Effect of a FastFES walking intervention on walking economy post-stroke
Date
2010
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Publisher
University of Delaware
Abstract
Introduction: Stroke survivors suffer marked gait deficits following their stroke, leading to a higher energy cost of transport during gait. Fast treadmill walking has been studied for its potential to improve walking economy in this population. Also, electrical stimulation of the plantar and dorsiflexors has been shown to improve walking speed through increased forward propulsion post-stroke. We intended to determine if a fast walking intervention that utilizes functional electrical stimulation (FES) improves walking economy among stroke survivors. We hypothesized that the intervention would improve gross walking economy indicated by downward shift of the U-shaped cost of transport vs. speed curve across all speeds. Methods: Eight subjects (age 60 + 9.4 years, self selected speed: 0.9 + 0.18 ms-1) visited the lab for pre-intervention VO2assessment. VO2 was assessed on a treadmill at selfselected and two "fast" speeds. These subjects then underwent a 12-week treadmill training regimen consisting of three, 90-minute training sessions per week. Each session consisted of five, six-minute bouts of walking at a ‘training’ speed determined based on their self-selected speed. Subjects wore 2x2in and 3x5in VersaStim electrodes on the tibialis anterior and gastrocnemius muscles respectively, with stimulation provided at varying intervals depending on the walking bout. Subjects returned to the lab immediately following the 12-week intervention to assess post-training VO2. This post-intervention VO2 data was also assessed on a treadmill at self-selected speed, one ‘slow’ speed and two ‘fast’ speeds. VO2data were analyzed over the last minute of each walking bout for energy cost of transport (ml O2 . kg-1 . m-1) and caloric unit cost (Kcal . kg-1 . m-1) pre- and post-intervention. Results: Despite a faster self-selected walking speed, energy cost of transport was less following the intervention (p<0.05). There was no difference in caloric unit cost pre- to post- intervention (p=0.07). Respiratory Exchange Ratio values measured at the same absolute speeds were found to decrease significantly following the intervention (p<0.05). Discussion: A FastFES treadmill walking intervention improves walking economy in stroke subjects via movement of self selected speed to an area of lower energy cost of transport on the U-shaped economy curve. Treadmill training does not affect gross economy across all speeds, but reduces cost of transport at self-selected speed.