Effects of Trunk Functional Capacity on the Control of Angular Momentum During Manual Wheelchair Braking

Abstract

Background: Manual wheelchair braking induces an upper body angular impulse which must be controlled by joint moments to prevent a forward fall. Objective: The purpose of this study was to determine the effects of trunk functional capacity (low, high) on the rate of change in sagittal plane upper body angular momentum during manual wheelchair braking. Methods: Eight wheelchair users (4 low function, 4 high function) completed 10 trials of abrupt wheelchair braking. Trunk segment angles and abdominal joint angles, and normalized upper-body angular impulses were computed for each trial. Linear mixed effects models with initial velocity as a covariate were used to determine differences between groups. Results: The low function group had a higher angular impulse than the high function group with a mean difference (MD) ± SE of 1.59 ± 0.65 N∙m∙s/kg/m2, with a 95% CI 0.287 to 2.89, p = 0.018. The low function group also had a higher trunk segment extension angle, MD = –13.98 degrees, 95% CI: –26.27 to –1.69, p = .027. The low function group employed a greater trunk segment range of motion during braking when compared to the high function group, MD = 12.14 degrees, 95% CI: –24.48 to 0.21, p = 0.054. Lower trunk functional capacity wheelchair users had a higher fall risk during braking. Conclusion: Wheelchair users with less trunk function may be at increased risk of suffering a fall when bringing their wheelchair to an abrupt stop due to an impaired ability to arrest angular momentum.