The Acute Effects of Passive Vibration on Cardiovascular Function in Individuals With Stroke
Condition: Stroke; Hemiparesis; Pre-Hypertension; Hypertension
MeSH terms: Stroke; Paresis; Hypertension; Prehypertension
Study type: Interventional

Summary: 
      Stroke is the third leading cause of death in the United States. Of those who are affected by
      stroke, a third becomes permanently disabled. Risk factors for stroke include, but are not
      limited to, advancing age, physical inactivity, arterial stiffness, and most commonly, high
      blood pressure. Stroke is a major form of a much boarder problem, cardiovascular disease
      (CVD). CVD is considered the primary cause of death in the US. Interestingly, increased
      arterial stiffness of elastic arteries (carotid and aorta) has been shown to be strongly
      correlated to CVD and stroke. Increased arterial stiffness is considered an independent risk
      for the development of CVD and stroke. Hence, arterial stiffness has been suggested as a
      potential therapeutic target for CVD and more specifically stroke.

      Recently, whole-body vibration (WBV) exercise has been proposed as a new and effective method
      to improve muscle mass and muscle strength in younger and older individuals. It is known that
      systemic arterial stiffness decreased 40 min after a single WBV session in healthy men. In
      our laboratory, we have shown that leg arterial stiffness decreases after a session of WBV.
      Taken together, this data seems to suggest WBV may be used as a viable way to decrease
      arterial stiffness. Special populations, such as post-stroke patients, may be unwilling or
      unable to perform WBV exercise so an inactive form of exercise (vibration) therapy is needed.

      Passive vibration (PV), allows patients to lie in an inactive, supine position, with their
      legs placed onto the vibration plate. This exposes the lower limbs to continuous vibration
      without performing voluntary muscle contraction. PV has been shown to increase skin blood
      flow on the vibrated extremity through vasodilation in healthy individuals and type 2
      diabetics. Previous work in our laboratory has demonstrated that a 10-min session of PV on
      the legs decreases augmentation index (AIx) , a marker of pressure wave reflection, as well
      as leg and systemic PWV through decreases in local peripheral resistance in young men.
      However, the effects of PV on arterial function in post-stroke patients are unknown.

      It is hypothesized that post-stroke patients will demonstrate a decrease in leg PWV and
      central AIx. However, greater responses are expected with the lower vibration frequency.
    

Detailed description: 
      The purpose of this study is to examine the effects of one acute bout of low and high
      frequency passive vibration on blood pressure, heart rate, arterial stiffness, wave
      reflection, and autonomic function in post-stroke patients.

      The specific aim of this study is:

      -To evaluate the effects of an acute bout of both high (40Hz/low amplitude) and low frequency
      (25Hz/high amplitude) passive vibration on arterial function and aortic hemodynamics by
      assessing blood pressures (systolic, diastolic, mean, pulse pressure), arterial stiffness
      (aortic, systemic, leg), aortic wave reflection (augmentation index), and autonomic function
      (heart rate variability).
    

Intervention name(s): Low-Frequency Passive Vibration; High-Frequency Pasive Vibration
Intervention type(s): Other; Other
Intervention description(s): 10 minute session of passive vibration set to a frequency of 25Hz and a high amplitude exposed to the legs; 10 minute session of passive vibration set to a frequency of 40Hz and a low amplitude exposed to the legs
Other intervention name(s): Power Plate Pro5 AIRdaptive; Power Plate Pro5 AIRdaptive
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: Stroke; Hemiparetic; Passive Vibration; Arterial Stiffness; Pulse Wave Velocity; Wave Reflection; Body Composition; Autonomic Function