Assessment of variability in the shape of the
motor unit action potential, the “jiggle,” at consecutive discharges.
De Luca and Erim (4) examined interaction of
motor units in the extensor carpi radialis longus and extensor carpi ulnaris muscles during isometric wrist extensions.
2002)
Motor unit recruitment strategies investigated by surface EMG variables.
Motor unit recruitment for dynamic tasks: Current understanding and future directions.
In the present study, the comparison between the level of activation obtained in different intensities indicates that the difference in the amplitude of the EMG signal, which reflects the number of
motor units recruited and the firing rate of these units, occurred between the intensities of 60, 70 and 80%.
This intensity was selected because it allows for recruitment of a sufficient number of
motor units in the quadriceps muscle and is generally well tolerated by participants.
Activity of
motor units during concentric and eccentric contractions // American Journal of Physiology.
EMG signals are essentially made up of superimposed
motor unit action potentials [MUAP's] from several
motor units.
The very small duration, low amplitude
motor unit potentials with the very low amplitude early recruitment pattern observed only over proximal muscles and the absence of any form of spontaneous activity 3 weeks after the onset of weakness seem to be the characteristic EMG changes that correlated well with the clinical picture.
Their control needle EMG studies also showed their improvement with a full recruitment pattern and reinnervation of
motor units.
A repeat laryngeal EMG identified fibrillation potentials at rest and no
motor unit activation on attempted phonation.
Although this would assure a fast movement, it would involve less than maximum
motor unit involvement.
