Abstract
BackgroundHolding 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.MethodsFifteen 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.ResultsHandrail 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.ConclusionHandrail 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-015-0051-3) contains supplementary material, which is available to authorized users.
Highlights
Holding a handrail or using a cane may decrease the energy cost of walking in stroke survivors
Our research aims were 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 stroke survivors, and 2) to examine which changes in step parameters and muscle activity are associated with the observed changes in energy cost
Energy cost HOLD caused a significant decrease in net energy cost (p = .023) of 11.8 % (0.86 J · kg-1 · m-1) on average compared to NORM, while touch handrail contact (TOUCH) had no significant effect on energy cost (Fig. 1)
Summary
Holding a handrail or using a cane may decrease the energy cost of walking in stroke survivors. 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]. 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 [9,10,11,12,13] 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
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