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

Christine K Thomas, R. S. Johansson, B. Bigland-Ritchie

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Few studies have analyzed activity-induced changes in EMG activity in individual human motor units. We studied the changes in human thenar motor unit EMG that accompany the potentiation of twitch force and fatigue of tetanic force. Single motor unit EMG and force were recorded in healthy subjects in response to selective stimulation of their motor axons within the median nerve just above the elbow. Twitches were recorded before and after a series of pulse trains delivered at frequencies that varied between 5 and 100 Hz. This stimulation induced significant increases in EMG amplitude, duration, and area. However, in relative terms, all of these EMG changes were substantially smaller than the potentiation of twitch force. Another 2 min of stimulation (13 pulses at 40 Hz each second) induced additional potentiation of EMG amplitude, duration, and area, but the tetanic force from every unit declined. Thus activity-induced changes in human thenar motor unit EMG do not indicate the alterations in force or vice versa. These data suggest that different processes underlie the changes in EMG and force that occur during human thenar motor unit activity.

Original languageEnglish
Pages (from-to)1518-1526
Number of pages9
JournalJournal of Neurophysiology
Volume95
Issue number3
DOIs
StatePublished - Mar 1 2006

Fingerprint

Fatigue
Median Nerve
Elbow
Axons
Healthy Volunteers
Motor Activity

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

Cite this

EMG changes in human thenar motor units with force potentiation and fatigue. / Thomas, Christine K; Johansson, R. S.; Bigland-Ritchie, B.

In: Journal of Neurophysiology, Vol. 95, No. 3, 01.03.2006, p. 1518-1526.

Research output: Contribution to journalArticle

Thomas, Christine K ; Johansson, R. S. ; Bigland-Ritchie, B. / EMG changes in human thenar motor units with force potentiation and fatigue. In: Journal of Neurophysiology. 2006 ; Vol. 95, No. 3. pp. 1518-1526.
@article{4cc9616a4bbe44a7b8853f2f651e0b0b,
title = "EMG changes in human thenar motor units with force potentiation and fatigue",
abstract = "Few studies have analyzed activity-induced changes in EMG activity in individual human motor units. We studied the changes in human thenar motor unit EMG that accompany the potentiation of twitch force and fatigue of tetanic force. Single motor unit EMG and force were recorded in healthy subjects in response to selective stimulation of their motor axons within the median nerve just above the elbow. Twitches were recorded before and after a series of pulse trains delivered at frequencies that varied between 5 and 100 Hz. This stimulation induced significant increases in EMG amplitude, duration, and area. However, in relative terms, all of these EMG changes were substantially smaller than the potentiation of twitch force. Another 2 min of stimulation (13 pulses at 40 Hz each second) induced additional potentiation of EMG amplitude, duration, and area, but the tetanic force from every unit declined. Thus activity-induced changes in human thenar motor unit EMG do not indicate the alterations in force or vice versa. These data suggest that different processes underlie the changes in EMG and force that occur during human thenar motor unit activity.",
author = "Thomas, {Christine K} and Johansson, {R. S.} and B. Bigland-Ritchie",
year = "2006",
month = "3",
day = "1",
doi = "10.1152/jn.00924.2005",
language = "English",
volume = "95",
pages = "1518--1526",
journal = "Journal of Neurophysiology",
issn = "0022-3077",
publisher = "American Physiological Society",
number = "3",

}

TY - JOUR

T1 - EMG changes in human thenar motor units with force potentiation and fatigue

AU - Thomas, Christine K

AU - Johansson, R. S.

AU - Bigland-Ritchie, B.

PY - 2006/3/1

Y1 - 2006/3/1

N2 - Few studies have analyzed activity-induced changes in EMG activity in individual human motor units. We studied the changes in human thenar motor unit EMG that accompany the potentiation of twitch force and fatigue of tetanic force. Single motor unit EMG and force were recorded in healthy subjects in response to selective stimulation of their motor axons within the median nerve just above the elbow. Twitches were recorded before and after a series of pulse trains delivered at frequencies that varied between 5 and 100 Hz. This stimulation induced significant increases in EMG amplitude, duration, and area. However, in relative terms, all of these EMG changes were substantially smaller than the potentiation of twitch force. Another 2 min of stimulation (13 pulses at 40 Hz each second) induced additional potentiation of EMG amplitude, duration, and area, but the tetanic force from every unit declined. Thus activity-induced changes in human thenar motor unit EMG do not indicate the alterations in force or vice versa. These data suggest that different processes underlie the changes in EMG and force that occur during human thenar motor unit activity.

AB - Few studies have analyzed activity-induced changes in EMG activity in individual human motor units. We studied the changes in human thenar motor unit EMG that accompany the potentiation of twitch force and fatigue of tetanic force. Single motor unit EMG and force were recorded in healthy subjects in response to selective stimulation of their motor axons within the median nerve just above the elbow. Twitches were recorded before and after a series of pulse trains delivered at frequencies that varied between 5 and 100 Hz. This stimulation induced significant increases in EMG amplitude, duration, and area. However, in relative terms, all of these EMG changes were substantially smaller than the potentiation of twitch force. Another 2 min of stimulation (13 pulses at 40 Hz each second) induced additional potentiation of EMG amplitude, duration, and area, but the tetanic force from every unit declined. Thus activity-induced changes in human thenar motor unit EMG do not indicate the alterations in force or vice versa. These data suggest that different processes underlie the changes in EMG and force that occur during human thenar motor unit activity.

UR - http://www.scopus.com/inward/record.url?scp=33645966530&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33645966530&partnerID=8YFLogxK

U2 - 10.1152/jn.00924.2005

DO - 10.1152/jn.00924.2005

M3 - Article

C2 - 16267110

AN - SCOPUS:33645966530

VL - 95

SP - 1518

EP - 1526

JO - Journal of Neurophysiology

JF - Journal of Neurophysiology

SN - 0022-3077

IS - 3

ER -