PHYSIOLOGICAL EVALUATION OF A NEWLY DESIGNED LEVER MECHANISM FOR WHEELCHAIRS

Lever-propelled wheelchairs have been described as more efficient and less physically demanding than hand-rim-propelled wheelchairs. To eval uate a newly designed lever mechanism (MARC) in both one- and two-arm use, a series of wheelchair exercise tests were performed on a motor-d riven treadmill. Eight able-bodied male subjects performed a standard exercise test in the prototype MARC, both in an asynchronic and a sync hronic bimanual propelling mode and in an unilateral (left-sided) mode . Subsequently the subjects performed additional exercise tests in a c onventional crank-to-rod lever mechanism with unilateral and bimanual propulsion and in a conventional hand rim wheelchair. Analysis of vari ance was used to study the effect of the different work modes upon pow er output and cardiorespiratory parameters statistically (p < 0.05). T he MARC stood out well in comparison with the conventional lever desig n. The additional design features which are to be implemented (variabl e gearing, reverse gear) will make the MARC a useful wheelchair. One-a rm wheelchair propulsion is a very strenuous form of locomotion, requi ring careful consideration in terms Of provision. Mechanical and ergon omic improvements are quite feasible in lever propulsion and may to a certain extent reduce this problem. To improve overall mobility of whe elchair-dependent subjects further, ergonomic and mechanical design im provements are very necessary in lever as well as hand-rim wheelchairs . A combined biomechanical and physiological research approach will he lp in the definition of design criteria and fitting guidelines.