Short-term microcurrent electrical neuromuscular stimulation to improve muscle function in the elderly: A randomized, double-blinded, sham-controlled clinical trial

Population-specific equations of age-related maximum handgrip force: a comprehensive review

Background

The measurement of handgrip force responses is important in many aspects, for example: to complement neurological assessments, to investigate the contribution of muscle mass in predicting functional outcomes, in setting realistic treatment goals, evaluating rehabilitation strategies. Normative data about handgrip force can assist the therapist in interpreting a patient's results compared with healthy individuals of the same age and gender and can serve as key decision criteria. In this context, establishing normative values of handgrip strength is crucial. Hence, the aim of the this study is to develop a tool that could be used both in rehabilitation and in the prevention of work-related musculoskeletal disorders. This tool takes the form of population-specific predictive equations, which express maximum handgrip force as a function of age.

Methodology

In order to collect data from studies measuring maximum handgrip force, three databases were searched. The search yielded 5,058 articles. Upon the removal of duplicates, the screening of abstracts and the full-text review of potentially relevant articles, 143 publications which focussed on experimental studies on various age groups were considered as fulfilling the eligibility criteria. A comprehensive literature review produced 1,276 mean values of maximum handgrip force.

Results

A meta-analysis resulted in gender- and world region-specific (general population, USA, Europe and Asia) equations expressing maximum force as a function of age. The equations showed quantitative differences and trends in maximum handgrip force among age, gender and national groups. They also showed that values of maximum handgrip force are about 40% higher for males than for females and that age-induced decrease in force differs between males and females, with a proved 35% difference between the ages of 35 and 75. The difference was lowest for the 60-64 year olds and highest for the 18-25 year-olds. The equations also showed that differences due to region are smaller than those due to age or gender.

Conclusions

The equations that were developed for this study can be beneficial in setting population-specific thresholds for rehabilitation programmes and workstation exposure. They can also contribute to the modification of commonly used methods for assessing musculoskeletal load and work-related risk of developing musculoskeletal disorders by scaling their limit values.

Bioelectric medicine: unveiling the therapeutic potential of micro-current stimulation

Bioelectric medicine (BEM) refers to the use of electrical signals to modulate the electrical activity of cells and tissues in the body for therapeutic purposes. In this review, we particularly focused on the microcurrent stimulation (MCS), because, this can take place at the cellular level with sub-sensory application unlike other stimuli. These extremely low-level currents mimic the body's natural electrical activity and are believed to promote various physiological processes. To date, MCS has limited use in the field of BEM with applications in several therapeutic purposes. However, recent studies provide hopeful signs that MCS is more scalable and widely applicable than what has been used so far. Therefore, this review delves into the landscape of MCS, shedding light on the multifaceted applications and untapped potential of MCS in the realm of healthcare. Particularly, we summarized the hierarchical mediation from cell to whole body responses by MCS including its physiological applications. Our final objective of this review is to contribute to the growing body of literature that unveils the captivating potential of BEM, with MCS poised at the intersection of technological innovation and the intricacies of the human body.

Do Electrical Stimulation Devices Reduce Pain and Improve Function?-A Comparative Review

BACKGROUND

Multiple forms of electrical stimulation (ES) potentially offer widely varying clinical benefits. Diminished function commonly associated with acute and chronic pain lessens productivity and increases medical costs. This review aims to compare the relative effects of various forms of ES on functional and pain outcomes.

METHODS

A comprehensive literature search focused on studies of commonly marketed forms of ES used for treatment of pain and improvement of function. Peer-reviewed manuscripts were categorized as "Important" (systematic review or meta-analysis, randomized controlled trial, observational cohort study) and "Minor" (retrospective case series, case report, opinion review) for each identified form of ES.

RESULTS AND DISCUSSION

Varying forms of ES have markedly different technical parameters, applications, and indications, based on clinically meaningful impact on pain perception, function improvement, and medication reduction. Despite being around for decades, there is limited quality evidence for most forms of ES, although there are several notable exceptions for treatment of specific indications. Neuromuscular electrical stimulation (NMES) has well-demonstrated beneficial effects for rehabilitation of selective spinal cord injured (SCI), post-stroke, and debilitated inpatients. Functional electrical stimulation (FES) has similarly shown effectiveness in rehabilitation of some stroke, SCI, and foot drop outpatients. H-Wave® device stimulation (HWDS) has moderate supportive evidence for treatment of acute and refractory chronic pain, consistently demonstrating improvements in function and pain measures across diverse populations. Interestingly, transcutaneous electrical nerve stimulation (TENS), the most widely used form of ES, demonstrated insignificant or very low levels of pain and functional improvement.

CONCLUSION

Ten of 13 reviewed forms of ES have only limited quality evidence for clinically significant reduction of pain or improvement of function across different patient populations. NMES and FES have reasonably demonstrated effectiveness, albeit for specific clinical rehabilitation indications. HWDS was associated with the most clinically significant outcomes, in terms of functional improvement combined with reduction of pain and medication use. More rigorous long-term clinical trials are needed to further validate appropriate use and specific indications for most forms of ES.

LEVEL OF EVIDENCE

II.

Physiological effects of microcurrent and its application for maximising acute responses and chronic adaptations to exercise

Microcurrent is a non-invasive and safe electrotherapy applied through a series of sub-sensory electrical currents (less than 1 mA), which are of a similar magnitude to the currents generated endogenously by the human body. This review focuses on examining the physiological mechanisms mediating the effects of microcurrent when combined with different exercise modalities (e.g. endurance and strength) in healthy physically active individuals. The reviewed literature suggests the following candidate mechanisms could be involved in enhancing the effects of exercise when combined with microcurrent: (i) increased adenosine triphosphate resynthesis, (ii) maintenance of intercellular calcium homeostasis that in turn optimises exercise-induced structural and morphological adaptations, (iii) eliciting a hormone-like effect, which increases catecholamine secretion that in turn enhances exercise-induced lipolysis and (iv) enhanced muscle protein synthesis. In healthy individuals, despite a lack of standardisation on how microcurrent is combined with exercise (e.g. whether the microcurrent is pulsed or continuous), there is evidence concerning its effects in promoting body fat reduction, skeletal muscle remodelling and growth as well as attenuating delayed-onset muscle soreness. The greatest hindrance to understanding the combined effects of microcurrent and exercise is the variability of the implemented protocols, which adds further challenges to identifying the mechanisms, optimal patterns of current(s) and methodology of application. Future studies should standardise microcurrent protocols by accurately describing the used current [e.g. intensity (μA), frequency (Hz), application time (minutes) and treatment duration (e.g. weeks)] for specific exercise outcomes, e.g. strength and power, endurance, and gaining muscle mass or reducing body fat.

The Potential of Electrical Stimulation and Smart Textiles for Patients with Diabetes Mellitus

Diabetes mellitus is one of the most frequent diseases in the general population. Electrical stimulation is a treatment modality based on the transmission of electrical pulses into the body that has been widely used for improving wound healing and for managing acute and chronic pain. Here, we discuss recent advancements in electroceuticals and haptic/smart devices for quality of life and present in which patients and how electrical stimulation may prove to be useful for the treatment of diabetes-related complications.

Comparative evaluation of effect of microcurrent electrical stimulation on acupoints to control gag reflex in patients receiving prosthodontic treatment: An in vivo study

Aims

The aim of this study is to see if microcurrent electrical stimulation on two acupoints, auricular and Hegus, can help patients prevent their gag reflex.

Settings and Design

This was an in vivo cross-sectional study.

Materials and Methods

Thirty patients were randomly assigned to three groups: A, B, or C, of ten patients present in each group. Group A and Group B undergone electroacupuncture (microcurrent electrical stimulation) using electroacupuncture device on auricular point and Hegus point (Li 4), respectively, for 1 min and Group C formed the placebo group, point Shou San Li (Li 10). The gag severity index and the gag prevention index were used to measure the gag reflex, which was done in two steps.

Statistical Analysis Used

SPSS (SPSS Inc., Chicago IL, USA) version 24 software was used for statistical analysis. Paired t-test, one-way analysis of variance test, post hoc Bonferroni test was used to analyse and compare the data.

Results

It was found that Point A and Point B were significantly effective in reducing the severity of gag reflex. Point C demonstrated insignificant results. In addition, Point B (Hegus [Li4]) is more effective than Point A (auricular) in controlling the gag reflex in patients within the set age group of 20-70 years of age.

Conclusions

Microcurrent electrical stimulation is a useful adjuvant in the treatment of unfavorable gag reflexes during routine dental procedures. Point Hegus and point auricular acupuncture are both useful in decreasing the severity of gag reflex, with point Hegus being more effective than point auricular.

Effects of Acute Microcurrent Electrical Stimulation on Muscle Function and Subsequent Recovery Strategy

Microcurrent electrical neuromuscular stimulation (MENS) is believed to alter blood flow, increasing cutaneous blood perfusion, with vasodilation and hyperemia. According to these physiological mechanisms, we investigated the short-term effects of MENS on constant-load exercise and the subsequent recovery process. Ten healthy subjects performed, on separate days, constant-load cycling, which was preceded and followed by active or inactive stimulation to the right quadricep. Blood lactate, pulmonary oxygen, and muscle deoxyhemoglobin on-transition kinetics were recorded. Hemodynamic parameters, heart rate variability, and baroreflex sensitivity were collected and used as a tool to investigate the recovery process. Microcurrent stimulation caused a faster deoxyhemoglobin (4.43 ± 0.5 vs. 5.80 ± 0.5 s) and a slower VO₂ (25.19 ± 2.1 vs. 21.94 ± 1.3 s) on-kinetics during cycling, with higher lactate levels immediately after treatments executed before exercise (1.55 ± 0.1 vs. 1.40 ± 0.1 mmol/L) and after exercise (2.15 ± 0.1 vs. 1.79 ± 0.1 mmol/L). In conclusion, MENS applied before exercise produced an increase in oxygen extraction at muscle microvasculature. In contrast, MENS applied after exercise improved recovery, with the sympathovagal balance shifted toward a state of parasympathetic predominance. MENS also caused higher lactate values, which may be due to the magnitude of the muscular stress by both manual treatment and electrical stimulation than control condition in which the muscle received only a manual treatment.

Effects of adding post-workout microcurrent in males cross country athletes

Post-exercise microcurrent based treatments have shown to optimise exercise-induced adaptations in athletes. We compared the effects of endurance training in combination with either, a microcurrent or a sham treatment, on endurance performance. Additionally, changes in body composition, post-exercise lactate kinetics and perceived delayed onset of muscle soreness (DOMS) were determined. Eighteen males (32.8 ± 6.3 years) completed an 8-week endurance training programme involving 5 to 6 workouts per week wearing a microcurrent (MIC, n=9) or a sham (SH, n=9) device for 3-h post-workout or in the morning during non-training days. Measurements were conducted at pre- and post-intervention. Compared to baseline, both groups increased (P < 0.01) maximal aerobic speed (MIC, pre = 17.6 ± 1.3 to post=18.3 ± 1.0; SH, pre=17.8 ± 1.5 to post = 18.3 ± 1.3 km^.h^-1) with no changes in V˙O_2peak. No interaction effect per group and time was observed (P=0.193). Although both groups increased (P < 0.05) trunk lean mass (MIC, pre=23.2 ± 2.7 to post=24.2 ± 2.0; SH, pre=23.4 ± 1.7 to post=24.3 ± 1.6 kg) only MIC decreased (pre=4.8 ± 1.5 to post=4.5 ± 1.5, p=0.029) lower body fat. At post-intervention, no main differences between groups were observed for lactate kinetics over the 5 min recovery period. Only MIC decreased (P<0.05) DOMS at 24-h and 48-h, showing a significant average lower DOMS score over 72-h after the completion of the exercise-induced muscle soreness protocol. In conclusion, a 3-h daily application of microcurrent over an 8-week endurance training programme produced no further benefits on performance in endurance-trained males. Nonetheless, the post-workout microcurrent application promoted more desirable changes in body composition and attenuated the perception of DOMS over 72-h post-exercise.

Effects of Microcurrent on Oxygen Saturation by Controlling Rectus Abdominis Activity in Preterm Infant With Desaturation During Feeding: A Pilot Study

Objective: To determine whether a portable microcurrent therapy device (PMTD) of the rectus abdominis muscles is effective for treating desaturation during feeding in preterm infants and to evaluate the association between initial electrical activity of respiratory muscle and long-term development delay. Methods: Twenty preterm infants with desaturation during feeding were recruited. Respiratory muscle activity was quantified by calculating the root mean square (RMS) of the electromyography. All preterm infants received a 30 min PMTD application to the rectus abdominis and diaphragm daily for 2 weeks. RMS of diaphragm and rectus abdominis, feeding volume, frequency of desaturation during feeding at baseline (pre-PMTD) and 1, 2 week post-PMTD were measured. The number of days it took to treat desaturation after PMTD was measured. A Denver developmental screening test was performed and infants were divided into 3 groups: (1) normal; (2) caution; and (3) delayed at 3months after PMTD. Results: The desaturation during feeding of all the preterm infants subsided after PMTD and the mean days took to treat desaturation was 25.4 ± 14.2 days. The RMS of diaphragm, rectus abdominis, and frequency of desaturation during feeding were significantly decreased and the feeding volume was significantly increased after PMTD (p < 0.01). The mean treatment duration for desaturation was negatively correlated with RMS of rectus abdominis at baseline and 1 week post-PMTD, respectively (Pearson's correlation coefficient = -0.461,-0.514, p-value = 0.047, 0.029). RMS of rectus abdominis of Group 3 is lower than that of group 1 and 2 (p < 0.01). Conclusions: This pilot study showed that the microcurrent therapy of rectus abdominis is an efficient therapy for the treatment of preterm infants with desaturation during feeding, especially preterm infants with higher activity of the rectus abdominis. In preterm infants with lower rectus abdominis activity, longer time is required to treat desaturation by microcurrent therapy and developmental delay is observed at months post-treatment.

Microcurrent therapy in the treatment of knee osteoarthritis: could it be more than a placebo effect? A randomized controlled trial

BACKGROUND

Microcurrent therapy (MCT) is a novel electrotherapy modality with very low current-levels that may reduce pain especially in joints and muscles.

AIM

The aim of this study is to explore potential effects of MCT on pain in patients with knee osteoarthritis, to explore effects of different treatment parameters and to distinguish them from placebo-effects.

DESIGN

Randomized four arms controlled clinical trial.

SETTING

Outpatient tertiary medical care center.

POPULATION

Fifty-six patients with knee OA (Kellgren-Lawrence Score II or III, 14 male and 38 female, mean age: 71.7±7.3 years, pain intensity higher than Numeric Rating Scale [NRS] score 3 from 10).

METHODS

Patients were randomized into four groups: MCT with 100 µA (group A), MCT with 25 µA (group B), sham-treatment (group C) and a control-group without intervention. Treatment groups received 10 sessions of MCT for 30 minutes each over a period of 22 days. The primary outcome was daily pain intensity throughout the treatment period measured by a NRS from 0-10. Second outcome measurements were the Knee Osteoarthritis Outcome Score (KOOS), the SF-36 Questionnaire, the Six-Minute Walking Test and the Get-Up-and-Go Test.

RESULTS

Evening pain was reduced significantly in the verum-groups compared to sham group (Group A vs. Group C: P<0.001, Group B vs. Group C: P=0.006) and to no intervention (Group A vs. Group D: P<0.001, Group B vs. Group D: P=0.002). The difference between sham-therapy and no therapy was not significant. In the pre-post analysis of the KOOS group A improved significantly in the subscale Symptoms. Group A and B and D improved in the Activities of Daily Living subscale.

CONCLUSIONS

The results of this RCT suggest that MCT has beneficial effects on pain in patients with knee osteoarthritis that are not explained by a placebo effect. Due to the explorative, pilot character of the study, further confirmation is needed before clear recommendations can be given.

CLINICAL REHABILITATION IMPACT

More high-quality RCTs with transparent parameters should be investigated to elucidate potential effects of MCT in the field of physical medicine and rehabilitation. At the present time MCT is a treatment option that could be helpful, in particular for patients who are afraid of unpleasant sensations from electrotherapy with stronger currents.

Electrical Stimulation of Muscle: Electrophysiology and Rehabilitation

The generation of action potentials in intramuscular motor and sensory axons in response to an imposed external current source can evoke muscle contractions and elicit widespread responses throughout the nervous system that impact sensorimotor function. The benefits experienced by individuals exposed to several weeks of treatment with electrical stimulation of muscle suggest that the underlying adaptations involve several physiological systems, but little is known about the specific changes elicited by such interventions.

Effectiveness of combining microcurrent with resistance training in trained males

Introduction

Microcurrent has been used to promote tissue healing after injury or to hasten muscle remodeling post exercise post exercise.

Purpose

To compare the effects of resistance training in combination with either, microcurrent or sham treatment, on-body composition and muscular architecture. Additionally, changes in performance and perceived delayed onset muscle soreness (DOMS) were determined.

Methods

Eighteen males (25.7 ± 7.6 years) completed an 8-week resistance training program involving 3 workouts per week (24 total sessions) wearing a microcurrent (MIC, n = 9) or a sham (SH, n = 9) device for 3-h post-workout or in the morning during non-training days. Measurements were conducted at pre and post intervention.

Results

Compared to baseline, both groups increased (p < 0.05) muscle thickness of the elbow flexors (MIC + 2.9 ± 1.4 mm; SH + 3.0 ± 2.4 mm), triceps brachialis (MIC + 4.3 ± 2.8 mm; SH + 2.7 ± 2.6 mm), vastus medialis (MIC + 1.5 ± 1.5 mm; SH + 0.9 ± 0.8 mm) and vastus lateralis (MIC + 6.8 ± 8.0 mm; SH + 3.2 ± 1.8 mm). Although both groups increased (p < 0.01) the pennation angle of vastus lateralis (MIC + 2.90° ± 0.95°; SH + 1.90° ± 1.35°, p < 0.01), the change measured in MIC was higher (p = 0.045) than that observed in SH. Furthermore, only MIC enlarged (p < 0.01) the pennation angle of brachialis (MIC + 1.93 ± 1.51). Both groups improved (p < 0.05) bench press strength and power but only MIC enhanced (p < 0.01) vertical jump height. At post intervention, only MIC decreased (p < 0.05) DOMS at 12-h, 24-h, and 48-h after performing an exercise-induced muscle soreness protocol.

Conclusion

A 3-h daily use of microcurrent maximized muscular architectural changes and attenuated DOMS with no added significant benefits on body composition and performance.

Comparative Study of Pain Relief in Two Non-Pharmacological Treatments in Patients with Partial Rotator Cuff Tears: A Randomized Trial

Background

Pain induction is the primary characteristic of a rotator cuff tear while muscle weakness appears as a secondary feature, leading to further disability.

Objectives

The study aimed to determine the effectiveness of physiotherapeutic interventions through transcutaneous electrical nerve stimulation (TENS) or microcurrent electrical nerve stimulation (MENS) in conjunction with kinesiotherapy in patients with partial thickness rotator cuff tear.

Methods

This was a blinded randomized prospective study. The study recruited 42 outpatients with partial rotator cuff tear under conservative treatment selected from the 401 General Military Hospital of Athens and the University General Hospital ‘Attikon’ during 2015 - 2017. Patients were assessed for pain and disability using the SPADI (shoulder pain and disability index), a numerical rating scale (NRS) for pain, and the EuroQoL-5 questionnaire for the evaluation of the quality of life. The first group received TENS and kinesiotherapy while the second group received MENS and kinesiotherapy. Three measurements were recorded. The first assessment was performed during the initial patient visit; the second after completion of the physiotherapeutic sessions, and the third one three months after the initial assessment. A follow-up ultrasound scan was performed three months after the completion of the therapeutic sessions to assess the anatomical healing of the rotator cuff tear.

Results

Repeated measurements analysis indicated a significant improvement in pain scores, functionality, and patients’ quality of life (P value < 0.001). Comparison of the two treatment methods did not reveal any significant differences (P value > 0.05) despite the fact that the MENS was associated with a greater improvement in pain intensity and TENS with a greater improvement in functionality and quality of life.

Conclusions

Using MENS and TENS appears to be equally effective in terms of pain relief, functional improvement, and quality of life enhancement in patients.

Effects of whole-body ELECTROMYOSTIMULATION on health and performance: a systematic review

BACKGROUND

Whole-body electrical myostimulation (WB-EMS) is a relatively recent training methodology that has been extraordinarily used in recent years. However, there is a lack of consensus on the effectiveness of WB-EMS in the situations in which its use has been largely popularized. The objective of this systematic review was to determine the effects produced by WB-EMS.

METHODS

A search of PubMed, Web of Science, Scopus and Cochrane was performed to identify all the studies that have applied electrical stimulation in lower and upper limbs simultaneously and that have clearly presented their protocols for the training and application of the stimulation. The last search was performed on September 9, 2018. Studies written in English or German were included.

RESULTS

A total of 21 articles met the inclusion criteria and were analyzed following the guidelines of the Cochrane Guide for Systematic Reviews. Nineteen studies analyzed the chronic effects of WB-EMS, and 2 analyzed acute effects with a total of 505 subjects (310 men and 195 women). In total, 35% were moderately trained, and 65% were sedentary subjects. Different dependent variables were studied, such as anthropometric parameters, strength parameters, energy expenditure, psychophysiological parameters and blood parameters. There is a lack of randomized controlled studies, and the studies included exhibit a moderate to high level of risk of bias.

CONCLUSIONS

Given the limited number of available studies on WB-EMS, the scarce amount of scientific evidence found does not allow definitive conclusions about its effects; therefore, future studies about WB-EMS are necessary.