What Does the Research Show About Center of Gravity?
In 1991, Edward D. Lemaire and colleagues published a study in the Journal of Rehabilitation Research and Development regarding center of gravity and rolling resistance for tilt-seat wheelchairs. The study showed that moving the rear wheels toward the front of the chair reduces rolling resistance and decreases the rearward tip angle.
“These facts are directly related to the center of gravity position since, as the wheelbase is decreased, the center of gravity moves closer to the rear axle,” explains Kay E. Koch, OTR/L, ATP, rehab clinical consultant for Invacare Corp. “This results in more weight being centralized over the rear wheels, thereby reducing the rolling resistance. However, when the wheelchair is tipped backward, the center of gravity does not have as far to move before the wheelchair passes the balance point (the point at which the center of gravity passes behind the rear axle).”
Koch also notes that a longer wheelbase increases the rearward tip as well as rolling resistance.
This research can help clinicians decide on the appropriate wheelchair configuration during setup by promoting safety and minimizing function loss, Koch says.
This article originally appeared in the Seating & Position Handbook 2014-2015 issue of Mobility Management.