Abstract
To investigate the mechanical efficiency of surviving motor units of anterior tibial muscle in patients with amyotrophic lateral sclerosis (ALS), we studied motor unit action potentials, muscle force, and muscle fatigability in patients with ALS and controls using 25 min of low to moderate intensity voluntary isometric exercise. During exercise, tetanic force (TF) and maximum voluntary contraction declined more in patients than in controls. The mean motor unit action potential duration, amplitude, and polyphasia were increased in patients compared to controls but did not change during 9 months of disease progression. The enlarged motor units in patients were negatively correlated to the muscle force and positively correlated to muscle fatigability. Furthermore, after a mean follow-up period of 9 months, the decline in force-generating capacity of the anterior tibial muscle in patients (twitch tension by 37.5 ± 11.2%, TF by 30.6 ± 7.4%) was greater than the decline in the amplitude of the compound muscle action potential (21.1 ± 8.8%, P < 0.05), suggesting a relative dissociation between electrical and mechanical properties. In conclusion, the enlarged motor units in patients with ALS are mechanically less efficient and fatigue relatively more than in healthy muscles, possibly due to an abnormality that is primarily distal to the muscle membrane.
| Original language | English |
|---|---|
| Pages (from-to) | 1391-1400 |
| Number of pages | 10 |
| Journal | Muscle and Nerve |
| Volume | 19 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 1 1996 |
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Keywords
- denervation
- excitation-contraction coupling
- exercise
- fatigue
- motor unit potential
ASJC Scopus subject areas
- Clinical Neurology
- Neuroscience(all)
Cite this
Electrical and mechanical properties of skeletal muscle underlying increased fatigue in patients with amyotrophic lateral sclerosis. / Sharma, Khema R; Miller, Robert G.
In: Muscle and Nerve, Vol. 19, No. 11, 01.11.1996, p. 1391-1400.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Electrical and mechanical properties of skeletal muscle underlying increased fatigue in patients with amyotrophic lateral sclerosis
AU - Sharma, Khema R
AU - Miller, Robert G.
PY - 1996/11/1
Y1 - 1996/11/1
N2 - To investigate the mechanical efficiency of surviving motor units of anterior tibial muscle in patients with amyotrophic lateral sclerosis (ALS), we studied motor unit action potentials, muscle force, and muscle fatigability in patients with ALS and controls using 25 min of low to moderate intensity voluntary isometric exercise. During exercise, tetanic force (TF) and maximum voluntary contraction declined more in patients than in controls. The mean motor unit action potential duration, amplitude, and polyphasia were increased in patients compared to controls but did not change during 9 months of disease progression. The enlarged motor units in patients were negatively correlated to the muscle force and positively correlated to muscle fatigability. Furthermore, after a mean follow-up period of 9 months, the decline in force-generating capacity of the anterior tibial muscle in patients (twitch tension by 37.5 ± 11.2%, TF by 30.6 ± 7.4%) was greater than the decline in the amplitude of the compound muscle action potential (21.1 ± 8.8%, P < 0.05), suggesting a relative dissociation between electrical and mechanical properties. In conclusion, the enlarged motor units in patients with ALS are mechanically less efficient and fatigue relatively more than in healthy muscles, possibly due to an abnormality that is primarily distal to the muscle membrane.
AB - To investigate the mechanical efficiency of surviving motor units of anterior tibial muscle in patients with amyotrophic lateral sclerosis (ALS), we studied motor unit action potentials, muscle force, and muscle fatigability in patients with ALS and controls using 25 min of low to moderate intensity voluntary isometric exercise. During exercise, tetanic force (TF) and maximum voluntary contraction declined more in patients than in controls. The mean motor unit action potential duration, amplitude, and polyphasia were increased in patients compared to controls but did not change during 9 months of disease progression. The enlarged motor units in patients were negatively correlated to the muscle force and positively correlated to muscle fatigability. Furthermore, after a mean follow-up period of 9 months, the decline in force-generating capacity of the anterior tibial muscle in patients (twitch tension by 37.5 ± 11.2%, TF by 30.6 ± 7.4%) was greater than the decline in the amplitude of the compound muscle action potential (21.1 ± 8.8%, P < 0.05), suggesting a relative dissociation between electrical and mechanical properties. In conclusion, the enlarged motor units in patients with ALS are mechanically less efficient and fatigue relatively more than in healthy muscles, possibly due to an abnormality that is primarily distal to the muscle membrane.
KW - denervation
KW - excitation-contraction coupling
KW - exercise
KW - fatigue
KW - motor unit potential
UR - http://www.scopus.com/inward/record.url?scp=0029848097&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029848097&partnerID=8YFLogxK
U2 - 10.1002/(SICI)1097-4598(199611)19:11<1391::AID-MUS3>3.0.CO;2-7
DO - 10.1002/(SICI)1097-4598(199611)19:11<1391::AID-MUS3>3.0.CO;2-7
M3 - Article
C2 - 8874396
AN - SCOPUS:0029848097
VL - 19
SP - 1391
EP - 1400
JO - Muscle and Nerve
JF - Muscle and Nerve
SN - 0148-639X
IS - 11
ER -