PMID- 15876553
OWN - NLM
STAT- MEDLINE
DCOM- 20050809
LR  - 20131121
IS  - 1388-2457 (Print)
IS  - 1388-2457 (Linking)
VI  - 116
IP  - 6
DP  - 2005 Jun
TI  - The effect of contraction intensity on motor unit number estimates of the 
      tibialis anterior.
PG  - 1342-7
AB  - OBJECTIVE: To examine the effect of contractile level on motor unit number 
      estimates (MUNEs) and establish the contraction intensity that will yield the 
      most representative MUNE for the tibialis anterior (TA) muscle. METHODS: Surface 
      and intramuscular electromyographic (EMG) signals were collected during a range 
      of submaximal (threshold, 10, 20, 30 and 40% MVC) isometric dorsiflexion 
      contractions using decomposition-enhanced spike-triggered averaging (DE-STA). Six 
      MUNEs were calculated, one for each of the five intensities, and an ensemble 
      sixth MUNE that had equal MU contributions from all intensities. RESULTS: Mean 
      surface-motor unit potential sizes increased significantly (26-69 microV) and 
      MUNEs decreased accordingly (226-91) as contraction intensity increased from 
      threshold to 40% MVC, respectively (P<0.05). The ensemble MUNE was 153, and 
      extrapolated to approximately 25% MVC. CONCLUSIONS: There was a significant and 
      progressive decline in the MUNE as contraction intensity increased, confirming 
      the importance of monitoring torque during data collection. The ensemble MUNE 
      suggests that collecting EMG signals at a contraction intensity of approximately 
      25% MVC provides the most representative sample of the actual number and sizes of 
      MUs in the TA. SIGNIFICANCE: Establishing appropriate contraction intensities 
      improves the utility of DE-STA as a useful method for tracking changes to the MU 
      pool in disease states and healthy aging.
FAU - McNeil, Chris J
AU  - McNeil CJ
AD  - Canadian Centre for Activity and Aging, St Joseph's Health Annex, School of 
      Kinesiology, Faculty of Health Sciences, The University of Western Ontario, 1490 
      Richmond Street, London, Ont., Canada, N6G 2M3.
FAU - Doherty, Timothy J
AU  - Doherty TJ
FAU - Stashuk, Daniel W
AU  - Stashuk DW
FAU - Rice, Charles L
AU  - Rice CL
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20050328
PL  - Netherlands
TA  - Clin Neurophysiol
JT  - Clinical neurophysiology : official journal of the International Federation of 
      Clinical Neurophysiology
JID - 100883319
SB  - IM
MH  - Action Potentials/*physiology
MH  - Adult
MH  - Algorithms
MH  - Biomechanical Phenomena
MH  - Dose-Response Relationship, Radiation
MH  - Electric Stimulation
MH  - Electromyography/methods
MH  - Humans
MH  - Isometric Contraction/*physiology
MH  - Male
MH  - Motor Neurons/*physiology
MH  - Muscle Fibers, Skeletal/physiology
MH  - Muscle, Skeletal/*innervation/*physiology
MH  - Sensory Thresholds/physiology
EDAT- 2005/05/07 09:00
MHDA- 2005/08/10 09:00
CRDT- 2005/05/07 09:00
PHST- 2004/11/22 00:00 [received]
PHST- 2005/01/12 00:00 [revised]
PHST- 2005/02/08 00:00 [accepted]
PHST- 2005/05/07 09:00 [pubmed]
PHST- 2005/08/10 09:00 [medline]
PHST- 2005/05/07 09:00 [entrez]
AID - S1388-2457(05)00049-0 [pii]
AID - 10.1016/j.clinph.2005.02.006 [doi]
PST - ppublish
SO  - Clin Neurophysiol. 2005 Jun;116(6):1342-7. doi: 10.1016/j.clinph.2005.02.006. 
      Epub 2005 Mar 28.