Energy expenditure of walking for adult patients with spinal cord lesions using the reciprocating gait orthosis and functional electrical stimulation.

A major factor influencing compliance with walking orthoses following spinal cord damage, is the energy requirement associated with them. We compared ambulatory energy expenditure in subjects using the reciprocating gait orthosis (RGO) with and without functional electrical stimulation (FES) of the thigh muscles at self selected walking speeds. Five adult subjects (median age 34 years, range 24-37) with spinal cord lesions ranging from C2 (incomplete) to T6 volunteered to participate in this study. All subjects were successful RGO users (median use 5.7 years, range 4.1-7.3). Walking speed (m/s), ambulatory energy consumption (J/kg/s) and energy cost (J/kg/m) were derived from oxygen uptake determined using the Douglas bag technique. We anticipated that subjects walking with FES would either: (a) walk at the same speed but reduce their energy cost or (b) increase their walking speed for the same (or less) energy cost. Walking speed and energy cost remained unchanged in one subject. One subject increased his walking speed by 14.0% and increased his energy consumption by 8.4%. His energy cost remained unchanged. Three subjects increased their walking speeds (by 12.4, 12.7 and 6.8%), energy consumption (by 25.9, 20.4 and 18.4% respectively) and energy cost (by 11.6, 6.8 and 10.5% respectively). We did not find a substantial benefit, in terms of energy expenditure, from the hybrid system when walking continuously for 5 min. We suggest that the hybrid system may be of greater benefit during prolonged walking, although other limitations, inherent in the RGO itself, may prevent an increase in compliance. Repetition of walking speed tests supported the reliability of our results. Tests on comparably aged, able-bodied subjects showed that an increase in energy cost of up to 5.8% was within the biological variability of the subject and the error of the methodology.