Wheelchair ergonomics and physiological testing of prototypes

Abstract

Two hand rim propelled wheelchairs, a daily-use (active) wheelchair (R) and a marathon sports wheelchair (S), were compared to a three-wheeled crank (C) and a (synchronic) lever (L) propelled wheelchair. All wheelchairs were analysed with respect to cardio-respiratory parameters ([Vdot] _E, [Vdot] _O2 , HR, RER), power output and gross mechanical efficiency during a continuous exercise test (speed of the treadmill V = 0·96 ms^-1; every third minute a one degree increase of the slope). Non-wheelchair users (NW: N = 10) were compared to wheelchair sportsmen (WS: N = 3).

The cardio-respiratory strain of hand rim propulsion increases more swiftly for both R and S wheelchairs than for the C and L systems. Mechanical efficiency is significantly lower for the hand rim wheelchairs with a remarkably low efficiency for the S wheelchair. The S wheelchair however showed the lowest energy losses and a lower [Vdot]_{O 2} compared to the R wheelchair, these being important modalities for high speed and long distance wheeling. The trend in the data was similar for the C and L wheelchairs. These systems showed a 2–3% higher mechanical efficiency in the NW group than for R and S wheelchairs. The trend in the data between wheelchairs for both groups is more or less identical, although the WS group showed lower cardiorespiratory responses and a higher mechanical efficiency. It is concluded that physiological testing of prototypes is useful and should be extended to biomechanical and anatomical aspects to learn more about the optimizing factors for efficiency and energy expenditure in the wheelchair/user interface.

Keywords:

• Manually propelled wheelchairs
• Efficiency
• Energy expenditure
• Work capacity
• Ergonomics