EMG Changes in Human Thenar Motor Units With Force Potentiation and Fatigue

Abstract

. EMG changes in human thenar motor units with force potentiation and fatigue.

Interpretation of EMG integral or RMS and estimates of “neuromuscular efficiency” can be misleading in fatiguing contraction

“…Following Hicks andMcComas (1989), andMcComas et al (1994), Klein et al (2006) as well as Thomas et al (2006) explained the elevated peak-to-peak amplitude and area of MUPs with increased Na + -K + pump activity and IAP amplitude. However, 15% hyperpolarization of muscle membrane (Hicks and McComas, 1989) could hardly explain 200% increase of MUP amplitude observed in some experiments.…”

“…In fatiguing conditions, not only amplitude characteristics of interference EMG but also amplitude of surface detected MUPs in human muscles (Gydikov et al, 1976;Klein et al, 2006;Thomas et al, 2006) could increase due to peripheral factors. Following Hicks andMcComas (1989), andMcComas et al (1994), Klein et al (2006) as well as Thomas et al (2006) explained the elevated peak-to-peak amplitude and area of MUPs with increased Na + -K + pump activity and IAP amplitude.…”

Decomposition of motor unit tetanic contractions of rat soleus muscle: Differences between males and females

“…The applied mathematical method also has limitations -the decomposition can be made only for unfused tetanic contractions, when the beginning of relaxation following a response to each stimulus is visible. Such unfused tetanic contractions can be evoked for isolated MUs only, and for humans this method was only used in experiments on small distal muscles of the limbs (Thomas et al, 2005;Häger-Ross et al, 2006). From these reasons one cannot simply generalize the obtained results to humans, neither with respect to high variability of responses to individual stimuli nor to sex differences in the process of force generation for slow soleus MUs.…”

Automatic Identification and Classification of Muscle Spasms in Long-Term EMG Recordings

“…Clonus involves periodic bursts of EMG between 4 and 12 Hz, the frequency of which largely depend on the length of the reflex arc [13], [14]. Clonus is documented clinically when there are four bursts of EMG [15].…”