on roads and excessive training frequency were all pin-pointed as causes of injury. If, on the other hand, the training regime is soundly executed it seems marathon racing presents no undue musculoskeletal stress on the well conditioned participant.

Poster presentations Throughout the conference there was a continual poster display of experimental work. During the conference the individual authors were available for questions and discussions about their work. There were 22 posters in all and the quality was excellent. This method provides an effective way to disseminate information where the recipient can develop a quick impression of the area that each author is working in and then focus on those of specific interest.

Applied Ergonomics September1983

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