title: Dynamic stiffness and transmissibility of commercially available wheelchair cushions using a laboratory test method.
abstract: Evidence suggests that wheelchair (WC) users are exposed to unhealthy levels of vibration during WC use. Health risks associated with vibration exposure include vertebral disc degeneration and back pain, which may consequently decrease the function and independence of WC users. Some evidence suggests that the cushions used in WCs may amplify vibrations, although conclusive evidence has not been presented in the literature. This study evaluated and compared the transmissibility of commercially available WC cushions with two laboratory test methods: (1) direct measurement of transmissibility while human subjects propelled a WC over a road course with different cushions and (2) characterization of cushions with a material testing system (MTS) combined with mathematical models of the apparent mass of the human body. Results showed that although dynamic characterization of WC cushions is possible with an MTS, the results did not correlate well with the transmissibility obtained in the WC road course. Significant differences were found for transmissibility among the cushions tested, with the air-based cushions having lower transmissibility than the foam- or gel-based cushions.
authors.affiliation: Human Engineering Research Laboratories and Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA 15206, USA.
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Garcia-Mendez
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Pearlman
authors.forename: Rory A
authors.initials: RA
authors.lastname: Cooper
authors.forename: Michael L
authors.initials: ML
authors.lastname: Boninger
mesh_terms: D004389:Durable Medical Equipment; D004735:Energy Transfer; D004867:Equipment Design; D006804:Ergonomics / Q000379:methods*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000209:etiology; D008297:Male; D008422:Materials Testing; D008962:Models, Theoretical; D003668:Pressure Ulcer / Q000517:prevention & control; D014732:Vibration / Q000009:adverse effects*; D014910:Wheelchairs