Center of mass dynamic stability of independently ambulating stroke survivors is moderated by speed, but not handrail use, during treadmill walking
Presenter Type
UNO Graduate Student (Doctoral)
Major/Field of Study
Biomechanics
Author ORCID Identifier
https://orcid.org/0000-0003-4331-5283
Advisor Information
Brian A Knarr PhD
Location
CEC RM #230
Presentation Type
Oral Presentation
Start Date
22-3-2024 1:00 PM
End Date
22-3-2024 2:15 PM
Abstract
Introduction: Stroke is a leading cause of adult long-term disability and survivors often have significant gait impairments [1]. Stroke survivors also often present with altered weight distributions and greater postural sway [2]. These presentations result in gait asymmetries that affect balance, and physical therapists often implement handrail use when conducting treadmill training paradigms [3]. Some evidence has demonstrated that stroke survivors have more normalized step parameters and reduced energy cost of walking on the treadmill while using the handrail with self-selected support rather than light-touch support [3,4]. One reason for this could be the role of stability in walking economy, which has been shown to have an inverse relationship in the context of walking speed [5]. However, the effects of handrail support on stability and variability of the center of mass (COM) during post-stroke treadmill walking have not been investigated. Therefore, the purpose of the study was to investigate the effects of handrail use during treadmill walking in individuals post-stroke on mediolateral COM stability using sample entropy. We hypothesized that COM entropy would decrease with increased handrail support during ambulation on a treadmill due to increased constraints imparted on the system. We also hypothesized that stroke survivors who are currently dependent on an assistive device (AD) would have greater reduction in entropy with increased handrail support.
Methods: 26 adults with chronic stroke walked at their self-selected walking speed on a steady state, instrumented treadmill for three minutes for each of the three conditions: walking without handrails (NoHR), walking with handrails at less than 5% body weight support (5%HR), and walking with handrails with self-selected support (SSHR). Handrails were used with the participants’ less affected arm. During the 5%HR condition, visual biofeedback of force application on the handrail was utilized. If participants were unable to walk on the treadmill without handrails, the no-handrail condition was excluded. Two participants were excluded due to inability to complete the no-handrail and 5%HR conditions. Full kinematic data were collected, and full-body COM was calculated. Sample entropy for the COM was calculated to determine stability. AD dependence or independence in daily life was recorded.
Results & Discussion: Handrail support condition did not significantly affect the sample entropy of the mediolateral COM when looking at the total sample. However, our sample had a large range of walking speeds (0.1-1.35 m/s), which has been shown to have a relationship with entropy [5]. Interestingly, when controlling for speed, there was still no difference in sample entropy of the mediolateral COM between any of the three handrail support conditions (5%HR-NoHR p = 0.198; 5%HR-SSHR p = 0.118; NoHR-SSHR p = 0.088), which did not support our first hypothesis. There was also no significant difference in COM entropy between handrail support conditions when grouped by AD dependence (AD user p = 0.209; AD non-user p = 0.804), not supporting our second hypothesis. However, there was a significant difference in the effect of speed on COM entropy between AD non-users (p = 0.044) and those who are AD-dependent (p = 0.100). The correlation between speed and entropy was strong for all handrail support condition in the AD non-user group (NoHR r = 0.67, p = 0.013; 5%HR r = 0.91, p < 0.001; SSHR r = 0.86, p < 0.001), which is consistent with previous work that demonstrated a direct relationship between walking speed and COM entropy [5]. However, this was not true for the AD-dependent group, where there were negligible correlations between speed and entropy for all handrail conditions (NoHR r = -0.35, p = 0.49; 5%HR r = 0.074, p = 0.83; SSHR r = -0.16, p = 0.64). See Fig. 1. The negligible relationship of speed and sample entropy in the AD-dependent group could be due to their generally slower walking speed and/or their dependence on the AD for daily life ambulation.
Significance: Our results here demonstrate that handrail support does not significantly affect mediolateral COM stability as measured by sample entropy. Speed, however, did have a strong relationship with mediolateral COM entropy, but only for individuals who are not dependent on assistive devices. Future research should explore the effects of speed and AD dependence on COM variability and its translation to rehabilitation outcomes.
References: [1] C.M. Cirstea, Stroke. (2020) 2892–2894. [2] S.F. Tyson, et. al, Phys Ther. 86 (2006) 30–38. [3] T. Ijmker, et. al, J Neuroeng Rehabil. 12 (2015). [4] T. Ijmker, et al., Arch Phys Med Rehabil. 94 (2013) 2255–2261. [5] L. Awad, et. al, JNPT. 47 (2023) 75–83.
Center of mass dynamic stability of independently ambulating stroke survivors is moderated by speed, but not handrail use, during treadmill walking
CEC RM #230
Introduction: Stroke is a leading cause of adult long-term disability and survivors often have significant gait impairments [1]. Stroke survivors also often present with altered weight distributions and greater postural sway [2]. These presentations result in gait asymmetries that affect balance, and physical therapists often implement handrail use when conducting treadmill training paradigms [3]. Some evidence has demonstrated that stroke survivors have more normalized step parameters and reduced energy cost of walking on the treadmill while using the handrail with self-selected support rather than light-touch support [3,4]. One reason for this could be the role of stability in walking economy, which has been shown to have an inverse relationship in the context of walking speed [5]. However, the effects of handrail support on stability and variability of the center of mass (COM) during post-stroke treadmill walking have not been investigated. Therefore, the purpose of the study was to investigate the effects of handrail use during treadmill walking in individuals post-stroke on mediolateral COM stability using sample entropy. We hypothesized that COM entropy would decrease with increased handrail support during ambulation on a treadmill due to increased constraints imparted on the system. We also hypothesized that stroke survivors who are currently dependent on an assistive device (AD) would have greater reduction in entropy with increased handrail support.
Methods: 26 adults with chronic stroke walked at their self-selected walking speed on a steady state, instrumented treadmill for three minutes for each of the three conditions: walking without handrails (NoHR), walking with handrails at less than 5% body weight support (5%HR), and walking with handrails with self-selected support (SSHR). Handrails were used with the participants’ less affected arm. During the 5%HR condition, visual biofeedback of force application on the handrail was utilized. If participants were unable to walk on the treadmill without handrails, the no-handrail condition was excluded. Two participants were excluded due to inability to complete the no-handrail and 5%HR conditions. Full kinematic data were collected, and full-body COM was calculated. Sample entropy for the COM was calculated to determine stability. AD dependence or independence in daily life was recorded.
Results & Discussion: Handrail support condition did not significantly affect the sample entropy of the mediolateral COM when looking at the total sample. However, our sample had a large range of walking speeds (0.1-1.35 m/s), which has been shown to have a relationship with entropy [5]. Interestingly, when controlling for speed, there was still no difference in sample entropy of the mediolateral COM between any of the three handrail support conditions (5%HR-NoHR p = 0.198; 5%HR-SSHR p = 0.118; NoHR-SSHR p = 0.088), which did not support our first hypothesis. There was also no significant difference in COM entropy between handrail support conditions when grouped by AD dependence (AD user p = 0.209; AD non-user p = 0.804), not supporting our second hypothesis. However, there was a significant difference in the effect of speed on COM entropy between AD non-users (p = 0.044) and those who are AD-dependent (p = 0.100). The correlation between speed and entropy was strong for all handrail support condition in the AD non-user group (NoHR r = 0.67, p = 0.013; 5%HR r = 0.91, p < 0.001; SSHR r = 0.86, p < 0.001), which is consistent with previous work that demonstrated a direct relationship between walking speed and COM entropy [5]. However, this was not true for the AD-dependent group, where there were negligible correlations between speed and entropy for all handrail conditions (NoHR r = -0.35, p = 0.49; 5%HR r = 0.074, p = 0.83; SSHR r = -0.16, p = 0.64). See Fig. 1. The negligible relationship of speed and sample entropy in the AD-dependent group could be due to their generally slower walking speed and/or their dependence on the AD for daily life ambulation.
Significance: Our results here demonstrate that handrail support does not significantly affect mediolateral COM stability as measured by sample entropy. Speed, however, did have a strong relationship with mediolateral COM entropy, but only for individuals who are not dependent on assistive devices. Future research should explore the effects of speed and AD dependence on COM variability and its translation to rehabilitation outcomes.
References: [1] C.M. Cirstea, Stroke. (2020) 2892–2894. [2] S.F. Tyson, et. al, Phys Ther. 86 (2006) 30–38. [3] T. Ijmker, et. al, J Neuroeng Rehabil. 12 (2015). [4] T. Ijmker, et al., Arch Phys Med Rehabil. 94 (2013) 2255–2261. [5] L. Awad, et. al, JNPT. 47 (2023) 75–83.