Intra-operator and inter-operator reliability of surface electromyography in the clinical evaluation of back muscles

As a prerequisite to the use of a test battery based on electromyographic (EMG) analysis of the paraspinal muscles for identifying and remedying back muscle dysfunction, the intra- and inter-operator reliability was assessed. Fifteen volunteers underwent EMG tests on three occasions. The test subjects were asked to perform 22 exercises, subdivided into four categories: coordination, stabilization, balance and strength exercises. The time interval between the tests was one week. The myoelectric signals of the multifidus (MF) and iliocostalis lumborum pars thoracis (ICLT) were analysed with regard to amplitude (averaged EMG) and frequency (zero cross rate). The results indicated that the reliability was better for the MF than for the ICLT, and also for exercises at higher loads (strength exercises). In the intra-operator condition, the reproducibility of the averaged EMG was good (ICC>0.75), except for the balance exercises (ICC = 0.40-0.74). In general, the averaged EMG in the inter-operator condition and the zero cross rate in both the intra- and inter-operator conditions are less or poorly reliable. These results demonstrate that when back muscle function is evaluated during coordination, stabilization and strength exercises, only the averaged EMG parameter has acceptable reproducibility over time when assessed by the same operator.     

腰椎间盘突出症患者首次核心稳定性训练前后表面肌电信号分析

目的：分析腰椎间盘突出症患者首次核心稳定性训练前后即刻的表面肌电信号特征。方法收集诊断明确且符合纳入标准的腰椎间盘突出症患者30例,均在专业的治疗师指导下进行一次核心稳定性训练,应用Biering-Sorensen腰背肌等长收缩测试方法,于腰部两侧竖脊肌及多裂肌处记录核心稳定性训练前和训练后即刻的表面肌电信号,并提取平均肌电值（AEMG）、中位频率值（MF）进行统计学分析。结果训练前的痛侧竖脊肌MF值、多裂肌MF值、多裂肌AEMG值均小于非痛侧,差异均有统计学意义（t分别=3.44、6.06、4.02,P均＜0.05）;训练后的痛侧竖脊肌MF值、多裂肌MF值、多裂肌AEMG值仍小于非痛侧,差异均有统计学意义（t分别=2.24、6.27、4.12,P均＜0.05）;训练后痛侧竖脊肌与多裂肌AEMG值较训练前增大,但均差异无统计学意义（t分别=1.65、1.23,P均＞0.05）;训练后痛侧多裂肌MF值较训练前低,差异有统计学意义（t=3.91,P＜0.05）。结论核心稳定性训练可激活腰椎间盘突出症患者腰背部核心肌群,可针对性的应用于深层核心肌群多裂肌的强化训练。     

The Effects of Sling Exercise Using Vibration on Trunk Muscle Activities of Healthy Adults

[Purpose] This study compared the effects of sling exercises with and without vibration on the muscular activity of the internal oblique (IO), rectus abdominis (RA), multifidus (MF), and erector spinae (ES) muscles of healthy adults. [Methods] Eleven healthy university students (11 men) with a mean age of 22.8 years were enrolled in this study. Subjects performed supine and prone bridge exercises with the knees flexed using a sling suspension system with and without vibration. The amplitudes of the EMG activities of selected trunk muscles (internal oblique, rectus abdominis, erector spinae, multifidus) were recorded. Two types of exercise conditions were executed in a random sequence for 5 seconds each. The signals detected from the middle 3 seconds (after discarding the signals of the first and the last one seconds) were used in the analysis. A 3-minute break was given after each exercise to minimize muscle fatigue. [Results] During the supine bridge exercise with vibration, the activities of the IO, RA, MF, and ES muscles were significantly higher than those of the supine bridge exercise without vibration. Additionally, during the prone bridge exercise with vibration, the activities of the IO, RA, MF, and ES were significantly higher than those of the prone bridge exercise without vibration. [Conclusion] Sling exercises with vibration improved the trunk muscle activities of healthy adults compared to the sling exercises without vibration. The information presented here is important for clinicians who use lumbar stabilization exercises as an evaluation tool or a rehabilitation exercise.Key words: Sling exercise, Vibration, Trunk muscle     

慢性腰痛患者深层多裂肌EMG信号时频特征变化

目的:采用表面肌电(sEMG)分析系统结合丝电极观察慢性腰痛(cLBP)患者与健康对照者腰部深层多裂肌的肌电活动,比较二者的EMG信号时域和频域特征,探讨腰痛深层多裂肌功能状态变化。方法:选取22例cLBP患者(10男12女)和30例健康对照者(15男15女)采用一次性无菌针头导入不锈钢丝电极(直径0.16mm)至L4水平深层多裂肌后完成改良BST动作,采集多裂肌最大随意收缩时的EMG信号,比较两组平均肌电值(AEMG)、均方根值(RMS)、中位频率(MF)、平均功率频率(MPF)及其频率的特征差异。结果:cLBP腰部深层多裂肌EMG信号时域指标AEMG、RMS明显低于健康对照组(P0.001);频域指标MF、MPF明显高于对照组(P0.05),MFs、MPFs绝对值明显低于对照组(P=0.001/0.001)。结论:最大等长收缩运动中,cLBP患者腰部深层多裂肌电活动异常,可能是持续疼痛刺激引起多裂肌募集能力降低,耐力代偿性增加。     

Effect of different exercise programs on non-specific chronic low back pain and disability in people who perform sedentary work

BackgroundThis study compared the short- and long-term effects of different exercise programs on lumbar muscle function, cross-sectional area of the multifidus muscle, functional disability and low back pain in people who perform sedentary work.MethodsA total of 70 volunteer women with sedentary occupations suffering from low back pain were randomized to either the lumbar stabilization exercise program group or the lumbar muscle strengthening exercise program group. All subjects entered the 20-week exercise programs. The measurement of the cross-sectional area of the multifidus muscle was executed by using an ultrasound system, isokinetic peak torque was measured applying an isokinetic dynamometer.FindingsThe results indicated that the 20-week exercise programs reduced low back pain and functional disability. Positive effects for the cross-sectional area of the multifidus muscle, functional disability and low back pain lasted for 4 weeks after the application of lumbar muscle strengthening exercise program and for 12 weeks after the application of lumbar stabilization exercise program. The lumbar muscle strength increased and lasted for 8 weeks after both exercise programs.InterpretationThe 20-week lumbar stabilization exercise and muscle strengthening exercise programs were efficacious in decreasing LBP and functional disability in people performing sedentary work, however the lumbar stabilization exercise program was more effective, and this effect lasted for 12 weeks after completion of the program.     

悬吊训练对慢性腰痛患者运动皮质区神经网络的影响

目的:研究悬吊训练对慢性腰痛(chronic low back pain,cLBP)患者运动皮质区神经网络的影响.方法:招募20例cLBP患者和与之年龄等特征相匹配的10例健康对照者,对cLBP患者进行2周悬吊训练干预.使用经颅磁刺激技术记录干预前后cLBP患者和健康对照组多裂肌的运动诱发电位,经过数据处理绘制脑部地形...     

Insertion and Presence of Fine-Wire Intramuscular Electrodes to the Lumbar Paraspinal Muscles Do Not Affect Muscle Performance and Activation During High-Exertion Spinal Extension Activities

Background

Low back pain (LBP) is commonly associated with paraspinal muscle dysfunctions. A method to study deep lumbar paraspinal (ie, multifidus) muscle function and neuromuscular activation pattern is intramuscular electromyography (EMG). Previous studies have shown that the procedure does not significantly impact muscle function during activities involving low-level muscle contractions. However, it is currently unknown how muscular function and activation are affected during high-exertion contractions.

Effects of different verbal instructions on change of lumbar multifidus muscle thickness in asymptomatic adults and in patients with low back pain

Background: Spinal stabilisation exercise has been shown to be effective in the rehabilitation of low back pain (LBP). Due to the isometric nature of spinal stabilisation exercise, manual therapists use various verbal instructions to elicit lumbar multifidus muscle contraction.

Objectives: The purpose of this study was to assess whether or not three verbal instructions would alter muscle thickness of the lumbar multifidus muscle differently in asymptomatic individuals and patients with LBP.

Methods: Three verbal instructions were selected for this study: (1) swell the muscle underneath the transducer, (2) draw your belly button in towards your spinal column and (3) think about tilting your pelvis but without really doing it. Lumbar multifidus muscle thickness was determined using parasagittal ultrasound (US) imaging. Measurements of muscle thickness were collected at rest and during verbal instructions from 21 asymptomatic adults and 21 patients with LBP. Percent changes of muscle thickness during contraction and at rest were compared between groups and across verbal instructions.

Results: ANOVA results showed no significant interaction for both L4-5 and L5-S1, but a significant main effect of verbal instruction (P?=?0.049) at L4-5.Post hoc analysis showed a greater increase with verbal instruction #3 than verbal instruction #2 (P?=?0.009). There was no significant main effect of group at either segment.

Discussion: The results of the study suggest that both groups responded similarly to the three verbal instructions. Verbal instructions may increase lumbar multifidus muscle thickness by different amounts at L4-5, but by the same amount at L5-S1.     

Motor Training of the Lumbar Paraspinal Muscles Induces Immediate Changes in Motor Coordination in Patients With Recurrent Low Back Pain

Recurrent low back pain (LBP) is associated with altered motor coordination of the lumbar paraspinal muscles. Whether these changes can be modified with motor training remains unclear. Twenty volunteers with unilateral LBP were randomly assigned to cognitively activate the lumbar multifidus independently from other back muscles (skilled training) or to activate all paraspinal muscles with no attention to any specific muscles (extension training). Electromyographic (EMG) activity of deep (DM) and superficial multifidus (SM) muscles were recorded bilaterally using intramuscular fine-wire electrodes and that of superficial abdominal and back muscles using surface electrodes. Motor coordination was assessed before and immediately after training as onsets of trunk muscle EMG during rapid arm movements, and as EMG amplitude at the mid-point of slow trunk flexion-extension movements. Despite different intentions of the training tasks, the pattern of activity was similar for both. After both training tasks, activation of the DM and SM muscles was earlier during rapid arm movements. However, during slow trunk movements, DM and SM activity was increased, and EMG activity of the superficial trunk muscles was reduced only after skilled training. These findings show the potential to alter motor coordination with motor training of the lumbar paraspinal muscles in recurrent LBP.     

悬吊运动疗法对产后下背痛的疗效和表面肌电信号观察

目的：观察常规康复基础上辅以悬吊运动疗法对产后下背痛患者的疼痛、日常生活活动能力以及竖脊肌表面肌电信号的影响。方法：32例产后下背痛患者按分娩方式分为观察组和对照组各16例。对照组采用常规康复治疗,观察组在此基础上增加悬吊运动疗法。2组治疗时间均为3d/周,共计4周。于治疗前、后评定患者疼痛相关的视觉模拟量表法（VAS）、简体中文版Oswestry失能问卷(SCODI),于治疗后使用时域指标平均肌电值（AEMG）、平均功率频率（MPF）和中位频率（MF）评价患者竖脊肌的痛侧和对侧表面肌电信号（sEMG）活动,比较2组疗效差异。结果：治疗后,2组患者VAS和SCODI评分均较治疗前明显降低(均P<0.05),且观察组患者VAS和SCODI评分更低于对照组(均P<0.05)。治疗后,观察组痛侧的竖脊肌的MF、MPF均较对照组痛侧下降、AEMG较对照组痛侧升高（均P＜0.05）。结论：常规康复基础上辅以悬吊运动疗法能够明显改善产后下背痛患者的疼痛和日常生活活动能力,同时sEMG变化亦提示悬吊运动疗法对患者竖脊肌功能水平和疲劳程度明显改善。     

Editorial

Abstract

The aim of this study was to compare the magnitude of selective core muscle activation during supine bridging to neutral exercises (three on a stable and three on an unstable surface). Surface EMG analysis was performed on the lumbar multifidus, gluteus medius, gluteus maximus, and hamstrings from 13 male and 13 female subjects. Lumbar multifidus recruitment was not influenced by exercise or condition and ranged between 29.2 and 35.9% of maximum voluntary isometric contraction (MVIC). Peak gluteus medius activation (42.0% MVIC) occurred in unstable single-leg bridge. Maximum recruitment of gluteus maximus (32.6% MVIC) appeared during stable single-leg bridge. Peak hamstring activation (59.6% MVIC) occurred during stable double-leg hamstring curl. Regardless of condition, hamstrings demonstrated high (51.9–59.6% MVIC) muscle recruitment during double-leg hamstring curls compared with the single-leg bridge or double-leg bridge. Various supine bridging to neutral exercises activated the hamstrings at levels conducive to strengthening, whereas recruitment of lumbar multifidus, gluteus medius, and gluteus maximus promoted endurance training. Clinically, we were unable to conclude the unstable support surface was preferable to the stable surface for boosting muscle recruitment of spine stabilizers, gluteals, and hamstring muscles during supine bridge to neutral position.     

艾灸结合中药熏蒸干预对慢性腰肌劳损患者疼痛及腰背功能恢复的影响

目的探究艾灸结合中药熏蒸干预对慢性腰肌劳损患者疼痛及腰背功能恢复的影响.方法选取某院2016年7月至2018年5月诊治的慢性腰肌劳损患者90例,采用随机数表法分为两组,各45例.对照组给予功能康复锻炼干预,观察组在对照组基础上采用艾灸联合中药熏蒸,对比两组临床疗效、治疗前后疼痛评分及腰背功能恢复情况.结果观察组治疗总有效率91.11%,高于对照组的66.67%,差异有统计学意义(P<0.05);观察组治疗后视觉模拟评分法(VAS)评分低于对照组,背肌力高于对照组,腰肌耐力时间长于对照组,差异有统计学意义(P<0.05).结论艾灸结合中药熏蒸干预可有效改善慢性腰肌劳损患者的临床症状,降低其腰痛评分,利于促进腰背功能的恢复,改善预后.     

The effect of six weeks of sling exercise training on trunk muscular strength and endurance for clients with low back pain

[Purpose] The purpose of this study was to investigate the effects of 6 weeks sling exercise training for clients with low back pain on the levels of pain, disability, muscular strength and endurance. [Subjects and Methods] Twelve chronic LBP subjects participated in this study. Subjects were randomly divided into a control group and a training group. Subjects in the training group performed sling exercise training for six weeks, and participants in the control group did not perform any exercise. [Results] Pain, disability levels and muscular strength significantly improved in the training group, but not in the control group. The left multifidus showed a significant improvement in muscular endurance, measured as the slope of the median frequency after training. [Conclusion] Six weeks of sling exercise training was effective at reducing pain intensity, and improving the disability level and trunk muscular strength of subjects with low back pain.Key words: Chronic low back pain, Sling exercise training, Slope of median frequency     

Reliability of measurements of endurance time,electromyographic fatigue and recovery,and associations to activity limitations,in patients with lumbar disc herniation

Background. Electromyographic (EMG) spectral parameters and endurance tests for back muscles have long been used to estimate low‐back muscle fatigue. Purpose. The present purpose was to evaluate the test–retest reliability of a fatigue‐testing protocol and to investigate associations between activity limitations and fatigue in patients with lumbar disc herniation. Methods. To evaluate the reliability, endurance time, EMG spectral parameters and ratings of lumbar muscle fatigue and back pain were measured three times in 15 patients with lumbar disc herniation. The patients performed a modified Sørensen test with concurrent recordings of electromyography from the lumbar muscles at four recording sites. Ratings of their perceived fatigue and pain on a Borg scale were collected simultaneously. Recovery over five minutes was recorded. Questionnaires about activity, participation, self‐efficacy and health were also used. Results. Endurance time had an ICC of 0.85 indicating good reliability. Initial, end and median frequency recovery had intraclass correlation coefficients (ICCs) over 0.6 that is acceptable but with large standard errors of measurement. The median frequency slopes for the four recording sites had ICCs of 0.19–0.48. Agreement coefficients for the Borg ratings ranged between 0.78 and 0.97. Moderate correlation was found between activity limitations and endurance time. Conclusions. Endurance time measurement and Borg ratings may be recommended for evaluating intervention both with groups of patients, i.e. for research purposes, and for individuals. The median frequency parameters may be recommended for groups only. The study shows the importance of establishing the reliability of the patient category if the results are to be used to evaluate intervention. Copyright © 2010 John Wiley & Sons, Ltd.     

Correlation between electromyographic spectral changes and subjective assessment of lumbar muscle fatigue in subjects without pain from the lower back

OBJECTIVE: The purpose of this study was to correlate objective measurements of muscle fatigue in the lower back to the subject's own assessment of fatigue. DESIGN: Muscle fatigue in the lower back was assessed in healthy subjects using electromyography (EMG), endurance time and the Borg scale. BACKGROUND: Muscle fatigue, measured with EMG and endurance time, in the lower back, is significant for patients with pain in the lower back. METHODS: Fifty healthy subjects participated. EMG was detected from the lumbar extensor muscles during a modified S?rensen's test, an isometric contraction for the back extensors until exhaustion. During the test, subjects rated their subjective fatigue on a Borg CR-10 scale. RESULTS: Borg scale ratings correlated with endurance time (0.68) and EMG median- and mean power frequency slopes (0.41-0.50). At a Borg rating of 3, median- and mean power frequency and endurance time were reduced by 30%. At a Borg rating of 5, median- and mean power frequency and endurance time were reduced by 50%. At a Borg rating of 7, median- and mean power frequency and endurance time were reduced by 60-70%. CONCLUSIONS: Significant correlation between the Borg scale, EMG and endurance time suggests a close relationship between subjective and objective assessment of muscle fatigue.     

Supplementation of general endurance exercise with stabilisation training versus general exercise only. Physiological and functional outcomes of a randomised controlled trial of patients with recurrent low back pain

BACKGROUND: Determination of the mode of action of new exercise techniques in different back pain populations is lacking. The effectiveness of supplementing an exercise programme with stabilisation exercises concerning physiological and functional parameters in non-specific back pain patients is unknown. METHODS: Randomised controlled trial, comparing a general trunk muscle endurance exercise approach enhanced with specific muscle stabilisation exercises (S&G group) with a general exercise approach only (G group). 55 patients with recurrent back pain were randomised in S&G group (n=29) and G group (n=26). Both groups received an 8-week exercise intervention and written advice. Paraspinal muscle strength and electromyographic fatigue of the erector spinae and multifidus were measured. Additionally, 3 functional speed tests were assessed. Outcomes were collected pre- and post-intervention. FINDINGS: No differences were detected for any of the paraspinal fatigue characteristics either within or between groups, apart from a significant decrease in normalised median frequency slope of the erector spinae for the G group. Paraspinal muscle strength and all functional tests have demonstrated significant within-group improvements for both groups, without any between-group differences. INTERPRETATION: An 8-week stabilisation exercise-enhanced approach presented equal benefits to a general endurance-based exercise programme for patients with recurrent non-specific back pain. A slightly steeper slope for the erector spinae in the G group was the only electromyographic fatigue alteration noted. Concomitant strength improvement probably reflects neural input changes rather than histochemical muscle changes. Physical exercise alone and not the exercise type was the key determinant for improvement in this patient group.     

Needle EMG Response of Lumbar Multifidus to Manipulation in the Presence of Clinical Instability

Abstract

A proposed mechanism for the persistence of low back pain due to clinical instability is a decrease in control of local spinal musculature, more specifically decreased recruitment of multifidus. Altered segmental mechanoreceptor input has been proposed as a contributing factor responsible for a decrease in local muscle recruitment. In this case report, immediate changes in the recruitment of the deep multifidus following manipulation were examined using needle EMG and isometric testing of trunk rotational force. Trunk rotational force appeared to improve while the multifidus demonstrated a decrease in activity as measured by needle EMG. No specific conclusions can be drawn from this report; however, the results do suggest that immediate multifidus function may be influenced with manipulation, resulting in improved muscular control of the trunk.     

The Effects of Combination Patterns of Proprioceptive Neuromuscular Facilitation and Ball Exercise on Pain and Muscle Activity of Chronic Low Back Pain Patients

[Purpose] The purpose of this study was to compare two methods for the muscle stabilization of the trunk of patients with chronic low back pain. The methods comprised combination patterns of proprioceptive neuromuscular facilitation (PNF) and ball exercise. [Subjects and Methods] The subjects were 40 volunteers who had low back pain. All subjects were randomly assigned to either a group which received proprioceptive neuromuscular facilitation or a group which performed ball exercise. Measurements were taken four times in total, at pre-intervention, two weeks later, four weeks later, and six weeks later. The main measurement methods used were the visual analogue scale (VAS) for pain and electromyography (EMG) for muscle activity. [Results] VAS and EMG activity were significantly reduced in the PNF combination pattern group and the ball exercise group. A comparison of the groups showed significant differences. In VAS and EMG activity; in particular, the combination pattern group using PNF increased EMG activity more than the ball exercise group did after six weeks of intervention. [Conclusion] This study showed that PNF combination pattern training for six weeks was more effective for patients with low back pain than performing ball exercise.Key words: PNF, Ball exercise, Chronic low back pain     

Dorsal horn neurons having input from low back structures in rats

The mechanisms of nociception in the low back are poorly understood, partly because systematic recordings from dorsal horn neurons with input from the low back are largely missing. The purpose of this investigation was to (1) identify spinal segments and dorsal horn neurons receiving input from the low back, (2) test the effect of nerve growth factor (NGF) injected into the multifidus muscle (MF) on the neurons’ responsiveness, and (3) study the influence of a chronic MF inflammation on the responses. In rats, microelectrode recordings were made in the segments L2, L3, and L5 to find dorsal horn neurons having input from the low back (LB neurons). In control animals, the proportion of LB neurons in L2 was larger than in L3 and L5. Most LB neurons had a convergent input from several tissues. Injections of NGF into MF increased the proportion of LB neurons significantly. A chronic MF inflammation likewise increased the proportion of LB neurons and the input convergence. The centers of the neurons’ receptive fields (RFs) were consistently located 2–3 segments caudally relative to their recording site. The results show that (1) input convergence from various tissues is common for LB neurons, (2) the input from structures of the low back is processed 2–3 segments cranially relative to the vertebral level of the RFs, and (3) the responsiveness of LB neurons is increased during a pathologic alteration of the MF. The above findings may be relevant for some cases of chronic low back pain in patients.