Energy consumption of paraplegic locomotion using reciprocating gait orthosis

Abstract

The energy cost of walking using a reciprocating gait orthosis (RGOII) with functional electrical stimulation (FES) was assessed in 14 patients with spastic complete paraplegia from six rehabilitation centres. Before and after training asing RGOII with FES, the subjects performed a progressive maximal test on an arm-crank ergometer to obtain their laboratory peak oxygen uptake$(L\dot VO_{2peak} )$ heart rate (HR) and blood lactate concentration changes. At the end of the training session, oxygen uptake$(\dot VO_2 )$ was measured during a walking test with orthosis at different speeds (6 min steady state at 0.1 m · s⁻¹, followed by 2-min stages at progressively increasing speeds up to exhaustion). Of the subjects 4 repeated this test using orthosis without FES. At a speed of 0.1 m · s⁻¹,$\dot VO_2$ represented 47 (SD 23)% of$L\dot VO_{2peak}$, mean HR was 137 (SD 21) beats · min⁻¹ and mean blood lactate concentration 2.4 (SD 1.4) mmol · l⁻¹. Maximal speed ranged from 0.23 to 0.5 m · s⁻¹. At maximal speed,$\dot VO_2$ was 91 (SD 18) % of$L\dot VO_{2peak}$ mean HR reached 96 (SD 7)% and mean blood lactate concentration only 52 (SD 19)% of the maximal values measured during the laboratory test. Walking without electrical stimulation induced an increase in HR but there was no difference in$\dot VO_2$ and blood lactate compared to walking with stimulation. The training period did not result in any improvement in maximal physiological data. We concluded that the free cadence walking speed with orthosis remains much lower than that of able-bodied people or wheelchair users. The metabolic cost at a given speed is much higher even if, using a stimulation device, the cardiovascular stress is reduced.