scholarly journals The Effect of Spinal Manipulation on the Electrophysiological and Metabolic Properties of the Tibialis Anterior Muscle

Healthcare ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 548
Author(s):  
Imran Khan Niazi ◽  
Ernest Nlandu Kamavuako ◽  
Kelly Holt ◽  
Taha Al Muhammadee Janjua ◽  
Nitika Kumari ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Motor Unit ◽  
Repeated Measures ◽  
Tibialis Anterior ◽  
Spinal Manipulation ◽  
Near Infrared ◽  
Discharge Rate ◽  
Tibialis Anterior Muscle ◽  
Passive Movement ◽  
Metabolic Properties

There is growing evidence showing that spinal manipulation increases muscle strength in healthy individuals as well as in people with some musculoskeletal and neurological disorders. However, the underlying mechanism by which spinal manipulation changes muscle strength is less clear. This study aimed to assess the effects of a single spinal manipulation session on the electrophysiological and metabolic properties of the tibialis anterior (TA) muscle. Maximum voluntary contractions (MVC) of the ankle dorsiflexors, high-density electromyography (HDsEMG), intramuscular EMG, and near-infrared spectroscopy (NIRS) were recorded from the TA muscle in 25 participants with low level recurring spinal dysfunction using a randomized controlled crossover design. The following outcomes: motor unit discharge rate (MUDR), strength (force at MVC), muscle conduction velocity (CV), relative changes in oxy- and deoxyhemoglobin were assessed pre and post a spinal manipulation intervention and passive movement control. Repeated measures ANOVA was used to assess within and between-group differences. Following the spinal manipulation intervention, there was a significant increase in MVC (p = 0.02; avg 18.87 ± 28.35%) and a significant increase in CV in both the isometric steady-state (10% of MVC) contractions (p < 0.01; avg 22.11 ± 11.69%) and during the isometric ramp (10% of MVC) contractions (p < 0.01; avg 4.52 ± 4.58%) compared to the control intervention. There were no other significant findings. The observed TA strength and CV increase, without changes in MUDR, suggests that the strength changes observed following spinal manipulation are, in part, due to increased recruitment of larger, higher threshold motor units. Further research needs to investigate the longer term and potential functional effects of spinal manipulation in various patients who may benefit from improved muscle function and greater motor unit recruitment.

scholarly journals The force-generation capacity of the tibialis anterior muscle at different muscle–tendon lengths depends on its motor unit contractile properties

2021 ◽  
Author(s):  
Alessandro Cudicio ◽  
Eduardo Martinez-Valdes ◽  
Marta Cogliati ◽  
Claudio Orizio ◽  
Francesco Negro
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Discharge Rate ◽  
Tibialis Anterior Muscle ◽  
Muscle Length ◽  
Motor Units ◽  
Surface Emg ◽  
Contractile Properties ◽  
Force Generation ◽  
Generation Capacity

Abstract Purpose Muscle–tendon length can influence central and peripheral motor unit (MU) characteristics, but their interplay is unknown. This study aims to explain the effect of muscle length on MU firing and contractile properties by applying deconvolution of high-density surface EMG (HDEMG), and torque signals on the same MUs followed at different lengths during voluntary contractions. Methods Fourteen participants performed isometric ankle dorsiflexion at 10% and 20% of the maximal voluntary torque (MVC) at short, optimal, and long muscle lengths (90°, 110°, and 130° ankle angles, respectively). HDEMG signals were recorded from the tibialis anterior, and MUs were tracked by cross-correlation of MU action potentials across ankle angles and torques. Torque twitch profiles were estimated using model-based deconvolution of the torque signal based on composite MU spike trains. Results Mean discharge rate of matched motor units was similar across all muscle lengths (P = 0.975). Interestingly, the increase in mean discharge rate of MUs matched from 10 to 20% MVC force levels at the same ankle angle was smaller at 110° compared with the other two ankle positions (P = 0.003), and the phenomenon was explained by a greater increase in twitch torque at 110° compared to the shortened and lengthened positions (P = 0.002). This result was confirmed by the deconvolution of electrically evoked contractions at different stimulation frequencies and muscle–tendon lengths. Conclusion Higher variations in MU twitch torque at optimal muscle lengths likely explain the greater force-generation capacity of muscles in this position.

Decreased motor unit discharge rate in the potentiated human tibialis anterior muscle

2011 ◽  
Vol 201 (4) ◽  
pp. 483-492 ◽  
Author(s):  
J. G. Inglis ◽  
J. Howard ◽  
K. McIntosh ◽  
D. A. Gabriel ◽  
R. Vandenboom
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Discharge Rate ◽  
Tibialis Anterior Muscle ◽  
Unit Discharge ◽  
Motor Unit Discharge ◽  
Human Tibialis Anterior Muscle

scholarly journals The Effects of Spinal Manipulation on Motor Unit Behavior

2021 ◽  
Vol 11 (1) ◽  
pp. 105
Author(s):  
Lucien Robinault ◽  
Aleš Holobar ◽  
Sylvain Crémoux ◽  
Usman Rashid ◽  
Imran Khan Niazi ◽  
...  
Keyword(s):  
Motor Unit ◽  
Conduction Velocity ◽  
Spinal Manipulation ◽  
Maximum Voluntary Contraction ◽  
Force Production ◽  
Movement Control ◽  
Position Sense ◽  
Joint Position Sense ◽  
Voluntary Contraction ◽  
Passive Movement

Over recent years, a growing body of research has highlighted the neural plastic effects of spinal manipulation on the central nervous system. Recently, it has been shown that spinal manipulation improved outcomes, such as maximum voluntary force and limb joint position sense, reflecting improved sensorimotor integration and processing. This study aimed to further evaluate how spinal manipulation can alter neuromuscular activity. High density electromyography (HD sEMG) signals from the tibialis anterior were recorded and decomposed in order to study motor unit changes in 14 subjects following spinal manipulation or a passive movement control session in a crossover study design. Participants were asked to produce ankle dorsiflexion at two force levels, 5% and 10% of maximum voluntary contraction (MVC), following two different patterns of force production (“ramp” and “ramp and maintain”). A significant decrease in the conduction velocity (p = 0.01) was observed during the “ramp and maintain” condition at 5% MVC after spinal manipulation. A decrease in conduction velocity suggests that spinal manipulation alters motor unit recruitment patterns with an increased recruitment of lower threshold, lower twitch torque motor units.

Blockade of 5-HT2 receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions

2021 ◽  
Author(s):  
Benjamin Ian Goodlich ◽  
Sean A Horan ◽  
Justin J Kavanagh
Keyword(s):  
Motor Unit ◽  
Unit Activity ◽  
Repeated Measures ◽  
Discharge Rate ◽  
Voluntary Contraction ◽  
Unit Discharge ◽  
Motor Unit Activity ◽  
Rate Of Torque Development ◽  
Motor Unit Discharge ◽  
Torque Development

Serotonin (5-HT) is a neuromodulator that is critical for regulating the excitability of spinal motoneurons and the generation of muscle torque. However, the role of 5-HT in modulating human motor unit activity during rapid contractions has yet to be assessed. Nine healthy participants (23.7 ± 2.2 yr) ingested 8 mg of the competitive 5-HT2 antagonist cyproheptadine in a double-blinded, placebo-controlled, repeated-measures experiment. Rapid dorsiflexion contractions were performed at 30%, 50% and 70% of maximal voluntary contraction (MVC), where motor unit activity was assessed by high-density surface electromyographic decomposition. A second protocol was performed where a sustained, fatigue-inducing dorsiflexion contraction was completed prior to undertaking the same 30%, 50% and 70% MVC rapid contractions and motor unit analysis. Motor unit discharge rate (p < 0.001) and rate of torque development (RTD; p = 0.019) for the unfatigued muscle were both significantly lower for the cyproheptadine condition. Following the fatigue inducing contraction, cyproheptadine reduced motor unit discharge rate (p < 0.001) and RTD (p = 0.024), where the effects of cyproheptadine on motor unit discharge rate and RTD increased with increasing contraction intensity. Overall, these results support the viewpoint that serotonergic effects in the central nervous system occur fast enough to regulate motor unit discharge rate during rapid powerful contractions.

Modulation of H reflexes in human tibialis anterior muscle with passive movement

1997 ◽  
Vol 766 (1-2) ◽  
pp. 236-239 ◽  
Author(s):  
John D Brooke ◽  
William E McIlroy ◽  
Michelle Miklic ◽  
William R Staines ◽  
John E Misiaszek ◽  
...  
Keyword(s):  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Passive Movement ◽  
Human Tibialis Anterior Muscle

scholarly journals Persistent Inward Currents Increase With The Level Of Voluntary Drive In Plantar Flexor Low-Threshold Motor Units

2020 ◽  
Author(s):  
Lucas B. R Orssatto ◽  
Karen Mackay ◽  
Anthony J Shield ◽  
Raphael L. Sakugawa ◽  
Anthony J. Blazevich ◽  
...  
Keyword(s):  
Motor Unit ◽  
Repeated Measures ◽  
Discharge Rate ◽  
Motor Units ◽  
Plantar Flexors ◽  
Force Output ◽  
Persistent Inward Currents ◽  
Gastrocnemius Medialis ◽  
Inward Currents ◽  
Maximal Discharge

This study tested the hypothesis that estimates of persistent inward currents (PICs) in the human plantar flexors would increase with the level of voluntary drive. Twenty-one participants volunteered for this study (29.2±2.6 years). High-density surface electromyograms were collected from soleus and gastrocnemius medialis during ramp-shaped isometric contractions to 10%, 20%, and 30% (torque rise of 2%/s and 30-s duration) of each participant's maximal torque. Motor units identified in all the contraction intensities were included in the paired-motor unit analysis to calculate delta frequency (ΔF) and estimate the PICs. Increases in PICs were observed from 10% to 20% (Δ=0.6 pps; p<0.001) and 20% to 30% (Δ=0.5 pps; p<0.001) in soleus, and from 10% to 20% (Δ=1.2 pps; p<0.001) but not 20% to 30% (Δ=0.09 pps; p=0.724) in gastrocnemius medialis. Maximal discharge rate increased for soleus and gastrocnemius medialis from 10% to 20% (respectively, Δ=1.75 pps, p<0.001; and Δ=2.43 pps, p<0.001) and 20% to 30% (respectively, Δ=0.80 pps, p<0.017; and Δ=0.92 pps, p=002). The repeated-measures correlation identified associations between ΔF and increases in maximal discharge rate for both soleus (r=0.64; p<0.001) and gastrocnemius medialis (r=0.77; p<0.001). An increase in voluntary drive tends to increase PIC strength, which has key implications for the control of force but also for comparisons between muscles or between studies when relative force levels might be different. These data indicate that increases in voluntary descending drive amplify PICs in humans and provide an important spinal mechanism for motor unit firing, and thus force output modulation.

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