Quantitative EMG and Biomechanics
Lippold (1952) was a pioneer in studying relationships between the surface EMG and muscle force. Since then, an easy recording of surface EMG and close relation between muscle force and integrated EMG under isometric contraction, attract investigators to searching for force-EMG quantitative relationships. The general force-EMG relationships, however, are still not obtained probably due to incomplete knowledge of EMG quantitative characteristics. The greater the number of active fibres the greater both the integrated EMG and muscle force. The opposite statement is, however, not true because not only the number of fibres producing extracellular potentials affects the surface EMG, but so does the profile of intracellular action potential (IAP) along each fibre. Could variations in the IAP profile induce significant changes in the motor unit potentials (MUPs) and thus in the EMG signals?
KeywordsMotor Unit Muscle Force Motor Unit Potential Extracellular Potential Intracellular Action Potential
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- Bigland-Ritchie B, Donovan EF, Roussos CS (1981) Conduction velocity and EMG power spectrum changes in fatigue of sustained maximal efforts. J Appl Physiol 51: 1300–1305Google Scholar
- Cobb S, Forbes A (1923) Electromyographic studies of muscle fatigue in man. Am J Physiol 65: 234–251Google Scholar
- Dimitrov GV (1987) Changes in the extracellular potentials produced by unmyelinated nerve fibre resulting from alterations in the propagation velocity or the duration of the action potential Electromyogr Clin Neurophysiol 27: 243–249Google Scholar
- Dimitrova NA (1974) Model of the extracellular potential field of a single striated muscle fibre. Electromyogr Clin. Neurophysiol 14: 53–66Google Scholar
- Frank GB (1957) Negative afterpotential of frog’s skeletal muscle. J Neurophysiol 20: 602–614Google Scholar
- Lippold OCJ (1952) The relation between integrated action potentials in a human muscle and its isometric tension. J Physiol (London) 117: 492–499Google Scholar
- Lüttgau HC (1965) The effect of metabolic inhibitors on the fatigue of the action potential in single muscle libers. J Physiol (London) 178: 45–67Google Scholar
- Piper H (1912) Electrophysiologic Muschliche Muskein. Verlag von Julius Springer BaselGoogle Scholar