Evidence of facilitation of soleus‐coupled Renshaw cells during voluntary co‐contraction of antagonistic ankle muscles in man.

Nielsen, Jens Bo; Pierrot-Deseilligny, E

doi:10.1113/jphysiol.1996.sp021407

Cited by 45 publications

(28 citation statements)

References 23 publications

(27 reference statements)

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“…The eect of Renshaw cell activity during dierent contraction conditions has not, to our knowledge, been studied. However, data from Nielsen and Pierrot-Deseilligny (1996) and Bussel and Pierrot-Deseilligny (1977) showed a reduced level of recurrent inhibition onto SOL motonuerones during strong plantar¯exor eorts (50% of maximal eort) when compared to weak plantar¯exor eorts (10% of maximal eort).…”

Section: Discussionmentioning

confidence: 78%

Tension regulation during lengthening and shortening actions of the human soleus muscle

et al. 2000

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In the present study we investigated tension regulation in the human soleus (SOL) muscle during controlled lengthening and shortening actions. Eleven subjects performed plantar flexor efforts on an ankle torque motor through 30 degrees of ankle displacement (75 degrees -105 degrees internal ankle angle) at lengthening and shortening velocities of 5, 15 and 30 degrees. S(-1). To isolate the SOL from the remainder of the triceps surae, the subject's knee was flexed to 60 degrees during all trials. Voluntary plantar flexor efforts were performed under two test conditions: (1) maximal voluntary activation (MVA) of the SOL, and (2) constant submaximal voluntary activation (SVA) of the SOL. SVA trials were performed with direct visual feedback of the SOL electromyogram (EMG) at a level resulting in a torque output of 30% of isometric maximum. Angle-specific (90 degrees ankle angle) torque and EMG of the SOL, medial gastrocnemius (MG) and tibialis anterior (TA) were recorded. In seven subjects from the initial group, the test protocol was repeated under submaximal percutaneous electrical activation (SEA) of SOL (to 30% isometric maximal effort). Lengthening torques were significantly greater than shortening torques in all test conditions. Lengthening torques in MVA and SVA were independent of velocity and remained at the isometric level, whereas SEA torques were greater than isometric torques and increased at higher lengthening velocities. Shortening torques were lower than the isometric level for all conditions. However, whereas SVA and SEA torques decreased at higher velocities of shortening, MVA torques were independent of velocity. These results indicate velocity- and activation-type-specific tension regulation in the human SOL muscle.

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Section: Discussionmentioning

confidence: 78%

Tension regulation during lengthening and shortening actions of the human soleus muscle

et al. 2000

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“…For example, animal experiments have shown that descending pathways can modulate recurrent inhibition and thereby motor unit discharge rate (Baldissera et al, 1981), which could serve as a variable gain regulator for motor output (Hultborn et al, 1979). Such control seems plausible given that the amount of recurrent inhibition differs during co-activation and flexion-extension movements (Nielsen and Pierrot-Deseilligny, 1996). However, this possibility needs to be substantiated with experimental data.…”

Section: Spinal Mechanismsmentioning

confidence: 86%

Neural control of lengthening contractions

Duchateau

Enoka

2016

Journal of Experimental Biology

164

181

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A number of studies over the last few decades have established that the control strategy employed by the nervous system during lengthening (eccentric) differs from those used during shortening (concentric) and isometric contractions. The purpose of this review is to summarize current knowledge on the neural control of lengthening contractions. After a brief discussion of methodological issues that can confound the comparison between lengthening and shortening actions, the review provides evidence that untrained individuals are usually unable to fully activate their muscles during a maximal lengthening contraction and that motor unit activity during submaximal lengthening actions differs from that during shortening actions. Contrary to common knowledge, however, more recent studies have found that the recruitment order of motor units is similar during submaximal shortening and lengthening contractions, but that discharge rate is systematically lower during lengthening actions. Subsequently, the review examines the mechanisms responsible for the specific control of maximal and submaximal lengthening contractions as reported by recent studies on the modulation of cortical and spinal excitability. As similar modulation has been observed regardless of contraction intensity, it appears that spinal and corticospinal excitability are reduced during lengthening compared with shortening and isometric contractions. Nonetheless, the modulation observed during lengthening contractions is mainly attributable to inhibition at the spinal level.

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“…The changes observed in the descending part of the recruitment curve are more difficult to interpret because in this part of the recruitment curve the reflex response is little sensitive to excitation or inhibition (Pierrot-Deseilligny and Burke 2005). The H-reflex is mainly mediated by the monosynaptic Ia afferent pathway to the spinal motoneurons, although other less direct pathways such as Ib inhibition or recurrent inhibition may also contribute (Burke et al 1983(Burke et al , 1984Marchand-Pauvert et al 2002;Nielsen and Pierrot-Deseilligny 1996). Although there is thus a possibility that the depression of the H-reflex may be caused by changes in the excitability of interneurons interposed in these indirect pathways, it seems more likely that increased presynaptic inhibition of the Ia afferents is involved.…”

Section: Mechanisms Contributing To the H-reflex And Mep Depressionmentioning

confidence: 93%

“…Indeed, presynaptic inhibition of Ia afferents is increased and as a result the SOL H-reflex size is depressed during cocontraction of antagonistic ankle muscles (Nielsen and Kagamihara 1993). In addition, recurrent inhibition from Renshaw cells activated by motor axon collaterals is increased during cocontraction (Nielsen and Pierrot-Deseilligny 1996). This likely occurs to ensure that disynaptic reciprocal inhibition is maintained low and thus facilitate the simultaneous activation of the antagonistic muscles (Nielsen and Kagamihara 1992).…”

Section: Introductionmentioning

confidence: 97%

Task-Specific Depression of the Soleus H-Reflex After Cocontraction Training of Antagonistic Ankle Muscles

Perez

Lundbye‐Jensen

Nielsen

2007

Journal of Neurophysiology

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Perez MA, Lundbye-Jensen J, Nielsen JB. Task-specific depression of the soleus H-reflex after cocontraction training of antagonistic ankle muscles. J Neurophysiol 98: 3677-3687, 2007. First published October 17, 2007 doi:10.1152/jn.00988.2007. Ballet dancers have small soleus (SOL) H-reflex amplitudes, which may be related to frequent use of cocontraction of antagonistic ankle muscles. Indeed, SOL H-reflexes are depressed during cocontraction compared with plantarflexion at matched background EMG level. We investigated the effect of 30-min training of simultaneous activation of ankle dorsiand plantarflexor muscles (cocontraction task) on the SOL H-reflex in 10 healthy volunteers. Measurements were taken during cocontraction. After training, there was a significant improvement in the ability of the subjects to perform a stable cocontraction. SOL H-reflex recruitment curves and H-max/M-max ratios were decreased after cocontraction training but not after 30 min of static dorsi or plantarflexion. The decreased H-reflex size correlated with improved motor performance. No changes in SOL and tibialis anterior (TA) EMG activity or EMG power were observed, suggesting that increased presynaptic inhibition of Ia afferents is a likely mechanism for H-reflex depression. In different sessions we measured SOL and TA motor-evoked potentials (MEPs) by using transcranial magnetic stimulation (TMS), TMS-elicited suppression of SOL EMG, and coherence between electroencephalographic (EEG) activity (Cz) and TA and SOL EMG. SOL and TA MEPs were depressed, whereas TMSelicited suppression of SOL EMG and coherence were increased after training. Decreased excitability of corticospinal neurons due to increased intracortical inhibition seems a likely explanation of these observations. Our results indicate that the depression in H-reflex observed during a cocontraction task can be trained and that repeated performance of tasks involving cocontraction may lead to prolonged changes in reflex and corticospinal excitability.

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Evidence of facilitation of soleus‐coupled Renshaw cells during voluntary co‐contraction of antagonistic ankle muscles in man.

Cited by 45 publications

References 23 publications

Tension regulation during lengthening and shortening actions of the human soleus muscle

Tension regulation during lengthening and shortening actions of the human soleus muscle

Neural control of lengthening contractions

Task-Specific Depression of the Soleus H-Reflex After Cocontraction Training of Antagonistic Ankle Muscles

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