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Fatigue‐related changes in motor unit action potentials of adult cats
Author(s) -
Enoka Roger M.,
Trayanova Natalia,
Laouris Yiannakis,
Bevan Leslie,
Reinking Robert M.,
Stuart Douglas G.
Publication year - 1992
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880150204
Subject(s) - motor unit , amplitude , mathematics , medicine , anatomy , physics , quantum mechanics
The purpose of this study was to quantify the changes in motor‐unit action potentials (MUAP) and force during a standard motor‐unit fatigue test. MUAP waveforms were characterized by the measurement of amplitude, duration, area, and shape (as reflected in a coefficient of proportionality). Fatigue‐resistant motor units exhibited small, but statistically significant, changes in MUAP amplitude and area during the fatigue test, whereas fatigable motor units displayed variable changes in MUAP amplitude, duration, and area. For all motor‐unit types, the coefficient of proportionality did not change, and hence the change in MUAP area was proportional to the combined changes in amplitude and duration. The between‐ and withintrain changes in MUAP were also distinct for the fatigue‐resistant and fatigable motor units. Although several mechanisms could be responsible for the changes in the MUAP as the fatigue test proceeded, the dissociation of the time courses for MUAP and force indicated that these MUAP changes were not the principal reason for the decline in force under these conditions.