Normal trunk muscle strength and endurance in women and the effect of exercises and electrical stimulation. Part 2: Comparative analysis of electrical stimulation and exercises to increase trunk muscle strength and endurance

Therapeutic Effectiveness of AxioBionics Wearable Therapy Pain Management System in Patients with Chronic Lower Back Pain

Chronic lower back pain is one of the most common medical conditions leading to a significant decrease in quality of life. This study retrospectively analyzed whether the AxioBionics Wearable Therapy Pain Management (WTPM) System, a customized and wearable electrical stimulation device, alleviated chronic lower back pain, and improved muscular function. This study assessed self-reported pain levels using the visual analog scale before and during the use of the AxioBionics WTPM System when performing normal activities such as sitting, standing, and walking (n = 69). Results showed that both at-rest and activity-related pain were significantly reduced during treatment with the AxioBionics WTPM System (% reduction in pain: 64% and 60%, respectively; P < .05). Thus, this study suggests that the AxioBionics WTPM System is efficacious in treating chronic lower back pain even when other therapies have failed to sufficiently decrease reported pain levels.

[Electrical muscle stimulation in combination with heat for patients with chronic, nonspecific low back pain : A randomized, double-blind, stratified, placebo-controlled clinical trial]

BACKGROUND

Chronic non-specific low back pain (LBP) causes more disability than any other medical condition worldwide. Electrical muscle stimulation in combination with heat (EMS/H) for management of LBP has yet not been properly studied. Our hypothesis was that EMS/H provides better pain relief and improves subjective and objective data compared to standard treatment.

METHODS

Between 2015 and 2017, we conducted a 6 week randomized, double-blind, stratified, placebo controlled clinical trial, comparing two different forms of EMS/H with placebo treatment with a follow-up 12 weeks after randomization. Patients >18 years with LBP for >6 months and a pain intensity of numerical rating scale (NRS) ≥4/10 were enrolled.

RESULTS

A total of 100 patients were recruited. Patients were representative of a LBP population with moderate to severe pain (NRS 5.7/10). After 18 treatments, we found a statistically significant pain reduction, which was also observed at the 12 week follow-up.

CONCLUSION

EMS/H is an effective and safe method for managing LBP. A clinically relevant and persisting pain reduction, a stable decrease in self-perceived disability, an improvement in both mood and affective characterization as well as sensory characterization of pain, muscle strength and endurance may have a significant impact on the management of LBP.

The Impact of Whole-Body Electromyostimulation on Body Posture and Trunk Muscle Strength in Untrained Persons

Muscular imbalances of the trunk muscles are held responsible for changes in body posture. At the same time, whole-body electromyostimulation (WB-EMS) has been established as a new training method that enables simultaneous stimulation of many muscle groups. This study was aiming to analyze if a 10 weeks WB-EMS training changes posture-relevant parameters and/or improves isometric strength of the trunk extensors and flexors, and if there are differences based on stimulation at 20 Hz and 85 Hz. Fifty eight untrained adult test persons were divided into three groups (control, CON; training with 20 Hz stimulation, TR20; training with 85 Hz, TR85). Anthropometric parameters, trunk extension and flexion forces and torques, and posture parameters were determined before (n = 58) and after (n = 53: CON: n = 15, TR20: n = 19, TR85: n = 19) a 10 weeks WB-EMS training program (15 applications, 9 exercises). Differences between the groups were calculated for pre- and post-tests using univariate ANOVA and between the test times using repeated (2 × 3) ANOVA. Comparisons of pairs were calculated post hoc based on Fisher (LSD). No differences between the groups were found for the posture parameters. The post hoc analysis of both trunk flexion and trunk extension forces and torques showed a significant difference between the groups TR85 and CON but no difference between the other group pairs. A 10 weeks whole-body electrostimulation training with a stimulation frequency of 85 Hz in contrast to training with a stimulation frequency of 20 Hz improves the trunk muscle strength of an untrained group but does not significantly change posture parameters.

Electrical Stimulation of Back Muscles Does Not Prime the Corticospinal Pathway

OBJECTIVES

To investigate whether peripheral electrical stimulation (PES) of back extensor muscles changes excitability of the corticospinal pathway of the stimulated muscle and synergist trunk muscles.

METHODS

In 12 volunteers with no history of low back pain (LBP), intramuscular fine-wire electrodes recorded electromyography (EMG) from the deep multifidus (DM) and longissimus muscles. Surface electrodes recorded general EMG from the erector spinae and abdominal muscles. Single- and paired-pulse transcranial magnetic stimulation (TMS) paradigms tested corticospinal excitability, short-interval intracortical inhibition (SICI-2 and 3 ms), and intracortical facilitation (ICF) optimized for recordings of DM. Active motor threshold (aMT) to evoke a motor-evoked potential (MEP) in DM was determined and stimulation was applied at 120% of this intensity. PES was provided via electrodes placed over the right multifidus. The effect of 20-min PES (ramped motor activation) was studied.

RESULTS

Mean aMT for DM was 42.7 ± 10% of the maximal stimulator output. No effects of PES were found on MEP amplitude (single-pulse TMS) for any trunk muscles examined. There was no evidence for changes in SICI or ICF; that is, conditioned MEP amplitude was not different between trials after PES.

CONCLUSION

Results indicate that, unlike previous reports that show increased corticospinal excitability of limb muscles, PES of back muscles does not modify the corticospinal excitability. This difference in response of the motor pathway of back muscles to PES might be explained by the lesser importance of voluntary cortical drive to these muscles and the greater role of postural networks. Whether PES influences back muscle training remains unclear, yet the present results suggest that potential effects are unlikely to be explained by the effects of PES at corticospinal level with the parameters used in this study.

The Strengthening Effect of Electrical Stimulation on Lumbar Paraspinal Muscles in the Sitting Position: A Randomized Controlled Trial

BACKGROUND

Sedentary lifestyle, a prevalent finding in modern society, can lead to weakness of the lumbar trunk musculature. Electrical stimulation (ES), in addition to lumbar strengthening exercises, has been shown to increase muscle strength.

OBJECTIVE

To assess the strengthening effect of ES on the lumbar paraspinal muscles during prolonged sitting.

DESIGN

Randomized, controlled, single-blind study.

SETTING

Tertiary hospital.

PARTICIPANTS

Thirty healthy subjects without low back pain.

METHODS

Thirty participants were randomly assigned to the ES group (n = 15) or the control group (n = 15). ES was administered over the lumbar paraspinal muscles, while subjects maintained a seated posture, at a maximal tolerable intensity for 60 minutes per day, three times per week, for 4 consecutive weeks. An identical protocol was used in the control group with muscle stimulation provided at the minimal sensory threshold intensity.

MAIN OUTCOME MEASUREMENTS

The isokinetic strength of the lumbar paraspinal muscles was evaluated at baseline, 4 weeks after the initiation of ES, and 8 weeks after the initiation of ES with an isokinetic dynamometer (Biodex Medical Dynamometer System-4) at 60°/s and 120°/s angular velocities.

RESULTS

The extension and flexion peak torque at 60°/s showed no significant interaction between the time and intervention or between the interventions. However, after 4 weeks of ES in the sitting position, the isokinetic extensor trunk muscle strength measured at 120°/s angular velocity significantly increased in the ES group (P < .05) compared with that in the control group. This effect was not maintained when measured at 4 weeks after the cessation of ES.

CONCLUSIONS

ES in a sitting position is a potentially effective and accessible rehabilitation treatment, which can lead to short-term improvement in the extensor trunk muscle strength of the lumbar paraspinal muscles.

LEVEL OF EVIDENCE

I.

Effects of therapeutic ultrasound and electrical stimulation program on pain, trunk muscle strength, disability, walking performance, quality of life, and depression in patients with low back pain: a randomized-controlled trial

The aim of this trial is to investigate and compare the effects of electrical stimulation (ES) program and ultrasound (US) therapy on pain, disability, trunk muscle strength, walking performance, spinal mobility, quality of life (QOL), and depression in the patients with chronic low back pain (CLBP). A total of 59 patients with definite CLBP were enrolled in this study. These patients were randomized into three groups. Group 1 (n = 20) was given an ES program and exercises. Group 2 (n = 19) was given an US treatment and exercises. Group 3 (n = 20) was accepted as the control group and was given only exercises. All of the programs were performed 3 days a week, for 6 weeks. The patients were evaluated according to pain, disability, walking performance, endurance, mobility, QOL, depression. The trunk muscle strength was measured with a hand-held dynamometer. All of the groups showed stastically significant improvements in pain, disability, muscle strength, endurance, walking performance, mobility, sub-scores of SF 36, and depression when compared with their initial status. The intergroup comparison showed significant difference in physical function, energy and social function sub-groups of SF-36, VAS pain, extensor muscle strength, between three groups. This difference was statistically significant in the groups 1 and 2 compared to the control group. There was also no significant difference between the groups 1 and 2. We observed that US treatment and ES treatment were effective in improving pain, isometric extensor muscle strength, and QOL in patients with CLBP.

Effect of electrical stimulation on musculoskeletal systems; a meta-analysis of controlled clinical trials

This study was a meta-analysis to examine whether electrical stimulation has specific effects in the healing of musculoskeletal repair process and in the diminution of symptoms with bone and joint disorders. Using MEDLINE (1966-1999) and EMBASE (1985-1999) a search for articles was carried out with four medical subject headings. Data were extracted from all the accessed articles and additionally collected from appropriate journal lists. A total of 20 randomized controlled trials on bones was identified which assessed healing of fractures, bone graft, and other conditions; and 29 randomized controlled trials on soft tissues and joints were also found, dealing with healing of skin wounds or dermal ulcers, soft tissue injury, and other conditions. Using criteria through which the quality of studies was assessed, the content of the articles was reorganized into a tabular form. The majority of the identified articles reported positive findings, but all the trials showed methodological flaws to some extent. Because of heterogeneity of the studies and the various outcome measurements, pooling of only part of the data was performed. The combined results of 12 trials on bones and 16 trials on soft tissues, the cases in which major endpoints were mainly union or healing rate, revealed statistically significant effects. The studies in this review had some methodological limitations, and the selected pooled trials do not constitute acceptable proof that electrical stimulation has specific effects on health. However, one cannot ignore the statistically significant positive findings reported in the trials, from which extracted data were able to be combined.

Electrical muscle stimulation as an adjunct to exercise therapy in the treatment of nonacute low back pain: A randomized trial

A prospective, randomized, double-blind, placebo-controlled clinical trial was performed to investigate the efficacy of electrical muscle stimulation when combined with a therapist-guided, standardized exercise therapy program in the treatment of nonacute low back pain. Eighty patients with low back pain of at least 6 weeks' duration were randomized into the following 2 groups: standardized exercise therapy with functional electrical muscle stimulation or standardized exercise therapy with placebo electrical stimulation. Subjects were evaluated at baseline, 2 months, and 6 months with a standardized back pain questionnaire and objective measurements of lumbar spine function. Exercise therapy was continued for 6 months, but electrical stimulation was discontinued at the 2-month interval. Of the 80 patients initially enrolled, 42 discontinued or withdrew before completing the entire study protocol. At the 2-month follow-up interval, subjects in the treatment group had statistically significantly improved lumbar spine function compared with the control subjects. This effect continued during the last 4 months of the study after electrical stimulation had been discontinued. This suggests that electrical muscle stimulation can be an effective adjunctive treatment modality for nonacute low back pain. The effects of this combined therapy seem to last beyond the duration of electrical stimulation treatment.

Electrical stimulation: a reflection on current clinical practices

This paper briefly reviews the basic principles of several clinical applications of electrical stimulation for therapeutic purposes. It is intended to facilitate the integration of electrical stimulation into routine clinical practice by clarifying the terminology and standard conventions of the field, explaining the delivery capabilities of common electrical stimulators commercially available for clinical use, summarizing several examples of evidence-based therapeutic applications, and providing guidelines for selection of most commonly used treatment parameters. Rather than an exhaustive survey of the field, the presentation touches broadly on guidelines for use of transcutaneous electrical stimulation employing surface electrodes for the purposes of analgesia (TENS), drug delivery (iontophoresis), or neuromuscular rehabilitation (NMES), as well as other selected clinical applications. The paper is a general review of common clinical practices of electrotherapy and should serve as an introduction to the important factors for clinicians to consider when contemplating electrical stimulation as a treatment option.

Age and physical work capacity

Aging is associated with a progressive decrement in various components of physical work capacity, including aerobic power and capacity, muscular strength and endurance, and the tolerance of thermal stress. A part of the functional loss can be countered by regular physical activity, control of body mass, and avoidance of cigarette smoking. Nevertheless, athletes who continue to train regularly still show a substantial aging of both physiological function and competitive performance, reflecting a deterioration of cardiac pump function, a decrease of muscle strength, and a progressive impairment of heat tolerance. These various changes are of concern to the occupational physician, because of the rising average age of the labor force. In theory, an over-taxing of the heart and skeletal muscles might be thought to lead to a decrease of productivity, manifestations of worker fatigue such as absenteeism, accidents, and industrial disputes, and an increased susceptibility to musculoskeletal injuries, heart attacks, and strokes. However, in practice, the productivity, health, and safety of the older worker pose relatively few problems. Reasons for this paradox are discussed, and it is stressed that in general there is no longer need to push workers to their physical limits because of automation-related changes in methods of production.

Functional electrical stimulation treatment of postradiculopathy associated muscle weakness

Eighteen chronic pain patients (CPPs) with postradiculopathy-associated muscle weakness were entered into a nonrandomized functional electrical stimulation (FES) clinical treatment study to determine if FES can improve postradiculopathy associated muscle weakness. Because of the clinical nature of the unit, the CPPs could not be denied treatments other than FES. To control for these other treatments, the CPPs were used as their own controls with two control conditions, ie, where possible, the contralateral probable normal muscle was used as a control (control 1) and; in a subgroup of CPPs (n = 6), FES treatment was initially withheld to the probable weak muscle (control 2). Strength was measured as isometric maximum voluntary contraction (IMVC) and was used as the outcome treatment variable. IMVC was measured in both the probable weak and contralateral probable normal muscles at entrance into the Pain Center, at beginning of FES treatment, at completion of FES treatment, and for the control 2 condition at the end of the non-FES treatment period. Statistical analyses of the IMVC strength results using the two control conditions indicated (1) both the FES-treated and untreated muscles increased significantly in IMVC strength, (2) improvement in IMVC strength for FES-treated muscles was significantly greater than for probable normal FES-untreated muscles and, (3) improvement in IMVC strength in FES-treated muscles was significantly greater during the FES-treatment period than during the non-FES treatment period. FES treatment of postradiculopathy-associated muscle weakness in CPPs seems to increase the strength of the probable weak muscle above the increase in strength provided by other concurrent treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical applicability of isokinetics: A review

The purpose of this paper is to review the recent advances made in the field of clinical isokinetics. Presentation of various methodological issues is followed by description and discussion of the role of isokinetic dynamometry in the assessment and treatment of orthopaedic disorders, mainly of the knee and trunk regions. Attention is also drawn to the possible application of isokinetics in neurological disorders. The limitations of this technique and its possible future developments conclude the review.