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Fay BT, Boninger ML, Fitzgerald SG, Souza AL, Cooper RA, Koontz AM. Manual wheelchair pushrim dynamics in people with multiple sclerosis. Arch Phys Med Rehabil 2004;85:935–42. Objectives To define differences in pushrim dynamics during manual wheelchair propulsion by users with multiple sclerosis (MS) relative to 2 control groups of subjects with spinal cord injury (SCI) and no disability (ND) and to investigate changes in propulsion biomechanics at different speeds and with fatigue. Design Case-control. Setting Biomechanics laboratory. Participants A convenience sample of 42 people, 8 women and 6 men per group. Interventions Not applicable. Main outcome measures The propulsion pattern, mean maximum speed, percentage of time in push and recovery phases, push angle, push frequency, mean maximum resultant pushrim force, mean work and push cycle, and hand-to-pushrim coupling and decoupling effects. Results The MS groups tended to use an arcing propulsion pattern more than did the control groups ( P max=.003). The MS group pushed at a lower mean maximum velocity ( v ) when allowed to choose the speed of propulsion ( v MS , .67±.20m/s; v SCI , 1.10±0.23m/s; P =.001), when asked to push at 1m/s ( v MS , .91±.26m/s; v SCI , 1.12±0.11m/s; v ND , 1.05±0.13m/s; P =.010), and were unable to maintain a self-selected speed during a 5-minute trial (Δ v MS , .15±.02m/s; Δ v ND , .03±.06m/s; P P max=.001). In general, the MS group had smaller push angles, but push frequencies similar to the controls. Statistically adjusted MS group pushrim forces and work per push measures varied depending on context, but in all trials the MS group displayed a braking effect when grasping and releasing the pushrim. The MS group had declines in most measures when pushing at a self-selected speed for 5 minutes. In all trials, the MS group was more likely to display asymmetry between right and left sides in biomechanic parameters. Conclusions Manual wheelchair users with MS have difficulty grasping and releasing the pushrim and maintaining speed during a fatigue trial. This likely leads to a slow self-selected speed of propulsion that may not be functional. Clinicians should remember these results when prescribing manual wheelchairs for people with MS.

Boninger ML, Souza AL, Cooper RA, Fitzgerald SG, Koontz AM, Fay BT. Propulsion patterns and pushrim biomechanics in manual wheelchair propulsion. Arch Phys Med Rehabil 2002;83:718-23. Objectives: To classify stroke patterns of manual wheelchair users and to determine if different patterns of propulsion lead to different biomechanics. Design: Case series. Setting: Biomechanics laboratory. Participants: Thirty-eight individuals with paraplegia who use manual wheelchairs for mobility. Intervention: Subjects propelled their own wheelchair on a dynamometer at 2 different steady state speeds. Bilateral biomechanical data were obtained by using a force and moment sensing pushrim and a motion analysis system. Main Outcome Measures: The propulsive stroke of each participant for each speed and side was classified as following 1 of 4 patterns. These 4 patterns were then compared by using a mixed-model analysis of variance. The biomechanical variables that were compared were cadence, peak and rate of rise of the resultant force, mechanical effective force, push angle, and ratio of time spent pushing to time in recovery. Results: The most common propulsive stroke involved the user lifting the hand over the pushrim during the recovery phase. The stroke pattern was independent of axle position and varied from side to side and between speeds. After controlling for subject characteristics, significant differences were observed between stroke patterns in cadence and ratio of time spent pushing to time in recovery. A stroke pattern that involves using a semicircular motion with the hand below the pushrim during the recovery phase of the propulsion stroke was associated with a lower cadence and more time spent in the push phase relative to the recovery phase. Conclusion: The semicircular motion of propulsion displayed characteristics consistent with reduced repetition and more efficient propulsion. Use of this propulsion style may reduce trauma to the upper extremities. Clinicians should consider training individuals in this propulsion style. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation