Abstract
Firing rates of motor units and surface EMG were measured from the triceps brachii muscles of able-bodied subjects during brief submaximal and maximal isometric voluntary contractions made at 5 elbow joint angles that covered the entire physiological range of muscle lengths. Muscle activation at the longest, midlength, and shortest muscle lengths, measured by twitch occlusion, averaged 98%, 97%, and 93% respectively, with each subject able to achieve complete activation during some contractions. As expected, the strongest contractions were recorded at 90° of elbow flexion. Mean motor unit firing rates and surface EMG increased with contraction intensity at each muscle length. For any given absolute contraction intensity, motor unit firing rates varied when muscle length was changed. However, mean motor unit firing rates were independent of muscle length when contractions were compared with the intensity of the maximal voluntary contraction (MVC) achieved at each joint angle.
| Original language | English |
|---|---|
| Pages (from-to) | 769-776 |
| Number of pages | 8 |
| Journal | Canadian Journal of Physiology and Pharmacology |
| Volume | 82 |
| Issue number | 8-9 |
| DOIs | |
| State | Published - Aug 1 2004 |
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Keywords
- Force-frequency relationships
- Length-tension relationships
- Muscle activation
ASJC Scopus subject areas
- Physiology
- Pharmacology
Cite this
Motor unit firing rates during isometric voluntary contractions performed at different muscle lengths. / Del Valle, Alejandro; Thomas, Christine K.
In: Canadian Journal of Physiology and Pharmacology, Vol. 82, No. 8-9, 01.08.2004, p. 769-776.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Motor unit firing rates during isometric voluntary contractions performed at different muscle lengths
AU - Del Valle, Alejandro
AU - Thomas, Christine K
PY - 2004/8/1
Y1 - 2004/8/1
N2 - Firing rates of motor units and surface EMG were measured from the triceps brachii muscles of able-bodied subjects during brief submaximal and maximal isometric voluntary contractions made at 5 elbow joint angles that covered the entire physiological range of muscle lengths. Muscle activation at the longest, midlength, and shortest muscle lengths, measured by twitch occlusion, averaged 98%, 97%, and 93% respectively, with each subject able to achieve complete activation during some contractions. As expected, the strongest contractions were recorded at 90° of elbow flexion. Mean motor unit firing rates and surface EMG increased with contraction intensity at each muscle length. For any given absolute contraction intensity, motor unit firing rates varied when muscle length was changed. However, mean motor unit firing rates were independent of muscle length when contractions were compared with the intensity of the maximal voluntary contraction (MVC) achieved at each joint angle.
AB - Firing rates of motor units and surface EMG were measured from the triceps brachii muscles of able-bodied subjects during brief submaximal and maximal isometric voluntary contractions made at 5 elbow joint angles that covered the entire physiological range of muscle lengths. Muscle activation at the longest, midlength, and shortest muscle lengths, measured by twitch occlusion, averaged 98%, 97%, and 93% respectively, with each subject able to achieve complete activation during some contractions. As expected, the strongest contractions were recorded at 90° of elbow flexion. Mean motor unit firing rates and surface EMG increased with contraction intensity at each muscle length. For any given absolute contraction intensity, motor unit firing rates varied when muscle length was changed. However, mean motor unit firing rates were independent of muscle length when contractions were compared with the intensity of the maximal voluntary contraction (MVC) achieved at each joint angle.
KW - Force-frequency relationships
KW - Length-tension relationships
KW - Muscle activation
UR - http://www.scopus.com/inward/record.url?scp=11244294817&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=11244294817&partnerID=8YFLogxK
U2 - 10.1139/y04-084
DO - 10.1139/y04-084
M3 - Article
C2 - 15523534
AN - SCOPUS:11244294817
VL - 82
SP - 769
EP - 776
JO - Canadian Journal of Physiology and Pharmacology
JF - Canadian Journal of Physiology and Pharmacology
SN - 0008-4212
IS - 8-9
ER -