Comparison of stimulation patterns for FES-cycling using measures of oxygen cost and stimulation cost

Hunt, K.J., Ferrario, C., Grant, S., Stone, B., McLean, A.N., Fraser, M.H. and Allen, D.B. (2006) Comparison of stimulation patterns for FES-cycling using measures of oxygen cost and stimulation cost. Medical Engineering and Physics, 28(7), pp. 710-718. (doi: 10.1016/j.medengphy.2005.10.006)

Abstract

<b>Aim</b><p></p> The energy efficiency of FES-cycling in spinal cord injured subjects is very much lower than that of normal cycling, and efficiency is dependent upon the parameters of muscle stimulation. We investigated measures which can be used to evaluate the effect on cycling performance of changes in stimulation parameters, and which might therefore be used to optimise them. We aimed to determine whether oxygen cost and stimulation cost measurements are sensitive enough to allow discrimination between the efficacy of different activation ranges for stimulation of each muscle group during constant-power cycling. <p></p> <b>Methods</b><p></p> We employed a custom FES-cycling ergometer system, with accurate control of cadence and stimulated exercise workrate. Two sets of muscle activation angles (“stimulation patterns”), denoted “P1” and “P2”, were applied repeatedly (eight times each) during constant-power cycling, in a repeated measures design with a single paraplegic subject. Pulmonary oxygen uptake was measured in real time and used to determine the oxygen cost of the exercise. A new measure of stimulation cost of the exercise is proposed, which represents the total rate of stimulation charge applied to the stimulated muscle groups during cycling. A number of energy-efficiency measures were also estimated. <p></p> <b>Results</b><p></p> Average oxygen cost and stimulation cost of P1 were found to be significantly lower than those for P2 (paired <i>t</i>-test, <i>p</i> < 0.05): oxygen costs were 0.56 ± 0.03 l min⁻¹ and 0.61 ± 0.04 l min⁻¹(mean ± S.D.), respectively; stimulation costs were 74.91 ± 12.15 mC min⁻¹ and 100.30 ± 14.78 mC min⁻¹ (mean ± S.D.), respectively. Correspondingly, all efficiency estimates for P1 were greater than those for P2. <p></p> <b>Conclusion</b><p></p> Oxygen cost and stimulation cost measures both allow discrimination between the efficacy of different muscle activation patterns during constant-power FES-cycling. However, stimulation cost is more easily determined in real time, and responds more rapidly and with greatly improved signal-to-noise properties than the ventilatory oxygen uptake measurements required for estimation of oxygen cost. These measures may find utility in the adjustment of stimulation patterns for achievement of optimal cycling performance. <p></p>

• Item Type: Articles
• Keywords: Functional electrical stimulation; Spinal cord injury; Cycle ergometry
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ferrario, Miss Chiara
• Authors: Hunt, K.J., Ferrario, C., Grant, S., Stone, B., McLean, A.N., Fraser, M.H., and Allen, D.B.
• Subjects: T Technology > T Technology (General)
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Medical Engineering and Physics
• Publisher: Elsevier
• ISSN: 1350-4533
• Copyright Holders: Copyright © 2006 Elseiver
• First Published: First published in Medical Engineering and Physics 28(7):710-718
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
32244	1	The development of systems for paraplegic cycling: improving health after spinal cord injury	Kenneth Hunt	Engineering & Physical Sciences Research Council (EPSRC)	GR/R92462/01	SCHOOL OF ENGINEERING