Motor innervation of skeletal muscle: multiple innervation of individual muscle fibres and motor unit function*

Hunt, Carlton C.; Kuffler, Stephen W.

doi:10.1113/jphysiol.1954.sp005210

Cited by 95 publications

(55 citation statements)

References 18 publications

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“…Thus F nl is a good functional representation of the total mechanical effects between parts of a muscle. Nonlinear summation has been previously studied between parts of whole muscle during isometric (fixed end) contractions (4,15) and between individual motor units during both isometric and slow ramp movements (7,9,27). In whole muscle studies, forces summed linearly during static isometric contractions.…”

mentioning

confidence: 99%

Nonlinear summation of force in cat soleus muscle results primarily from stretch of the common-elastic elements

Sandercock

2000

Journal of Applied Physiology

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The complex connective tissue structure of muscle and tendon suggests that forces from two parts of a muscle may not summate linearly. This study measured the nonlinear summation of force (Fnl) in whole cat soleus during isometric and ramp movements. In six anesthetized cats, the soleus was attached to a servomechanism to control muscle length and record force. The ventral roots were divided into two bundles, each innervating about half the soleus; thus the two parts could be stimulated alone or together. In all experiments, Fnl was small (<6% of maximum tetanic tension). Peak Fnl occurred during changes in muscle force, either as a result of imposed muscle movement or the onset or offset of a stimulus train. The data were fit to a model in which both parts of the muscle were assumed to stretch to a common elasticity. The servomechanism was programmed to compensate for reduced stretch of the common elasticity during partial compared with whole muscle activation. These compensatory movements showed how the model could account for most, but not all, of Fnl.

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confidence: 99%

Nonlinear summation of force in cat soleus muscle results primarily from stretch of the common-elastic elements

Sandercock

2000

Journal of Applied Physiology

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“…Muscle performance can also be assessed using the AMG signal. Immediate changes in the S-score, which is a measure of spatial summation, can inform the user as to whether more muscle fibers are being recruited with continuing physical performance [12]. Likewise, a change in the T-score, which represents temporal summation, can provide a minute-to-minute assessment of the frequency with which active fibers are being fired [12].…”

Section: Acoustic Myography Analysismentioning

confidence: 99%

“…Immediate changes in the S-score, which is a measure of spatial summation, can inform the user as to whether more muscle fibers are being recruited with continuing physical performance [12]. Likewise, a change in the T-score, which represents temporal summation, can provide a minute-to-minute assessment of the frequency with which active fibers are being fired [12]. Finally, the E-score, which represents muscle efficiency and coordination, can be used to assess early fatigue signs [12].…”

Section: Acoustic Myography Analysismentioning

confidence: 99%

“…Likewise, a change in the T-score, which represents temporal summation, can provide a minute-to-minute assessment of the frequency with which active fibers are being fired [12]. Finally, the E-score, which represents muscle efficiency and coordination, can be used to assess early fatigue signs [12]. Typically a fall in the E-score, representing relatively more fiber contraction time than relaxed time for a given physical activity, is an early sign of muscle…”

Section: Acoustic Myography Analysismentioning

confidence: 99%

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The Application of Acoustic Myography in Canine Muscle Function and Performance Testing

Fenger¹,

Harrison²

2017

SOJVS

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SOJ Veterinary Sciences Open Access Research Articlebegin to walk at a faster pace, the limbs begin to impact with the ground and in so doing behave elastically [5]. Clearly, there is then an inverse relation between limb stiffness and an ability to convert potential energy into kinetic energy thus stiffness decreases as speed increases.In the trot, the body's center of mass behaves differently. Rather than being raised in the first half of the stance phase, it is lowered and the body moves as a wave, often with minimal oscillation in those breeds of dogs that are used to trotting for long periods of time [6]. Here potential energy is converted into elastic energy and stored upon impact with the ground by passive stretching of tendons and muscles, to be released later on in the stance phase. This is the spring-mass model described by Blickhan [3]. The study undertaken by Gregersen and colleagues not only confirms this spring-mass model, it also reveals that the work performed by every joint of the fore-and hind-limbs is more efficient due to a reduced "cost" of physical activity resulting from the release of elastic energy [7]. Indeed, in the trot three quarters of the work performed by dogs is recoverable [7].Muscles used in locomotion are stretched prior to shortening while producing a force. Compared to concentric contractions (shortening), eccentric contractions (lengthening) result in the highest force with the lowest energy costs due to the higher energy absorption [7,2]. Subsequently, the stored energy can be converted back to kinetic energy in the rebound [1,2]. One of the situations in which this is used to great effect is in the very rapid protraction of a horse's fore-limb during periods of galloping, when elastic energy stored in the biceps muscle is released as a burst of energy that results in a catapult action propelling the fore-limb forward [8].Acoustic Myography (AMG), which directly measures muscle contractions, was recently documented as being a useful diagnostic tool for rapidly determining muscular injury in the veterinary clinic [9,10]. Indeed, this technique has been used in the assessment of veterinary clinical diagnosis and monitoring of such dysfunctions or diseases as lameness, kissing spine, crookedness and muscular atrophy as well as post surgery/ trauma monitoring (distance measurement) or retraining/ healthy daily training (http://www.myodynamikequine.com/ AbstractIt is generally known that muscles have the ability to store and convert energy making certain types of movement highly efficient with regard to muscle work. The principle behind this concept is summarized in what has become known as the "spring-mass" model. Whilst evidence of a change in gait from walk to trot has been documented for more than 35 years, quantitative measurements of comparable changes in muscle function remain elusive. In a study involving 11 Labrador dogs, looking at muscle function as assessed by acoustic myography, changes in muscle efficiency/coordination as well as both spatial-(fiber recruitment) a...

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“…Finally, should polyneuronal innervation occur in dystrophic muscle such that some fibres are common to several motor units, the mean population of fibres in individual units would not fall in proportion to the total reduction in muscle fibres in the whole muscle. Woolf and Coers (1974) have noted that multiterminal innervation may occur in muscular dystrophies and Hunt and Kuffler (1954) have claimed that polyneuronal innervation is present in normal muscles of the cat. Recently, Tate and Westerman (1973) reported multiple innervation of muscle fibres in the soleus muscle of the cat during reinnervation.…”

mentioning

confidence: 99%

Computer method for the analysis of evoked motor unit potentials. 2. Duchenne, limb-girdle, facioscapulohumeral and myotonic muscular dystrophies.

Ballantyne¹,

Hansen²

1975

Journal of Neurology, Neurosurgery & Psychiatry

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Motor innervation of skeletal muscle: multiple innervation of individual muscle fibres and motor unit function*

Cited by 95 publications

References 18 publications

Nonlinear summation of force in cat soleus muscle results primarily from stretch of the common-elastic elements

Nonlinear summation of force in cat soleus muscle results primarily from stretch of the common-elastic elements

The Application of Acoustic Myography in Canine Muscle Function and Performance Testing

Computer method for the analysis of evoked motor unit potentials. 2. Duchenne, limb-girdle, facioscapulohumeral and myotonic muscular dystrophies.

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