Influence of gait analysis on decision-marketing for lower extremity surgery

Effects of tire type and pressure on energy expenditure during wheelchair propulsion

B I SAWATZKY, I DENISON

  1. 1. Department of orthopaedics, University of British Columbia;
  2. 2. GF Strong Rehabilitation Centre, British Columbia, Canada

Background: The repetitive nature of wheelchair propulsion is now a significant contributor to overuse injuries in the shoulder and wrist. Wheelchair designs that are more ergonomic and use lighter material have made an impact. One aspect of the wheelchair that often gets overlooked among wheelchair users and therapists is the tire. Knowing the impact of different treads and under-inflated tires can help people select the best tire for their needs as well as understand the importance of keeping tires fully inflated.

Method:

Part I. Fifteen adults with spinal cord injury (age 19-55y), and 10 children (age range 10-17y) with myelomeningocele who use a manual wheelchair as their primary form of mobility were included in the study. Energy expenditure using oxygen expenditure (oxygen consumption/distance traveled) was measured while the participant wheeled at a self-selected pace for 8 minutes over linoleum flooring with each of the four randomized tire pressures (100, 75, 50, 25psi).

Part 2. Five pairs of brand-new 24-inch wheelchair tires were selected for the study. We used three types of pneumatic tires: Primo V-trak, Chen Shing, X-treme, and two types of solid tires: Kik-high profile and Kik-low profile. A lightweight manual wheelchair was used with a 56kg load and a 76/24 (rear/front) weight distribution to simulate a person in the wheelchair. Four tire pressures (100, 75, 50, 25%  of the recommended inflation level) were selected for each of the three pneumatic tires for the roll-down tests. Five runs of each sampling set were measured and recorded.

Results: A one-way repeated analysis of variance showed that tires deflated to 50 and 25psi from the recommended 100psi tire pressure had an increase in energy expenditure (p<0.01 and p<0.0001 respectively). The change between 50psi and 100psi represents a 12% increase in energy expenditure while the 25psi increased energy expenditure by 24%. This difference in tire pressure was also seen in the three pneumatic tires in the roll-down tests. The solid tires performed similarly to tires inflated to 25psi.

Conclusions: Wheelchair users must be educated about the importance of maintaining tire pressure to a minimum of 50psi or 50% of recommended tire pressure. Tires can lose up to 50% of their pressure in 1 month. Solid tires should be avoided if possible.
 
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