Short interspike intervals and double discharges of anconeus motor unit action potentials for the production of dynamic elbow extensions

Harwood, Brad; Rice, Charles L.

doi:10.1152/jn.00412.2013

Cited by 5 publications

(2 citation statements)

References 60 publications

(61 reference statements)

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“…Muscle fibers are extremely responsive to relatively small variations in MU firing rates, taking advantage of the ‘active state’ processes (41). When first recruited in a healthy system, MUs usually fire at 5-8 Hz (41), although in certain tasks some MUs may initially fire doublets (2-3 action potentials at 100 Hz or more) to rapidly enhance rates of force development (39). …”

Section: Changes In the Neuromuscular Pathway With Fatiguing Exercisementioning

confidence: 99%

Neural Contributions to Muscle Fatigue

Taylor

Amann

Duchateau

et al. 2016

Medicine &Amp; Science in Sports &Amp; Exercise

373

198

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During exercise, there is a progressive reduction in the ability to produce muscle forces. Processes within the nervous system, as well as within the muscles contribute to this fatigue. In addition to impaired function of the motor system, sensations associated with fatigue, and impairment of homeostasis can contribute to impairment of performance during exercise. This review discusses some of the neural changes that accompany exercise and the development of fatigue. The role of brain monoaminergic neurotransmitter systems in whole-body endurance performance is discussed, particularly with regard to exercise in hot environments. Next, fatigue-related alterations in the neuromuscular pathway are discussed in terms of changes in motor unit firing, motoneuron excitability and motor cortical excitability. These changes have mostly been investigated during single-limb isometric contractions. Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue are discussed. These afferents have roles in cardiovascular and respiratory responses to exercise, and in impairment of exercise performance through interaction with the motor pathway, as well as providing sensations of muscle discomfort. Thus, changes at all levels of the nervous system including the brain, spinal cord, motor output, sensory input and autonomic function occur during exercise and fatigue. The mix of influences and the importance of their contribution varies with the type of exercise being performed.

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Section: Changes In the Neuromuscular Pathway With Fatiguing Exercisementioning

confidence: 99%

Neural Contributions to Muscle Fatigue

Taylor

Amann

Duchateau

et al. 2016

Medicine &Amp; Science in Sports &Amp; Exercise

373

198

View full text Add to dashboard Cite

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“…Hoff and Grant 1944;Kirkwood and Munson 1996;see also Kernell 2006) as well as in motor units (MUs) of healthy humans (e.g. Denslow 1948;Kudina 1974;Bawa and Calancie 1983;Garland and Griffin 1999;Kudina andAndreeva 2010, 2013a;Stephenson and Maluf 2010;Piotrkiewicz et al 2013;Harwood and Rice 2014) and in neuromuscular diseases (e.g. Partanen and Lang 1978;Rowiñska-Marciñska et al 1999;Piotrkiewicz et al 2008;Weber et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Triplet firing origin in human motor units: emerging hypotheses

Kudina

Andreeva

2015

Exp Brain Res

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A specific feature of motor unit (MU) firing behaviour is rhythmic trains of single discharges at low rate resulting from the prolonged motoneuronal afterhyperpolarization. However, some MUs exhibit occasional doublets with uniquely short interspike intervals (2.5-20.0 ms). Motoneuronal delayed depolarization is commonly accepted to be doublet underlying mechanism. Apart from doublets, much scarcer MU triple discharges were described, but their mechanisms are disputable. The aim of the present study was to analyse MU triplet firing origin in healthy humans. MU triple discharges occasionally arising during gentle voluntary muscle contractions were compared with those arising in axons during motor nerve stimulation. Firing pattern was analysed in 109 MUs of four muscles: the tibialis anterior, the flexor carpi ulnaris, the abductor pollicis brevis, and the abductor digiti minimi. Our findings present evidence that during voluntary contractions two kinds of MU triplet firing can be occasionally observed: "true" motoneuronal triplets (interspike intervals of 3.6-17.3 ms) with the delayed depolarization as the possible underlying mechanism and axonal triple discharges including the M-response and F-wave. The findings can be useful not only for understanding mechanisms of the very rare motoneuronal firing in healthy humans but also for estimation of pathological triplet firing origin.

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