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Title: Effects of whole-body vibration therapy in individuals with chronic stroke
Authors: Liao, Lin Rong
Degree: Ph.D.
Issue Date: 2016
Abstract: Background: Whole-body vibration (WBV) has been shown to be effective in improving muscle strength and balance in older adults. Previous research on WBV in the stroke population has produced mixed results. No study has compared the effects of different WBV training protocols in persons with stroke. Purposes: This project consists of seven inter-related studies, with each study having specific objectives. There are: Study 1: To conduct a systematic review to examine the available evidence related to the use of WBV therapy on influencing body functions and structures, activity and participation in individuals with stroke, and other relevant issues including the safety of WBV applications. Study 2: To establish the reliability of outcome measures of the main study of this thesis (e.g., reliability and validity of the Craig Hospital Inventory of Environmental Factors scale). Study 3: To examine the acute effects of different WBV protocols on the activity of the vastus lateralis and gastrocnemius muscles during the performance of different static exercises in people with chronic stroke. Study 4: To examine the acute effect of different WBV protocols on the activity of biceps femoris and tibialis anterior muscles activity during static exercises among individuals with chronic stroke and how the neuromuscular response is influenced by severity of leg motor impairment. Study 5: To investigate the immediate effect of WBV in neuromuscular activity of leg muscles during dynamic exercises in individuals with stroke. Study 6: To determine the acute effect of different WBV protocols on oxygen consumption, heart rate, blood pressure, and rate-pressure product during the performance of different exercises among people with chronic stroke. Study 7 (main study): A single-blinded randomized controlled study was conducted to investigate the effects of different whole-body vibration (WBV) intensities on body funcitons/strudtures, activity and participation in individuals with stroke. Methods: Study 1: Electronic search were conducted on MEDLINE, CINAHL, PEDro, PubMed, PsycINFO, Science Citation Index. Randomized controlled trials (RCTs) that investigated the effects of WBV among individuals with stroke were identified by two independent researchers. Ten articles (nine studies) totaling 333 subjects satisfied the selection criteria and were included in this systematic review. The methodological quality was rated using the PEDro scale. The results were extracted by two independent researchers and confirmed with the principal investigator. Study 2: 107 individuals with chronic stroke and 56 age-matched healthy subjects participated in this study..The English version of the 25-item Craig Hospital Inventory of Environmental Factors was translated into Chinese using standardized procedures, and then administered to both the stroke and control groups. The same questionnaire was administered again to the stroke group at 1-2 weeks after the first session. The test-retest reliability, construct validity, and known-groups validity were assessed. Study 3: Forty-five chronic stroke patients were studied. Each subject was exposed to three WBV conditions of (1) no WBV, (2) low-intensity WBV protocol [peak acceleration: 0.96 unit of gravitational constant (g)], and (3) high-intensity WBV protocol (peak acceleration: 1.61g) while performing 8 different static exercises involving upright standing, semi squat, deep squat, weight-shifted-forward, weight-shifted-backward, weight-shifted-to-the-side, forward lunge and single-leg-standing. Bilateral VL and GS muscle activity was recorded with surface electromyography (EMG), and expressed as percentage of the EMG amplitude recorded during a maximal voluntary contraction of the respective muscles (%MVC). Study 4: Each of the 36 individuals with chronic stroke performed eight different static exercises under three WBV conditions: (1) no WBV, (2) low-intensity WBV as used in Study 3, and (3) high-intensity WBV as used in Study 3. The levels of bilateral TA and BF muscle activity were recorded using surface EMG. Study 5: Thirty people with chronic stroke performed a series of dynamic exercises with and without WBV: (1) no WBV, (2) low-intensity WBV, and (3) high-intensity WBV. Neuromuscular activation was measured by surface EMG on bilateral VL, TA, BF, and GS muscles and was reported as EMG root mean square normalized to % MVC. Study 6: Each of the 48 participants experienced the same three WBV protocols in separate sessions: (1) no WBV, (2) low-intensity WBV, and (3) high-intensity WBV. The order in which they encountered the WBV protocols was randomized, as was the order of exercises performed during each session. VO2, HR and RPE were measured throughout. BP and RPP were measured before and after each session. Study 7(main study): Eighty four people with chronic stroke (mean age: 61.2 years, SD: 9.2) who had mild to moderate motor impairment (Chedoke McMaster Stroke Assessment lower limb motor score: median=9 out of 14, interquartile range=7-11.8) were randomly assigned to the low-intensity WBV, high-intensity WBV, or control groups. The former two groups performed various leg exercises while receiving low-intensity and high-intensity WBV respectively. The controls performed the same exercises without WBV. All individuals received 30 training sessions over an average period of 75.5 days (SD=5.2). Outcome measurements included knee muscle strength (isokinetic dynamometry), spasticity at the knee and ankle joints (Modified Ashworth Scale), balance (Mini Balance Evaluation Systems Test, Mini-BESTest), mobility (Timed-Up-and-Go test, TUG), walking endurance (6-Minute Walk Test, 6MWT), balance self-efficacy (Activities-specific Balance Confidence scale, ABC), participation in daily activities (Frenchay Activity Index), perceived environmental barriers to societal participation (Craig Hospital Inventory of Environmental Factors), and quality of life (Short-Form 12 Health Survey, SF-12). The assessments were performed at baseline and post-intervention.
Results: Study 1: Only two RCTs were considered as level 1 evidence (PEDro score ≥6 and sample size >50). Two RCTs examined the effects of a single WBV session whereas seven examined the effects of WBV programs spanning 3-12 weeks. No consistent benefits on bone turnover, leg motor function, balance, mobility, sensation, fall rate, activities of daily living, and societal participation were found, regardless of the nature of the comparison group. Adverse events were not uncommon but minor. Study 2: The Craig Hospital Inventory of Environmental Factors had good internal consistency (Cronbach's alpha = 0.916) and test-retest reliability (intra-class correlation coefficient = 0.845). It also had significant association with Personal Wellbeing Index (r = -0.344, p< 0.001) but not with Fugl-Meyer Assessment upper limb motor score (r = -0.183, p = 0.088) among stroke subjects, thus demonstrating convergent and discriminant validity, respectively. The mean Craig Hospital Inventory of Environmental Factors score in the stroke group was also significantly higher than that in controls (p<0.05), thus showing good known-groups validity. Study 3: Exposure to WBV (low- and high-intensity protocols) significantly increased VL and GS EMG amplitude (large effect size, partial η²= 0.135-0.643, p<0.001) on both the paretic and non-paretic sides in different exercise conditions, compared with no WBV. No significant difference in EMG magnitude was found between the high- and low-intensity WBV protocols (p>0.05). With a few exceptions, WBV enhanced EMG activity in the paretic and non-paretic leg muscles to a similar extent in different exercise conditions. Study 4: The main effect of intensity was significant. Exposure to the low-intensity and high-intensity protocols led to a significantly greater increase in BF and TA EMG magnitude in both legs compared with no WBV (p<0.05). The intensity × exercise interaction was also significant (p<0.05), suggesting that the WBV-induced increase in EMG activity was exercise-dependent. The EMG responses to WBV were similar between the paretic and non-paretic legs, and were not associated with level of lower extremity motor impairment and spasticity. Study 5: The neuromuscular activation of VL, BF, TA and GS muscles of both legs was significantly increased by adding WBV during dynamic exercise (P<0.05) and that EMG neuromuscular activation in the BF, TA and GS muscles during exposure to the high-intensity WBV protocol was significantly greater than the low intensity WBV protocol (P<0.05). The WBV induced an increase in EMG neuromuscular activation in the TA and GS muscles that was exercise-dependent (P<0.05). The EMG response to WBV in the GS and BF muscles, but not the VL and TA muscles, was greater on the paretic leg than the non-paretic leg. Study 6: Low-intensity and high-intensity WBV induced significantly higher VO2 by an average of 0.69 and 0.79ml/kg/min respectively (P≤0.001) than the control condition. These protocols also increased HR by an average of 4 beats per minute (P≤0.05). The two WBV protocols induced higher RPE than the control condition during static standing exercise only (P≤0.001). While the diastolic and systolic BP and RPP were increased at the end of each exercise session (P≤0.001), the addition of WBV had no significant effect on these variables (P>0.05). Study 7 (main study): Intention-to-treat analysis revealed a significant time effect for muscle strength, TUG, distance and oxygen consumption rate achieved during 6MWT, Mini-BESTest, ABC, and SF-12 physical composite score domain (P<0.05). However, the time by group interactions effects were not significant for any of the outcome measures (P>0.05). Conclusions: Study 1: The Chinese version of the Craig Hospital Inventory of Environmental Factors is a reliable and valid tool for evaluating the environmental barriers experienced by people with chronic stroke. Study 2: There is insufficient evidence to support or refute the clinical use of WBV in enhancing body functions and structures, activity and participation after stroke. Study 3: Neuromusular activity in VL and GS muscles was increased significantly with addition of WBV. Further clinical trials are needed to determine the effectiveness of different WBV protocols for strengthening leg muscles in chronic stroke patients..Study 4: Adding WBV during exercise significantly increased EMG activity in TA and BF. The EMG responses to WBV in the paretic and non-paretic legs were similar, and were not related to degree of motor impairment and spasticity. The findings are useful for guiding the design of WBV training protocols for people with stroke. Study 5: This study found a positive relationship between the neuromuscular activation (EMGrms) of the bilateral VL, BF, TA and GS muscles and WBV intensity (up to 1.61g) in individuals with stroke. The increase in neuromuscular activation in the TA and GS muscles evoked by WBV was also influenced by the specific dynamic exercise performed. The EMG response in the BF and GS muscles was greater in the paretic than non-paretic lower extremity. The choice of WBV intensity, dynamic exercise and muscle trained should be important factors to consider when prescribing WBV exercise. Study 6: Addition of high- and low-intensity WBV significantly increased the VO2 and HR, but the increase was modest. WBV thus should not pose any substantial cardiovascular hazard in people with chronic stroke. Study 7 (main study): The addition of the 30-session WBV paradigm to the leg exercise protocol was no more effective in enhancing body functions/structures, activity and participation than leg exercises alone in people with stroke who sustained mild to moderate motor impairments. Overall, this thesis showed that WBV is safe and feasible when applied in stroke patients and the cardiovascular stress induced is modest. The addition of WBV also significantly augments the neuromuscular activation of leg muscles during exercise. However, the 10-week WBV training program does not lead to any additional benefits on body functions and structures, activity and participation in people with chronic stroke. Further study is required to identify the optimal WBV parameters for modifying different outcomes in stroke patients with various disability levels.
Subjects: Vibration -- Therapeutic use.
Cerebrovascular disease -- Patients -- Rehabilitation.
Hong Kong Polytechnic University -- Dissertations
Pages: xxxvii, 409 pages : color illustrations
Appears in Collections:Thesis

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