Comparison of four specific dynamic office chairs with a conventional office chair: Impact upon muscle activation, physical activity and posture

Prolonged and static sitting postures provoke physical inactivity at VDU workplaces and are therefore discussed as risk factors for the musculoskeletal system. Manufacturers have designed specific dynamic office chairs featuring structural elements which promote dynamic sitting and therefore physica...

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Bibliographic Details
Published in:	Applied ergonomics 2012-03, Vol.43 (2), p.296-307
Main Authors:	Ellegast, Rolf P., Kraft, Kathrin, Groenesteijn, Liesbeth, Krause, Frank, Berger, Helmut, Vink, Peter
Format:	Article
Language:	eng
Subjects:	Adult Analysis Chairs Comparative analysis Dynamic office chairs Electromyography EMG Ergonomics Exercise Female Humans Interior Design and Furnishings - instrumentation Male Motor Activity - physiology Muscle, Skeletal - physiology Musculoskeletal system Physical activity Posture Posture - physiology Risk factors VDU/computer workplace
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Summary:	Prolonged and static sitting postures provoke physical inactivity at VDU workplaces and are therefore discussed as risk factors for the musculoskeletal system. Manufacturers have designed specific dynamic office chairs featuring structural elements which promote dynamic sitting and therefore physical activity. The aim of the present study was to evaluate the effects of four specific dynamic chairs on erector spinae and trapezius EMG, postures/joint angles and physical activity intensity (PAI) compared to those of a conventional standard office chair. All chairs were fitted with sensors for measurement of the chair parameters (backrest inclination, forward and sideward seat pan inclination), and tested in the laboratory by 10 subjects performing 7 standardized office tasks and by another 12 subjects in the field during their normal office work. Muscle activation revealed no significant differences between the specific dynamic chairs and the reference chair. Analysis of postures/joint angles and PAI revealed only a few differences between the chairs, whereas the tasks performed strongly affected the measured muscle activation, postures and kinematics. The characteristic dynamic elements of each specific chair yielded significant differences in the measured chair parameters, but these characteristics did not appear to affect the sitting dynamics of the subjects performing their office tasks.
ISSN:	0003-6870 1872-9126