Whole-body vibration during manual wheelchair propulsion with selected seat cushions and back supports

Although the exposure to whole-body vibrations (WBV) has been shown to be detrimental to seated humans, the effects of wheelchairs and seating systems on the transmission of vibration to an individual have not been thoroughly examined. The purpose of this study was to determine if the selected wheelchair seat cushions and back supports minimize the transmission of vibrations. Thirty-two wheelchair users traversed an activities of daily living course three times using 16 randomly selected seating systems as well as their own. Vibrations were measured using triaxial accelerometers at the seat and participant´s head. The weighted fore-to-aft (T_x), vertical (T_z), and resultant (T_r) transmissibility based on the vibrational-dose-value (VDV) were used to determine if differences existed among the four seat cushions and back supports. The obstacles that seem to have the largest effect on the transmission of WBV are the single event shocks and the repeated event shocks. Comparisons between the individuals own seating system and the tested seating systems suggest that the individuals are not using the most appropriate seating system in terms of the reduction of vibration transmission.