Effect of handrim velocity on mechanical efficiency in wheelchair propulsion

H. E.J. Veeger*, L. H.V. Van Der Woude, R. H. Rozendal

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

To study the effect of tangential speed of the handrims independent of external power output on gross mechanical efficiency (ME), nine able-bodied subjects performed wheelchair exercise tests on a stationary ergometer. The ergorneter allowed for measurement of torque and three-dimensional forces on the rims and tangential velocity of the rear wheels. The experiment comprised two series of submaximal tests against constant external power outputs (0.25 and 0.50 W·kg−1) and four wheelchair speeds (0.83, 1.11, 1.39, and 1.67 m·s−1), which simulated a wheelchair speed of 1.67 m·s−1 and mechanical advantages of 0.43-0.87. ME stayed below 10.5% and changed inversely with speed of movement of the handrims. Peak torques on the right handrim stayed even with speed, leading to a significant increase in peak power output. Energy losses owing to braking torques at the beginning and end of the push phase increased with handrim speed but hardly exceeded 5 W. The effective force component applied to the handrims was below 71 % of the magnitude of the total force vector and dropped up to 13% with increasing handrim speed. It is suggested that an ineffective direction of forces on the rims might (partly) be responsible for the low ME and for a decrease in ME in relation to tangential handrim velocity. This suggestion is discussed from a number of theoretical perspectives. It is concluded that the use of handrims with a lower mechanical advantage will increase wheelchair propulsion efficiency.

Original languageEnglish
Pages (from-to)100-107
Number of pages8
JournalMedicine and Science in Sports and Exercise
Volume24
Issue number1
Publication statusPublished - 1 Jan 1992

Keywords

  • Constant power output
  • Force application
  • Mechanical advantage
  • Propulsion efficiency
  • Wheelchair ergometer

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