Title: Postural control in unstable sitting

Authors: Pranab Nag; Anjali Nag; Heer Vyas; Priyanka Shah Shukla

Addresses: National Institute of Occupational Health, Meghaninagar, Ahmedabad – 380016, India. ' National Institute of Occupational Health, Meghaninagar, Ahmedabad – 380016, India. ' National Institute of Occupational Health, Meghaninagar, Ahmedabad – 380016, India; National Institute of Fashion Technology, Ministry of Textiles, Government of India, NIFT Campus, Dharmsala, Mangattuparamba, Kannur – 670562, India. ' National Institute of Occupational Health, Meghaninagar, Ahmedabad – 380016, India

Abstract: We aimed to examine the influence of sitting instability, on the stabilometric dimensions and back and leg muscle with respect to postural control of women volunteers. Experimental seats with wooden hemispheres of distinct diameters were attached to achieve increasing levels of sitting instability. A two force plate experiment setup was assembled, where in one force plate served as seat pan and other plate as feet. The experimental seat was placed on a force plate and the participating volunteers were instructed to maintain their balance while sitting on the seat with their eyes open. Coordinates of centre of pressure (CoP) displacement, force distribution and electromyographic measurements of back and leg muscles were recorded and quantified with summary statistics. With an increase in seat instability, force distributions show a shift of load from seat pan to feet. Trajectory length and speed of CoP displacement significantly increased with increase in seat instability. Statistical analysis of the electromyography measurements indicated that leg muscle activities significantly increased in the unsupported sitting conditions.

Keywords: centre of pressure displacement; electromyography; EMG; stabilogram; force measurement; postural control; unstable seating; sitting instability; stabilometric dimensions; back muscles; leg muscles; seated women; seated females; force distribution; seated balance; ergonomics; human factors.

DOI: 10.1504/IJHFE.2012.050871

International Journal of Human Factors and Ergonomics, 2012 Vol.1 No.3, pp.254 - 267

Available online: 06 Dec 2012 *

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