Load on shoulder and elbow joints during autonomous hand-cycling

T Suzuki, H Uchiyama, Catherine Holloway, NA Tyler
in Journal of Biomechanical Science and Engineering, Journal article

Abstract

Hand cranking is an alternative method to handrim propulsion for imparting
power to a wheelchair. As such it is important that the method does not overload
the shoulder or elbow as these joints are at risk of overuse injury in the wheelchair
user population. The majority of hand-cycling wheelchair is done under what could
be termed 'autonomous control'. During autonomous control the wheelchair user is
travelling at a desired speed and automatically adjusts his or her
propulsion/cranking style to the terrain being traversed. Therefore, it is important to
understand the loading on the upper limbs during this type of cranking. The
experimental system was tested using 3 healthy subjects and the joint powers and
torques were measured during the autonomous cranking phase, along with heart
rate. From the results it is clear people regulate their hand-cranking in response to
increases in heart rate. The maximum cranking power was found to occur at 1.1
rad/s, which produced 3.8W. When the arm was at full stretch from the body (at
180°) the shoulder was working at its hardest. This is because the hand position on
the tip of crank is furthest from the shoulder. The elbow was found to be very weak
when it travels past 100 ° flexion angle, this means the elbow joint is having to
work hard when cranking between 270° to 70°. It is suggested that adapting the
cranking position and cranking length could reduce the maximum power
requirements on shoulder and elbow. It is also thought that correct gear ratio
settings for individual performances could also reduce overuse injury on shoulder
and elbow.