Muscle fiber conduction velocity related to stimulation rate

Nishizono, Hidetsugu; Kurata, Hiroshi; Miyashita, Mitsumasa

doi:10.1016/0013-4694(89)90230-7

Cited by 61 publications

(41 citation statements)

References 13 publications

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“…The slope of diagonal lines joining times of onsets of the dominant component of each potential gave the velocity of conduction. A uniform velocity of ϳ4 m/s corresponds to a volley of action potentials conducted along a group of muscle fibers (Stålberg, 1966;Nishizono et al, 1989). A substantially faster apparent velocity, 40 -70 m/s, would correspond to records from muscle fibers activated by branches of an intramuscular nerve axon, as seen in the cat sartorius muscle (Loeb et al, 1987).…”

Section: Methodsmentioning

confidence: 99%

Muscle Fiber and Motor Unit Behavior in the Longest Human Skeletal Muscle

Harris¹,

Duxson²,

Butler³

et al. 2005

J. Neurosci.

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The sartorius muscle is the longest muscle in the human body. It is strap-like, up to 600 mm in length, and contains five to seven neurovascular compartments, each with a neuromuscular endplate zone. Some of its fibers terminate intrafascicularly, whereas others may run the full length of the muscle. To assess the location and timing of activation within motor units of this long muscle, we recorded electromyographic potentials from multiple intramuscular electrodes along sartorius muscle during steady voluntary contraction and analyzed their activity with spike-triggered averaging from a needle electrode inserted near the proximal end of the muscle. Approximately 30% of sartorius motor units included muscle fibers that ran the full length of the muscle, conducting action potentials at 3.9 Ϯ 0.1 m/s. Most motor units were innervated within a single muscle endplate zone that was not necessarily near the midpoint of the fiber. As a consequence, action potentials reached the distal end of a unit as late as 100 ms after initiation at an endplate zone. Thus, contractile activity is not synchronized along the length of single sartorius fibers. We postulate that lateral transmission of force from fiber to endomysium and a wide distribution of motor unit endplates along the muscle are critical for the efficient transmission of force from sarcomere to tendon and for the prevention of muscle injury caused by overextension of inactive regions of muscle fibers.

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Section: Methodsmentioning

confidence: 99%

Muscle Fiber and Motor Unit Behavior in the Longest Human Skeletal Muscle

Harris¹,

Duxson²,

Butler³

et al. 2005

J. Neurosci.

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show abstract

“…duction velocity of nonactive motor units was not affected by ischemia for Յ13 min (Farina et al 2004a). Conduction velocity depends on the discharge rate (Farina et al 2004b;Nishizono et al 1989); thus a different discharge rate in C1 and C3 could have influenced the results. Discharge rate in C3 was Ͻ2 pps smaller than in C1 for both subject groups, and this difference was not significant.…”

Section: Membrane Properties Of Quiescent Muscle Fibersmentioning

confidence: 99%

Conduction Velocity of Quiescent Muscle Fibers Decreases During Sustained Contraction

Gazzoni

Camelia²,

Farina³

2005

Journal of Neurophysiology

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“…These results can be interpreted as due to the accumulation of metabolic byproducts in the muscle due to the activity of muscle fibers (26). However, average conduction velocity is affected by motor unit recruitment-derecruitment (1,17) and by the distribution of discharge rates (32); thus these studies do not provide a direct indication of the modifications of fiber membrane properties in single motor units with ischemia.…”

mentioning

confidence: 91%

Conduction velocity of low-threshold motor units during ischemic contractions performed with surface EMG feedback

Farina¹,

Gazzoni²,

Camelia³

2005

Journal of Applied Physiology

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Farina, Dario, Marco Gazzoni, and Federico Camelia. Conduction velocity of low-threshold motor units during ischemic contractions performed with surface EMG feedback. J Appl Physiol 98: 1487-1494, 2005. First published November 12, 2004 doi:10.1152/ japplphysiol.01032.2004.-The aim of this study was to analyze the effect of ischemia on low-threshold motor unit conduction velocity. Nine subjects were trained to isolate the activity of a single motor unit (target motor unit) in the abductor pollicis brevis muscle with feedback on surface EMG signals recorded with a 16-electrode linear array. After training, the subjects activated the target motor unit at ϳ8 pulses per second (pps) for five 3-min-long contractions. During the third and fourth contractions, a cuff inflated at 180 mmHg around the forearm induced ischemia of the hand. The exerted force (mean Ϯ SE, 4.6 Ϯ 2.1% of the maximal voluntary contraction force), discharge rate (8.6 Ϯ 0.4 pps), interpulse interval variability (34.8 Ϯ 2.5%), and peak-to-peak amplitude of the target motor unit action potentials (176.6 Ϯ 18.2 V) were not different among the five contractions. Conduction velocity, mean power spectral frequency, and action potential duration were the same in the beginning of the five contractions (2.8 Ϯ 0.2 m/s, 195.2 Ϯ 10.5 Hz, and 5.4 Ϯ 0.3 ms, respectively) and changed over the 3 min of sustained activation only during the fourth contraction. Conduction velocity and mean power spectral frequency decreased (10.05 Ϯ 1.8% and 8.50 Ϯ 2.18% during the 3 min, respectively) and action potential duration increased (8.2 Ϯ 4.6% in the 3 min) during the fourth contraction. In conclusion, 1) subjects were able to isolate the activity of a single motor unit with surface EMG visual feedback in ischemic conditions maintained for 16 min, and 2) the activation-induced decrease in single motor unit conduction velocity was significantly larger with ischemia than with normal circulation, probably due to the alteration of mechanisms of ion exchange across the fiber membrane.

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Muscle fiber conduction velocity related to stimulation rate

Cited by 61 publications

References 13 publications

Muscle Fiber and Motor Unit Behavior in the Longest Human Skeletal Muscle

Muscle Fiber and Motor Unit Behavior in the Longest Human Skeletal Muscle

Conduction Velocity of Quiescent Muscle Fibers Decreases During Sustained Contraction

Conduction velocity of low-threshold motor units during ischemic contractions performed with surface EMG feedback

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