|
|
Sitting Biomechanics Laboratory
Part of the |
Effects of a Dynamic Seating System on Wheelchair Propulsion
|
|
|
|
|
Background As the population of wheelchair users continues to grow, a strong understanding of propulsion becomes imperative. Specifically, wheelchair users need to maintain efficient motion without excessively exposing themselves to the risks of repetitive stress injury. The repetitive nature of propelling a wheelchair places significant stress on the hands and joints of the upper extremity creating notable risk of pain and muscular overload. The presence of SCI with its associated neuromuscular changes and compensatory muscle activity increases the mechanical strain placed on the upper extremities. The objective of this study was to compare the propulsion of a wheelchair with the seat in a standard and WO-BPS configuration. Ten volunteers with SCI were tested. None of the participants had a history of shoulder problems or presented with any medical contraindications that would have prevented their inclusion in this study.A wheelchair equipped with a Ipupc seating system was used for all tests ProtocolWheelchair propulsion was evaluated by measuring kinematics (Eight Camera MCam2, Vicon Peak, Centennial, CO), kinetics (SmartWheel®, Three Rivers Holdings LLC, Mesa, AZ), and muscle activities (Delsys Inc, Boston, Maryland) (Figure 2, experimental setup) during propulsion tasks. Subjects were given the following tasks: propelling in a straight line for 5 meters, propelling five meters with a 45o turn, propelling five meters with a 90o turn, performing a push-up from a seated position, propelling up a 10º ramp, propelling over carpet, propelling over an asphalt-like surface, and propelling over an uneven surface. The subject was asked to perform each of the propulsion tasks 3 times. All tasks were performed in both postures: Normal, and WO-BPS. Muscle activity was monitored by unilateral surface EMGs that were placed on rhomboid major, upper trapezius, posterior deltoid, triceps brachii, long head of biceps brachii, anterior deltoid, sternal pectoralis major, and sternocleidomastoid. Vicon motion capture system was used to collect kinematic data of the upper body (elbow flexion angle), and a SmartWheel was used to measure pushrim forces. |
|
|
Table 1 shows the muscle activity differences (mv, mean±SE) between Normal and WO-BPS postures as measured from shoulder and arm muscles during wheelchair propulsion tasks (a straight line, a line with a cut of 45° or 90° turn midway, propelling over carpet, over an asphalt-like surface, uneven surface and propelling up a 10? ramp). ConclusionsOur evidence shows that there were no significant changes in muscle activity, elbow flexion angle, and force efficiency between the two tested postures. The lack of significant differences implies that the WO-BPS seating system can be used to reap the benefits it confers to user posture and pressure relief without presenting significant detriment to wheelchair propulsion. |
Last updated
May 25, 2008 by Makhsous.
Send EMAIL
if there are questions or problems.