Changes in metabolic cost of transport following locomotor training poststroke

Abstract

Background: The energy cost of transport is higher for persons with stroke compared with neurologically intact subjects, and this has a negative impact on ambulatory activity and function. Whether the high energy cost of walking after stroke is influenced by gait training interventions is generally not considered.

Objective: To examine changes in the energy cost of transport with a gait training intervention after stroke and to identify whether energy cost changes independent of changes in walking speed.

Methods: Persons with chronic (≯6 months) stroke participated in an intervention combining fast walking and functional electrical stimulation of the ankle dorsi-and plantarflexor muscles. Oxygen consumption, walking speed, and endurance were measured pre and post training. Energy and caloric cost of transport were calculated at self-selected and absolute speeds at each time point.

Results: Eleven subjects (age 61.8 ± 8 years) participated. Self-selected and fastest walking speed and 6-minute walk test distance improved after the intervention (F = 67.5, P < .001; F = 40.9, P < .001; F = 20.2, P = .001, respectively). Energy and caloric cost of transport at self-selected speed improved (F = 8.63, P = .015, and F = 7.87, P = .019, respectively) but did not change at an absolute speed pre-to postintervention.

Conclusions: Energy and caloric cost of transport at self-selected walking speeds improved pre to post training but were unaffected at an absolute walking speed, suggesting that the improved energy cost of transport was through improvements in the subject's self-selected walking speed. These results illustrate that improvements in walking speed following an intervention are an important mechanism by which the energy cost of transport can be reduced post stroke.

Figure 1

A. Illustrates the pattern of electrical stimulation and walking during the training. B. Illustrates electrode placement and positioning for setting stimulation amplitude prior to training. C. Illustration of the components of the FES system: the footswitches provide timing information that is used by the real-time controller to control the delivery of FES to the subject.

Figure 2

Clinical measures. A. Self-selected walking speed before (Pre) and after (Post) FastFES training. B. Fast walking speed before (Pre) and after (Post) FastFES training. C. Distance covered during the 6 minute walk test before (Pre) and after (Post) FastFES training.

Figure 3

Correlation between the energy cost of transport at the subject's self-selected walking speed and the distance covered during the 6 minute walk test (6 MWT) prior to (A) and after (B) training. Each symbol represents data from a single subject.

Figure 4

Cost of transport. A. Energy cost of transport at self-selected walking speed before (Pre) and after (Post) FastFES training. B. Caloric cost of transport at self-selected walking speed before (Pre) and after (Post) FastFES training. C. Energy cost of transport at an absolute walking speed before (Pre) and after (Post) FastFES training. D. Caloric cost of transport at an absolute walking speed before (Pre) and after (Post) FastFES training.