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.
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