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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 47 (1981), S. 239-246 
    ISSN: 1439-6327
    Keywords: Surface EMG ; Frequency analysis ; Conduction velocity ; Muscle fatigue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A theory concerning the spectral density of surface electromyogram (EMG) in isometric contraction is described and herein, a conduction velocity measure, which was derived from a surface EMG model, is suggested. In order to confirm the validity of this measure, the spectral modification with respect to muscle fatigue is studied experimentally. The EMG signals were obtained from the biceps brachii and the rectus femoris in four subjects. The spectral modification shifted to a lower frequency as fatigue developed. The conduction velocity measure decreased linearly in both the biceps brachii and rectus femoris, but this tendency was more pronounced in the biceps. It is suggested that the spectral shift was concerned with conduction velocity of action potential along the muscle fibres. From these experimental results, we believe that we are justified in claiming that our conduction velocity measure is a useful index to estimate motor function.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 57 (1988), S. 767-771 
    ISSN: 1439-6327
    Keywords: Muscle ; Electromyography ; Conduction velocity ; Fibre type ; Biopsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between muscle fibre composition and fibre conduction velocity was investigated in 19 male track athletes, 12 sprinters and 7 distance runners, aged 20–24 years, using needle biopsy samples from vastus lateralis. Cross sectional areas of the fast twitch (FT) and slow twitch (ST) fibres were determined by histochemical analysis. The percentage of FT fibre areas ranged from 22.6 to 93.6%. Sprinters had a higher percentage of FT fibres than distance runners. Muscle fibre conduction velocity was measured with a surface electrode array placed along the muscle fibres, and calculated from the time delay between 2 myoelectric signals recorded during a maximal voluntary contraction. The conduction velocity ranged from 4.13 to 5.20 m·s−1. A linear correlation between conduction velocity and the relative area of FT fibres was statistically significant (r = 0.84,p〈0.01). This correlation indicates that muscle fibre composition can be estimated from muscle fibre conduction velocity measured noninvasively with surface electrodes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 40 (1979), S. 155-164 
    ISSN: 1439-6327
    Keywords: Surface EMG ; Stochastic model ; Spectral density ; Motor unit recruitment ; Entropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new stochastic model of the surface EMG is suggested and the spectral density of the surface EMG is studied theoretically and experimentally to confirm the validity of this model. Theoretical results show that while the contraction level is not so high, the shape of the spectral density (distribution) does not change and its amplitude is directly proportional to the motor unit firing frequency and recruitment. To illustrate the theoretical results, experiments were carried out for rectus femoris and biceps brachii. The surface EMG was lead off by bipolar surface electrodes. And the spectral density of the surface EMG was calculated using FFT algorithm. From these experimental results, it was confirmed that our theoretical results were almost valid.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 51 (1983), S. 247-256 
    ISSN: 1439-6327
    Keywords: Surface EMG ; Conduction velocity ; Spectral analysis ; Electrode array ; Sustained contraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A surface electrode array has been used to investigate the relationship between muscle fibre conduction velocity and the frequency spectrum during sustained isometric contractions of the biceps brachii. Measurement of muscle fibre conduction velocity was made directly, using the zero-crossing time delay method with two pairs of bipolar electrodes. It was found that the average conduction velocity during an intense (12 kg) sustained contraction decreased by about 20% at the end of the contracting period. Except for peak frequency, changes in the spectral parameters decreased in a similar manner. These results indicate that, during fatiguing contraction, spectral modifications are partly due to reduction in the action potential conduction velocity along the muscle fibres.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 23 (1985), S. 339-342 
    ISSN: 1741-0444
    Keywords: Conduction velocity ; Electrode array ; Motor endplate ; Surface EMG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Three factors influencing the accuracy of the muscle fibre conduction velocity estimates were studied. They were the recording position, the interelectrode distance and the misalignment of the electrode with respect to the muscle fibres. Experiments were performed on the biceps muscle of a normal subject. Bipolar recordings were made simultaneously from a linear electrode array consisting of 13 contacts. The accuracy of the conduction velocity was evaluated by the cross-correlation method. When the recording site was close to the innervation zone, the peak values of the cross-correlation function decreased and the estimates of the time delays became unreliable. High correlations were obtained when the interelectrode distance was small. Furthermore, the misalignment between electrode axis and muscle fibre axis led to overestimation of muscle fibre conduction velocity, but this effect was less if wider electrodes were used.
    Type of Medium: Electronic Resource
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