Do Improvements in Balance Relate to Improvements in Long-Distance Walking Function after Stroke?

Hindawi Publishing Corporation Stroke Research and Treatment Volume 2014, Article ID 646230, 6 pages http://dx.doi.org/10.1155/2014/646230 Research Article Do Improvements in Balance Relate to Improvements in Long-Distance Walking Function after Stroke? Louis N. Awad,1,2 Darcy S. Reisman,1,2 and Stuart A. Binder-Macleod1,2,3 1 Department of Physical Therapy, University of Delaware, 540 South College Avenue, Newark, DE 19713, USA Graduate Program in Biomechanics and Movement Science, Newark, DE 19713, USA 3 Delaware Clinical and Translational Research Accel Program, Newark, DE 19713, USA 2 Correspondence should be addressed to Louis N. Awad; Received 24 March 2014; Revised 4 June 2014; Accepted 8 June 2014; Published 10 July 2014 Academic Editor: Steve Kautz Copyright © 2014 Louis N. Awad et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Stroke survivors identify a reduced capacity to walk farther distances as a factor limiting their engagement at home and in community. Previous observational studies have shown that measures of balance ability and balance self-efficacy are strong predictors of long-distance walking function after stroke. Consequently, recommendations to target balance during rehabilitation have been put forth. The purpose of this study was to determine if the changes in balance and long-distance walking function observed following a 12-week poststroke walking rehabilitation program were related. For thirty-one subjects with hemiparesis after stroke, this investigation explored the cross-sectional (i.e., before training) and longitudinal (i.e., changes due to intervention) relationships between measures of standing balance, walking balance, and balance self-efficacy versus long-distance walking function as measured via the 6-minute walk test (6MWT). A regression model containing all three balance variables accounted for 60.8% of the variance in 6MWT performance (adj 𝑅2 = .584; 𝐹(3, 27) = 13.931; 𝑃 < .001); however, only dynamic balance (FGA) was an independent predictor (𝛽 = .502) of 6MWT distance. Interestingly, changes in balance were unrelated to changes in the distance walked (each correlation coefficient < .17, 𝑃 > .05). For persons after stroke similar to those studied, improving balance may not be sufficient to improve long-distance walking function. 1. Introduction The recovery of walking function is an ultimate goal of rehabilitation after stroke [1]. Indeed, for a majority of stroke survivors, impairments in their ability to walk farther limit their participation at home and in the community [2]. Unfortunately, current therapies are generally unable to improve the majority of subjects’ capacity for community ambulation [3]. Moreover, walking deficits that contribute to reduced endurance and speed persist following rehabilitation [4–6]. A better understanding of the changes underlying improvements in long-distance walking function following walking rehabilitation would inform future efforts and define specific targets for gait intervention. Recent observational studies have shown balance to be a powerful predictor of poststroke walking function [7–13] and a variable related to quality of life after stroke [14]. Specifically, individuals with better balance abilities typically present with better walking function. Based on such findings, recommendations to target balance during poststroke rehabilitation are commonly put forth. However, basing interventions on the results of cross-sectional studies may not be appropriate as cross-sectional analyses only measure the relationship between variables at a single time point. That is, a strong cross-sectional relationship between walking function and balance does not provide evidence for the potential effect on walking function of gait intervention that improves balance. Thus, this study aimed to determine if the changes in balance and long-distance walking function observed following a 12week poststroke walking rehabilitation program were related and if these findings were consistent with prior work carried out on slower [9] and faster [13] walkers in the chronic phase of stroke recovery. 2 Stroke Research and Treatment Table 1: Subject characteristics. Subject 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 a Sex Age, y Time since stroke, y Side of hemiparesis Walking speed, m/s Male Female Female Female Male Female Male Female Male Male Male Male Female Female Male Male Male Male Female Male Female Male Male Male Male Male Male Female Male Male Female Male: 65%a 63.5 63.2 65.4 64.9 60.0 47.6 54.2 55.5 57.8 60.1 68.7 49.0 55.1 63.0 42.7 45.1 57.5 67.9 56.7 70.7 48.7 54.9 69.5 55.1 55.7 61.5 71.3 56.0 25.3 43.2 64.2 57.2 (9.9)b 7.99 30.52 22.90 24.65 2.67 3.77 8.55 1.87 0.54 0.93 2.86 1.59 0.90 1.19 0.57 3.35 0.59 0.77 0.94 1.71 7.94 1.66 8.25 5.23 0.73 6.94 0.55 3.51 1.70 7.06 1.56 1.87 (0.94–7.00)c Right Right Left Right Left Left Left Left Right Right Left Right Right Right Left Left Left Left Left Left Right Left Right Left Left Right Left Left Left Left Left Right: 36%a 0.92 0.94 0.20 0.70 0.41 0.74 1.16 0.80 0.59 1.06 0.79 0.97 0.45 0.27 0.61 0.24 0.87 0.65 0.12 0.84 0.60 0.74 0.72 0.88 0.33 1.01 0.88 1.18 1.51 1.02 0.93 0.75 (0.32)b Percent; b mean (SD); c median (IQR). 2. Methods 2.1. Subjects. Thirty-one subjects with hemiparesis after stroke were studied. These subjects were those randomized to the treatment arms (see Section 2.2) of a clinical trial at the University of Delaware (Table 1). Subjects were those with single cortical or subcortical stroke, in the chronic phase of recovery (>six months after stroke), who had observable gait deficits but could ambulate independently for six minutes without orthotic support, were able to follow instruction and communicate with the investigators, and were able to passively dorsiflex the ankle to a neutral position with the knee extended and passively extend the hip at least ten degrees. A history of multiple strokes, cerebellar stroke, lower extremity joint replacement, orthopedic conditions that limited walking ability, neglect and hemianopia, unexplained dizziness in the last 6 months, and chest pain or shortness of breath without exertion excluded subjects from participating. All subjects signed written informed consent forms. This study was approved by the University of Delaware’s institutional review board. 2.2. Intervention. Subjects participated in a treadmill and overground walking retraining program at a frequency of 3 sessions per week for 12 weeks. On the treadmill, subjects walked five bouts of 6 minutes at the maximum walking speed they could maintain for four minutes. Subjects either walked with or without functional electrical stimulation applied Stroke Research and Treatment 2.4. Data Analyses. Statisti (...truncated)