Evaluation of ambulatory performance of the arm propelled three-wheeled chair using heart rate as a control index

Purpose : The Arm propelled three wheeled chair (APTWC) is in common use in the economically poor countries for outdoor ambulation, the propulsion force of which is exerted by arm cranking in asynchronous fashion. The purpose of the study was to assess the ambulatory performance of the users of the device using heart rate as a control index, at graded speeds. Method : Fifteen regular users of APTWC male with paraplegia and poliomyelitis were ambulated at seven different graded speeds in outdoor settings and the resting and ambulatory heart rate was measured during steady state and then physiological cost index and comfortable speed of propulsion was computed. Results : The physiological strain, linear regression of the relationship between heart rate and speed with correlation coefficient of r = 0.86 (p < 0.001), polynomial regression of the relationship between physiological cost index (PCI) and speed with correlation coefficient of r = 0.83 (p < 0.001) and comfortable speed of propulsion (120 m/min) was reported. Conclusions : Heart rate can be used to evaluate the ambulatory performance of the device, quantifying energy economy for outcome evaluation and decision making for clinical recommendation.