Functional electrical stimulation (FES) leg cycling exercise in paraplegia : a pilot study for the definition and assessment of exercise testing protocols and efficacy of exercise

A custom FES-cycling ergometer equipped with an electric motor and an integrated feedback system for accurate control of exercise workrate and cadence has been employed in this study. This experimental setup allowed the imposition of arbitrary workrate profiles with high precision and provided the potential for highly-sensitive exercise testing. One aim of the work described in this thesis was to propose and evaluate novel protocols for incremental exercise test (IET) and step exercise test (SET). Valid protocols would allow reliable estimation of the key markers of cardiopulmonary fitness in SCI subjects performing FES-cycling. 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, were also investigated. Thus, a second aim of this work was to determine whether oxygen uptake and a new measure of stimulation cost (i.e. the total rate of stimulation charge applied to the stimulated muscle groups during cycling) are sensitive enough to allow discrimination between the efficacy of different activation patterns during constant-power cycling. A discussion on the concept of metabolic efficiency in AB and SCI subjects is presented in this thesis. Efficiency of FES-cycling is much lower than that of voluntary cycling. Therefore, a third aim of this work was to define new efficiency measurements that are more appropriate for the SCI population. Two volunteer subjects took part in this study and the data obtained from the tests they performed are presented as case studies. The main outcome shows feasibility of the two exercise testing protocols. Moreover, the first report of a ventilatory threshold in SCI subjects during FES-cycling has been provided here. Oxygen uptake and stimulation cost measurements both allow discrimination between the efficacy of different muscle activation patterns. However, stimulation cost is more easily determined in real time, and responds more rapidly and with greatly improved signal-to-noise properties than oxygen uptake.EThOS - Electronic Theses Online ServiceGBUnited Kingdo