Shoulder load and daily activities compared between power assisted and manual wheelchair propulsion.

Manual wheelchair users rely extensively on their upper extremities for
mobility. Unfortunately, upper extremity complaints among wheelchair users are
a common problem. Work requirements of manual wheelchair propulsion that have
been linked to shoulder injuries are the repetitive (high) forces and moments
at the shoulder, extremes of motion during propulsion and muscular imbalance. A
power assisted wheelchair can be useful to decrease the workload, thereby
possibly reducing the risk on developing shoulder injuries. However, no
previous research has been published about the influence of power assisted
propulsion on forces and moments exerted on the rim and acting on the shoulder.
Therefore this is our primary goal. Because the force needed to propel the
wheelchair is partly delivered by a motor, we hypothesize that the forces and
moments exerted on the rim will decrease. Consequently, forces and moments at
the glenohumeral joint and muscle activation amplitude of push phase muscles
will decrease. Because, the transition to another type of wheelchair will
influence subjects in a broader perspective than only upper extremity function.
When a subject has less shoulder complaints or wheelchair propulsion costs less
energy, the activity level and participation in social activities can increase.
Because of this we will also investigate the differences on activity and
participation between manual and power assisted wheelchair propulsion.

The primary objective is to compare forces and moments acting on the shoulder
of manual wheelchair users during power assisted wheelchair propulsion and
manual wheelchair propulsion and the perceived upper extremity load. The
secondary objectives are to assess the differences between power assisted
wheelchair propulsion and manual wheelchair propulsion on (a) the intensity and
frequency of shoulder pain, and the influence of shoulder pain on daily
activities, (b) activity during a day and wheelchair skills, (c) self efficacy
and user satisfaction.

This study is a longitudinal intervention study with a cross-over design.

Power assisted wheels mounted on their own wheelchair frame.

Turns are easier in a power assisted wheelchair. By accidental means the
displacement of the wheelchair might be larger than expected, so people can
collide with obstacles in the environment. The power assist wheels are heavier
which might give problems in car transfers.