Comparison of two mobilization techniques in management of chronic non-specific low back pain

AIM

The aim of the study was to compare between the effects of Maitland's postero-anterior (PA glide) mobilization and Mulligan's sustained natural apophyseal glide (SNAG) on pain, mobility, muscle activation and functional disability in subjects with chronic, non-specific low back pain.

METHODS

The study was a two arm repeated measure design with random allocation of subjects (n = 33). Subjects in group 1 received Maitland's PA glide mobilization and those in group 2 received Mulligan's SNAG. Along with the respective mobilization technique, individualized exercises were common for subjects in both the groups. Subjects in both groups received treatment for 4 days a week for 4 weeks. The outcome measures were numeric pain rating scale (NPRS) scores, lumbar flexion and extension range of motion, erector spinae muscle activity and Oswestry low back pain disability questionnaire score.

RESULTS

The outcome measure scores showed statistical significance in time effect on NPRS (p = 0.001); lumbar flexion and extension range of motion (p = 0.001); erector spinae muscle activity (0.001); Oswestry low back pain disability questionnaire score (p = 0.001); group effect on lumbar flexion (p = 0.03) and extension range of motion (p = 0.05); and interaction effect (time x group) on lumbar flexion (p = 0.003) and extension range of motion (p = 0.002); and, erector spinae muscle activity (p = 0.05) at the 3rd lumbar vertebral level.

CONCLUSION

The addition of Maitland or Mulligan mobilization techniques of the spine does not show a difference in the improvement of symptoms associated with chronic non-specific low back pain.

Trunk and pelvic coordination at various walking speeds during an anterior load carriage task in subjects with and without chronic low back pain

[Purpose] This study compared the coordination patterns of the trunk and pelvis in the transverse plane between healthy subjects and patients with chronic low back pain during an anterior load carriage task at various walking speeds. [Subjects] Ten healthy subjects and 10 patients with chronic low back pain performed an anterior carriage task with a load of 10% body weight at walking speeds of 3.5, 4.5, or 5.5 km/h. [Methods] The trunk and pelvic kinematics were measured by using a motion analysis system. During the anterior carriage task, the continuous relative phase differed significantly between groups with respect to walking speed. [Results] The continuous relative phase was more anti-phase in the chronic low back pain group than the control group. The inter-group continuous relative phase pattern was affected by walking at 5.5 km/h. [Conclusion] Compared to controls, subjects with chronic low back pain are unable to establish an in-phase between the trunk and pelvis from walking at 3.5 to 5.5 km/h during an anterior carriage task.

The avoidance model in knee and hip osteoarthritis: a systematic review of the evidence

The avoidance model in patients with knee and hip osteoarthritis (OA) hypothesizes that pain and psychological distress lead to avoidance of activities, and thereby to muscle weakness and activity limitations. This paper systematically reviews the scientific evidence for the validity of this avoidance model. A qualitative data synthesis was used to identify levels of evidence. Sixty studies were included. In knee OA, strong evidence was found that avoidance of activities is associated with activity limitations via muscle weakness (mediation by muscle weakness), strong evidence was found for an association between muscle weakness and activity limitations, and weak evidence was found that pain and psychological distress are associated with muscle weakness via avoidance of activities (mediation by avoidance). In hip OA, weak evidence was found for mediation by muscle weakness; and strong evidence was found for an association between muscle weakness and activity limitations. More research is needed on the consecutive associations between pain or psychological distress, avoidance of activities and muscle weakness, and to confirm causal relationships.

Effects of the MWM Technique Accompanied by Trunk Stabilization Exercises on Pain and Physical Dysfunctions Caused by Degenerative Osteoarthritis

[Purpose] This study aimed to identify how treatment with the Mulligan technique of mobilization with movement (MWM) influences pain and physical function of patients with degenerative osteoarthritis. [Subjects] Thirty patients diagnosed with degenerative osteoarthritis were divided into an experimental group (n=15), and a control group (n=15). [Methods] The experimental group was treated with general physical therapy, trunk stabilization exercises, and performed the MWM using the Mulligan technique. The control group was treated with general physical therapy, and then performed trunk stabilization exercises. [Results] Statistically significant differences were found after the intervention in the experimental group in the visual analog scale and Western Ontario and McMaster Universities osteoarthritis index pain, stiffening, and physical function scores. [Conclusion] We consider the treatment of degenerative osteoarthritis patients using the MWM technique is effective for reducing pain and improving physical functions.

Multidisciplinary rehabilitation for chronic back pain in an outpatient setting: A controlled randomized trial

Based on existing models for pain chronicity and effective treatment strategies for patients with chronic low back pain, a multidisciplinary rehabilitation programme for an outpatient group setting was developed. The main treatment components address the patient's physical functional capacity (functional restoring), cognitive and affective processes (pain management strategies), and behavioural and ergonomical aspects (back school elements). Short-term (immediately after intervention) and long-term effects (at 6-months follow-up) of the intervention were assessed in a randomized controlled study. Dependent variables were pain measures, functional capacity, disability, muscular strength and endurance, pain and posture-related self-efficacy, attitudes, depression, well-being, behavioural habits and posture assessed by a standardized behavioural observation method. Immediately after the intervention, patients in the treatment group (n=36) showed significant improvement over patients in the control group (n=29) in all variables except depression and muscular strength and endurance. At 6-months follow-up, compared to pretreatment scores, patients continued to show beneficial effects in pain intensity and frequency, posture, posture-related self-efficacy and well-being. In contrast to post-treatment results, there were also significant improvements in strength and endurance. Overall results testify to the effectiveness of the intervention programme. Future studies (with larger sample sizes) should aim at a further improvement of functional capacity and disability perception, an analysis of differential treatment effects, and strategies for an improved long-term maintenance of the changes induced by the programme.

Attentional strategy moderates effects of pain catastrophizing on symptom-specific physiological responses in chronic low back pain patients

In the present study, we examined whether experimentally-manipulated attentional strategies moderated relations between pain catastrophizing and symptom-specific physiological responses to a cold-pressor task among sixty-eight chronic low back patients. Patients completed measures of pain catastrophizing and depression, and were randomly assigned to sensory focus, distraction or suppression conditions during a cold pressor. Lumbar paraspinal and trapezius EMG, and cardiovascular responses to the cold pressor were assessed. Attentional strategies moderated the relation between pain catastrophizing and lumbar paraspinal muscle, but not trapezius muscle or cardiovascular responses. Only for participants in the suppression condition was catastrophizing related significantly to lumbar paraspinal muscle responses. Depressed affect did not account for this relation. These findings indicate that 'symptom-specific' responses among pain catastrophizers with chronic low back depend on how they attend to pain-related information. Specifically, it appears that efforts to suppress awareness of pain exaggerate muscular responses near the site of injury.

The role of attentional strategies in moderating links between acute pain induction and subsequent psychological stress: Evidence for symptom-specific reactivity among patients with chronic pain versus healthy nonpatients

Vulnerability to stressors after pain may depend on the degree to which the strategy used to process information about pain perpetuates thoughts of suffering and distress. Patients with chronic low back pain (CLBP) may show susceptibility to stress after pain through symptom-specific (lower paraspinal [LP]) muscle reactivity. Patients with CLBP (n = 100) and healthy nonpatients (n = 105) underwent a cold pressor, under sensory focus, distraction, suppression, or control conditions, and then performed mental arithmetic. Only patients under the suppression condition revealed increased LP tension during pain that was sustained during mental arithmetic and sustained systolic blood pressure after mental arithmetic. Patients with CLBP who suppress pain may detrimentally affect responses to the next noxious event, particularly through prolonged LP muscle tension, that may contribute to a cycle of pain-stress-pain.

A Meta-Analytic Review of Surface Electromyography Among Persons With Low Back Pain and Normal, Healthy Controls

Significant differences in surface electromyography (SEMG) have been reported between persons with low back pain (LBP) and normal, healthy controls. This manuscript presents a systematic meta-analytic review of studies examining SEMG differences between these groups. Forty-four articles were identified using MEDLINE and a review of reference lists in articles. For static SEMG, the largest effect size was observed for SEMG while standing, with subjects having LBP demonstrating higher SEMG. The effect size for flexion/relaxation measures was found to be very high (d = -1.71). Studies examining SEMG during isometric exercise or muscle recovery following exercise produced inconsistent findings. Sensitivity and specificity of SEMG for dynamic SEMG measures averaged 88.8% and 81.3%. Most classification schemes were statistically determined and utilized a combination of measures. Only one published study prospectively validated a classification scheme. SEMG measures of flexion-relaxation appear to distinguish LBP subjects from controls with good accuracy, and the sensitivity and specificity of SEMG can be increased by using multiple measures. Further research is needed to determine the combination of measures that are cost-effective, reliable, valid and discriminate with a high degree of accuracy between healthy persons and those with LBP.

PERSPECTIVE

SEMG is a simple and noninvasive measure of muscle activity. SEMG measures hold promise as an objective marker of LBP.

Critical issues in the use of muscle testing for the determination of sincerity of effort

Over the past 20 years, there have been numerous attempts to identify methodologies that are capable of the determination of sincerity of effort during muscle testing. The ensuing paper reviewed this literature and drew several conclusions. Injured patients and healthy volunteers do produce less force and more variable force while performing submaximal contractions than maximal contractions. However, submaximal efforts during strength testing can be reproduced and the use of force variability is not adequate to distinguish sincerity of effort. Visual examination of the shape of force output curves is also not adequate for distinguishing sincerity of effort. Furthermore, much of the research using strength ratios, difference scores, and an assortment of different parameters derived during strength testing has not established reliable and clinically useful methods of differentiating effort levels. Methods examining motion variability, radial/ulnar force output ratios, difference scores of eccentric-concentric ratios, and electromyography offer some promise, but numerous critical issues need to addressed. The use of the coefficient of variation, for example, is statistically untenable given the number of trials appropriate for clinical samples. Several studies have inadequate sample size to number of variable ratios. Many studies have questionable or at least unknown generalizability to patient samples and actual functional capacity. It is critical that other explanatory variables such as fear of injury, pain, medications, work satisfaction, and other motivational factors be considered. It is our opinion that there is not sufficient empirical evidence to support the clinical application of muscle testing to determine sincerity of effort.

Pain-Related Fear, Lumbar Flexion, and Dynamic EMG Among Persons With Chronic Musculoskeletal Low Back Pain

OBJECTIVES

The purpose of this study was to examine the relationship between pain-related fear, lumbar flexion, and dynamic EMG activity among persons with chronic musculoskeletal low back pain. It was hypothesized that pain-related fear would be significantly related to decreased lumbar flexion and specific patterns of EMG activity during flexion and extension.

STUDY DESIGN

Data was obtained from subjects who, on a single day, completed self-report measures of pain and pain-related fear, and were interviewed to determine demographic and pain information. Subjects then underwent a dynamic EMG evaluation for which they were asked to stand, then bend forward as far as possible, stay fully flexed, and return to standing. Lumbar EMG and angle of flexion were recorded during this time. A flexion-relaxation ratio (FRR) was computed by comparing maximal EMG while flexing to the average EMG in full flexion.

SUBJECTS

Seventy-six persons with chronic musculoskeletal low back pain.

RESULTS

Zero-order correlations indicated that pain-related fear was significantly related to reduced lumber flexion (r = -0.55), maximum EMG during flexion (r = -0.38) and extension (r = -0.51), and the FRR (r = -0.40). When controlling for pain and demographic factors, pain-related fear continued to be related to reduced lumbar flexion. Using a path-analytic model to examine whether angle of flexion mediated the relationship between fear and EMG activity, the models examining maximal EMG during flexion and extension supported the notion that pain-related fear influences these measures indirectly through its association with decreased range of motion. Conversely, pain-related fear was independently related to higher average EMG in full flexion, while angle of flexion was not significantly related. Pain-related fear was directly related to a smaller FRR, as well as indirectly through angle of flexion.

CONCLUSIONS

Pain-related fear is significantly associated with reduced lumbar flexion, greater EMG in full flexion, and a smaller FRR. The relationship between pain-related fear and EMG during flexion and extension appears to be mediated by reduced lumbar flexion. These results suggest that pain-related fear is directly associated with musculoskeletal abnormalities observed among persons with chronic low back pain, as well as indirectly through limited lumbar flexion. These musculoskeletal abnormalities as well as limited movement may be involved in the development and maintenance of chronic low back pain. In addition, changes in musculoskeletal functioning and flexion associated with pain-related fear may warrant greater attention as part of treatment.

Trunk muscle activation in low-back pain patients, an analysis of the literature

This paper provides an analysis of the literature on trunk muscle recruitment in low-back pain patients. Two models proposed in the literature, the pain-spasm-pain model and the pain adaptation model, yield conflicting predictions on how low- back pain would affect trunk muscle recruitment in various activities. The two models are outlined and evidence for the two from neurophsysiological studies is reviewed. Subsequently, specific predictions with respect to changes in activation of the lumbar extensor musculature are derived from both models. These predictions are compared to the results from 30 clinical studies and three induced pain studies retrieved in a comprehensive literature search. Neither of the two models is unequivocally supported by the literature. These data and further data on timing of muscle activity and load sharing between muscles suggest an alternative model to explain the alterations of trunk muscle recruitment due to low-back pain. It is proposed that motor control changes in patients are functional in that they enhance spinal stability.

Activation imbalances in lumbar spine muscles in the presence of chronic low back pain

Paraspinal electromyographic (EMG) activity was recorded bilaterally from three lumbar levels during 30-s isometric trunk extensions [40 and 80% of maximum voluntary contraction (MVC)] in 20 healthy men and 14 chronic low back pain patients in pain. EMG parameters indicating neuromuscular fatigue and contralateral imbalances in EMG root-mean-square amplitude and median frequency were analyzed. Patients in pain showed less fatigue than controls at both contraction levels and produced only 55% of their MVC. Patients in pain likely did not produce a "true" maximum effort. A low MVC estimate would mean lower absolute contraction levels and less neuromuscular fatigue, thus explaining lower scores in the patients. Contralateral root-mean-square amplitude imbalances were present in both categories of subjects although such imbalances, when averaged across lumbar levels, were significantly larger in patients. Median frequency imbalances were significantly larger in the patients, at segmental as well as across lumbar levels. These results suggest that the presence of pain in these patients caused a redistribution of the activation behavior between synergistic muscles of the lumbar back.

EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls

Abnormal patterns of trunk muscle activity could affect the biomechanics of spinal movements and result in back pain. The present study aimed to examine electromyographic (EMG) activity of abdominal and back muscles as well as triaxial torque output during isometric axial rotation at different exertion levels in back pain patients and matched controls. Twelve back pain patients and 12 matched controls performed isometric right and left axial rotation at 100%, 70%, 50% and 30% maximum voluntary contractions in a standing position. Surface EMG activity of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results showed that there was a trend (P = 0.08) of higher flexion coupling torque during left axial rotation exertion in back pain patients. Higher activity for external oblique and lower activity for multifidus was shown during left axial rotation exertion in back pain group when compared to the control group. In right axial rotation, back pain patients exhibited lesser activity of rectus abdominis at higher levels of exertion when compared with matched controls. These findings demonstrated that decreased activation of one muscle may be compensated by overactivity in other muscles. The reduced levels of activity of the multifidus muscle during axial rotation exertion in back pain patients may indicate that spinal stability could be compromised. Future studies should consider these alternations in recruitment patterns in terms of spinal stability and internal loading. The findings also indicate the importance of training for coordination besides the strengthening of trunk muscles during rehabilitation process.

Readiness to adopt adequate postural habits: an application of the Transtheoretical Model in the context of back pain prevention

Based on a biomechanical model, an adequate body posture can contribute to the prevention of back pain and back pain chronicity. This study examines the explanatory value of the Transtheoretical Model (TTM) for the adoption of adequate postural habits in a cross-sectional sample of 149 employees of a German administration unit (mean age 40.2 years, 50% female). Using newly developed instruments with satisfactory psychometric properties, basic assumptions of the TTM could be confirmed: self-efficacy and the perceived pros for maintaining a good body posture increased significantly across the stages, while the perceived cons decreased. Additionally, the use of preventive strategies for back pain prevention increased linearly and significantly across the stages of change. The study supports the applicability of the TTM for postural behavior. Considering stages of change as an intervening variable may contribute to clarifying the relationship between participation in low back schools and prevention of back pain chronicity. Longitudinal and intervention study data are needed to support these assumptions.

An application of pattern recognition for the comparison of trunk muscles EMG waveforms between subjects with and without chronic low back pain during flexion-extension and lateral bending tasks

The purpose of the study was twofold: (1) to evaluate the reliability of distance measures computed from a principal component analysis (PCA) of electromyographic (EMG) waveforms of trunk muscles recorded during standardized trunk movements and (2) to evaluate their sensitivity to the load lifted, the trunk range of motion (ROM) and to low back status. Thirty-three male subjects (18 normals, 15 suffering from non specific CLBP) aged between 35-45 years participated. The EMG signals from 12 trunk muscles and the kinematics of trunk segments were recorded during 12 tasks. The subjects performed flexion-extension and lateral bending (left and right) tasks (three complete cycles) with and without a 12 kg load and at different trunk ROM (maximal or at defined submaximal angles). Distance measures locating each subject relative to a reference PCA model were computed for each muscle and task. The reliability of these distance measures was evaluated for 10 subjects (five normals and five CLBP) who performed two tasks on three different days. The reliability of distance measures was acceptable for agonist muscles only. The distance measures were sensitive to the load lifted and to the trunk ROM for different muscles and tasks but poorly sensitive to low back status. Several reasons that could explain the low sensitivity of these measures to low back status are discussed and potential solutions are proposed. A procedure based on a reliability analysis is proposed to select the number of principal components to include in the reference PCA model. It is expected that the refinement of the method used in this study could provide an effective clinical tool to assess EMG waveforms of trunk muscles during dynamic tasks.

Cervical muscle dysfunction in the chronic whiplash associated disorder grade II (WAD-II)

STUDY DESIGN

In a cross-sectional study, surface electromyography measurements of the upper trapezius muscles were obtained during different functional tasks in patients with a chronic whiplash associated disorder Grade II and healthy control subjects.

OBJECTIVES

To investigate whether muscle dysfunction of the upper trapezius muscles, as assessed by surface electromyography, can be used to distinguish patients with whiplash associated disorder Grade II from healthy control subjects.

SUMMARY OF BACKGROUND INFORMATION

In the whiplash associated disorder, there is need to improve the diagnostic tools. Whiplash associated disorder Grade II is characterized by the presence of "musculoskeletal signs." Surface electromyography to assess these musculoskeletal signs objectively may be a useful tool.

METHODS

Normalized smoothed rectified electromyography levels of the upper trapezius muscles of patients with whiplash associated disorder Grade II (n = 18) and healthy control subjects (n = 19) were compared during three static postures, during a unilateral dynamic manual exercise, and during relaxation after the manual exercise. Coefficients of variation were computed to identify the measurement condition that discriminated best between the two groups.

RESULTS

The most pronounced differences between patients with whiplash associated disorder Grade II and healthy control subjects were found particularly in situations in which the biomechanical load was low. Patients showed higher coactivation levels during physical exercise and a decreased ability to relax muscles after physical exercise.

CONCLUSIONS

Patients with whiplash associated disorder Grade II can be distinguished from healthy control subjects according to the presence of cervical muscle dysfunction, as assessed by surface electromyography of the upper trapezius muscles. Particularly the decreased ability to relax the trapezius muscles seems to be a promising feature to identify patients with whiplash associated disorder Grade II. Assessment of the muscle (dys)function by surface electromyography offers a refinement of the whiplash associated disorder classification and provides an indication to a suitable therapeutic approach.

The effect of load on the coordination of the trunk for subjects with and without chronic low back pain during flexion-extension and lateral bending tasks

OBJECTIVE

To evaluate if patients move their trunk sections differently than normal subjects and to determine if these differences increase when lifting a load.

DESIGN

Comparative study using a repeated measures design.

BACKGROUND

Many studies demonstrate a modification of the lumbar-pelvic rhythm for chronic low back pain patients but the large variability of the results impair the discrimination power. It was hypothesized that the lifting of a load would magnify the manifestation of lumbar impairments.

METHODS

Fifteen chronic low back pain patients and 18 normal subjects performed maximal flexion-extension and lateral bending of the trunk with and without a 12 kg load. The pelvic, lumbar and thoracic motions were measured with a motion analysis system.

RESULTS

During flexion-extension tasks, a significant decrease in lumbar flexion and increase in thoracic flexion were observed for the patients. The load effect was significant for all trunk sections but did not allow a better discrimination between groups.

CONCLUSIONS

Lifting a 12 kg load during flexion-extension of the trunk did confirm alteration in trunk section coordination but did not help to better discriminate patients from normal subjects. However, it was demonstrated for the first time that chronic low back pain patients compensate for a loss of lumbar flexion by increasing their thoracic flexion.

RELEVANCE

The lumbar-pelvic rhythm is routinely used to evaluate low back impairments. The use of kinematic measures enhance the objectivity of the examination but the large variability of the results impair the discrimination power. Lifting a load during such an evaluation might magnify the low back impairments and increase the discrimination power of this measure.

Motivation zur Prävention von Rückenschmerz — eine Studie zum transtheoretischen Modell Prochaskas

Zusammenfassung. Im Rahmen einer Querschnittsstudie wurden Hypothesen überprüft, die aus dem transtheoretischen Modell für den Bereich rückenbewußtes Verhalten abgeleitet wurden. Insbesondere waren dies Zusammenhänge zwischen motivationalen Stufen und Rückenschmerz, Wohlbefinden, Teilnahme an einer Rückenschule sowie Verhaltensgewohnheiten, die zur Prävention von Rückenschmerz beitragen sollen. Die Stichprobe bestand aus 160 Schülern (mittleres Alter 24.9 Jahre, SD = 7.3; 73 % weiblich) verschiedener Ausbildungsgänge des Klinikums Marburg, die sich zu 25 % in Vor-Handlungsstufen, zu 20 % in der Handlungsstufe und zu 55 % in der Stufe der Aufrechterhaltung befanden. In die Analyse wurden nur Personen in den Stufen des Bewußtwerdens, der Handlung oder der Aufrechterhaltung einbezogen. Schüler, die sich seit mindestens 6 Monaten rückenbewußt verhielten, berichteten der Tendenz nach seltener über Rückenschmerz als solche, die dieses Verhalten nicht oder erst seit kurzem zeigten (p = .052). Sie zeigten häufiger rückenbewußtes Verhalten, hatten häufiger bereits eine Rückenschule besucht und gaben ein besseres Wohlbefinden an als Personen auf vorangehenden Stufen. Krankengymnasten befanden sich häufiger in fortgeschrittenen Stadien der Verhaltensänderung als die anderen Berufsgruppen. Durch die Studie werden Annahmen des transtheoretischen Modells auch für den Bereich des rückenbewußten Verhaltens bestätigt.

Electromyography and chronic pain: do current electromyographic diagnostic techniques discriminate against injured female workers?

EMG recordings, typically obtained in biofeedback training sessions, tend to underestimate actual muscle activity in overweight and female pain patients. If unadjusted, these measures will likely result in erroneous diagnostic conclusions.

Ambulatory electromyogram activity in the upper trapezius region: patients with muscle pain vs. pain-free control subjects

STUDY DESIGN

This study compared the ambulatory electromyogram activity of persons reporting pain in the shoulder and cervical regions with an equal group of persons not reporting such pain. Ambulatory electromyogram data were obtained over 3-day periods. In addition, all participants completed several standard psychological questionnaires.

OBJECTIVES

The results were analyzed with inferential statistics to determine whether subjects reporting significant pain in the shoulder and cervical regions had greater ambulatory electromyogram activity than an equal number of subjects not reporting pain.

SUMMARY OF BACKGROUND DATA

Considerable controversy exists regarding the role of muscle activity in the etiology and maintenance of muscle pain disorders. Given the availability of ambulatory recording devices that can provide a detailed record of muscle activity over an extended period of time, the present research was conducted to determine whether persons reporting shoulder and cervical pain could be differentiated from a group of normal subjects.

METHODS

All subjects (N = 20) completed a battery of tests with standardized psychometric instruments and then were fitted with ambulatory electromyogram monitors to record electromyographic activity of the upper trapezius region of the dominant side; the time, duration, and amplitude of electromyogram activity greater than 2 microV was recorded. The monitors were worn during normal working hours (mean, 6.2 hours per day) over 3 consecutive days. In addition to wearing the monitors, all subjects completed hourly self-ratings of perceived muscle tension during the recording periods.

RESULTS

As expected, subjects with muscle pain reported significantly more pain (mean, 4.9) than did the normal control subjects (mean, 0.9), t(15) = 3.29, P < 0.01. However, patients with muscle pain did not have greater average electromyogram activity (mean, 6.4 microV) over the 3-day period as compared to the normal controls (mean, 7.1 microV), t(18) = -0.25, P < 0.80. Self-monitoring of perceived muscle tension also did not reveal differences between pain subjects and the normal control subjects (P < 0.75).

CONCLUSIONS

Ambulatory measurements of electromyogram activity did not differentiate persons reporting upper trapezius or cervical pain from those that did not report such pain. Persons reporting pain are also not distinguishable from normal control subjects on a variety of self-report measures. These results raise questions regarding the role of ambulatory electromyogram recordings in the evaluation and treatment of muscle pain disorders.

A time series analysis of the relationship between ambulatory EMG, pain, and stress in chronic low back pain

Twenty-one subjects with chronic back pain (CBP) participated in an ambulatory electromyography (EMG) monitoring study to ascertain the relationships between muscle activity, physical activity, psychosocial stress, and pain. A time-series analysis approach was adopted to investigate both immediate and lagged associations between these variables in an attempt to determine potential causal relationships. Results for group relationships showed a significant relationship between physical activity and pain, self-report of stress and pain, but no relationship between EMG activity and pain. A lagged relationship between physical activity and pain was found, suggesting a causal relationship between physical activity and pain. However, no time lag was observed between stress and pain, hence no causal relationship can be elucidated. Analysis at the individual level indicated stronger relationships between several combinations of these variables, highlighting the need to consider the heterogeneity of the CBP population and etiology of CBP. The use of ambulatory monitoring of pain, stress, and EMG is suggested as one avenue to further explore the population's heterogeneity.

Effects of chair design on back muscle fatigue

The electromyographic activity of the paraspinal muscles were examined to investigate the effects of chair sitting on muscle activation patterns and muscle fatigue. Twenty-four subjects were studied on the Balans, Back Up, and standard office chairs during a seated writing task and standing while performing a standardized muscle fatigue assessment test. The results of the study indicate that in 87.5% of the comparisons at the L3 site, the Back Up chair has lower readings of muscular effort compared to the Balans and office chair. During the muscle fatigue testing, the greatest amount of fatigue was noted in those subjects who sat in the Back Up chair last. When the Back Up chair was first or second, the least amount of fatigue was observed. The sEMG results supports a biomechanical model. The ergonomics of the Balans and office chairs give the least amount of support to the low back, while the Back Up chair provides the greatest amount of support. It is suggested that adequate pelvic girdle support during seated tasks will lower the threshold of back fatigue and thus facilitate return to work for low back pain patients.

Assessment of lumbar EMG during static and dynamic activity in pain-free normals: implications for muscle scanning protocols

The purpose of this study was to provide a thorough description of lumbar surface integrated electromyography (EMG) in pain-free normals during a standardized assessment protocol of static isometric and unresisted dynamic tasks. It has been proposed that in pain-free normals, symmetrical tasks that bend the trunk forward or extend the trunk backward produce symmetrical paraspinal EMG activity, and asymmetrical tasks that rotate or laterally bend the trunk produce asymmetrical paraspinal EMG activity. In addition, it has been observed that lumbar EMG assessment during static tasks has been more consistent than tasks involving dynamic activities. Twenty-eight pain-free normals were assessed during symmetrical and asymmetrical tasks in both static and dynamic activities in a counterbalanced manner. The assessment of paraspinal EMG patterns was conducted while subjects were secured in a triaxial dynamometer, which provided standardization of body position and concurrent measurement of torque, range of motion, and velocity. The results provided experimental evidence for the above-stated propositions. An implication derived from this research is that clinicians may be better served utilizing local norms when using EMG for classification purposes.

Electromyographic recordings of paraspinal muscles: variations related to subcutaneous tissue thickness

The aim of this study was to assess the effect on EMG amplitude measures of variations in the thickness of underlying tissue between surface electrodes and the active muscle. 20 normal subjects with different amounts of subcutaneous tissue performed comparable constant force contractions for a 45-second period, during which paraspinal EMG recordings were taken. Three measures of subcutaneous tissue thickness were obtained from each subject: Body Mass Index, total body fat as calculated by Durnin's formula, and skinfold thickness at the recording sites. The results show that (i) the greater the thickness of subcutaneous tissue between the surface recording site and the contracting muscles, the lower the recorded electromyographic activity, and that (ii) up to 81.2% of the variance in the EMG measures can be explained by variation in the amount of subcutaneous tissue. These findings support the view that the absolute level of surface-recorded EMG cannot simply be taken at face value. The amplitude of the signal will be affected by, for example, the amount of body fat.

Paraspinal EMG and autonomic reactivity of patients with back pain and controls to personally relevant stress

The reactivity of surface paraspinal EMG was contrasted among groups of (1) patients seeking treatment for chronic back pain, (2) nonpatients reporting chronic back pain, and (3) healthy controls. The EMG response to the personally relevant stressor (all stimuli were 1 min.) tasks was greater for the patient group relative to the other two groups. However, the patients' magnitude of response elicited by the control task was nearly equal to that of the personally relevant task, suggesting that the task demand to "describe a recent event" may be the "personally relevant" stressor component rather than the emotional valence attached to the content of that description.

Scanning paraspinal surface EMG: A method for corroborating post-treatment spinal and related neuromusculoskeletal symptom improvement

This study evaluated the relationship between post-treatment paraspinal surface EMG improvement in the static sitting and standing postures, with patient post-treatment subjective regional spinal pain and/or related neuromusculoskeletal symptoms, using hand held scanning electrodes. A retrospective review of consecutive files of patients who had presented with regional spinal pain and/or related neuromusculoskeletal symptoms was undertaken. The files considered for this study needed to meet a set of pre-established criteria in order to qualify for selection. Forty-two patients met the criteria for review. Forty-one patients reported post-treatment reduction in their symptoms. Of the 42 patients indicating improvement on post-treatment static scanning SEMG examination, 41 (97.6%) had indicated symptomatic improvement as well. The findings warrant further investigation to determine whether hand-held surface EMG scanners can be reliably utilized as a post-treatment objective instrument for determining symptomatic improvement in commonly seen physical conditions of the spine which are of spinal biomechanical/postural etiology.

Quantitative surface EMG of pericranial muscles. Relation to age and sex in a general population

Quantitative EMG levels in pericranial muscles were studied in 547 subjects randomly selected from the general population aged 25-64 years. Surface EMGs of the right frontal and both temporal muscles were examined during rest and maximal voluntary contraction by a blind, standardized method. The amplitude of the EMG was expressed as the root mean square and mean rectified voltage. The power spectrum was calculated and the mean and median frequencies were extracted. During rest no significant differences were found between amplitude levels of the temporal muscles, while higher frequency levels were detected on the left side. Amplitude and frequency levels were higher in the frontal than the temporal muscles during rest, but lower during maximal voluntary contraction, probably for morphological differences. In the frontal muscle, females had increased amplitudes during rest and decreased levels during maximal voluntary contraction compared to males, indicating a higher tension at rest and a reduced number and/or size of muscle fibers in females. During maximal voluntary contraction a highly significant decrease with age was seen in amplitude and frequency in the temporal muscles. The present study is the first population study of EMG levels in pericranial muscles and constitutes the necessary basis for evaluating the EMG in tension-type headache.

A randomized crossover investigation of a back pain and disability prevention program: Possible mechanisms of change

An educational program which emphasized the symmetrical use of back muscles was studied at a health care facility which had extremely high time lost injury rates due to back strains. Participants (N=180) were involved with half studying an educational program entitled "Back to Balance" with the remainder serving as controls. After 3 months, the controls studied the program. All subjects completed psychological tests, received cervical and lumbar paraspinal dynamic EMG evaluations four times (pre-and post-treatment, and after 3 and 12 months). Administrative indices (costs, incidence, and time lost injury rate) were obtained for the 3 years prior to the study and for the 1 year of the study. The 1-year results showed decreased pain, retained knowledge which was generalized to the home, and significantly improved symmetry of both sets of muscles. Administrative data revealed a 72% decrease in the time lost injury rate with reduced costs.

Negative affect, pain and disability in osteoarthritis patients: the mediating role of muscle weakness

Negative affect has been shown to be associated with high levels of pain and disability in osteoarthritis (OA) patients. As an explanation of this association, it was hypothesized that muscle weakness is a mediating factor between negative affect, pain and disability. Accordingly, negative affect enhances the patient's tendency to avoid pain-related activities; a low activity level induces muscle weakness, instability of joints and thus pain and disability. This theory leads to the prediction that the association between negative affect, pain and disability is most pronounced in patients with weak muscles. The prediction was tested in a study on patients with OA of the hip and/or knee. Regarding disability (but not pain), the prediction was confirmed. This study indicates that muscle weakness is a mediating factor between negative affect and disability in OA-patients.

Quantitative surface EMG of pericranial muscles. Reproducibility and variability

We present reproducibility data on a quantitative electromyographic investigation of the temporal and frontal muscles using surface electrodes. Such data have not been published before. They constitute a necessary basis for future evaluation of the importance of pericranial muscles in tension-type headache. Root mean squares and mean rectified values of the electrical activity were measured in 20 healthy subjects. Power spectra were calculated and the mean and median frequencies were extracted. The coefficient of intraindividual variation in RMS from the right temporal muscle within the same examination was 14%, between several examinations on the same day 18% and between measurements on 2 different days 18%. The corresponding coefficients of interindividual variation were 36, 31 and 38%. The left temporal and frontal muscles showed similar coefficients of variation. At rest, no differences were found between muscles, but during maximal voluntary contraction the frontal muscle revealed a 55% lower RMS values than the temporal muscles. The method used was reproducible and reliable in measuring quantitative electrical activity of pericranial muscles.

Back schools in prevention of chronicity

This chapter has reviewed the role of back school and educational programmes for the common and non-specific acute and subacute low back pain patient. The following seems to come out of this review. Education is an important part of patient care. However, several questions arise about the content of the education, the selection of patients, the patient compliance to instruction given, how the information is retained, and which outcome measures should be used. It is also important to realize that the back school is a modality or a tool that may be used as an adjunct, but as a sole treatment it seems to have less impact than in combination with other structured or goal-oriented programmes. When a back school is instituted in a hospital or in industry, it requires administrative and budgetary support and a multidisciplinary staff to successfully carry out the programme. The information given must be adapted to the needs of the participants and all members of the team must give the same information to the patient. A poorly structured back school where patients are dumped because the physician or other health care provider has nothing else to offer is a poor solution for the patient, a poor solution for the health care provider, and can only increase the patient's discomfort and health care costs.

Pain and disability in osteoarthritis: a review of biobehavioral mechanisms

Pain and disability are cardinal symptoms in osteoarthritis. The literature is reviewed in order to identify causes of these symptoms at the articular, kinesiological, and psychological level. It is concluded that pain and disability are associated with degeneration of cartilage and bone (articular level), with muscle weakness and limitations in joint motion (kinesiological level), and with anxiety, coping style, attentional focus on symptoms, and possibly depression (psychological level). Biobehavioral mechanisms of pain and disability which explain the observed associations are described and the empirical evidence for these mechanisms is evaluated. Methodological and conceptual deficiencies in the research reviewed are pointed out and suggestions for further research are given.

An identification of low back pain groups using biobehavioral variables

A multivariate predictive model of low back pain (LBP) was developed. Following a semi-structured interview, 73 participants were assigned to dysfunctional chronic low back pain (DCLBP), functional chronic low back pain (FCLBP), acute low back pain (ALBP), and healthy control (HC) groups. All participants underwent a comprehensive physical, psychophysiological, and psychological evaluation. Multivariate analyses indicated no psychophysiological, few physical, and many psychological differences among the groups. The DCLBP group was found to be most impaired in flexion (p<.001), and the HC group performed the most total work (ft-lb) in extension (p<.001). Psychologically, the DCLBP group displayed greater levels of emotional distress and characterological disturbances and were more functionally impaired (p<.001). Few differences between FCLBP and HC were found. A classification analysis using physical and psychological variables correctly classified 83.3% of DCLBP patients, and it was found that the ALBP group was heterogeneous with some patients having a dysfunctional profile and other patients having a functional profile. The psychological variables were more potent predictors of group membership than were the physical variables. These findings indicate that potential DCLBP and FCLBP patients can be identified shortly following an injury, suggesting important implications for assessment and treatment of low back pain in general, and more specifically, for reducing health care costs and human suffering.

Psychophysiological responses to repeated acute pain stimulation in chronic low back pain patients

Psychophysiological recordings (electrodermal activity, heart rate, respiration rate and frontalis and back muscle tension) were taken in chronic low back pain (CLBP) patients and control subjects during baseline conditions and during the presentation of six acute pressure pain stimuli. No baseline differences in back muscle tension between CLBP patients and controls were found, but CLBP patients did have higher baseline electrodermal activity. During pain stimulation, CLBP patients showed larger skin conductance reactions than controls. Also, the CLBP patient group showed a marked increase in lumbar muscle tension during the test compared to baseline, whereas the EMG level of the control group remained unchanged. This increase in muscle tension seemed to be more related to the postural change than to the pain stimulus, and it is hypothesized that some CLBP patients react with exaggerated and non-functional back muscle contractions to slight changes in posture. Contrary to expectation, no differences were found between CLBP patients and controls in physiological habituation after repeating the pain stimulus. Comparison of subjective pain ratings and psychophysiological variables showed that for control subjects arousal and subjective pain were related. For CLBP patients there was no such clear relationship.

Comparison of lumbar paravertebral EMG patterns in chronic low back pain patients and non-patient controls

According to myogenic models that relate abnormal EMG patterns to the experience of pain, lumbar paravertebral muscle activity has been considered to play an important role in chronic low back pain. In the present study, 40 chronic low back pain patients and 40 matched non-patient controls were compared on lumbar paravertebral EMG during mechanically stabilized static and dynamic postures. Differences between groups in lumbar curvature and spinal range of motion were determined using a dual goniometer technique. Although the two groups did not differ on absolute levels of EMG during quiet standing, significant differences were found for EMG patterns during dynamic postures. In addition, most patients did not show the flexion-relaxation response or the expected pattern of EMG responses during trunk rotation, most likely because of restricted range of motion and/or compensatory posturing. These findings provide support for the biomechanical model of chronic pain and indicate the need for further research pertaining to pain behavior and movement-related lumbar muscle activity.

Surface EMG recordings and pain-related disorders: a diagnostic framework

Surface electromyography provides a very valuable set of information when used diagnostically with pain-related disorders. Unfortunately, most researchers and clinicians limit their investigation to only one level of diagnostic information available concerning the neuromuscular system. This article develops and encourages the clinician/researcher to consider three levels of diagnostic information: emotional, organ-related, and postural aspects. The theoretical background and diagnostic procedures used to investigate each is presented. Differential treatment considerations, given differential diagnostic findings, are discussed.

Medically incongruent chronic back pain: physical limitations, suffering, and ineffective coping

Chronic low back pain (CLBP) patients with pain and symptomatology incongruent with physical pathology have been found to have a poorer outcome to medical treatment and rehabilitation, and to use health care resources excessively. To examine possible psychological and behavioral bases for this pattern, this investigation contrasted 40 CLBP patients who displayed non-organic physical signs, inappropriate symptoms, and/or anatomically incongruent pain drawings with 40 'control' CLBP patients without incongruent pain criteria. Multivariate analyses revealed that the incongruent CLBP group reported greater pain intensity and depression, received higher observer ratings of pain, displayed more ambulatory/postural pain behavior, and reported more dysfunctional cognitions during pain. Incongruent CLBP patients also were found to have greater physical impairment and disability. When group differences on physical impairment/disability were controlled statistically, all the afore-mentioned differences disappeared, with one exception. Incongruent CLBP patients still displayed more maladaptive and dysfunctional cognitions. These findings indicate that incongruent CLBP patients may be conceptualized as ineffective and overwhelmed in their attempts to cope and as more physically disabled as a result of their pain. The role of cognitive factors, reasons for failure of physically based interventions, and implications for patient management are discussed.

Pain assessment methods in mechanical dysfunction

This paper considers the reliability and validity of pain assessment methods in mechanical dysfunction. A distinction is drawn between measures of subjective report and those of pain behaviour. The latter is observable and therefore more amenable to direct study than subjective report. Measures of subjective report include rating scales, the McGill Pain Questionnaire, and diary cards. Consideration is also given to personality assessment in this context. It is concluded that measurement needs to proceed from a number of standpoints, with the importance of each of these dependent upon the context. For chronic pain, emphasis on pain behaviours is appropriate.