The Influence of Seat Pan and Trunk Inclination on Muscles Activity during Sitting on Forward Inclined Seats

摘要

Sit-to-stand position required lower muscle activity during motion and sitting. The prolonged low-level static load on the back during sitting can be hypothesized to an effect back muscles adversely. The aim of the study was the estimation of the influence of seat pan inclination on muscle activity during sitting on forward inclined seats. Two types of sitting positions were applied with thighs angles: 120° and 135°. Those conditions were modified by trunk inclinations: -30°, -15°, 0°, 15"and 30° and the backrest heights: Th§, Th8 and LI. During unsupported sitting statistical influence of the trunk inclination were noticed for ES, GL and TB (p<0,05). Especially, inclination of seat pan influenced on TB activity (10%), although EMG measured during sitting did not exceed 20 % of MVC. No effect of applied seatpan and backrest adjustments on trunk muscles EMG was found during different backrest heights. Rectus femoris and gastrocnemius lat. reveal higher EMG activity with the seatpan adjusted to 135°. The backrest position influenced the EMG of tibialis anterior only.