Effects of handrail hold and light touch on energetics, step parameters, and neuromuscular activity during walking after stroke

A couple of important points from this, your doctor should  be able to determine which 60% successfully walk again in a community setting.
http://www.jneuroengrehab.com/content/12/1/70

T. IJmker^12*, C. J. Lamoth³, H. Houdijk¹², M. Tolsma², L. H. V. van der Woude³, A. Daffertshofer¹ and P. J. Beek¹

• * Corresponding author: T. IJmker t.ijmker@vu.nl

Author Affiliations

¹ MOVE Research Institute Amsterdam, Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, VU University Amsterdam, van der Boechorststraat 9, Amsterdam, 1081 BT, The Netherlands
² Heliomare Rehabilitation, Research and Development, Relweg 51, Wijk aan Zee, 1949 EC, The Netherlands
³ University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, Center for Rehabilitation, Antonius Deusinglaan 1, Groningen, 9713AV, The Netherlands

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Journal of NeuroEngineering and Rehabilitation 2015, 12:70  doi:10.1186/s12984-015-0051-3
The electronic version of this article is the complete one and can be found online at: http://www.jneuroengrehab.com/content/12/1/70

Received:	5 February 2015
Accepted:	26 June 2015
Published:	23 August 2015

© 2015 IJmker et al.

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Abstract

Background

Holding a handrail or using a cane may decrease the energy cost of walking in stroke survivors. However, the factors underlying this decrease have not yet been previously identified. The purpose of the current study was to fill this void by investigating the effect of physical support (through handrail hold) and/or somatosensory input (through light touch contact with a handrail) on energy cost and accompanying changes in both step parameters and neuromuscular activity. Elucidating these aspects may provide useful insights into gait recovery post stroke.

Methods

Fifteen stroke survivors participated in this study. Participants walked on a treadmill under three conditions: no handrail contact, light touch of the handrail, and firm handrail hold. During the trials we recorded oxygen consumption, center of pressure profiles, and bilateral activation of eight lower limb muscles. Effects of the three conditions on energy cost, step parameters and neuromuscular activation were compared statistically using conventional ANOVAs with repeated measures. In order to examine to which extent energy cost and step parameters/muscle activity are associated, we further employed a partial least squares regression analysis.

Results

Handrail hold resulted in a significant reduction in energy cost, whereas light touch contact did not. With handrail hold subjects took longer steps with smaller step width and improved step length symmetry, whereas light touch contact only resulted in a small but significant decrease in step width. The EMG analysis indicated a global drop in muscle activity, accompanied by an increased constancy in the timing of this activity, and a decreased co-activation with handrail hold, but not with light touch. The regression analysis revealed that increased stride time and length, improved step length symmetry, and decreased muscle activity were closely associated with the decreased energy cost during handrail hold.

Conclusion

Handrail hold, but not light touch, altered step parameters and was accompanied by a global reduction in muscle activity, with improved timing constancy. This suggests that the use of a handrail allows for a more economic step pattern that requires less muscular activation without resulting in substantial neuromuscular re-organization. Handrail use may thus have beneficial effects on gait economy after stroke, which cannot be accomplished through enhanced somatosensory input alone.

Keywords:

Energy cost; Stroke; Neuromuscular function; Gait; Balance support

Background

Regaining the ability to walk independently is an important goal in the rehabilitation of stroke survivors. Only 60 % of all stroke survivors eventually attain this goal to the level of community walking [1]. An important limiting factor in this regard is the substantial metabolic cost of hemiparetic gait, which can be more than two times larger than in healthy subjects [2]–[4], and which is predictive of community ambulation [5]. We have previously shown that an increased (metabolic) effort to control balance contributes to this decreased gait economy [6], and that this cost can be reduced considerably by providing balance support in the form of a handrail or cane [7].

Using a handrail or cane may have biomechanical and/or somatosensory advantages that could facilitate balance control. Biomechanically, the use of a handrail or cane increases the base of support, resulting in greater margins of stability, and enables one to generate corrective forces via the hands to compensate for perturbations [8]. Apart from this biomechanical advantage, the use of a handrail or cane may provide additional somatosensory (tactile and proprioceptive) information about body orientation and movement relative to the point of contact [8], [9]. This may reduce sensory noise/uncertainty and might therefore lead to better balance control [9], [10]. There is experimental support that, even in the absence of additional biomechanical support, the mere contact of fingertips or hand with a stable support surface can decrease the excursion of the center of mass during standing and walking [9]–[13]. This decrease matched that observed with firm handrail hold in healthy participants and stroke survivors. This suggests that enhanced somatosensory information may add to the mechanical stabilization through holding a handrail, which in turn may result in a decreased energy cost of walking after stroke.

To unravel the factors underlying the differential effects of handrail hold and light touch on the energy cost of walking, it is imperative to investigate which gait parameters alter in line with metabolic changes and which neuromuscular modifications might engender these effects. In stroke survivors, handrail or cane use yields increased stride length and time as well as decreased cadence and step width and variability [14], [15]. These changes may be linked to an improved gait efficiency through a more optimal step length/frequency combination [16], [17], and lower step-to-step transition costs with a smaller step width [18]. Using a handrail or cane may also improve gait symmetry [19], [15], which may also contribute to enhanced gait economy [20].

Effects of holding a handrail or cane have also been examined in terms of changes in neuromuscular control as reflected in altered amplitude and timing of muscle activation. Some studies reported decreases in EMG burst duration and a decrease in amplitude of several lower limb muscles during cane use [21], [22]. Furthermore, a decrease in the variability of EMG profiles of the lower leg muscles has been found as a result of handrail support, which indicates a more consistent timing of muscle activity possibly relating to increased (lateral) gait stability [23], [24]. Reduced EMG amplitude and more accurate timing of muscle activity may reflect improved economy [25]. In contrast, other studies reported no effect of firm handrail hold or light touch contact with a cane on muscle activity [26], [27], while light touch contact has even been shown to result in higher activation amplitudes than force contact [12], [26].

As of yet, it is unclear whether somatosensory and/or biomechanical aspects of handrail or cane use affect the energy cost of walking after stroke, nor whether altered step parameters and/or altered neuromuscular control are responsible for this effect. Our research aims were therefore twofold: 1) to compare the effects of light touch contact with a handrail and firm handrail hold on the energy cost of walking, step parameters, and muscle activity (in terms of amplitude and timing) in stroke survivors, and 2) to examine which changes in step parameters and muscle activity are associated with the observed changes in energy cost. To evaluate changes in muscle activation amplitude and timing we used a principal component analysis (PCA), since this method allows for studying patterns of multivariate muscle activation instead of looking at isolated muscle activities alone. 

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