Modulation of torque evoked by wide-pulse, high-frequency neuromuscular electrical stimulation and the potential implications for rehabilitation and training

Abstract

The effectiveness of neuromuscular electrical stimulation (NMES) for rehabilitation is proportional to the evoked torque. The progressive increase in torque (extra torque) that may develop in response to low intensity wide-pulse high-frequency (WPHF) NMES holds great promise for rehabilitation as it overcomes the main limitation of NMES, namely discomfort. WPHF NMES extra torque is thought to result from reflexively recruited motor units at the spinal level. However, whether WPHF NMES evoked force can be modulated is unknown. Therefore, we examined the effect of two interventions known to change the state of spinal circuitry in opposite ways on evoked torque and motor unit recruitment by WPHF NMES. The interventions were high-frequency transcutaneous electrical nerve stimulation (TENS) and anodal transcutaneous spinal direct current stimulation (tsDCS). We show that TENS performed before a bout of WPHF NMES results in lower evoked torque (median change in torque time-integral: − 56%) indicating that WPHF NMES-evoked torque might be modulated. In contrast, the anodal tsDCS protocol used had no effect on any measured parameter. Our results demonstrate that WPHF NMES extra torque can be modulated and although the TENS intervention blunted extra torque production, the finding that central contribution to WPHF NMES-evoked torques can be modulated opens new avenues for designing interventions to enhance WPHF NMES.

Modulating swallowing-related functional connectivity and behavior via modified pharyngeal electrical stimulation: A functional near-infrared spectroscopy evidence

“…The parameters for mPES include "mixing triangular and square wave, frequency: 5 Hz, pulse width: 10 ms, 10 min/day, " while the parameters of PES are "square wave, frequency: 5 Hz, pulse width: 0.2 ms, 10 min/day" (1,2). A wide pulse duration may enhance the evoked sensory volley to the central nervous system and may lead to short-and long-term plasticity in circuits to help restore function (3)(4)(5) and reduce the fatigability of contractions (6). Meanwhile, the triangular waveform and wide pulse duration synergistically stimulate denervated muscle (7,8).…”

Acute Effects of Neuromuscular Electrical Stimulation on Contralateral Plantar Flexor Neuromuscular Function

“…Each participant took part in a single experimental session that consisted of a preparation phase—during which subjects were positioned and individual stimulation intensities were carefully determined [ 10 , 12 , 13 ]—and an experimental phase ( Figure 1 ), during which the ipsilateral plantar flexors were subjected to four different experimental conditions while the contralateral plantar flexors were concurrently evaluated with tibial nerve stimulation, surface EMG, and maximal voluntary contractions (MVC). The experimental conditions were passive rest (REST), a submaximal voluntary contraction (VOL), a conventional NMES train (CONV) and a WPHF NMES train (WPHF), all lasting 15 s and generating approximately the same initial torque (10% MVC), except REST.…”

“…Surface EMG signals of the contralateral soleus and tibialis anterior muscles were recorded with pairs of circular silver-chloride electrodes (recording diameter: 1 cm; inter-electrode distance: 2 cm) (Meditrace 100, Tyco, Markham, Canada) that were placed lengthwise over respective muscle bellies according to SENIAM recommendations [ 14 ]. The reference electrode was placed on the ipsilateral patella [ 10 , 12 , 13 ]. Inter-electrode resistance was reduced by shaving and cleaning the skin with alcohol.…”

“…Third, only one of these previous studies tested the influence of different NMES parameters on the magnitude of contralateral facilitation, but no difference was observed between a low- and a high-intensity protocol [ 3 ]. It could be hypothesized that a NMES paradigm known to induce reflexive recruitment of spinal motoneurons, such as the wide-pulse high-frequency (WPHF) modality [ 8 , 9 , 10 ], would result in greater contralateral facilitation than a conventional NMES protocol that mainly generate contractions through a peripheral mechanism (motor axon depolarization). Fourth, only global proxies of voluntary activation (twitch interpolation) and muscle excitation (surface EMG) were used in these previous studies [ 3 , 4 ], so that no specific neurophysiological mechanisms underlying the contralateral facilitation effect could be identified.…”

Wound Healing with Electrical Stimulation Technologies: A Review

“…ES has been clinically practised since the 19th century when the electrocardiogram (ECG) was introduced to detect heart electrical activity and has improvised to the current 12-lead ECG [73], which is the gold standard investigation to detect myocardial infarction [74]. Concurrently, cardiac pacing was introduced for cardiac resuscitation and technology advances, including cardiac pacemaker and defibrillator [75]. Other than cardiac devices, neuromuscular electrical stimulation (NMES) in sports medicine [76], transcutaneous nerve stimulation (TENS) for chronic pain [77], electroconvulsive therapy in psychiatric disorders [78,79], and deep brain stimulation in Parkinson's disease [80] are included as ES.…”