Trunk and glenohumeral joint adaptations to manual wheelchair propulsion over a cross-slope : an exploratory study
Article [Accepted Manuscript]
Abstract(s)
Background: Cross-slopes are often encountered by manual wheelchair users propelling
within an urban setting. While propulsion over cross-slopes is more difficult than on level
surfaces, little is known about how the users counter the downhill turning tendency of the
wheelchair over cross-slopes. This study aimed to identify the adaptations of the manual
wheelchair users to the presence of cross-slopes and examine how these might impact
shoulder injury.
Methods: Nine manual wheelchair users propelled themselves across a cross-slope and over a
level surface. The trunk and glenohumeral joint kinematics, as well as the handrim contact
tangential force were compared between both conditions for the uphill and downhill limbs.
Findings: The uphill arm technique used to counter the downhill turning tendency varied
greatly in terms of potential injury risk and efficiency between participants. Trunk flexion
increased the turning tendency of the manual wheelchair, yet only one participant decreased
his flexion when rolling over the cross-slope. Various potential pathomecanisms related to the
trunk lateral flexion and the glenohumeral kinematics over a cross-slope were identified.
Interpretation: Both the uphill arm technique and trunk kinematics are important to propel
over a cross-slope both efficiently and safely. Accordingly, tips about posture and kinematics
are needed to teach this skill to manual wheelchair users. Additionally, as wheelchair
positioning seems to influence the cross-slope skill, more research is needed to explore the
impact of positioning devices (e.g., lateral supports) and wheelchair modifications (e.g.,
power assist wheels, handrim projections) on this skill.