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Study On Attenuation Characteristics Of Ultrasonic Signal In Muscle Fatigue Process

Posted on:2016-09-09Degree:MasterType:Thesis
Country:ChinaCandidate:P C LiFull Text:PDF
GTID:2208330473962282Subject:Signal and Information Processing
Abstract/Summary:PDF Full Text Request
The capability of the muscle tissue export power would decline with the muscle tissue constantly work. Meanwhile, the maximum muscle contraction strength, the maximum output power would temporary decline, this phenomenon is in called the muscle fatigue. The fatigue is related to the individual constitution, exercise type, exercise amount, and muscle microstructure. If the muscle fatigue did not be processed suitably, the muscle would be damaged and affect human’s daily life and work seriously, especially to the sports training of athletes. Therefore, in the domain of the exercise recovery, muscle disease treatment, sports training and other areas, the assessing muscle fatigue is very important.When the ultrasonic wave spread in human tissues, its energy will be attenuated. The ultrasonic attenuation is due to the absorption, reflection, refraction and scattering by the tissue. As the muscle tissue gradually fatigues, its thickness, hardness and the order of muscle fibers changes. It caused the changes of attenuation. In this paper, we study the attenuation of ultrasound transmission in the fatigue process and explore the better technical route for the fatigue assessment.This paper was carried out as the following:(1)Based on that the propagation mechanism of ultrasonic wave in biological soft tissue and the thickness variation of the tissue in the gradual fatigue process, we theoretically analyzed the correlation between the ultrasonic attenuation and muscle fatigue. The function of the ultrasonic amplitude was deduced in the muscle gradual fatigue process. The paper studied the correlation of the incident frequency and the ultrasonic attenuation coefficient in human muscle tissue.(2)For these conclusions, we designed the measured experiment of the ultrasonic attenuation in the fatigue process of muscle tissue reasonably. The experiment consists of three parts, namely, that the measuring of muscle fatigue extent, the acquisition of surface EMG and the collecting of the ultrasonic response signal.(3)The attenuation of the response signal in fatigue process was analyzed. The average amplitude of the response signal was calculated. In this paper, the different models were chose to fit for the changes of the average value. we have come to the ultrasonic attenuation regular in muscle fatigue process.(4)When the ultrasonic wave propagated in the fatigue process of muscle tissue, we studied the correlation between the ultrasonic attenuation coefficient and the incident frequency. We explored the variation of surface EMG and the characteristics of ultrasonic attenuation about the correlation.In this paper, we drew the following conclusions:As the gradual fatigue in the muscle tissue, the amplitude of response signal shows a gradual decay trend. Choosing different function to fit for the experimental data, the amplitude attenuation of response signal meets a exponential decay law. Changing the center frequency of the input transducer, with the increase of the frequency, the attenuation curve becomes steeper, the attenuation enhances and the attenuation coefficient increases. With the gradual fatigue, the RMS value of the surface EMG signal increases, consistent with the existing research findings, which also reflects a fatigue state of the muscle tissue in the experimental process. The muscle tissue fatigues in the process gradually, with the increases of RMS of the surface EMG and the amplitude of response signal decreases.
Keywords/Search Tags:Ultrasonic, Attenuation, Muscle fatigue, Surface EMG, Fitting
PDF Full Text Request
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