Paraspinal strength and electromyographic fatigue in patients with sub-acute back pain and controls: Reliability, clinical applicability and between-group differences.

BACKGROUND: Paraspinal muscle strength and fatigue are considered important in low back pain (LBP) prevention and rehabilitation. High reliability of paraspinal strength and electromyographic (EMG)-fatigue parameters has not been universally reported. Moreover, the discriminative validity of these parameters requires further exploration, under the threat of potentially poor reliability of the methods examined. AIM: To investigate the reliability and discriminative validity of paraspinal strength and EMG-related fatigue in subjects with recurrent LBP and healthy participants. METHODS: Test-retest measurements were performed in 26 healthy and 66 LBP volunteers, for reliability. Paraspinal isometric maximal and mean strength were determined with a maximum voluntary isometric contraction (MVIC) protocol, performed in a custom-made device. For the fatigue test, participants performed a 60% MIVC level continuous isometric contraction of the paraspinals, in conjunction with EMG analysis from 4 muscle sites of the lumbar spine. Initial median frequency (IMF), the median frequency slope (MFslope), as well as the root mean square (RMS) slope EMG parameters were used as fatigue measures. Data were analysed with repeated measures ANOVA for test-retest differences. For reliability, the intraclass correlation coefficient (ICC3,1), standard error of the measurement (SEM) and the smallest detectable difference (SDD) were reported. Group-related differences for fatigue measures were analysed with a Multivariate Analysis of Covariance, with age, weight and strength as covariates. RESULTS: Isometric strength presented statistically significant between-day differences (P < 0.01), however these did not exceed 10% (healthy: 7.2%/LBP-patients: 9.7%) and ICC reliability values were excellent, yet test-retest error was increased for the patient group (healthy: ICC3,1: 0.92-0.96, SEM: 5.72-5.94 Hz, SDD: 18.51%-18.57%/LBP-patients: ICC3,1: 0.91-0.96, SEM: 6.49-6.96, SDD: 30.75%-31.61%). For the frequency data, IMF reliability was excellent (healthy: ICC3,1: 0.91-0.94, SEM: 3.45-7.27 Hz, SDD: 9.56%-20.14%/patients: ICC3,1: 0.90-0.94, SEM: 6.41-7.59 Hz, SDD: 17.75%-21.02%) and of MF raw and normalised slopes was good (healthy: ICC3,1: 0.78-0.82, SEM: 4.93-6.02 Hz, SDD: 13.66-16.67%/LBP-patients: ICC3,1: 0.83-0.85, SEM: 6.75-7.47 Hz, SDD: 18.69%-20.69%). However, the reliability for RMS data presented unacceptably high SDD values and were not considered further. For discriminative validity, less MVIC and less steep MFslopes were registered for the patient group (P < 0.01). CONCLUSION: Reliability and discriminative ability of paraspinal strength and EMG-related frequency parameters were demonstrated in healthy participants and patients with LBP.

Attitudes and diagnostic practice in low back pain: A qualitative study amongst Greek and British physiotherapists.

AIM: To explore current diagnostic practice and attitudes of Greek and United Kingdom physiotherapists (PTs) on assessing low back pain (LBP) patients. METHODS: Three focus groups were undertaken, followed by a structured questionnaire-type survey comprising 23 health professionals and a random stratified sample of 150 PTs, respectively. Twenty-nine themes relating to LBP diagnostic practice emerged. These were then given to 30 British PTs assessing their level of agreement with their Greek counterparts. Analysis was performed by percentage agreements and χ (2) tests. RESULTS: The survey was divided into three subsections; PTs' attitudes on LBP assessment, patients' attitudes and diagnostic/healthcare issues, each constituting 14, 7 and 8 statements, respectively. Over half of the statements fell within the 30%-80% agreement between Greece and United Kingdom whereas, 5 statements reported low (< 10%) and 8 statements demonstrated high (> 90%) PT percentage agreement. Similarities across British and Greek PTs were detected in history taking methods and in the way PTs feel patients perceive physiotherapy practice whereas, re-assessment was undertaken less frequently in Greece. Diagnosis according to 91% of the Greek PTs is considered a "privilege" which is exclusive for doctors in Greece (only 17% British PTs agreed) and is accompanied with a great overuse of medical investigations. Forty percent of Greek PTs (compared to 0% of British) consider themselves as "executers", being unable to interfere with treatment plan, possibly implying lack of autonomy. CONCLUSION: Although similarities on history taking methods and on patients' attitudes were detected across both groups, gross differences were found in re-assessment procedures and diagnostic issues between Greek and British physiotherapists, highlighting differences in service delivery and professional autonomy.

The use of phototherapy in peripheral nerve regeneration: an updated critical review.

This review describes the possible factors that may have contributed to the variability of the results between studies that have assessed the effects of phototherapy on peripheral nerve regeneration. Furthermore, it aims to make recommendations to overcome the methodological shortcomings identified. A search of the literature was conducted. In vitro and in vivo experimental studies and clinical trials were included. Twenty five studies were critically reviewed and showed considerable variability in irradiation parameters, techniques, approaches, length of irradiation courses, experimental injury tools and procedures. Many studies that have investigated the use of phototherapy in nerve regeneration produce positive results. However, the majority of these studies suffered from a number of shortcomings: no evidence of blinding and/or randomizing procedures, lack of specification of irradiation parameters, unspecified and/or inadequate tests in their experimental injury procedures, inappropriate irradiation parameters and/or poor experimental conditions.

Sub-grouping patients with non-specific low back pain based on cluster analysis of discriminatory clinical items.

OBJECTIVE: To identify potential subgroups amongst patients with non-specific low back pain based on a consensus list of potentially discriminatory examination items. DESIGN: Exploratory study. PARTICIPANTS: A convenience sample of 106 patients with non-specific low back pain (43 males, 63 females, mean age 36 years, standard deviation 15.9 years) and 7 physiotherapists. METHODS: Based on 3 focus groups and a two-round Delphi involving 23 health professionals and a random stratified sample of 150 physiotherapists, respectively, a comprehensive examination list comprising the most "discriminatory" items was compiled. Following reliability analysis, the most reliable clinical items were assessed with a sample of patients with non-specific low back pain. K-means cluster analysis was conducted for 2-, 3- and 4-cluster options to explore for meaningful homogenous subgroups. RESULTS: The most clinically meaningful cluster was a two-subgroup option, comprising a small group (n = 24) with more severe clinical presentation (i.e. more widespread pain, functional and sleeping problems, other symptoms, increased investigations undertaken, more severe clinical signs, etc.) and a larger less dysfunctional group (n = 80). CONCLUSION: A number of potentially discriminatory clinical items were identified by health professionals and sub-classified, based on a sample of patients with non-specific low back pain, into two subgroups. However, further work is needed to validate this classification process.

Inter-tester reliability of discriminatory examination items for sub-classifying non-specific low back pain.

OBJECTIVE: To investigate the inter-tester reliability of a non-specific low back pain examination procedure, for sub-classifying non-specific low back pain. DESIGN: Reliability study. PARTICIPANTS: Thirty patients with non-specific low back pain (12 males, 18 females, mean age: 27.7 years (standard deviation 10.3) and 7 physiotherapists (raters). METHODS: Based on a health professionals' consensus via focus groups and a Delphi servey, an examination procedure was developed comprising 206 items discriminatory for non-specific low back pain, 108 of which were from the History (clinical questions) and 98 from the Physical Examination (clinical tests) section. Utilizing this procedure, each patient was examined by a blinded pair of raters. RESULTS: Moderate to excellent agreement was obtained in 125 (61%) items (77 History and 48 Physical Examination items), 47 of which obtained substantial or excellent agreement (kappa >0.61), 37 moderate agreement (kappa between 0.41 and 0.6), and 41 excellent percentage agreements. Poor reliability (kappa < 0.41) was yielded in the remaining 81 items (31 History and 50 Physical Examination items). CONCLUSION: Satisfactory reliability was obtained in nearly two-thirds of History and half of the Physical Examination items on a non-specific low back pain assessment list generated through consensus agreement. These findings provide clinicians and researchers with valuable information regarding which items are considered reliable and can be utilized in non-specific low back pain patient evaluation/assessment procedures, classification attempts and clinical trials.

Effects of patellar taping on brain activity during knee joint proprioception tests using functional magnetic resonance imaging.

BACKGROUND: Patellar taping is a common treatment modality for physical therapists managing patellofemoral pain. However, the mechanisms of action remain unclear, with much debate as to whether its efficacy is due to a change in patellar alignment or an alteration in sensory input. OBJECTIVE: The purpose of this study was to investigate the sensory input hypothesis using functional magnetic resonance imaging when taping was applied to the knee joint during a proprioception task. DESIGN: This was an observational study with patellar taping intervention. METHODS: Eight male volunteers who were healthy and right-leg dominant participated in a motor block design study. Each participant performed 2 right knee extension repetitive movement tasks: one simple and one proprioceptive. These tasks were performed with and without patellar taping and were auditorally paced for 400 seconds at 72 beats/min (1.2 Hz). RESULTS: The proprioception task without patellar taping caused a positive blood oxygenation level-dependant (BOLD) response bilaterally in the medial supplementary motor area, the cingulate motor area, the basal ganglion, and the thalamus and medial primary sensory motor cortex. For the proprioception task with patellar taping, there was a decreased BOLD response in these regions. In the lateral primary sensory cortex, there was a negative BOLD response with less activity for the proprioception task with taping. Limitations This study may have been limited by the small sample size, a possible learning effect due to a nonrandom order of tasks, and use of a single-joint knee extension task. CONCLUSIONS: This study demonstrated that patellar taping modulates brain activity in several areas of the brain during a proprioception knee movement task.

Cognitive determinants of pain and disability in patients with chronic whiplash-associated disorder: a cross-sectional observational study.

OBJECTIVE: To delineate the relative extent to which specific cognitive factors are related to levels of pain and disability in patients with chronic whiplash-associated disorder. DESIGN: Cross-sectional observation study. SETTING: Three secondary care physiotherapy departments in the Greater Manchester region of the UK. PARTICIPANTS: All patients with chronic whiplash-associated disorder referred to the participating departments were invited to take part in the study. In total, 124 patients were invited to participate, and 63 (51%) agreed to do so. Complete data were available for 55 (44%) of those invited to participate in the study. MAIN OUTCOME MEASURES: Pain and disability, as assessed by the Neck Disability Index. RESULTS: Cognitive factors were strongly related to levels of disability (R(2) change=0.39, P<0.001). Specifically, greater catastrophising (beta=0.41, P<0.01) and lower functional self-efficacy beliefs (beta=-0.47, P<0.001) were significantly related to greater levels of disability. Significant univariate correlations were seen between the cognitive factors and current pain intensity. However, no significant associations were seen between the cognitive factors and current pain intensity in the multivariate analysis. CONCLUSIONS: Interventions which aim to reduce catastrophising and enhance functional self-efficacy beliefs should be included alongside conventional physiotherapy interventions when treating patients with chronic whiplash-associated disorder.

Which are the most important discriminatory items for subclassifying non-specific low back pain? A Delphi study among Greek health professionals.

RATIONALE, AIMS AND OBJECTIVES: Developing homogenous low back pain (LBP) classification groups is recommended for enhancing clinical outcomes. However, an important step towards the development of specific subgroups is the selection and consensus agreement among health professionals on the discriminatory clinical items (sings and symptoms) that should be included in the classification process. Thus, this study's objective was to develop a list of clinical features for the assessment of LBP by health care providers within Greece, which are believed to be discriminatory in identifying LBP subgroups. METHODS: A random sample stratified by geographical region and work status of 150 Greek physiotherapists (PTs) participated in a two-round Delphi study. PTs were asked to obtain consensus and hierarchy, the most important items out of a list of evaluating/diagnostic features believed to be discriminatory for LBP patients. These items included 80 clinical features and were generated in by PTs and doctors previous work. RESULTS: Second-round questionnaires were returned by 112 PTs (74.6% response rate). A total of 66 clinical features were rated as important discriminatory items in LBP assessment. Clinical items included characteristics of present symptoms and the history's condition, general medical history, information regarding patient function, patients' attitudes regarding movement, diagnosis, expectations, fear-avoidance beliefs as well as aspects of a physical examination including observation, active and passive movements, neurological and muscular examination. CONCLUSIONS: This is the first study identifying important clinical items for LBP patients in Greece. It may be that these features are 'discriminatory' for different LBP subsets; however, further research is needed.

The reliability of surface electromyography to assess quadriceps fatigue during multi joint tasks in healthy and painful knees.

This study's aim was to determine the between days reliability of surface EMG recordings from the superficial quadriceps during a multi joint sub-maximal fatiguing protocol. Three subject groups (healthy n=29; patellofemoral pain syndrome n=74; knee osteoarthritis n=55) performed the task at 60 maximum voluntary isometric contraction on three separate days. Spectral and amplitude EMG parameters were recorded from vastus medialis oblique, vastus lateralis and rectus femoris and were analysed for between days reliability using intraclass correlation coefficient (ICC((2,1))), the standard errors of measure and smallest detectable differences. For frequency results, initial and final frequency values had 'good' or 'excellent' reliability in all groups for all muscles. ICCs for median frequency slopes for vastus medialis oblique, vastus lateralis, and rectus femoris respectively, in the osteoarthritis group were 0.04, 0.55, and 0.72; in the patellofemoral pain group were 0.41, 0.17, and 0.33; in the healthy group were 0.68, 0.64, and 0.31. The standard errors of measurement and smallest detectable differences for all groups and for all muscles were unacceptably high. For amplitude results, ICC root mean squared initial and final values were 'good' to 'excellent' for all groups and all muscles, albeit with high measurement error. The ICCs for root mean squared slopes in all tests were 'poor' with extremely high measurement error. The poor between days reliability and high measurement error suggests that surface EMG should not be adopted to assess fatigue during multi joint sub-maximal isometric quadriceps testing.

The effects of the Mulligan Sustained Natural Apophyseal Glide (SNAG) mobilisation in the lumbar flexion range of asymptomatic subjects as measured by the Zebris CMS20 3-D motion analysis system.

BACKGROUND: Mulligan's mobilisation techniques are thought to increase the range of movement (ROM) in patients with low back pain. The primary aim of this study was to investigate the application of the Mulligan's Sustained Natural Apophyseal Glide (SNAG) technique on lumbar flexion ROM. The secondary aim was to measure the intra- and inter-day reliability of lumbar ROM employing the same procedure. METHODS: 49 asymptomatic volunteers participated in this double-blinded study. Subjects were randomly assigned to receive either SNAG mobilisation (n = 25), or a sham mobilisation (n = 24). The SNAG technique was applied at the L3and L4 spinal levels with active flexion in sitting by an experienced manual therapist. Three sets of 10 repetitions at each of the two spinal levels were performed. The sham mobilisation was similar to the SNAG but did not apply the appropriate direction or force. Lumbar ROM was measured by a three dimensional electronic goniometer (Zebris CMS20), before and after each technique. For the reliability, five measurements in two different days (one week apart) were performed in 20 healthy subjects. RESULTS: When both interventions were compared, independent t tests yielded no statistically significant results in ROM between groups (p = 0.673). Furthermore no significant within group differences were observed: SNAG (p = 0.842), sham (p = 0.169). Intra- and inter-day reliability of flexion measurements was high (ICC(1,1) > 0.82, SEM < 4.0 degrees , SDD<16.3%) indicating acceptable clinical applicability. CONCLUSION: While the Zebris proved to be a reliable device for measuring lumbar flexion ROM, SNAG mobilisation did not demonstrate significant differences in flexion ROM when compared to sham mobilisation. TRIAL REGISTRATION: Current Controlled Trials NCT00678093.

Effects of patellar taping on knee joint proprioception in patients with patellofemoral pain syndrome.

The aim of this study was to assess the effect of patellar taping of the proprioceptive status of patients with patellofemoral pain syndrome (PFPS). A total of 32 subjects (18 males, 14 females of age 31.9 +/- 11.2, body mass index 25.8 +/- 5.3) with PFPS were tested for Joint Position Sense (JPS) using a Biodex dynamometer. Outcomes of interest were the absolute error (AE), the variable error (VE) and the relative error (RE) of the JPS values for both active (AAR) and passive (PAR) angle reproduction at an angular velocity of 2 degrees /s with a start angle at 90 degrees and target angles of 60 degrees and 20 degrees . Taping was applied in random order across the patella of each subject with each of the subjects acting as their own internal control. Results indicated initially that application of patellar tape did not enhance and in some cases worsened the JPS of the subjects (P > 0.05). However, when the subjects' proprioceptive status was graded according to their closeness to the target angles into 'good' (5 degrees , N = 10) and 'poor' ( > 5 degrees , N = 22) taping enhanced nearly all values of those with 'poor' proprioception, with AE at 20 degrees to statistical significance (P = 0.021). In conclusion, this study has shown that patellar taping did not improve the AAR and PAR JPS tests of a whole sample of 32 PFPS patients. It also has shown that a subgroup of PFPS patients with poor proprioception may exist and be helped by patellar taping.

The reliability of isometric strength and fatigue measures in patients with knee osteoarthritis.

Patients with knee osteoarthritis have both poor strength and endurance of their quadriceps muscles. It is possible to assess muscle fatigue by monitoring frequency spectrum using electromyography (EMG). This study used the closed kinetic chain approach to muscle assessment. Fifty-five subjects with knee osteoarthritis were examined twice within 1 week. To test maximum voluntary isometric contraction into extension an isokinetic dynamometer, with a closed kinetic chain "leg press" attachment was used. EMG assessment of signal median frequency was done by measuring median frequency shift associated with fatiguing of muscle during a 60s isometric contraction at 60% of maximum isometric contraction. Intra-class correlation coefficients with 95% confidence intervals, standard errors of measurement and smallest detectable differences were calculated. Results showed the reliability of the maximum voluntary isometric contraction extension strength test was ICC 0.99 and SEM 3.95Nm. The initial median frequency indices also demonstrated excellent ICC and SEM statistics (ICC 0.84-0.91, SEM 9.2-11Hz) for the three heads of the quadriceps; however, the fatigue slopes for all three muscles were unreliable with poor ICCs (0.04-0.72) and SDD values (2207-4000%). The assessment of peak muscle torque using a closed kinetic chain isometric technique is reliable, as is the determination of median frequency values for the quadriceps. Error for the assessment of fatigue was of an unacceptable scale. While the use of a closed kinetic chain leg press technique provides a reliable measurement of lower limb strength, EMG power spectrum decrease during an isometric contraction is of little value.

Subclassification of low back pain: a cross-country comparison.

Various health professionals have attempted to classify low back pain (LBP) subgroups and have developed several LBP classification systems. Knowing that culture has an effect on LBP symptomatology, assessment findings and clinical decision making, the aim of this review is to perform a cross-country comparative review amongst the published classification systems, addressing each country's similarities and differences as well as exploring whether cultural factors have been incorporated into the subclassification process. A systematic search of databases limited to human adults was undertaken by Medline, Cinahl, AMED and PEDro databases between January 1980 and October 2005. Classification systems from nine countries were identified. Most studies were classified according to pathoanatomic and/or clinical features, whereas fewer studies utilized a psychosocial and even less, a biopsychosocial approach. Most studies were limited in use to the country of the system's developer. Very few studies addressed cultural issues, highlighting the lack of information on the impact of specific cultural factors on LBP classification procedures. However, there seem to be certain 'cultural trends' in classification systems within each country, which are discussed. Despite the plethora of classification studies, there is still no system which is internationally established, effective, reliable and valid. Future research should aim to develop a LBP classification system within a well identified cultural setting, addressing the multi-dimensional features of the LBP presentation.

The clinical and cultural factors in classifying low back pain patients within Greece: a qualitative exploration of Greek health professionals.

RATIONALE, AIMS AND OBJECTIVES: Identifying homogenous subgroups of low back pain (LBP) patients is considered a priority in musculoskeletal rehabilitation and is believed to enhance clinical outcomes. In order to achieve this, the specific features of each subgroup need to be identified. The aim of this study was to develop a list of clinical and cultural features that are included in the assessment of LBP patients in Greece, among health professionals. This 'list' will be, utilized in a clinical study for developing LBP subgroups. METHODS: Three focus groups were conducted, each one comprising health professionals with homogenous characteristics and all coordinated by a single moderator. There were: 11 physiotherapists (PTs) with clinical experience in LBP patients, seven PTs specialized in LBP management, and five doctors with a particular spinal interest. The focus of discussions was to develop a list of clinical and cultural features that were important in the examination of LBP. Content analysis was performed by two researchers. RESULTS: Clinicians and postgraduates developed five categories within the History (Present Symptoms, History of Symptoms, Function, Psychosocial, Medical History) and six categories within the Physical Examination (Observation, Neurological Examination, Active and Passive Movements, Muscle Features and Palpation). The doctors identified four categories in History (Symptomatology, Function, Psychosocial, Medical History) and an additional in Physical Examination (Special Tests). All groups identified three cultural categories; Attitudes of Health Professionals, Patients' Attitudes and Health System influences. CONCLUSION: An extensive Greek 'list' of clinical and cultural features was developed from the groups' analysis. Although similarities existed in most categories, there were several differences across the three focus groups which will be discussed.

Development of a clinical examination in non-specific low back pain: a Delphi technique.

OBJECTIVE: To establish the discriminatory items of the clinical examination of non-specific low back pain, important to physiotherapists. DESIGN: A focus group and Delphi technique with UK physiotherapists. SUBJECTS: A purposive sample of 30 physiotherapists attended a focus group and completed 3 rounds of Delphi questionnaires. METHODS: Data were analysed using mixed qualitative and quantitative approaches. A frequency content analysis identified commonly identified tests and questions, whilst the Delphi consensus technique assumed consensus had been reached with greater than 80% agreement on item inclusion or exclusion. RESULTS: The focus group established the structure of the clinical examination with 15 domains of questioning or physical testing. Three rounds of Delphi questionnaires established the important items of the clinical examination. The list of tests and questions included items evaluating both the psychosocial and biomedical status of the patient as well as questions screening for red flags. CONCLUSION: This is the first work to establish discriminatory tests in the clinical examination of non-specific low back pain, important to physiotherapists. The clinical examination will subsequently be evaluated for item validity and data will undergo cluster analysis. The items of this clinical examination may provide evidence for the existence of homogenous sub-groups within the heterogeneous non-specific low back pain diagnosis.

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.

Trunk muscle stabilization training plus general exercise versus general exercise only: randomized controlled trial of patients with recurrent low back pain.

BACKGROUND AND PURPOSE: The purpose of this randomized controlled trial was to examine the usefulness of the addition of specific stabilization exercises to a general back and abdominal muscle exercise approach for patients with subacute or chronic nonspecific back pain by comparing a specific muscle stabilization-enhanced general exercise approach with a general exercise-only approach. SUBJECTS: Fifty-five patients with recurrent, nonspecific back pain (stabilization-enhanced exercise group: n=29, general exercise-only group: n=26) and no clinical signs suggesting spinal instability were recruited. METHODS: Both groups received an 8-week exercise intervention and written advice (The Back Book). Outcome was based on self-reported pain (Short-Form McGill Pain Questionnaire), disability (Roland-Morris Disability Questionnaire), and cognitive status (Pain Self-Efficacy Questionnaire, Tampa Scale of Kinesiophobia, Pain Locus of Control Scale) measured immediately before and after intervention and 3 months after the end of the intervention period. RESULTS: Outcome measures for both groups improved. Furthermore, self-reported disability improved more in the general exercise-only group immediately after intervention but not at the 3-month follow-up. There were generally no differences between the 2 exercise approaches for any of the other outcomes. DISCUSSION AND CONCLUSION: A general exercise program reduced disability in the short term to a greater extent than a stabilization-enhanced exercise approach in patients with recurrent nonspecific low back pain. Stabilization exercises do not appear to provide additional benefit to patients with subacute or chronic low back pain who have no clinical signs suggesting the presence of spinal instability.

Electric muscle stimulation of the quadriceps in the treatment of patellofemoral pain.

OBJECTIVE: To compare a commercially available electric muscle stimulation regimen with a novel form of stimulation for the rehabilitation of the quadriceps muscle, in patients with patellofemoral pain syndrome. DESIGN: Double-blinded randomized trial with a parallel control group and stratified randomization. SETTING: Home-based rehabilitation program assessed in research center. PARTICIPANTS: Eighty patients (47 women, 33 men) with patellofemoral pain syndrome. INTERVENTIONS: One group (EMPI) received 1 uniform constant frequency component of 35Hz. The other (EXPER) group received an experimental form of stimulation that contained 5 simultaneously delivered frequency components of 125, 83, 50, 2.5, and 2Hz. Stimulation was applied to the quadriceps muscles of the affected leg for 1 hour daily for 6 weeks, a total of 42 treatments. MAIN OUTCOME MEASURES: Lower-limb isometric and isokinetic torque, quadriceps fatigue, knee flexion, patellar pain, a step test, quadriceps cross-sectional area, and Kujala patellofemoral score for pain before and after treatment. RESULTS: Seventy-four patients (43 women, 31 men) completed the trial. Patients in both groups showed significant improvements in all outcomes (P<.05). No significant differences existed between the 2 stimulators in any outcome (P>.05) except for quadriceps cross-sectional area (P=.023). CONCLUSIONS: One form of stimulation was just as efficacious as the other in improving subjective and objective measures.

Chronic low back pain-associated paraspinal muscle dysfunction is not the result of a constitutionally determined "adverse" fiber-type composition.

STUDY DESIGN: Investigative case control study. OBJECTIVES: To determine whether excessive paraspinal muscle fatigue in chronic low back pain results from a paucity of muscle type I fiber content. SUMMARY OF BACKGROUND DATA: Paraspinal muscle function is vital for spinal protection. Prospective studies suggest that excessive paraspinal muscle fatigability may increase risk of first-time low back pain. As contractile performance of the paraspinal muscles is governed by their constitutionally determined fiber composition, the question arises whether a constitutionally determined "adverse" composition could predispose to low back pain through impaired spinal protection. METHODS: Thirty-five male patients with chronic low back pain were compared with 32 male control patients of similar age and anthropometry. During Sorensen and 60% of maximum voluntary isometric contraction fatigue tests, median frequency declines in the paraspinal muscle surface electromyograph signal were monitored and correlated with muscle histomorphometry. RESULTS: Patients were weaker than controls during maximum voluntary isometric contractions (84.47 [28.44]vs. 98.74 [18.11] kg, respectively; P = 0.02) and more fatigable during their Sorensen tests (endurance time 105.29 [28.53]vs. 137.50 [40.38] sec, respectively; P < 0.01). There were no between-group differences in median frequency declines during the Sorensen (-0.37 [0.16]vs. -0.36 [0.12]%.sec) or 60% maximum voluntary isometric contraction (-0.42 [0.31]vs. -0.51 [0.29]%.sec) tests, for patients and controls, respectively. There were no between-group differences in the percent number of paraspinal muscle type I fibers (64 [11]vs. 64 [9]%) or the percent area occupied by type I fibers (67 [11]vs. 69 [9]%), for patients and controls, respectively. Type I and II muscle fiber narrow diameters were similar for both groups. CONCLUSION: In the patients with chronic low back pain tested, their associated paraspinal muscle dysfunction was not the result of a constitutionally determined "adverse" fiber type composition.

Between-days reliability of electromyographic measures of paraspinal muscle fatigue at 40, 50 and 60% levels of maximal voluntary contractile force.

OBJECTIVE: To ascertain which percentage of maximal voluntary contractile force of the paraspinal muscles, when tested in a functional position, is most reliable for assessing electromyographic (EMG) fatigue changes. SUBJECTS: Ten healthy volunteers with no history of low back pain (six males). MAIN OUTCOME MEASURES: The surface EMG signal during 60-second isometric contractions of the paraspinal muscles at 40, 50 and 60% levels of maximal voluntary contractile force was captured and analysed. Each contraction level was assessed on two occasions, at least three days apart. The initial median frequency, the decline in median frequency slope and the increase in root mean square values were assessed for between-days reliability, using intraclass correlation coefficients (ICCs) and standard errors of measurements (SEM). Normalized median frequency and root mean square values were also assessed. RESULTS: At 40% of maximal voluntary contraction, little or no EMG fatigue changes occurred in any of the observed parameters. At 50% maximal voluntary contraction the initial mean frequency and root mean square changes proved highly reliable, with ICCs ranging from 0.74 to 0.86 and 0.75 to 1.00 respectively. Normalizing the root mean square data reduced the reliability, but this was still acceptable with ICCs 0.70-0.83. The median frequency decline slope proved less reliable with ICCs 0.24-0.74 for raw and 0.26-0.77 for normalized data. At 60% maximal voluntary contraction the initial mean frequency proved as reliable as initial median frequency at 50% with ICCs 0.70-0.89. The raw and normalized root mean squares (ICCs 0.43-0.89 and 0.30-0.87 respectively) and raw and normalized median frequency (ICCs 0.27-0.51 and 0.24-0.53 respectively) changes were less reliable than at 50% MVC. Overall, the reliability is better at the L4/5 than at the L2/3 level. CONCLUSION: Outcome measures taken at 50% maximal voluntary contraction are the most reliable in functional testing the paraspinal muscles of healthy volunteers. With initial median frequency and root mean square values being more reliable parameters than median frequency decline. At the L4/5 level, however, all parameters were acceptably reliable at 50% of maximum effort. However the between-subject variability of the median frequency decline and root mean square incline slopes suggest that these parameters are not yet fully suitable for monitoring fatigue changes during prolonged isometric contraction.