The lumbar multifidus: does the evidence support clinical beliefs?

The contribution of the trunk muscles to spinal stability is well established. There is convincing evidence for the role of multifidus in spinal stability. Recently, emphasis has shifted to the deep fibres of this muscle (DM) and five key clinical beliefs have arisen: (i) that DM stabilizes the lumbar spine whereas the superficial fibres of lumbar multifidus (SM) and the erector spinae (ES) extend and/or rotate the lumbar spine, (ii) that DM has a greater percentage of type I (slow twitch) muscle fibres than SM and ES, (iii) that DM is tonically active during movements of the trunk and gait, whereas SM and ES are phasically active, (iv) that DM and the transversus abdominis (TrA) co-contract during function, and (v) that changes in the lumbar paraspinal muscles associated with LBP affect DM more than SM or ES. This paper reviews the biomechanical, electromyographic, histochemical and morphological data that underpin these beliefs. Although there is support for the importance of the lumbar multifidus and the specific contribution of this muscle to intervertebral control, several of the clinical beliefs have little or no support and require further evaluation. These findings have implications for clinical practice.     

Changes in postural activity of the trunk muscles following spinal manipulative therapy

Spinal manipulative therapy (SMT) is common in the management of low back pain (LBP) and has been associated with changes in muscle activity, but evidence is conflicting. This study investigated the effect of SMT on trunk muscle activity in postural tasks in people with and without LBP. In 20 subjects (10 with LBP and 10 controls), EMG recordings were made with fine-wire electrodes inserted into transversus (TrA), obliquus internus (OI), and externus (OE) abdominis. Rectus abdominis (RA) and anterior deltoid EMG was recorded with surface electrodes. Standing subjects rapidly flexed an arm in response to a light, before and after a small amplitude end range rotational lumbar mobilization at L4-5. In controls, there was no change in trunk muscle EMG during the postural perturbation after SMT. In LBP subjects there was an increase in the postural response of OI and an overall increase in OE EMG. There was no change in TrA or RA EMG. These results indicate that SMT changes the functional activity of trunk muscles in people with LBP, but has no effect on control subjects. Importantly, SMT increased the activity of the oblique abdominal muscles with no change in the deep trunk muscle TrA, which is often the target of exercise interventions.     

慢性腰痛患者站立位躯干屈伸运动时腰背肌的功能变化研究

目的:研究慢性腰痛(CLBP)患者在站立位矢状面屈伸运动时腰背肌功能状况的变化,揭示其改变的可能机制及临床意义。方法:慢性非特异性腰痛患者25例和健康人25例,在站立位进行躯干的屈曲伸展运动,运用表面肌电图(sEMG)仪和摄像系统同步采集记录双侧L2/3、L4/5水平最长肌、多裂肌在站立位、前屈运动、完全屈曲及回到直立位不同运动时相的sEMG值。结果:两组受试对象站立位时,最长肌及多裂肌均方根(RMS)值差异无显著性意义(P>0.05);前屈运动时,最长肌及多裂肌RMS值增大,完全屈曲时,最长肌及多裂肌RMS值减小,腰痛组在前屈运动和完全屈曲时,最长肌和多裂肌RMS值较健康对照组增大,差异具有显著性意义(P<0.05);由屈曲位回至直立位时,腰痛组最长肌和多裂肌的RMS值明显小于健康对照组,差异具有显著性意义(P<0.05);腰痛组最长肌和多裂肌的屈曲-放松比较健康对照组降低,差异具有显著性意义(P<0.05);运动时相对两组受试对象的最长肌和多裂肌RMS值影响均有显著性意义(P<0.05)。结论:在躯干屈伸运动中,健康人腰背肌存在屈曲-放松现象(FRP),腰痛患者腰背肌功能发生疼痛适应性改变,表现为屈曲-放松反应缺如和主动活动机能不足。     

Driving plasticity in the motor cortex in recurrent low back pain

The sensory and motor systems can reorganise following injury and learning of new motor skills. Recently we observed adaptive changes in motor cortical organisation in patients with recurrent low back pain (LBP), which are linked to altered motor coordination. Although changes in motor coordination can be trained and are associated with improved symptoms and function, it remains unclear whether these training‐induced changes are related to reorganisation of the motor cortex. This was investigated using the model of a delay in postural activation of the deep abdominal muscle, transversus abdominis (TrA) in 20 individuals with recurrent LBP. Subjects were allocated to either motor skill training that involved isolated voluntary contractions of TrA, or a control intervention of self‐paced walking exercise for 2 weeks. Electromyographic (EMG) activity was recorded from TrA bilaterally using intramuscular fine‐wire electrodes. Motor cortical organisation using transcranial magnetic stimulation (TMS) and postural activation associated with single rapid arm movements were investigated before and after training. Motor skill training induced an anterior and medial shift in motor cortical representation of TrA, towards that observed in healthy individuals from our previous study. This shift was associated with earlier postural activation of TrA. Changes were not observed following unskilled walking exercise. This is the first observation that motor training can reverse reorganisation of neuronal networks of the motor cortex in people with recurrent pain. The observed relationship between cortical reorganisation and changes in motor coordination following motor training provides unique insight into potential mechanisms that underlie recovery.     

Spinal kinematics and trunk muscle activity in cyclists: a comparison between healthy controls and non-specific chronic low back pain subjects-a pilot investigation

The aim of this pilot study was to examine whether differences existed in spinal kinematics and trunk muscle activity in cyclists with and without non-specific chronic low back pain (NSCLBP). Cyclists are known to be vulnerable to low back pain (LBP) however, the aetiology of this problem has not been adequately researched. Causative factors are thought to be prolonged forward flexion, flexion-relaxation or overactivation of the erector spinae, mechanical creep and generation of high mechanical loads while being in a flexed and rotated position. Nine asymptomatic cyclists and nine cyclists with NSCLBP with a flexion pattern disorder primarily related to cycling were tested. Spinal kinematics were measured by an electromagnetic tracking system and EMG was recorded bilaterally from selected trunk muscles. Data were collected every five minutes until back pain occurred or general discomfort prevented further cycling. Cyclists in the pain group showed a trend towards increased lower lumbar flexion and rotation with an associated loss of co-contraction of the lower lumbar multifidus. This muscle is known to be a key stabiliser of the lumbar spine. The findings suggest altered motor control and kinematics of the lower lumbar spine are associated with the development of LBP in cyclists.     

Why do some patients keep hurting their back? Evidence of ongoing back muscle dysfunction during remission from recurrent back pain

Approximately thirty-four percent of people who experience acute low back pain (LBP) will have recurrent episodes. It remains unclear why some people experience recurrences and others do not, but one possible cause is a loss of normal control of the back muscles. We investigated whether the control of the short and long fibres of the deep back muscles was different in people with recurrent unilateral LBP from healthy participants. Recurrent unilateral LBP patients, who were symptom free during testing, and a group of healthy volunteers, participated. Intramuscular and surface electrodes recorded the electromyographic activity (EMG) of the short and long fibres of the lumbar multifidus and the shoulder muscle, deltoid, during a postural perturbation associated with a rapid arm movement. EMG onsets of the short and long fibres, relative to that of deltoid, were compared between groups, muscles, and sides. In association with a postural perturbation, short fibre EMG onset occurred later in participants with recurrent unilateral LBP than in healthy participants (p = 0.022). The short fibres were active earlier than long fibres on both sides in the healthy participants (p < 0.001) and on the non-painful side in the LBP group (p = 0.045), but not on the previously painful side in the LBP group. Activity of deep back muscles is different in people with a recurrent unilateral LBP, despite the resolution of symptoms. Because deep back muscle activity is critical for normal spinal control, the current results provide the first evidence of a candidate mechanism for recurrent episodes.     

Selective Activation of Lumbar Paraspinal Muscles during Various Exercises in the Prone Position as Measured by EMG

[Purpose] This study compared the effects of three exercises performed in a prone position on the selective activation of the lumbar erector spinae (LES) and lumbar multifidus (LM) muscles in healthy males to investigate the effective method for selective activation of the LM. [Subjects] Twenty-two healthy males were recruited. Surface EMG data were collected from the right LES and LM muscles during three exercises: 1) trunk extension, 2) hip extension, and 3) the arm lift. [Results] The ratio of LM to LES EMG activity during hip extension was higher than those during trunk extension and the arm lift. [Conclusion] Hip extension in a prone position may be effective for selective activation of the lumbar multifidus muscles in healthy males.Key words: Lumbar erector spinae, Lumbar multifidus, Selective activation     

Comparison of selective electromyographic activity of the superficial lumbar multifidus between prone trunk extension and four-point kneeling arm and leg lift exercises

[Purpose] This study examined the selective electromyographic activity of the lumbar paraspinal muscles in healthy male and female subjects in the prone trunk extension (PTE) and four-point kneeling arm and leg lift (FPKAL) exercises to determine the most beneficial exercise for selective activation of the lumbar multifidus (LM). [Subjects and Methods] Twenty healthy male and female subjects participated in this study. Surface electromyographic data were collected from the left-side lumbar erector spinae (LES) and LM muscles during PTE and FPKAL exercises. [Results] The LM/LES ratio related to selective activation of the lumbar paraspinal muscles during the FPKAL exercise was higher than that during PTE. [Conclusion] FPKAL exercise is safe and effective for the selective activation of the LM muscle.Key words: Lumbar paraspinal muscles, Selective activation, Surface electromyography     

Trunk muscle fatigue during a back extension task in standing

There is some evidence that the fatiguing characteristics during isometric back extension tasks may assist in identifying differences between individuals with and without low back pain (LBP). During these tasks, especially in standing, other abdominal trunk muscles are also active. The abdominal trunk muscles acting across multiple segments of the lumbar spine function in isolation or in synergy to create flexion torques. It is suggested that co-activation patterns of the trunk muscles are able to control the axis of rotation of the extension torque and also provide multi-segmental stability of the spine. The purpose of this study was to examine the fatigue responses in 4 asymptomatic individuals to a sustained isometric extension task of the trunk muscles evaluating the shifts in the median frequency of the electromyographic (EMG) signal. This study suggests that in asymptomatic subjects, the more superficial abdominal muscles (External Oblique and Rectus Abdominis) increased in activity as the test progressed. There was large inter-individual variation in both amplitude and median frequency changes. Rectus abdominis and the back extensors demonstrated characteristics of fatigue during the task. Studies to test for any characteristic trends in whether specific trunk muscles fatigue in standing is a feature in chronic LBP, invites a formal investigation.     

Different ways to balance the spine in sitting: Muscle activity in specific postures differs between individuals with and without a history of back pain in sitting

BackgroundPrevious research explored muscle activity in four distinct sitting postures with fine-wire electromyography, and found that lumbar multifidus muscle activity increased incrementally between sitting with flat thoracolumbar and lumbar regions, long thoracolumbar lordosis, or short lordosis confined to the lumbar region. This study used similar methods to explore whether people with a history of low back pain provoked by prolonged sitting used different patterns of trunk muscle activity in specific postures.MethodsFine-wire electromyography electrodes were inserted into the right lumbar multifidus (deep and superficial), iliocostalis (lateral and medial), longissimus thoracis and transversus abdominis muscles. Superficial abdominal muscle activity was recorded with surface or fine-wire electrodes. Electromyography amplitude was compared between postures for the back pain group and observations were contrasted with the changes previously reported for pain-free controls. For comparison between groups normalised and non-normalised electromyography amplitudes were compared.FindingsIndividuals with a history of back pain demonstrated greater activity of the longissimus thoracis muscle in the long lordosis compared with the flat posture [mean difference (95% CI): 46.6 (17.5–75.7)%, normalised to sitting posture peak activity], but pain-free participants did not [mean difference: 7.7 (minus 12–27.6)%]. Pain-free participants modulated lumbar multifidus activity with changes in lumbar curve, but people with a history of pain in prolonged sitting did not change multifidus activity between the long and short lordotic postures.InterpretationIn clinical ergonomic interventions that modify spinal curves and sagittal balance in sitting, the muscle activity used in those postures may differ between people with and without a history of back pain.     

The effect of lumbar back support tension on trunk muscle activity

OBJECTIVE: Assess the effect of different controlled lumbar back support tightness levels on trunk muscle activity. DESIGN: Two-way repeated measure design assessing lumbar back support tension and submaximal trunk extension moments on trunk muscle electromyographic activity. BACKGROUND: Biomechanical studies on lumbar back supports often use electromyography (EMG) to assess the affect on trunk muscle activity. However, the lumbar back support may alter the electromyographic signal by changing the electrode-muscle distance. METHODS: Subjects performed trunk extensions at three static submaximal extension moment levels (25%, 50% and 75% MVC) while stabilized at the hips and shoulders, with the back support tensioned to three different tightness levels (44.5, 66.7 and 89.0 N) as well as a no-back support condition. RESULTS: Statistical analysis failed to find a significant effect (P相似文献   

Association of low back pain with muscle stiffness and muscle mass of the lumbar back muscles,and sagittal spinal alignment in young and middle-aged medical workers

BackgroundMuscle stiffness of the lumbar back muscles in low back pain (LBP) patients has not been clearly elucidated because quantitative assessment of the stiffness of individual muscles was conventionally difficult. This study aimed to examine the association of LBP with muscle stiffness assessed using ultrasonic shear wave elastography (SWE) and muscle mass of the lumbar back muscle, and spinal alignment in young and middle-aged medical workers.MethodsThe study comprised 23 asymptomatic medical workers [control (CTR) group] and 9 medical workers with LBP (LBP group). Muscle stiffness and mass of the lumbar back muscles (lumbar erector spinae, multifidus, and quadratus lumborum) in the prone position were measured using ultrasonic SWE. Sagittal spinal alignment in the standing and prone positions was measured using a Spinal Mouse. The association with LBP was investigated by multiple logistic regression analysis with a forward selection method. The analysis was conducted using the shear elastic modulus and muscle thickness of the lumbar back muscles, and spinal alignment, age, body height, body weight, and sex as independent variables.FindingsMultiple logistic regression analysis showed that muscle stiffness of the lumbar multifidus muscle and body height were significant and independent determinants of LBP, but that muscle mass and spinal alignment were not. Muscle stiffness of the lumbar multifidus muscle in the LBP group was significantly higher than that in the CTR group.InterpretationThe results of this study suggest that LBP is associated with muscle stiffness of the lumbar multifidus muscle in young and middle-aged medical workers.     

The effect of unilateral muscle pain on recruitment of the lumbar multifidus during automatic contraction. An experimental pain study

Changes in control of the multifidus muscle are a likely contributor to low back pain (LBP), however, the underlying mechanisms of these changes are not well understood. To date it remains uncertain if pain has a selective effect on the multifidus muscles, in line with the observations of the selective changes in structure in acute LBP, or a more generalized effect.The objective of this study is to help to elucidate whether acute unilateral muscle pain alters the activation of the multifidus specific at the level and side of the pain or has a more widespread effect.An experimental pain protocol using hypertonic saline was applied to induce unilateral low back muscle pain. Automatic activity of the multifidus muscle during arm lifts was evaluated with dynamic ultrasound measurement, by assessing muscle thickness change during contraction. Multifidus activity of 15 healthy subjects was compared in a non-pain and in a pain condition, at different spinal levels (L3–L4–L5) and at both body sides.Unilateral induced pain at one segmental level reduced muscle thickness increase during contraction, at both body sides and at different lumbar levels.These results do suggest that unilateral pain may have a more widespread effect on multifidus muscle recruitment, affecting the left and right muscles, at different lumbar levels.     

Properties of Paraspinal Muscles in Japanese High School Baseball Players With Terminal-Stage Lumbar Spondylolysis

Background

Lumbar spondylolysis is a defect in the pars interarticularis that is common in young athletes; the stress distribution at the pars interarticularis is the highest in extension and rotation movements. The paraspinal muscles play an important role in stabilization of the lumbar spine; however, no study has assessed the properties of paraspinal muscles in athletes with lumbar spondylolysis.

Effects of tactile feedback on lumbar multifidus muscle activity in asymptomatic healthy adults and patients with low back pain

Background

Reduced lumbar multifidus (LM) muscle contraction has been observed in patients with low back pain (LBP). Clinicians often use various strategies to ensure LM activation, including tactile feedback and verbal instruction. However, the effects of tactile feedback on muscle activation have not been studied previously. Therefore, the purpose of this study was to investigate whether or not tactile feedback would increase LM muscle activity in adults with and without LBP.

Intermittent isometric fatigue study of the lumbar multifidus muscle in four-point kneeling: an intra-rater reliability investigation.

Back muscle endurance is considered important in low back pain (LBP) rehabilitation. Specific training of multifidus may also be necessary to restore normal low back function. The reliability of surface electromyogram (EMG) to assess endurance of the multifidus muscle during intermittent isometric exercise was evaluated. Multifidus endurance was monitored in the four-point kneeling exercise position using the power spectral analysis method. Twenty healthy volunteers were tested on three separate occasions. Subjects performed repeat 10 s high-intensity voluntary contractions of multifidus for 3 min. The median frequency (MF) and the integrated-rectified (I-R) EMG signal displayed the fatigue pattern of multifidus. Intraclass correlation coefficients indicated fair-good reproducibility for MF (0.48-0.67) but poor reliability for IR-EMG. In conclusion, problems concerning functional testing protocols for the back muscles remain and careful development is necessary for more realistic rehabilitation monitoring.     

Can we reduce the effort of maintaining a neutral sitting posture? A pilot study

Neutral sitting postures encouraging lumbar lordosis have been recommended in the management of sitting-related low back pain (LBP). However, prolonged lordotic sitting postures can be associated with increased fatigue and discomfort. This pilot study investigated whether changing the type of chair used in sitting can reduce the effort of maintaining a neutral sitting posture. The muscle activation of six trunk muscles was recorded using surface electromyography in 12 painfree participants. Participants were facilitated into a neutral sitting posture for 1 min on both a standard backless office chair and a dynamic, forward-inclined chair (Back App). Lumbar multifidus activity was significantly lower on the Back App chair (p = 0.013). None of the other five trunk muscles measured demonstrated a significant difference in activity between the chairs. There was no significant difference (p = 0.108) in the perceived effort of maintaining the neutral sitting posture on the two chairs. This study suggests that the lumbar multifidus activation required to maintain a neutral sitting posture can be reduced by considering the type of chair used. The mechanism through which the Back App chair reduces lumbar multifidus activation is unclear, but the greatest difference between chairs is the degree of hip flexion. The ability to maintain a neutral lumbar posture with less lumbar multifidus activation is potentially advantageous during prolonged sitting. Further investigations of the effects of chair design on longer duration sitting, and among LBP subjects, are warranted.     

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。     

Effects of capacitive and resistive electric transfer therapy on pain and lumbar muscle stiffness and activity in patients with chronic low back pain

[Purpose] In this study, we investigated the therapeutic effects of capacitive and resistive electric transfer therapy in patients with chronic low back pain. [Participants and Methods] The study included 24 patients with chronic low back pain (12 patients each in the intervention and sham groups). Pain intensity, superficial and deep lumbar multifidus stiffness and maximum forward trunk flexion and associated activation level of the iliocostalis (thoracic and lumbar component) and lumbar multifidus muscles were measured. [Results] Post-intervention pain intensity and muscle stiffness were significantly lower than pre-intervention measurements in the intervention group. However, no between-group difference was observed in the muscle activation level at the end-point of standing trunk flexion. [Conclusion] Our findings highlight a significant therapeutic benefit of capacitive and resistive electric transfer therapy in patients with chronic low back pain and muscle stiffness.     

不同性别健康人群腰部深层多裂肌肌电差异的研究

目的:采用表面肌电(sEMG)分析系统结合丝电极探讨健康人群腰部深层多裂肌活动的EMG信号特征,分析不同性别健康人群多裂肌功能状态差异。方法:31例健康受试者(15男,16女)采用针头导入0.16mm钢丝电极线至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,比较不同性别健康受试者平均肌电值(AEMG)、均方根值(RMS)、中位频率(MF)、平均功率频率(MPF)和非线性指标LZ复杂度的差异性。结果:不同性别健康人群腰部深层多裂肌电信号时域指标差异有显著性意义,男性多裂肌AEMG、RMS明显大于女性(P0.05);两组间频域指标MF、MPF、MFs、MPFs差异无显著性意义(P0.05)。男性和女性中,双侧多裂肌电活动无显著性差异(P0.05)。结论:采用sEMG系统结合丝电极能够可靠、灵敏地检测出腰部深层多裂肌的肌电活动,这是一种针对性地评估深层肌肉功能活动的有效方法,具有较好的临床应用价值;同时不同性别健康人群深层多裂肌EMG的差异性为设置多裂肌正常肌电值提供了一定参考价值。