1986 Fiscal Year Final Research Report Summary
A Comparative Study of Muscle Fatigue during Electrically-induced and Voluntary Contractions.
| Project/Area Number |
60580099
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
体育学
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| Research Institution | Kyoto University |
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Principal Investigator |
MORITANI Toshio Kyoto University College of Liberal Arts, 教養部, 助教授 (90175638)
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| Co-Investigator(Kenkyū-buntansha) |
ODA Shingo Kyoto University College of Liberal Arts, 教養部, 助手 (10169310)
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| Project Period (FY) |
1985 – 1986
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| Keywords | ELECTRICAL STIMULATION / VOLUNTARY CONTRACTIONS / MUSCLE FATIGUE / EMG POWER SPECTRA / 運動単位 |
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| Research Abstract |
1. We have developed an on-line computer analysis system for studying electromyographic changes associated with muscular fatigue. The computer subroutines developed under the present study consisted of fast Fourier transform algorithm for obtaining mean power frequency and root mean square value of the surface EMG amplitude and analog-to-digital conversion programs. The system was calibrated by feeding various types of waveform and found that the above-decribed EMG parameters could be determined within 0.5% error.
2. A preliminary study was undertaken to determine the relationship between stimulation frequency and muscular force output according to the procedures described by deVries et al. (1981) and Moritani et al. (1985). The results indicated that for the human triceps surae muscle group it was possible to match the force output during maximal voluntary contraction by percutaneously simulating the poterior tibial nerve with 75 - 110 V, stimulus pulse width of 500 uV at 50 - 80 Hz.
3.
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To determine the relationship between muscle fiber types (Soleus and Gastrocnemius muscles) and fatigue characteristics, five male subjects were tested. It was found that force output was sharply declined in comparison to that obtained during voluntary contraction as a result of continuous high frequency (50 & 80 Hz) electrical stimulations. The recorded mass action potentials (M-wave) from the surface and intramuscular electrodes indicated that the force decline was accompanied by a progressive decline in M-wave amplitude and slowing of action potential conduction velocity, indicating the existence of impaied muscle membrane excitation.
4. However, these phenomena could not be observed during sustained maximal voluntary contractions, but there were progressive motor unit (MU) firing frequency decay and mean spike amplitude decline along with significant decreases in mean power frequency of the surface EMG spectra. Since the gastrocnemius muscle with more fast-twitch fibers showed marked changes in these parameters as compared to the soleus muscle, it was suggested that the metabolic profiles of muscle might paly an important role in regulating the muscle membrane excitability during fatigue. Less
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