Neuromuscular and Biomechanical Control of Lower Limb Loading in Individuals With Chronic Stroke

Stroke is the leading cause of long-term disability in the U.S. Individuals with hemiparesis due to stroke often have difficulty bearing weight on their legs and transferring weight from one leg to the other. The ability to bear weight on the legs is important during functional movements such as rising from a chair, standing and walking. Diminished weight transfer contributes to asymmetries during walking which commonly leads to greater energy expenditure. Moreover, deficits in bearing weight on the paretic leg contribute to lateral instability and are associated with decreased walking speed and increased risk of falling in individuals post-stroke. These functional limitations affect community participation and life quality. Thus, restoring the ability to bear weight on the legs, i.e., limb loading, is a critical goal for rehabilitation post-stroke. The purpose of this research is to identify the impairments in neuromechanical mechanisms of limb loading and determine whether limb loading responses can be retrained by induced forced limb loading.

Study Overview

• Status: Completed
• Conditions: Stroke; Hemiparesis
• Intervention / Treatment: Other: Limb Loading; Other: Conventional Training

Detailed Description

Stroke is the leading cause of long-term disability in the U.S. Individuals with hemiparesis due to stroke often have difficulty bearing weight on the paretic lower extremity and transferring weight from one leg to the other. Impaired weight transfer and limb loading contribute to lateral instability and are associated with decreased walking speed and increased risk of falling. Consequently, restoring limb loading ability is an important goal for rehabilitation post-stroke. Despite considerable rehabilitation efforts aimed at enhancing paretic limb loading, their effectiveness on improving neuromotor and functional outcomes remains limited possibly due to poorly understood limb loading mechanisms and the reluctance to use the paretic limb. The coordination of neuromuscular actions to regulate loading force during weight acceptance is an important component of functional limb loading. Because altered neuromuscular control is common in persons with stroke, it is possible that these abnormalities may impair limb loading ability. The long-term objective of this project is to develop a mechanism-based framework for designing and testing the effectiveness of novel rehabilitation interventions to enhance lower limb weight transfer and limb loading to improve balance and mobility. This project aims to (1) identify the neuromuscular and biomechanical abnormalities in limb loading responses in individuals post-stroke, (2) determine the underlying mechanisms responsible for the deficits in limb loading, and (3) test the short-term effectiveness of a 6-week perturbation-induced limb load training program on improving limb loading responses and mobility function. The investigators propose to apply a sudden unilateral lowering of the supporting surface to induce lateral weight transfer that forces limb loading. Kinetic, kinematic, and lower extremity muscle activation patterns will be recorded. The investigators expect that, compared to healthy controls, individuals with stroke will show increased muscle co-activation of the knee musculature with decreased knee flexion and torque production, and irregular impact force regulation during loading that will disrupt weight transfer and loading of the paretic limb. Furthermore, the investigators hypothesize that compared to a conventional clinical weight-shift rehabilitation training program, the imposed limb loading group will show greater improvements during voluntary stepping and walking following training. Specifically, the investigators expect the knee muscle co-activation duration will be reduced, with increased knee joint torque, and the paretic single stance/double support time will increase, reflecting improved paretic limb loading ability during gait following training.

• Study Type: Interventional
• Enrollment (Actual): 25
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Maryland
    • Baltimore, Maryland, United States, 21201
      • PTRS Research Lab

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Hemiparesis as a result of a stroke greater than 6 months previous to the study if participants with stroke.
• Able to walk 10 meters with or without a walking aid.
• Able to stand unsupported for 5 minutes.

Exclusion Criteria:

• Medical condition precluding participation in regular exercises, such as acute cardiac or respiratory conditions limiting activity and other health conditions significantly impacting the ability to walk beyond the effects of the stroke, such as other neurological conditions or peripheral neuropathies.
• Not able to follow commands.
• Pregnancy by self-report.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: TREATMENT
• Allocation: RANDOMIZED
• Interventional Model: FACTORIAL
• Masking: NONE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Limb Loading; This group will be exposed to a sudden unilateral lowering of the supporting surface to induce lateral weight transfer of the paretic limb.	Other: Limb Loading; Participants will be assigned to one of two interventions. The intervention will occur 3 times a week for six weeks (18 sessions) each session for one hour.
Active Comparator: Conventional Training; This group will practice weight shifting and step training that focuses on the paretic limb.	Other: Conventional Training; Participants will be assigned to one of two interventions. The intervention will occur 3 times a week for six weeks (18 sessions) each session for one hour.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gait single stance time asymmetry and duration ratio	single stance time asymmetry and duration ratio	Post training at 6 weeks
Gait paretic double support/single stance	paretic double support/single stance	Post training at 6 weeks
Stepping weight transfer time	weight transfer time	Post training at 6 weeks
Stepping knee angular displacement	knee angular displacement	Post training at 6 weeks
Stepping peak torque	peak torque	Post training at 6 weeks

Collaborators and Investigators

• Sponsor: University of Maryland, Baltimore
• Investigators: Principal Investigator: Vicki L Gray, MPT, PhD, Assistant Professor

Study record dates

Study Major Dates

• Study Start (Actual): February 4, 2019
• Primary Completion (Actual): June 2, 2022
• Study Completion (Actual): June 2, 2022

Study Registration Dates

• First Submitted: September 29, 2018
• First Submitted That Met QC Criteria: October 1, 2018
• First Posted (Actual): October 3, 2018

Study Record Updates

• Last Update Posted (Actual): October 4, 2022
• Last Update Submitted That Met QC Criteria: October 3, 2022
• Last Verified: October 1, 2022

More Information

Terms related to this study

• Keywords: biomechanical; torque; muscle coactivation; kinematic
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurologic Manifestations; Stroke; Paresis
• Other Study ID Numbers: HP-00072173

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No