Concurrent Achilles tendon vibration and tibial nerve stimulation to estimate persistent inward current strength in motoneurons

Vibratory (Tvib) and sustained (Tsust) torque responses to concurrent Achilles tendon vibration and neuromuscular electrical stimulation applied over the muscle belly (vib+stim) are used as indicators of motoneuron facilitation and, theoretically, persistent inward current strength. However, neuromuscular electrical stimulation (NMES) applied to the nerve trunk may potentiate motoneuronal excitability more than muscle belly NMES, yet it remains unclear whether NMES applied over the nerve evokes robust Tvib and Tsust responses when used during the vib+stim protocol. This study tested whether a nerve-targeted vib+stim protocol elicits Tvib and Tsust responses in the ankle plantar flexors with acceptable intra- and inter-session reliability. Fifteen men performed the vib+stim protocol with NMES applied over the tibial nerve three times across two sessions; twice in a single session (5-min apart) to test intrasession reliability and then again after 48 h to test intersession reliability. Intraclass correlation coefficients (ICC3,1), within-participant coefficients of variation (CV) and pairwise comparisons were used to verify relative and absolute reliability as well as systematic bias. Thirteen men presented Tvib and Tsust responses (response rate of 87%). Intrasession Tvib and Tsust ICCs were >0.73 but inter-session ICCs were <0.5. Although no systematic bias was detected (p>0.05), both intra- and inter-session CVs were large (>10%) for Tvib and Tsust. The Vib+stim protocol with NMES applied over the nerve evoked Tvib and Tsust in almost all participants, but presented a large intra- and inter-session variability. The method does not appear to be effective for assessing motoneuron facilitation in the plantar flexors.

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Motor unit recruitment when neuromuscular electrical stimulation is applied over a nerve trunk compared with a muscle belly: triceps surae

Journal of Applied Physiology ◽

10.1152/japplphysiol.01103.2010 ◽

2011 ◽

Vol 110 (3) ◽

pp. 627-637 ◽

Cited By ~ 53

Author(s):

A. J. Bergquist ◽

J. M. Clair ◽

D. F. Collins

Keyword(s):

Electrical Stimulation ◽

Motor Unit ◽

Tibial Nerve ◽

Plantar Flexion ◽

Neuromuscular Electrical Stimulation ◽

Nerve Trunk ◽

Triceps Surae ◽

Size Principle ◽

Muscle Belly ◽

Triceps Surae Muscles

Neuromuscular electrical stimulation (NMES) can be delivered over a nerve trunk or muscle belly and can generate contractions by activating motor (peripheral pathway) and sensory (central pathway) axons. In the present experiments, we compared the peripheral and central contributions to plantar flexion contractions evoked by stimulation over the tibial nerve vs. the triceps surae muscles. Generating contractions through central pathways follows Henneman's size principle, whereby low-threshold motor units are activated first, and this may have advantages for rehabilitation. Statistical analyses were performed on data from trials in which NMES was delivered to evoke 10–30% maximum voluntary torque 2–3 s into the stimulation (Time1). Two patterns of stimulation were delivered: 1) 20 Hz for 8 s; and 2) 20–100-20 Hz for 3–2-3 s. Torque and soleus electromyography were quantified at the beginning (Time1) and end (Time2; 6–7 s into the stimulation) of each stimulation train. H reflexes (central pathway) and M waves (peripheral pathway) were quantified. Motor unit activity that was not time-locked to each stimulation pulse as an M wave or H reflex (“asynchronous” activity) was also quantified as a second measure of central recruitment. Torque was not different for stimulation over the nerve or the muscle. In contrast, M waves were approximately five to six times smaller, and H reflexes were approximately two to three times larger during NMES over the nerve vs. the muscle. Asynchronous activity increased by 50% over time, regardless of the stimulation location or pattern, and was largest during NMES over the muscle belly. Compared with NMES over the triceps surae muscles, NMES over the tibial nerve produced contractions with a relatively greater central contribution, and this may help reduce muscle atrophy and fatigue when NMES is used for rehabilitation.

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An evaluation of paired motor unit estimates of persistent inward current in human motoneurons

Journal of Neurophysiology ◽

10.1152/jn.00469.2013 ◽

2014 ◽

Vol 111 (9) ◽

pp. 1877-1884 ◽

Cited By ~ 14

Author(s):

Michael S. Vandenberk ◽

Jayne M. Kalmar

Keyword(s):

Motor Unit ◽

Reciprocal Inhibition ◽

Primary Objective ◽

Spike Frequency ◽

Spike Frequency Adaptation ◽

Plantar Flexors ◽

Inward Current ◽

Spike Threshold ◽

Frequency Adaptation ◽

Persistent Inward Current

Persistent inward current (PIC) plays an important role in setting the input-output gain of motoneurons. In humans, these currents are estimated by calculating the difference between synaptic input at motor unit recruitment and derecruitment (ΔF) derived from paired motor unit recordings. The primary objective of this study was to use the relationship between reciprocal inhibition (RI) and PIC to estimate the contribution of PIC relative to other motoneuron properties that result in nonlinear motor unit firing behavior. This study also assessed the contribution of other intrinsic properties (spike threshold accommodation and spike frequency adaptation) to ΔF estimates of PIC in human motor units by using ramps with varying rates of rise and duration. It was hypothesized that slower rates of ramp rise and longer ramp durations would inflate ΔF estimates of PIC, and RI and PIC values would only be correlated during the ramp with the fastest rate of rise and shortest duration when spike threshold accommodation and spike frequency adaptation is minimized. Fourteen university-aged participants took part in this study. Paired motor unit recordings were made from the right soleus muscle during ramp contractions of plantar flexors with three different rates of rise and durations. ΔF estimates of PIC increased with decreased rates of ramp rise ( P < 0.01) and increased ramp durations ( P < 0.01), most likely due to spike frequency adaptation. A correlation ( r = 0.41; P < 0.03) between ΔF and RI provides evidence that PIC is the primary contributor to ΔF in shorter ramps with faster rates of rise.

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Influence of wide-pulse neuromuscular electrical stimulation frequency and superimposed tendon vibration on occurrence and magnitude of extra torque

Journal of Applied Physiology ◽

10.1152/japplphysiol.00968.2020 ◽

2021 ◽

Author(s):

Loïc Espeit ◽

Vianney Rozand ◽

Guillaume Y. Millet ◽

Julien Gondin ◽

Nicola A. Maffiuletti ◽

...

Keyword(s):

Electrical Stimulation ◽

High Frequency ◽

Plantar Flexion ◽

Neuromuscular Electrical Stimulation ◽

Low Frequency ◽

Force Production ◽

Voluntary Contraction ◽

Tendon Vibration ◽

Afferent Pathways ◽

Design Decisions

Low-frequency and high-frequency wide-pulse neuromuscular electrical stimulation (NMES) can generate extra-torque (ET) via afferent pathways. Superimposing tendon vibration (TV) to NMES can increase the activation of these afferent pathways and favour ET generation. Knowledge of the characteristics of ET is essential to implement these stimulation paradigms in clinical practice. Thus, we aimed at investigating the effects of frequency and TV superimposition on the occurrence and magnitude of ET in response to wide-pulse NMES. NMES-induced isometric plantar flexion torque was recorded in 30 healthy individuals who performed five NMES protocols: wide-pulse low-frequency (1 ms; 20 Hz; WPLF) and wide-pulse high-frequency (1 ms; 100 Hz; WPHF) without and with superimposed TV (1 mm; 100 Hz) and conventional NMES (50 µs; 20 Hz; reference protocol). Each NMES protocol began with an adjustment of NMES intensity in order to reach 10% of maximal voluntary contraction then consisted of three 20-s trains interspersed by 90 s of rest. The ET occurrence was similar for WPLF and WPHF (p=0.822). In the responders, the ET magnitude was greater for WPHF than WPLF (p<0.001). There was no effect of superimposed TV on ET characteristics. This study reported an effect of NMES frequency on ET magnitude, whereas TV superimposition did not affect this parameter. In the context of our experimental design decisions, the present findings question the clinical use of wide-pulse NMES and its combination with superimposed TV. Yet, further research is needed in order to maximize force production through the occurrence and magnitude of ET.

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Short-term inhibition of spinal reflexes in multiple lower limb muscles after neuromuscular electrical stimulation of ankle plantar flexors

Experimental Brain Research ◽

10.1007/s00221-018-5437-6 ◽

2018 ◽

Vol 237 (2) ◽

pp. 467-476 ◽

Cited By ~ 6

Author(s):

Matija Milosevic ◽

Yohei Masugi ◽

Hiroki Obata ◽

Atsushi Sasaki ◽

Milos R. Popovic ◽

...

Keyword(s):

Electrical Stimulation ◽

Lower Limb ◽

Neuromuscular Electrical Stimulation ◽

Spinal Reflexes ◽

Plantar Flexors ◽

Short Term ◽

Lower Limb Muscles ◽

Limb Muscles ◽

Stimulation Of

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Effects Of Blood Flow Restriction And Neuromuscular Electrical Stimulation On Strength Of The Plantar Flexors

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000685068.07154.29 ◽

2020 ◽

Vol 52 (7S) ◽

pp. 878-878

Author(s):

Jonathan A. Aguilera ◽

Yaremi Ontiveros ◽

John Poli ◽

Joshua A. Cotter

Keyword(s):

Blood Flow ◽

Electrical Stimulation ◽

Neuromuscular Electrical Stimulation ◽

Blood Flow Restriction ◽

Plantar Flexors ◽

Flow Restriction

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Wide-pulse-width, high-frequency neuromuscular stimulation: implications for functional electrical stimulation

Journal of Applied Physiology ◽

10.1152/japplphysiol.00871.2005 ◽

2006 ◽

Vol 101 (1) ◽

pp. 228-240 ◽

Cited By ~ 46

Author(s):

Evan R. L. Baldwin ◽

Piotr M. Klakowicz ◽

David F. Collins

Keyword(s):

Electrical Stimulation ◽

Nerve Stimulation ◽

Maximal Voluntary Contraction ◽

Neuromuscular Electrical Stimulation ◽

Initial Step ◽

Voluntary Contraction ◽

Triceps Surae ◽

Muscle Stimulation ◽

Plantar Flexors ◽

Wrist Flexors

Electrical stimulation (1-ms pulses, 100 Hz) produces more torque than expected from motor axon activation (extra contractions). This experiment investigates the most effective method of delivering this stimulation for neuromuscular electrical stimulation. Surface stimulation (1-ms pulses; 20 Hz for 2 s, 100 Hz for 2 s, 20 Hz for 3 s) was delivered to triceps surae and wrist flexors (muscle stimulation) and to median and tibial nerves (nerve stimulation) at two intensities. Contractions were evaluated for amplitude, consistency, and stability. Surface electromyograph was collected to assess how H-reflexes and M-waves contribute. In the triceps surae, muscle stimulation produced the largest absolute contractions (23% maximal voluntary contraction), evoked the largest extra contractions as torque increased by 412% after the 100-Hz stimulation, and was more consistent and stable compared with tibial nerve stimulation. Absolute and extra contraction amplitude, consistency, and stability of evoked wrist flexor torques were similar between stimulation types: torques reached 11% maximal voluntary contraction, and extra contractions increased torque by 161%. Extra contractions were 10 times larger in plantar flexors compared with wrist flexors with muscle stimulation but were similar with nerve stimulation. For triceps surae, H reflexes were 3.4 times larger than M waves during nerve stimulation, yet M waves were 15 times larger than H reflexes during muscle stimulation. M waves in the wrist flexors were larger than H reflexes during nerve (8.5 times) and muscle (18.5 times) stimulation. This is an initial step toward utilizing extra contractions for neuromuscular electrical stimulation and the first to demonstrate their presence in the wrist flexors.

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No. 139 Full-Movement Neuromuscular Electrical Stimulation Can Reduce Plantar Flexors Spasticity and Increase Ankle Joint Movement But Can’t Improve Gait Function in Stroke Patients

PM&R ◽

10.1016/j.pmrj.2014.08.265 ◽

2014 ◽

Vol 6 (8) ◽

pp. S124

Author(s):

Yonghui Wang ◽

Fei Meng ◽

Yang Zhang ◽

Shouwei Yue

Keyword(s):

Electrical Stimulation ◽

Ankle Joint ◽

Neuromuscular Electrical Stimulation ◽

Joint Movement ◽

Plantar Flexors ◽

Stroke Patients ◽

Gait Function

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Involuntary sustained firing of plantar flexor motor neurones: effect of electrical stimulation parameters during tendon vibration

European Journal of Applied Physiology ◽

10.1007/s00421-020-04563-7 ◽

2021 ◽

Author(s):

Ricardo N. O. Mesquita ◽

Janet L. Taylor ◽

Benjamin Kirk ◽

Anthony J. Blazevich

Keyword(s):

Electrical Stimulation ◽

Pulse Width ◽

Neuromuscular Electrical Stimulation ◽

Voluntary Contraction ◽

Triceps Surae ◽

Tendon Vibration ◽

Plantar Flexor ◽

Intensity Pattern ◽

Simultaneous Application ◽

Motor Neurones

Abstract Purpose Simultaneous application of tendon vibration and neuromuscular electrical stimulation (NMES) induces an involuntary sustained torque. We examined the effect of different NMES parameters (intensity, pattern of stimulation and pulse width) on the magnitude of the evoked involuntary torque. Methods Plantar flexor torque was recorded during 33-s Achilles tendon vibration with simultaneous 20-Hz NMES bouts on triceps surae (n = 20; 13 women). Intensity was set to elicit 10, 20 or 30% of maximal voluntary contraction torque (MVC), pulse width was narrow (0.2 ms) or wide (1 ms), and the stimulus pattern varied (5 × 2-s or 10 × 1-s). Up to 12 different trials were performed in a randomized order, and then repeated in those who produced a sustained involuntary torque after the cessation of vibration. Results Six of 7 men and 5 of 13 women produced a post-vibration sustained torque. Eight of 20 participants did not complete the 30% trials, as they were perceived as painful. Torque during vibration at the end of NMES and the increase in torque throughout the trial were significantly higher in 20 than 10% trials (n = 11; 9.7 ± 9.0 vs 7.1 ± 6.1% MVC and 4.3 ± 4.5 vs 3.6 ± 3.5% MVC, respectively). Post-vibration sustained torque was higher in wide pulse-width trials (5.4 ± 5.9 vs 4.1 ± 4.3% MVC). Measures of involuntary torque were not different between 20 and 30% trials (n = 8). Conclusion Bouts of 5 × 2-s NMES with wide pulse width eliciting 20% MVC provides the most robust responses and could be used to maximise the production of involuntary torque in triceps surae.

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