When active skeletal muscle is stretched, it generally responds with a contraction which resists the stretch. This response is termed the muscle stretch reflex. The size (gain) and timing (phase) of the response has been found to depend on many factors including the characteristics of the applied stretch, the muscle contraction level and the subject's intention. Investigations of this stretch reflex have often involved stretches to muscle which contained frequencies either beyond the range of voluntary movement or else which could be consciously tracked. This study sought to characterise the frequency response of the stretch reflex, in terms of its gain and phase, under a variety of conditions while using stretches to the muscle which were relevant to voluntary movement, yet which were too irregular to be tracked. The types of stretch which satisfied these criteria had first to be determined by an investigation of tracking performance under different conditions of peripheral feedback. Having established the types of stretch which could be used to guarantee reflex rather than voluntary responses, the stretch reflex was investigated using stretches of different amplitude and bandwidth and spanning the full range of contraction level. Research was also undertaken to determine whether the gain and phase of the reflex response could be decoupled from the background contraction level of the muscle and to examine any associated effects on the mechanical properties of the limb. Explanatory models for some of these reflex responses were developed. An interaction between normal physiological tremor and the stretch reflex response was also investigated.
| Identifer | oai:union.ndltd.org:ADTP/187773 |
| Date | January 2000 |
| Creators | Cathers, Ian, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Ian Cathers, http://unsworks.unsw.edu.au/copyright |
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