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

Relevance of adding a triangular dynamic cushion on a traditional chair: A 3D-analysis of seated schoolchildren

“…In contrast, a 3D-evaluation is very accurate, with a motion detection threshold of~1° (Ellegast et al, 2012). The SPs of our young subjects without the cushion are in accordance with the findings of previous studies conducted on adolescent or adult subjects (Annetts et al, 2012;Ellegast et al, 2012). Mainly, SP on traditional furniture induces an average trunk-thigh angle of 100°so that a posterior tilt of the pelvis and lumbar kyphosis appear.…”

“…However, this assessment is not very accurate because it cannot detect segmental movements smaller than 20°. In contrast, a 3D-evaluation is very accurate, with a motion detection threshold of~1° (Ellegast et al, 2012). The SPs of our young subjects without the cushion are in accordance with the findings of previous studies conducted on adolescent or adult subjects (Annetts et al, 2012;Ellegast et al, 2012).…”

“…This result seems logical because those structures are just above the instable air-inflated cushion. Moreover, the link between pelvis and lumbar spine has already been demonstrated (Annetts et al, 2012;Ellegast et al, 2012;O'Sullivan et al, 2010aO'Sullivan et al, , 2010b.…”

“…Finally, few studies have evaluated the natural position of the feet on the ground in SP (Annetts et al, 2012;Ellegast et al, 2012;O'Sullivan et al, 2012a). However, an adequate position and force of the feet on the ground seem essential for the "ideal" SP: they reduce compression of the thighs and thus discomfort, induce better vascular circulation, and reduce intra-discal pressure (Claus et al, 2009).…”

Development of Tilting Chair for Maintaining Working Position at Reclined Posture

“…People who work sitting long hours steadily change their postures, and they take a posture tilting waist forward and concentrate on computer monitor (Grandjean and Hunting, 1997). It was also reported word processing or CAD computer workers tend to erect their trunk and head without using the backrest (Ellegast et al, 2012). From this, it is known that workers concentrating on work reduce burden to the lumbar by tilting their back, but take a posture not sufficiently supporting the lumbar by sitting in the middle of the seat.…”