Author: Yang, Zhenhui
Title: Muscle-bone unit properties in individuals with chronic stroke
Advisors: Pang, Marco (RS)
Benzie, Iris Frances Forster (HTI)
Zou, Xiang (HTI)
Degree: Ph.D.
Year: 2021
Subject: Cerebrovascular disease -- Patients
Bones -- Mechanical properties
Hong Kong Polytechnic University -- Dissertations
Department: Department of Rehabilitation Sciences
Pages: xv, 158 pages : illustrations
Language: English
Abstract: The possible influence of stroke on bone properties has been well studied in a good number of studies. However, a comprehensive collation of the impact of stroke on bone properties has not been disseminated. In addition, whole-body vibration may be a useful method to improve the health status of the muscle-bone unit in stroke patients due to its reported effects on muscle-bone unit in other population, such as older adults, whereas no study to date has examined the effects of different WBV frequencies on the properties of the muscle-bone unit in stroke patients. Therefore, this thesis aimed to address the knowledge gap which was achieved through a series of integrated studies. Study 1 (Chapter 2) is a systematic review aimed to synthesize the literature related to the impact of stroke on bone properties, and summarize the research evidence on the relationship between muscle function and bone properties in individuals with stroke. Based on extensive review of the literature, it was concluded that significant changes in bone mass and macrostructure occurred after stroke, and these changes were more compromised in the paretic sides and in first few months post-stroke. The paretic upper limb exhibited more pronounced bone properties compared with the paretic lower limb. Moreover, there was a strong relationship between muscle strength/power and bone quality, while the impact of muscle spasticity on bone quality remained unclear.
Exploring the relationship between bone quality and muscle strength for different types of contraction (i.e., dynamic Vs isometric) at different contraction velocities would be useful in guiding the design of physical activity or exercise programs for enhancing bone health in individuals with stroke. Study 2 (Chapter 3) aimed to investigate the association of bone strength index at the tibial diaphysis with strength measured during different types of muscle contraction (i.e., isometric, concentric, eccentric) and at different contraction speeds. The results showed that concentric muscle contraction power was the most import determinant of bone strength index measured at the tibial diaphyseal site. Research on the effects of different WBV frequencies on the properties of the muscle-bone unit in people with stroke is lacking. In the final study of this thesis (Chapter 4), a randomized controlled trial was conducted to investigate the effect of two different WBV frequencies on leg muscle strength and rate of bone resorption after stroke. The results showed that while both the 30 Hz frequency and 20 Hz frequency WBV protocols induced a significant increase in concentric and eccentric knee muscle strength and reduction in rate of bone resorption, the 30 Hz frequency protocol was more effective than the 20 Hz protocol in improving eccentric knee extension strength on the paretic side following 8 weeks of training. Overall, the thesis indicates that stroke has considerable impact on bone health, and that leg muscle strength, particularly concentric muscle strength, is independently associated with tibial bone strength index among persons with chronic stroke. This thesis also showed that WBV is a safe training modality in people with chronic stroke, and a frequency of 30 Hz should be the more appropriate choice for enhancing leg muscle strength in individuals with chronic stroke.
Rights: All rights reserved
Access: open access

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