The Effects of WBV on Muscle Stiffness and Reflex Activity in Stroke.

Not yet recruiting

Phase N/A Results N/A

Trial Description

Whole body vibration is an exercise modality that could modulate tissue blood perfusion and neural reflexes, and thus may have the potential to alter muscle stiffness through modulation of contractile properties or/and neurological adaptation. However, the potential effects of WBV on leg muscle stiffness in stroke rehabilitation remains unknown. The overall aim is to investigate the effects of whole body vibration (WBV) on leg muscle stiffness and Hoffman reflex (H-reflex) and to identify the optimal vibration parameters that may reduce leg muscle stiffness among people with stroke.

Detailed Description

Muscle stiffness is common among stroke survivors. Leg muscle stiffness would hinder mobility and balance function of people with stroke. The whole body vibration is an exercise modality that may have beneficial effects in modulating neural reflex and tissue perfusion. Thus, it could alter muscle stiffness by modulating reflex activity or muscle contractile properties. However, the potential effects of WBV on leg muscle stiffness in stroke rehabilitation remains unknown. Scientific evidence is warranted to fill the knowledge gap.
Purpose This study aims to 1) to investigate effects of whole body vibration (WBV) on leg muscle stiffness and reflex activity among people with chronic stroke; 2) to identify the optimal vibration parameters that may reduce leg muscle stiffness.
Methods Individuals with chronic stroke will be recruited from community self-help groups and existing patient database. Relevant information (e.g. demographic information, medical history) will be obtained from medical records and subject interviews. Each subject will have to fulfill the following inclusion criteria: (1) diagnosis of chronic stroke, (2) community-dwelling, (3) able to follow simple verbal instructions. Exclusion criteria are: (1) other diagnoses of neurological conditions, (2) significant musculoskeletal conditions (e.g. amputations), (3) metal implants in the lower extremity or spine, (4) recent fracture in the lower extremity, (5) diagnosis of osteoporosis, (6) vestibular disorders, (7) peripheral vascular disease, and (11) other serious illnesses or contraindications to exercise.
This study will be repeated measures design. Subject will stand with knees flexed at 60° in the WBV platform which will generate thre two different vibration conditions(0Hz, 40Hz/high amplitude. Note: Hz is short for Hertz). The duration of the vibration stimulation will be 90-second per protocol. Muscle elasticity or neural modulation will be measured before and after the vibration stimulation. Muscle elasticity will be measured using supersonic ultrasound elastography. Neural modulation will be measured in soleus muscle H-reflex (H[max]/M[max]). Resting intervals will be provided in each session. All experiments should be completed in 2 separate days.

Conditions

Interventions

  • Control Other
    Intervention Desc: 1 single session of standing on the vibration platform, with no vibration signals delivered.
    ARM 1: Kind: Experimental
    Label: Control
    Description: This group will stand with knee flexion 30 degrees on the same vibration platform for 90 seconds, but no vibration will be given.
  • Low intensity whole body vibration Device
    Intervention Desc: 1 single session of whole body vibration therapy at 20Hz
    ARM 1: Kind: Experimental
    Label: Low intensity whole body vibration
    Description: This group will stand with knee flexion 30 degrees on the same vibration platform for 90 seconds. The frequency of the vibration signals will be set at 20Hz.
  • High intensity whole body vibration Device
    Intervention Desc: 1 single session of whole body vibration therapy at 40Hz
    ARM 1: Kind: Experimental
    Label: High intensity whole body vibration
    Description: This group will stand with knee flexion 30 degrees on the same vibration platform for 90 seconds. The frequency of the vibration signals will be set at 40Hz.
  • Whole body vibration intervention Device
    Intervention Desc: 1 single session of whole body vibration therapy at 40Hz
    ARM 1: Kind: Experimental
    Label: High intensity whole body vibration
    Description: This group will stand with knee flexion 30 degrees on the same vibration platform for 90 seconds. The frequency of the vibration signals will be set at 40Hz.

Outcomes

Type Measure Time Frame Safety Issue
Primary H-reflex of paretic soleus muscle Immediately before the intervention
Primary Muscle elasticity of paretic medial gastrocnemius Immediately before the intervention
Secondary H-reflex of paretic flexor carpi radialis Immediately before the intervention
Secondary Blood flow velocity of paretic side popliteal artery Immediately before the intervention
Secondary Moving Blood volume of paretic medial gastrocnemius muscle Immediately before the intervention
Primary H-reflex of non-paretic soleus muscle Immediately before the intervention
Primary Muscle elasticity of non-paretic medial gastrocnemius Immediately before the intervention
Secondary Moving Blood volume of non-paretic medial gastrocnemius muscle Immediately before the intervention

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