Electrical Stimulation Research Articles

Muscle Metabolism During Multiple Muscle Stimulation Using an Affordable Equipment

Background/Objectives: Previous studies have shown that neuromuscular electrical stimulation (NMES), while expensive, can provide some of the health benefits of exercise to people who cannot exercise their legs normally. The aim of this study was to quantify the increases in muscle metabolism in four muscles of the legs of able-bodied individuals with NMES. Methods: Healthy college-aged students were tested. NMES of four muscle groups was performed with inexpensive stimulators and reusable tin foil electrodes. The biceps femoris, vastus lateralis, medial gastrocnemius, and tibialis anterior muscles on one leg were stimulated for ten minutes with twitch stimulations at the highest comfortable stimulation current. Muscle metabolism was measured using the slope of oxygen consumption measured with near-infrared spectroscopy (NIRS) during 5 s of cuff ischemia. Results: Initial studies found fold increases in muscle metabolism above rest of 8.9 ± 8.6 for the vastus lateralis, 7.9 ± 11.9 for the biceps femoris, 6.6 ± 7.8 for the medial gastrocnemius, and 4.9 ± 3.9 for the tibialis anterior. Some participants were able to obtain large increases in muscle metabolism, while other participants had lower increases. Conclusions: The ability to produce large increases in metabolism has the potential to allow NMES to replace or augment exercise to improve health in people who cannot otherwise exercise. The devices used were inexpensive and could be adapted for easy use by a wide range of individuals.

Effects of electrical muscle stimulation exercise on lower limb muscles and lumbar movement in older adults with disabilities: A pre- and post-test controlled experimental study

In older adults with disabilities, muscle weakness reduces mobility and causes postural issues. Electrical muscle stimulation (EMS) training is effective for increasing strength by inducing involuntary skeletal muscle contractions. Thus, this study aimed to examine changes in lumbar movement, muscle activity during walking, and maximum muscle strength of lower-limb joints based on an 8-week EMS exercise program for older adults with physical disabilities. Sixteen older adults (aged 56–78 years) with physical disabilities were selected and randomly assigned to either the exercise group (EG, n = 8) or the control group (CG, n = 8). EG participants were instructed to wear EMS suits and participate in an elastic band and bare-body exercise program, whereas CG participants performed the exercise program without the EMS suits. Lumbar range of motion (ROM), body circumference, partial volume, maximum muscle strength, and muscle activity were measured. Statistical analysis was performed using SPSS 28.0 for Windows, with the critical value of α = 0.05. Compared to CG participants, EG participants had a superior ROM, body volume, partial volume, maximum muscle strength (knee joints), and muscle activity while walking. These positive outcomes highlight the efficacy of combining EMS with an exercise program for strength and rehabilitation training in older adults with physical disabilities.

Effect of electroacupuncture on synaptic ultrastructure and synaptic function related proteins PSD95 and MeCP2 in sleep deprivation rats

To observe the effect of electroacupuncture (EA) on the expression of synaptic function related proteins PSD95 and MeCP2 and synaptic ultrastructure in sleep deprived rats, so as to explore its mechanism underlying improvement of learning and memory ability caused by sleep deprivation. SD rats were randomly divided into normal, model, EA and sham EA groups (n=10). The sleep deprivation model was prepared by modified multi-platform water environment. Rats of the EA group received EA stimulation at "Baihui" (GV20) and "Dazhui" (GV14), while the sham EA group received shallow needling 4 mm away from the above acupoints without electrical stimulation. The learning and memory ability was evaluated with Morris water maze test. The density of dendritic spines in hippocampal CA1 region was detected by Golgi staining. The synaptic ultrastructure of hippocampus was observed by electron microscope. The protein expression levels of PSD95 and MeCP2 in hippocampus was detected by Western blot. Compared with the normal group, the escaping latency of the positioning navigation experiment in the model group was prolonged (P<0.05), the number of crossing the platform and the residence time in the target quadrant were decreased(P<0.05), the density of dendritic spines in the hippocampal CA1 area was decreased (P<0.05), the number of synapses was reduced, with swollen synaptosomes, blurred synaptic structure, disappeared and narrowed synaptic clefts, the protein expression levels of PSD95 and MeCP2 were significantly decreased (P<0.05) in the model group. Compared with the model group, the escape latency of the positioning navigation experiment was shortened (P<0.05), the number of crossing platforms and the time spent in the target quadrant were increased (P<0.05), the density of dendritic spines in the hippocampal CA1 region was increased (P<0.05), the morphology of synaptic improved, the protein expression levels of PSD95 and MeCP2 were increased (P<0.01) in the EA and sham EA groups. The improvement of the above indexes in EA group was more obvious than those in sham EA group. EA can improve the learning and memory of sleep deprivation rats, which may be related to its function in regulating the expressions of synaptic related proteins PSD95 and MeCP2, and improving the synaptic structure.

Up versus down: Does cuff spine orientation affect early adherence to upper airway stimulation?

Upper airway stimulation (UAS) is a treatment option for moderate-to-severe OSA, in which electrical stimulation is applied to the hypoglossal nerve via an electrode cuff. In this study, we assess the effect of electrode cuff positioning on UAS outcomes, in particular device adherence. Patients at a single academic institution who met the Food and Drug Administration criteria for UAS between 2016 and 2021 were included. The electrode position was documented as superior (cuff spine up) or inferior (cuff spine down) to the hypoglossal nerve based on postoperative lateral neck X-ray. Patients underwent titration polysomnography 2-6months following surgery. The most recent postoperative variables from sleep studies following titration polysomnogram were used for statistical analysis.Adherence data was downloaded from the UAS device. 327 patients met inclusion criteria. The average age of patients was 60.9 ± 11.1years, with 105 (32.1%) females. Cuff spine up position was present in 169 (51.7%) patients as compared to 158 (48.3%) with cuff spine down. UAS adherence was significantly higher among cuff spine down patients (45.4 vs. 41.0h device use/week, p = 0.015). Cuff position was not significantly associated with therapeutic amplitude, change in apnea hypopnea index, or change in symptoms as measured by the Epworth Sleepiness Scale. On multivariable linear regression analysis, cuff spine down position (β = 3.7, CI [1.3, 7.4], p = 0.038) and increased age (β = 0.22, CI [0.07, 0.38], p = 0.005) were associated with increased adherence. UAS cuff spine down position is associated with increased device adherence. Further investigation into cuff positioning is warranted.

Effects of dual plasticizers for improved PVC gel-based varifocal tiny lens

Abstract Electroactive polyvinyl chloride (PVC) gel-based varifocal lenses are attractive due to their excellent transparency, simple fabrication, compact structure, and good flexibility. In this work, dibutyl adipate (DBA) and propylene carbonate (PC) were utilized to plasticize PVC for fabricating transparent, soft, and flexible gels by solvent casting method. The PVC gels were characterized by various experimental techniques to investigate their optical, electrical, mechanical, and thermal properties. Further, the PVC gels were examined to construct a compact plano-convex tiny lens structure for varifocal lens application under electrical stimulation. The work revealed that the introduction of a co-plasticizer PC improves the overall dielectric property as well as transparency of the PVC gels. The observed enhancement in dielectric constant of the PC incorporated gels increased up to 6 times of the only DBA plasticized PVC gel (D9) while the transmittance value is ~5% higher than that of D9 gel. Moreover, the optimal ratio of DBA and PC in PVC gel was found to be 8.6: 0.4: 1 (wt %) and the optimized D8.6P0.4 gel induces better actuation properties resulting in improved focal length variation for the developed lens. The proposed adaptive tiny lens could change its focal length from 3 mm to 20.5 mm with increasing input voltage from 0 V to 1000 V. The developed tiny lens exhibited excellent optical characteristics including fast response speed and good stability. Moreover, this study broadens the scope for property tuning strategies for the EAP design and application.

Resting-state fNIRS reveals changes in prefrontal cortex functional connectivity during TENS in patients with chronic pain

Transcutaneous electrical nerve stimulation (TENS) has been used to treat chronic pain. However, the potential efficacy and mechanism of the effect of applying TENS for a short time in chronic pain patients remains unclear. To identify the effect of short-term TENS on chronic pain patients and to clarify the mechanism of the effect, we investigated abnormalities of functional connectivity (FC) within the prefrontal cortex (PFC) using resting-state functional near-infrared spectroscopy (rs-fNIRS). Fifteen patients (56.8 ± 17.4 years, nine females) with chronic pain participated in this rs-fNIRS study. The fNIRS scans included two parts: a 5-minute resting-state scan followed by a 5-minute scan during TENS (150 Hz) application. The pain intensity was measured using a Visual Analog Scale (VAS) and Pittsburgh Sleep Quality Index (PSQI). The spontaneous brain activity of the PFC and resting-state functional connectivity (rsFC) in the PFC were examined during TENS and compared to before TENS. The results showed that Pain intensity significantly decreased after TENS (p < 0.001). During TENS, fALFF values were significantly lower in BA46 (**p = 0.0025) and BA45 (**p = 0.0056). rsFC strength increased during TENS compared to before, with significant group-level increases in BA10, BA9, BA46, and BA44/45 (p < 0.05). Notably, the variation between BA10 and BA44/45 was highly significant (***p < 0.001). These findings suggest that FC between BA10 and BA44/45 was associated with analgesia of TENS in patients with chronic pain, indicating the potential role of FC as a novel objective parameter to predict the outcome of clinical use of TENS for pain relief in chronic pain patients.

Transcutaneous Electrical Nerve Stimulation for Prevention and Treatment of Post-Herpetic Neuralgia: A Narrative Review

Transcutaneous Electrical Nerve Stimulation for Prevention and Treatment of Post-Herpetic Neuralgia: A Narrative Review

Local field potential-based brain-machine interface to inhibit epileptic seizures by spinal cord electrical stimulation

Objective.This study proposes a closed-loop brain-machine interface (BMI) based on spinal cord stimulation to inhibit epileptic seizures, applying a semi-supervised machine learning approach that learns from Local Field Potential (LFP) patterns acquired on the pre-ictal (preceding the seizure) condition.Approach.LFP epochs from the hippocampus and motor cortex are band-pass filtered from 1 to 13 Hz, to obtain the time-frequency representation using the continuous Wavelet transform, and successively calculate the phase lock values (PLV). As a novelty, theZ-score-based PLV normalization using both modifiedk-means and Davies-Bouldin's measure for clustering is proposed here. Consequently, a generic seizure's detector is calibrated for detecting seizures on the normalized PLV, and enables the spinal cord stimulation for periods of 30 s in a closed-loop, while the BMI system detects seizure events. To calibrate the proposed BMI, a dataset with LFP signals recorded on five Wistar rats during basal state and epileptic crisis was used. The epileptic crisis was induced by injecting pentylenetetrazol (PTZ). Afterwards, two experiments without/with our BMI were carried out, inducing epileptic crisis by PTZ in Wistar rats.Main results.Stronger seizure events of high LFP amplitudes and long time periods were observed in the rat, when the BMI system was not used. In contrast, short-time seizure events of relative low intensity were observed in the rat, using the proposed BMI. The proposed system detected on unseen data the synchronized seizure activity in the hippocampus and motor cortex, provided stimulation appropriately, and consequently decreased seizure symptoms.Significance.Low-frequency LFP signals from the hippocampus and motor cortex, and cord spinal stimulation can be used to develop accurate closed-loop BMIs for early epileptic seizures inhibition, as an alternative treatment.

The Effectiveness and Application of Transcutaneous Electrical Acupoint Stimulation in the Prevention of Postoperative Nausea and Vomiting

Background: Effective management of postoperative nausea and vomiting (PONV) is crucial for enhancing postoperative recovery and improving the quality of life. Transcutaneous electrical acupoint stimulation (TEAS) is an innovative non-pharmacological intervention that has gained significant attention in PONV management, especially following thoracic surgery. Methods: This systematic review aims to evaluate the effectiveness and application potential of TEAS in alleviating PONV and promoting postoperative recovery. The review includes a detailed analysis of recent randomized controlled trials (RCTs) and observational studies that investigate the use of TEAS in various surgical procedures, with a particular focus on video-assisted thoracoscopic lobectomy (VATSL). The principles, procedures, and safety aspects of TEAS are comprehensively discussed. Results: The analysis of the included studies demonstrates that TEAS is effective in reducing the incidence of PONV and improving postoperative recovery outcomes across different types of surgeries, including VATSL and other common surgical procedures. The effectiveness of TEAS in PONV management is supported by evidence from multiple RCTs and observational studies, which report a significant reduction in nausea and vomiting rates, as well as improved recovery indicators. Conclusion: TEAS shows promising potential as a non-pharmacological intervention for managing PONV and enhancing postoperative recovery. However, the current evidence highlights several limitations and controversies that require further investigation. Future research should focus on addressing these gaps and exploring new directions for the application of TEAS. Practical recommendations are provided for the clinical application of TEAS, emphasizing its role in effective PONV management to promote better postoperative outcomes.

A flexible, sustainable, and deep learning-assisted triboelectric patch for self-powered interactive sensing and wound healing applications

Multi-functional cellulose-based triboelectric nanogenerators (TENGs) with sensing and energy-harvesting capabilities are emerging as promising candidates for next-generation healthcare electronics. However, insufficient output performance and device sustainability limits their further application. In this study, we developed a SnS₂-based nanocomposite with tunable surface triboelectric properties, simulated by Density Functional Theory (DFT) and characterized via Kelvin Probe Force Microscopy (KPFM). The SnS₂-based nanocomposite was then integrated into a cellulose-based TENG (C-TENG) to enhance output performance and function as a biomechanical sensing medium for human motion monitoring. A one-dimensional geometric fast data density functional transform (1-D g-fDDFT) model was also employed to improve the as-designed sensor prediction accuracy. Moreover, the C-TENG was utilized as a self-powered in vitro electrical stimulation device for wound therapy. The C-TENG not only shows excellent potential for future sustainable, self-powered healthcare sensors, but also represents a promising advancement in future wearable wound management systems.

The intersubject reliability of cortical auditory evoked potential (CAEP) in pediatric cochlear implant recipients: comparisons between acoustic and electrical stimulations.

To compare the intersubject reliability of cortical auditory evoked potential (CAEP) elicited by acoustic and electrical stimulations in pediatric cochlear implant (CI) recipients. Twenty-two MED-EL CI recipients (aged 13-93 months) participated in this study. The acoustic CAEP (aCAEP) waveforms were elicited using four speech stimuli (/ba/, /m/, /g/, and /t/) presented at 65 dB SPL in a free-field condition. The electrical CAEP (eCAEP) responses were obtained by presenting electrical pulses through apical, medial, and basal electrodes. The aCAEP and eCAEP data (n = 28 ears) were analyzed using coefficient of variation (CV) and other appropriate statistics. P1, N1, and P2 peaks were observed in most of the children (92.9% response rate). The CV values were smaller for the latency metric (13.6-34.2%) relative to the amplitude metric (51.3-92.4%), and the differences were statistically significant (p < 0.001). The aCAEP yielded smaller mean CV values than the eCAEP (for both latency and amplitude measures), and the mean CV value for the aCAEP (15.6%) was found to be statistically different from that of the eCAEP (31.0%) for the P1 latency (p = 0.001). This study is the first to report the intersubject reliability of aCAEP and eCAEP in pediatric CI recipients. Overall, CAEP latencies were found to be more reliable than CAEP amplitudes, and the aCAEP testing demonstrated higher intersubject reliability compared to the eCAEP assessment. The present study's findings can be beneficial for researchers and clinicians in documenting CAEP in children who use CI.

Skeletal muscle hypertrophy and enhanced mitochondrial bioenergetics following electrical stimulation exercises in spinal cord injury: a randomized clinical trial.

We examined the combined effects of neuromuscular electrical stimulation-resistance training (NMES-RT) and functional electrical stimulation-lower extremity cycling (FES-LEC) compared to passive movement training (PMT) and FES-LEC on mitochondrial electron transport chain (ETC) complexes and citrate synthase (CS) in adults with SCI. Thirty-two participants with chronic SCI were randomized to 24weeks of NMES-RT + FES [n = 16 (14 males and 2 females) with an age range of 20-54years old] or PMT + FES [n = 16 (12 males and 4 females) with an age range of 21-61years old]. The NMES-RT + FES group underwent 12weeks of surface NMES-RT using ankle weights followed by an additional 12weeks of FES-LEC. The PMT + FES performed 12weeks of passive leg extension movements followed by an additional 12weeks of FES-LEC. Using repeated measures design, muscle biopsies of the vastus lateralis were performed at baseline (BL), post-intervention 1 (P1) and post-intervention 2 (P2). Spectrophotometer was used to measure ETC complexes (I-III) and CS using aliquots of the homogenized muscle tissue. Magnetic resonance imaging was used to measure skeletal muscle CSAs. A time effect was noted on CS (P = 0.001) with an interaction between both groups (P = 0.01). 46% of the participants per group had zero activities of CI without any changes following both interventions. A time effect was noted in CII (P = 0.023) following both interventions. Finally, NMES-RT + FES increased CIII at P1 compared to BL (P = 0.023) without additional changes in P2 or following PMT + FES intervention. Skeletal muscle hypertrophy may potentially enhance mitochondrial bioenergetics after SCI. NMES-RT is likely to enhance the activities of complex III in sedentary persons with SCI. Clinical trials # NCT02660073.

Theta Burst Stimulation Modulates Exercise Performance by Influencing Central Fatigue and Corticospinal Excitability.

Theta-burst stimulation (TBS) over the primary motor cortex modulates activity of the underlying neural tissue, but little is known about its consequence on neuromuscular fatigue (NMF) and its neural correlates. This study aimed to compare the effects of facilitatory versus inhibitory TBS on the NMF and excitability/inhibition of the corticospinal pathway in an unfatigued/fatigued muscle. The effects of three TBS protocols (facilitatory/intermittent: iTBS; inhibitory/continuous: cTBS, and sham: sTBS) were tested on exercise performance, neuromuscular function, corticospinal excitability and inhibition in twenty young healthy participants. Transcranial magnetic and peripheral electrical stimulations were used at baseline, following TBS (unfatigued state), and after a fatiguing sustained contraction (fatigued state) at 35% of the maximal voluntary isometric contraction (MVIC) of the elbow flexors. Time-to-task failure was shorter for cTBS (142±51 s) and longer for iTBS (214±68 s) compared with sTBS (173±65 s) (P < .05). In an unfatigued state, cTBS reduced MVIC and voluntary activation (VA), increased motor-evoked potential (MEP), and silent period (SP) (P < 0.05), while iTBS did not cause any change. In a fatigued state, MVIC and VA decreased in all TBS sessions (P < 0.05). However, the reduction in VA was larger after cTBS (Δ-18±18%) compared with iTBS (Δ-3±5%), and sTBS (Δ-9±9%) (P < 0.001). Furthermore, the increase in MEP and SP were greater for cTBS (P < .05), compared to iTBS and sTBS (P < .05). Facilitatory TBS augments exercise performance that is independent of central parameters and corticospinal mechanisms whilst inhibitory TBS attenuates exercise performance through an exacerbation in the development of central fatigue and possibly intracortical inhibition.

The fascicular anatomy of the sciatic nerve may not influence the muscular activity of the biceps femoris after applying percutaneous electrical nerve stimulation: a randomized clinical trial.

Electrical nerve stimulation is an effective therapeutic tool in the field of rehabilitation for the management of musculoskeletal conditions. To analyze the muscle activity of the short head of the biceps femoris (SHBF) and long head of the biceps femoris (LHBF) after the application of percutaneous electrical nerve stimulation to the common fibular versus tibial nerve compartment of the sciatic nerve. Thirty-eight healthy subjects received electrical stimulation (asymmetric biphasic rectangular waveforms) through a needle in the sciatic nerve. The sample was divided into two groups in which the technique was applied to the lateral compartment versus medial compartment of the nerve, respectively. The protocol used included 5 s of stimulation at a frequency of 100 Hz and a phase duration of 350 ms, followed by 55 s of rest, for 5 min. The electrical activity of the SHBF and LHBF and the muscle strength of the knee flexors was assessed by surface electromyography during isometric knee flexion in the prone position. Neither group showed significant changes (p > 0.05) in any variable after the intervention compared with baseline values. Similarly, there were no significant differences in any of the study variables when comparing both groups (p > 0.05). Selective stimulation of the sciatic nerve by percutaneous electrical nerve stimulation had no measurable effects on muscle activity in the SHBF or LHBF, regardless of the approach applied. NCT05549700 (ClinicalTrials.gov).

Electrical Muscle Stimulation for the Conservative Management of Female Pelvic Floor Muscle Dysfunction: A Scoping Review

Background: Electrical muscle stimulation (EMS) is a conservative management tool for the treatment of pelvic floor dysfunctions (PFDs). The aim of this review was to scope, summarize and critically evaluate available research investigating the impact of various modes of EMS on PFDs in females. Methods: Joanna Briggs Institute methodology for scoping reviews was used with The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews. Three databases were searched. Articles published in English that included female participants living with pelvic floor muscle dysfunction where EMS was used as a conservation care intervention were included in the review. Included studies were analyzed following Arksey and O’Malley’s framework. The Cochrane Risk of Bias Tool for randomized trials was used to assess risk of bias for the randomized controlled trials (RCTs), and Hawker and Payne’s quality appraisal criteria was used to appraise the data from the other included papers systematically. Results: A total of 37 studies, including 20 RCTs were included. A favorable impact, across various outcomes, was found across trials which investigated different types of EMS with varying protocols. The heterogenous nature of intervention protocols limited the ability to apply any statistical or meta-analyses. EMS demonstrates a positive effect for improving outcomes related to PFDs in adult women. Included studies support the use of EMS for stress, urgency and mixed urinary incontinence. All versions of EMS studied were found to provide significant improvements, which included them being used as a sole intervention or as an adjunct intervention. High intensity forms of EMS were consistently found to require shorter intervention times. Conclusions: EMS demonstrates improvement across outcomes for PFDs among adult women. In particular, the results of this review suggest that EMS may be particularly useful in women living with stress urinary incontinence (SUI) or who those are unable to perform voluntary muscle contractions when pelvic floor muscle training is attempted. Further research related to more novel versions of high intensity EMS approaches is needed.

Trametinib alters contractility of paediatric Noonan syndrome-associated hypertrophic myocardial tissue slices.

No curative treatment is available for RASopathy-associated childhood-onset hypertrophic cardiomyopathy (RAS-CM). Preclinical data and individual reports suggest a beneficial effect of small molecules targeting the RAS-mitogen-activated protein (MAP) kinase (MAPK) pathway in severely affected RAS-CM patients. The aim of this study was to evaluate the biophysical effects of trametinib, rapamycin and dasatinib on cultivated myocardial tissue slices of a paediatric RAS-CM patient using biomimetic cultivation chambers (BMCCs) and to correlate the findings with clinical data. Contracting right ventricular (RV) tissue slices were prepared from resected myocardium, cultivated in BMCCs and treated with distinct molecules directly and indirectly targeting the RAS-MAPK pathway (trametinib, rapamycin and dasatinib) or dimethyl sulfoxide (DMSO). Tissue biophysical properties were assessed using electrical stimulation protocols. Contractile function, force-frequency relationship and post-pause potentiation were compared before and after treatment. These parameters correlated to L-type Ca2+ channel function and sarcoplasmic Ca2+ loading. In vivo, off-label treatment with MAPK kinase (MEK) inhibitor trametinib of a child with severe RAS-CM resulted in a modest reduction of RV outflow tract (RVOT) obstruction (RVOT 151 to 122mmHg after 11weeks) and improved diastolic function (E/A 0.68 to 1.09 after 11weeks) and myocardial strain [RV global radial strain (RV-GRS) 25.94 to 42.76; RV global circumferential strain (RV-GCS) -15.26 to -18.61; and RV global longitudinal strain (RV-GLS) -10.31 to -16.78 at 11weeks], as determined by echocardiography and cardiac magnetic resonance tomography. In cultivated RV myocardial tissue slices, contraction force decreased after addition of trametinib and rapamycin but not after addition of DMSO and dasatinib. Improvement of Ca2+ handling, as depicted by a more positive force-frequency relationship and enhanced post-pause potentiation (31.2%), was noted in the trametinib-treated slice. The increase in post-pause potentiation was less pronounced in rapamycin-treated (26%) and absent in dasatinib-treated (<1%) slices. Ex vivo analysis of cultivated and electrically stimulated RV myocardial tissue slices of a patient with RAS-CM showed decreased contractility and improved sarcoplasmic reticulum function after addition of trametinib and in part after addition of rapamycin, but not after addition of dasatinib.

Transcutaneous Electric Nerve Stimulation for Analgesia During Outpatient Endometrial Biopsy: A Randomized Controlled Trial.

To evaluate whether transcutaneous electric nerve stimulation (TENS) decreases pain at the time of outpatient endometrial biopsy. We conducted a randomized, double-blind trial of active TENS compared with placebo TENS at the time of endometrial biopsy. The primary outcome was pain measured on a 0- to 100-mm visual analog scale immediately after biopsy, with secondary outcomes including satisfaction and tolerability of TENS and pain scores at other procedural time points. To detect a 15-mm reduction in pain with a 30-mm SD, 80.0% power, and a significance level of 0.05, 64 participants were required in each arm. From December 2022 to December 2023, 135 participants were randomized with 67 in the placebo TENS arm and 68 in the active TENS arm. Baseline demographic and clinical characteristics were similar between groups. The median (interquartile range) pain score immediately after biopsy was 50 mm (20-80 mm) in the active TENS group and 60 mm (40-100 mm) in the placebo TENS group (P=.039). Pain scores at other time intervals were not statistically significantly different. In a subset analysis, participants with higher-than-median baseline anxiety had postprocedural pain scores (interquartile range) of 50 mm (40-80 mm) in the active TENS group compared with 80 mm (50-100 mm) in the placebo TENS group. Overall satisfaction (interquartile range) with pain control (with 100 mm representing completely satisfied) was 87.5 mm (60-100 mm) for active TENS and 70 mm (41-100 mm) for placebo TENS; 85.3% of active TENS participants would use TENS in a future endometrial biopsy. Minimal side effects were associated with TENS, with one participant reporting itching at the pad sites. Despite a statistical difference in pain scores, a clinical difference was not seen between active and placebo TENS for pain during endometrial biopsy. Satisfaction was higher in the active TENS group, and there were overall minimal side effects associated with TENS. ClinicalTrials.gov, NCT05472740.

Corticospinal excitability and voluntary activation of the quadriceps muscle is not affected by a single session of anodal transcutaneous spinal direct current stimulation in healthy, young adults.

The aim of the present study was to determine if anodal transcutaneous spinal direct current stimulation (tsDCS) affects corticospinal excitability (CSE) and voluntary activation (VA) of the quadriceps femoris muscle (QM). This was a double-blind, randomized study in which spine-shoulder anodal tsDCS (active electrode centered over T11-12, 2.5mA, 20 min) was applied in a seated position. Transcranial magnetic stimulation (TMS) was used to measure motor evoked potentials (MEP) and construct stimulus-response curves in healthy participants (eight females and five males, Experiment 1). VA was measured via the interpolated twitch technique, whereby muscle twitches were evoked using electrical femoral nerve stimulation and TMS (seven females and six males, Experiment 2). Measurements were carried out before, directly, and 30 min after sham and anodal tsDCS (with ≥4days between sessions). There was no interaction between stimulation × time on stimulus-response curve expressed by slope, stimulus intensity corresponding to 50% of the maximal MEP, and peak-to-peak amplitude of the maximal MEP. Maximal voluntary isometric contraction (MVIC) torque did not change and VA was not affected regardless of the QM torque level (25, 50, or 100% of MVIC). A single, twenty-minute session of spine-shoulder anodal tsDCS did not increase CSE and VA of QM during submaximal and maximal contraction. This suggests that neither excitability to a known input nor responsiveness of motoneurons to submaximal and maximal cortical drive were affected by anodal tsDCS.

Effect of subtetanic neuromuscular electrical stimulation on sprint interval exercise.

The study aimed to determine the acute effects of subtetanic neuromuscular electrical stimulation (NMES) combined with active recovery between sprint exercises on blood lactate accumulation, sprint performance, and muscle fatigue. Sixteen healthy young individuals [23(4) years, 10 males] underwent a 1-min rest followed by sprint interval training consisting of four 15-sec maximal sprint exercises with three 5-min active cycling sessions. Participants engaged in voluntary cycling at 40% of peak oxygen consumption, with or without NMES (VOLES or VOL; interventions). Blood lactate concentration ([La]b) was assessed at the end of the rest and each intervention periods. Mean power was assessed during each sprint exercise session. Maximum voluntary contraction (MVC) of the knee extensor was measured before and after sprint interval training to evaluate muscle fatigue. The [La]b was significantly higher in VOLES than in VOL (main effect, P=0.037). Mean power did not differ between conditions (main effect and interaction, P>0.050). MVC after sprint interval exercise was significantly lower in VOLES than in VOL (interaction, P<0.001). Subtetanic NMES combined with voluntary cycling enhanced blood lactate accumulation and induced greater voluntary fatigue but resulted in similar peripheral muscle fatigue and sprint exercise performance compared with voluntary cycling without NMES.

Vagal stimulation ameliorates murine colitis by regulating SUMOylation.

Inflammatory bowel diseases (IBDs) are chronic debilitating conditions without cure, the etiologies of which are unknown, that shorten the lifespans of 7 million patients worldwide by nearly 10%. Here, we found that decreased autonomic parasympathetic tone resulted in increased IBD susceptibility and mortality in mouse models of disease. Conversely, vagal stimulation restored neuromodulation and ameliorated colitis by inhibiting the posttranslational modification SUMOylation through a mechanism independent of the canonical interleukin-10/α7 nicotinic cholinergic vagal pathway. Colonic biopsies from patients with IBDs and mouse models showed an increase in small ubiquitin-like modifier (SUMO)2 and SUMO3 during active disease. In global genetic knockout mouse models, the deletion of Sumo3 protected against development of colitis and delayed onset of disease, whereas deletion of Sumo1 halted the progression of colitis. Bone marrow transplants from Sumo1-knockout (KO) but not Sumo3-KO mice into wild-type mice conferred protection against development of colitis. Electric stimulation of the cervical vagus nerve before the induction of colitis inhibited SUMOylation and delayed the onset of colitis in Sumo1-KO mice and resulted in milder symptoms in Sumo3-KO mice. Treatment with TAK-981, a first-in-class inhibitor of the SUMO-activating enzyme, ameliorated disease in three murine models of IBD and reduced intestinal permeability and bacterial translocation in a severe model of the disease, suggesting the potential to reduce progression to sepsis. These results reveal a pathway of vagal neuromodulation that reprograms endogenous stress-adaptive responses through inhibition of SUMOylation and suggest SUMOylation as a therapeutic target for IBD.