Comparison of F-waves of motor unit action potentials activated during voluntary contraction.
The system for classifying F-waves was developed to study the properties of F-wave and to compare single motor unit (MU) F-waves with motor unit action potentials (MUAPs) activated during voluntary contraction. The F-waves evoked by submaximal stimulation as well as the EMG signals during voluntary contraction at 6 levels of 10-100% of maximum voluntary contraction (MVC) were measured in the tibialis anterior muscles of 3 healthy volunteers. Nine channel F-wave waveforms in a selected electrode array were classified using a template-matching method. After the detection procedure of MUAPs in voluntary EMG signals, the MUAPs were also classified by the same method. Most of the F-waves (88.4%) were composed of a single MUAP. The numbers of MU classified from single MU F-waves in 3 subjects were 12, 12 and 15, and the numbers of MU classified from the voluntary EMG signals at 6 contraction levels were 20, 27 and 24, respectively. A total of 26 single MU F-waves were identified with the MUs extracted from the data during voluntary contractions. The results suggest that the F-waves are composed of a population of the MUs, which are recruited at a wide range of contraction levels. The classification procedures of F-waves and voluntary EMG signals have made it possible to recognize the same MU in both signals and to analysis the firing thresholds of F-waves.
Kanagawa Rehabilitation Institute, Nanasawa 516, Atsugi, Kanagawa 243-0121, Japan. masafumiyamada@hi-ho.ne.jp
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D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography / Q000145:classification*; D019054:Evoked Potentials, Motor / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D010543:Peroneal Nerve / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values