Exercise therapy including the cervical extensor muscles in individuals with neck pain: A systematic review.

OBJECTIVE: To review the use (dosage parameters and combination with other therapeutic interventions) of cervical extensor muscle exercises and their effect on pain, disability (primary outcomes), range of motion, endurance and strength (secondary outcomes) in people with neck pain. DATA SOURCES: An extensive literature search was conducted through MEDLINE (Ovid), Scopus (Elsevier) and Physiotherapy Evidence Database (PEDro) up to May 2023. The reference lists of all included studies and relevant reviews were screened for additional studies. REVIEW METHODS: Randomised controlled trials reporting the use of cervical extensor muscle exercises (alone or combined) applied to adults with idiopathic or traumatic neck pain were included. Study selection, data extraction and critical appraisal (PEDro assessment scale) were performed by two blinded reviewers. Data extraction included dosage parameters, other modalities combined with these exercises and outcomes. RESULTS: Thirty-five randomised controlled trails (eight of which were complementary analyses) with 2409 participants fulfilled the inclusion criteria. Twenty-six were of moderate to high quality. In most studies, cervical extensor muscle exercises were combined with various other therapeutic modalities and applied at different dosages. Only two studies (one high and one low quality) specifically assessed their effectiveness. The high-quality study showed significant improvements in neck pain and disability, pressure point threshold and neck mobility after both low load and high load training for 6 weeks. CONCLUSION: The results suggest cervical extensor muscle exercises may reduce neck pain and disability; however firm conclusions cannot be drawn because of the few studies that addressed this question and the heterogeneity of the dosage parameters.

The Effect of Praying on Endogenous Pain Modulation and Pain Intensity in Healthy Religious Individuals in Lebanon: A Randomized Controlled Trial.

Prayer is considered to be the most common therapy used in alternative medicine. This study aimed to explore the effect of prayers on endogenous pain modulation, pain intensity, and sensitivity in healthy religious participants. A total of 208 healthy religious participants were enrolled in this study and randomly distributed into two groups, a prayer group (n = 156) and a poem reading or control group (n = 52). Participants from the prayer group were then selectively allocated using the prayer function scale to either an active prayer group (n = 94) receiving an active type of praying or to a passive prayer group (n = 62) receiving a passive type of praying. Pain assessments were performed before and following the interventions and included pressure pain threshold assessment (PPT), conditioned pain modulation (CPM), and a numerical pain rating scale. A significant group-by-time interaction for PPT (p = 0.014) indicated post-intervention increases in PPT in the prayer group but not in the poem reading control group. Participants experienced a decrease in CPM efficacy (p = 0.030) and a reduction in their NPRS (p < 0.001) following the interventions, independent of their group allocation. The results showed that prayer, irrespective of the type, can positively affect pain sensitivity and intensity, but does not influence endogenous pain inhibition during hot water immersion. Future research should focus on understanding the mechanism behind "prayer-induced analgesia."

Foci of Segmentally Contracted Sarcomeres in Trapezius Muscle Biopsy Specimens in Myalgic and Nonmyalgic Human Subjects: Preliminary Results.

OBJECTIVE: The myofascial trigger point hypothesis postulates that there are small foci of contracted sarcomeres in resting skeletal muscle. Only one example, in canine muscle, has been published previously. This study evaluated human muscle biopsies for foci of contracted sarcomeres. SETTING: The Departments of Rehabilitation Sciences and Physiotherapy at Ghent University, Ghent, Belgium. SUBJECTS: Biopsies from 28 women with or without trapezius myalgia were evaluated, 14 in each group. METHODS: Muscle biopsies were obtained from regions of taut bands in the trapezius muscle and processed for light and electron microscopy and for histochemical analysis. Examination of the biopsies was blinded as to group. RESULTS: A small number of foci of segmentally contracted sarcomeres were identified. One fusiform segmental locus involved the entire muscle fiber in tissue from a myalgic subject. Several transition zones from normal to contracted sarcomeres were found in both myalgic and nonmyalgic subjects. The distance between Z-lines in contracted sarcomeres was about 25-45% of the same distance in normal sarcomeres. Z-lines were disrupted and smeared in the contracted sarcomeres. CONCLUSIONS: A small number of foci of segmentally contracted sarcomeres were found in relaxed trapezius muscle in human subjects, a confirmation of the only other example of spontaneous segmental contraction of sarcomeres (in a canine muscle specimen), consistent with the hypothesis of trigger point formation and with the presence of trigger point end plate noise.

Electroencephalography During Nociceptive Stimulation in Chronic Pain Patients: A Systematic Review.

BACKGROUND: With its high temporal resolution, electroencephalography (EEG), a technique that records electrical activity of cortical neuronal cells, is a potentially suitable technique to investigate human somatosensory processing. By using EEG, the processing of (nociceptive) stimuli can be investigated, along with the functionality of the nociceptive pathway. Therefore, it can be applied in chronic pain patients to objectify whether changes have occurred in nociceptive processing. Typically, so-called event-related potential (ERP) recordings are used, where EEG signals are recorded in response to specific stimuli and characterized by latency and amplitude. OBJECTIVE: To summarize whether differences in somatosensory processing occur between chronic pain patients and healthy controls, measured with ERPs, and determine whether this response is related to the subjective pain intensity. DESIGN: Systematic review. SETTING AND METHODS: PubMed, Web of Science, and Embase were consulted, and 18 case-control studies were finally included. SUBJECTS: The chronic pain patients suffered from tension-type headache, back pain, migraine, fibromyalgia, carpal tunnel syndrome, prostatitis, or complex regional pain syndrome. RESULTS: Chronic neuropathic pain patients showed increased latencies of the N2 and P2 components, along with a decreased amplitude of the N2-P2 complex, which was also obtained in FM patients with small fiber dysfunction. The latter also showed a decreased amplitude of the N2-P3 and N1-P1 complex. For the other chronic pain patients, the latencies and the amplitudes of the ERP components did not seem to differ from healthy controls. One paper indicated that the N2-P3 peak-to-peak amplitude correlates with the subjective experience of the stimulus. CONCLUSIONS: Differences in ERPs with healthy controls can mostly be found in chronic pain populations that suffer from neuropathic pain or where fiber dysfunction is present. In chronic pain populations with other etiological mechanisms, limited differences were found or agreed upon across studies.

Does Pain Neuroscience Education and Cognition-Targeted Motor Control Training Improve Cervical Motor Output? Secondary Analysis of a Randomized Clinical Trial.

BACKGROUND: In the context of interventions aimed at reducing pain, disability, and maladaptive pain cognitions in chronic neck pain, it is hypothesized that patients who have greater symptom reduction possibly also demonstrate greater improvement in cervical motor output. Therefore, the aim of this study was to examine the effect of pain neuroscience education plus cognition-targeted motor control training on cervical motor output. METHODS: Impairments in cervical motor output were measured in 64 subjects with chronic neck pain using standardized tests. Cervical muscle strength, cervical mobility, balance, and cervical neuromuscular control were derived. To assess the differences between groups in response to treatment, a random-intercept linear mixed-models analysis, applying a diagonal covariance matrix, was used. RESULTS: A significant treatment × time interaction effect was found for neuromuscular control of the deep cervical flexors, favoring the experimental treatment at 3 months' follow-up (mean group difference: 1.982; 95% confidence interval 0.779, 3.185; large effect size d = 0.82). Significant main effects of time were found for the neuromuscular capacity of scapulothoracic muscles and for cervical mobility. No significant effects were found for balance, cervical muscle strength, or endurance of cervical flexors. CONCLUSION: Pain neuroscience education combined with cognition-targeted motor control training is not more effective than biomedically focused education and exercise therapy for improving cervical motor output in people with chronic neck pain. Our findings question the relative importance of factors such as pain, disability, and maladaptive pain cognitions on cervical motor output and the need to address it in treatment.

Associations between brain morphology and motor performance in chronic neck pain: A whole-brain surface-based morphometry approach.

Changes in brain morphology are hypothesized to be an underlying process that drive the widespread pain and motor impairment in patients with chronic neck pain. However, no earlier research assessed whole-brain cortical morphology in these patients. This case-control study assesses group-differences in whole-brain morphology between female healthy controls (HC; n = 34), and female patients with chronic idiopathic neck pain (CINP; n = 37) and whiplash-associated disorders (CWAD; n = 39). Additionally, the associations between whole-brain morphology and motor performance including balance, strength, and neuromuscular control were assessed. Cortical volume, thickness, and surface area were derived from high resolution T1-weighted images. T2*-weighted images were obtained to exclude traumatic brain injury. Vertex-wise general-linear-model-analysis revealed cortical thickening in the left precuneus and increased volume in the left superior parietal gyrus of patients with CINP compared to HC, and cortical thickening of the left superior parietal gyrus compared to HC and CWAD. Patients with CWAD showed a smaller cortical volume in the right precentral and superior temporal gyrus compared to HC. ANCOVA-analysis revealed worse neuromuscular control in CWAD compared to HC and CINP, and in CINP compared to HC. Patients with CWAD showed decreased levels of strength and sway area compared to CINP and HC. Partial correlation analysis revealed significant associations between the volume of the precentral gyrus, and neuromuscular control and strength together with an association between the volume of the superior temporal gyrus and strength. Our results emphasize the role of altered gray matter alterations in women with chronic neck pain, and its association with pain and motor impairment.

Convergent Validity of the Dutch Central Sensitization Inventory: Associations with Psychophysical Pain Measures, Quality of Life, Disability, and Pain Cognitions in Patients with Chronic Spinal Pain.

OBJECTIVE: Symptoms of central sensitization (CS) have been described in patients with chronic spinal pain (CSP). Although a gold standard to diagnose CS is lacking, psychophysical pain measures are often used. The Central Sensitization Inventory (CSI) is proposed as an alternative method and indirect tool for the evaluation of CS symptomatology. The aim of the current study was to evaluate the convergent validity of the CSI by investigating the association with psychophysical pain measures and self-reported measures of current pain intensity, quality of life, disability, and catastrophizing in CSP patients. METHODS: One hundred sixteen patients with nonspecific CSP were included in the present study. Patients completed the CSI, were subjected to pressure pain thresholds (PPTs) and a conditioned pain modulation (CPM) paradigm, and completed questionnaires for current pain intensity, quality of life, pain disability, and pain catastrophizing. RESULTS: Higher CSI scores were weakly correlated with lower PPTs (-0.276 ≤ r ≤ -0.237; all P ≤ 0.01) and not with CPM efficacy (r = 0.017; P = 0.858). Higher CSI scores were moderately correlated with higher current pain intensity (r = 0.320; P < 0.001), strongly correlated with lower physical (r = -0.617; P < 0.001) and emotional (r = -0.635; P < 0.001) quality of life, and moderately correlated with higher pain disability (r = 0.472; P < 0.001) and higher pain catastrophizing (r = 0.464; P < 0.001). CONCLUSION: The CSI was weakly associated with PPTs and not with CPM efficacy in CSP patients. Moderate to strong associations were found with current pain intensity, quality of life, disability, and catastrophizing. The current results illustrate that the CSI does not reflect a direct measure of CS, yet is a representation of general distress, possible originating from CS symptoms.

The influence of induced shoulder muscle pain on rotator cuff and scapulothoracic muscle activity during elevation of the arm.

BACKGROUND: Altered recruitment of rotator cuff and scapulothoracic muscles has been identified in patients with subacromial impingement syndrome. To date, however, the cause-consequence relationship between pain and altered muscle recruitment has not been fully unraveled. METHODS: The effect of experimental shoulder pain induced by injection of hypertonic saline in the supraspinatus on the activity of the supraspinatus, infraspinatus, subscapularis, trapezius, and serratus anterior activity was investigated during the performance of an elevation task by use of muscle functional magnetic resonance imaging in 25 healthy individuals. Measurements were taken at 4 levels (C6-C7, T2-T3, T3-T4, and T6-T7) at rest and after the elevation task performed without and with experimental shoulder pain. RESULTS: During arm elevation, experimentally induced pain caused a significant activity reduction, expressed as reduction in T2 shift of the IS (P = .029). No significant changes in T2 shift values were found for the other rotator cuff muscles or the scapulothoracic muscles. CONCLUSIONS: This study demonstrates that acute experimental shoulder pain has an inhibitory effect on the activity of the IS during arm elevation. Acute experimental shoulder pain did not seem to influence the scapulothoracic muscle activity significantly. The findings suggest that rotator cuff muscle function (infraspinatus) should be a consideration in the early management of patients with shoulder pain.

Scapular muscle dysfunction associated with subacromial pain syndrome.

STUDY DESIGN: Narrative Review. INTRODUCTION: One of the shoulder pain disorders in which the function of the scapula is comprised is the subacromial pain syndrome. Several rehabilitation guidelines and exercises have been proposed to improve scapulothoracic muscle dysfunction. Consideration of muscle activation patterns may help to select the most appropriate rehabilitation exercise in these patients. To date, suggesting rehabilitation exercises is often based upon the knowledge of the superficial lying scapulothoracic muscles' activity. In the assumption that the deeper lying scapulothoracic muscles' activity may hinder normal scapular movement in case of tightness or hyperactivity, exercise protocols for patients with altered pattern in scapulothoracic muscles should also integrate knowledge on the deeper lying scapulothoracic muscle activity. PURPOSE OF THE STUDY: To help clinicians choosing the most appropriate exercise in patients with subacromial pain syndrome related to scapulothoracic muscle dysfunction. METHODS: First, a summary of key alterations in scapulothoracic (muscle) function in patients with subacromial pain was accomplished. Second, promising practical rehabilitation strategies toward restoring scapulothoracic muscle dysfunction (with a focus on scapulothoracic exercises) were developed, integrating current new research evidence (including information about the deeper lying scapulothoracic muscles) with clinical practice. CONCLUSION: This review details clinical exercises and their muscular activity to guide clinicians to optimize individualized scapulothoracic training and treatment programs by selecting the most appropriate exercise, based on knowledge from the clinical examination. LEVEL OF EVIDENCE: Level 5.

Comparing Trigger Point Dry Needling and Manual Pressure Technique for the Management of Myofascial Neck/Shoulder Pain: A Randomized Clinical Trial.

OBJECTIVE: The aim of this study was to investigate short-term and long-term treatment effects of dry needling (DN) and manual pressure (MP) technique with the primary goal of determining if DN has better effects on disability, pain, and muscle characteristics in treating myofascial neck/shoulder pain in women. METHODS: In this randomized clinical trial, 42 female office workers with myofascial neck/shoulder pain were randomly allocated to either a DN or MP group and received 4 treatments. They were evaluated with the Neck Disability Index, general numeric rating scale, pressure pain threshold, and muscle characteristics before and after treatment. For each outcome parameter, a linear mixed-model analysis was applied to reveal group-by-time interaction effects or main effects for the factor "time." RESULTS: No significant differences were found between DN and MP. In both groups, significant improvement in the Neck Disability Index was observed after 4 treatments and 3 months (P < .001); the general numerical rating scale also significantly decreased after 3 months. After the 4-week treatment program, there was a significant improvement in pain pressure threshold, muscle elasticity, and stiffness. CONCLUSION: Both treatment techniques lead to short-term and long-term treatment effects. Dry needling was found to be no more effective than MP in the treatment of myofascial neck/shoulder pain.

Determining Predictive Outcome Factors for a Multimodal Treatment Program in Low Back Pain Patients: A Retrospective Cohort Study.

OBJECTIVE: The purpose of this study was to determine the factors predictive of outcomes in a multifaceted rehabilitation program for acute and chronic low back pain (LBP) patients. METHODS: A retrospective cohort study was performed on 565 LBP patients (153 acute and 412 chronic) who participated in a multimodal treatment program at an outpatient clinic in Belgium between 2007 and 2010. The predictive value of several factors, including age, sex, body mass index, fat percentage, Oswestry Disability Index score, Beck Depression Index score, Numeric Pain Rating Scale score for back and leg pain intensity, and Tampa Scale for Kinesiophobia score on favorable treatment outcomes was examined using logistic regression analysis. RESULTS: The results from the multivariate regression indicated that a higher score on the Tampa Scale for Kinesiophobia (odds ratio [OR] = 0.92) decreases the odds of a favorable outcome following a multimodal treatment program in acute LBP. Older age (OR = 0.97), low LBP intensity (OR = 1.191), and higher scores on the Beck Depression Index (OR = 0.96) and the Oswestry LBP Disability Index (OR = 0.93) decreased the odds of a favorable treatment outcome in chronic LBP. CONCLUSIONS: The findings of this study indicate that factors predictive of a (un)favorable treatment outcome differ between acute and chronic LBP. Specifically, kinesiophobia is predictive of poor treatment outcome in acute LBP. In chronic LBP, older age, low LBP intensity, and higher degrees of depression and LBP-related disability are predictive of poor treatment outcome. Therapists should consider assessing these predictive factors at intake to tailor the content of the multimodal treatment program to individual patient needs.

The impact of different lenses on visual and musculoskeletal complaints in VDU workers with work-related neck complaints: a randomized controlled trial.

OBJECTIVES: The impact of wearing lenses on visual and musculoskeletal complaints in VDU workers is currently unknown. The goal of this study was 1) to evaluate the impact of wearing VDU lenses on visual fatigue and self-reported neck pain and disability, compared to progressive lenses, and 2) to measure the effect of both lenses on head inclination and pressure pain thresholds during the performance of a VDU task. METHODS: Thirty-five eligible subjects were randomly assigned to wear progressive VDU lenses (VDU group) (n = 18) or progressive lenses (P group) (n = 17). They were enquired about visual complaints (VFQ), self-perceived pain (NRS) and disability (NDI) at baseline (with old lenses), and 1 week, 3 months and 6 months after wearing their new lenses. In addition, Forward Head Angle (FHA) and PPTs were assessed during and after a VDU task before and 6 months after wearing the new lenses. A short questionnaire concerning the satisfaction about the study lenses was completed at the end of the study. RESULTS: In both groups, visual fatigue and neck pain was decreased at 3 and 6 months follow up, compared to baseline. All PPTs were higher during the second VDU task, independent of the type of lenses. The VDU group reported a significantly higher suitability of the lenses for VDU work. CONCLUSION: It can be concluded that there is little difference in effect of the different lenses on visual and musculoskeletal comfort. Lenses should be adjusted to the task-specific needs and habits of the participant.

The effect of experimental low back pain on lumbar muscle activity in people with a history of clinical low back pain: a muscle functional MRI study.

In people with a history of low back pain (LBP), structural and functional alterations have been observed at several peripheral and central levels of the sensorimotor pathway. These existing alterations might interact with the way the sensorimotor system responds to pain. We examined this assumption by evaluating the lumbar motor responses to experimental nociceptive input of 15 participants during remission of unilateral recurrent LBP. Quantitative T2 images (muscle functional MRI) were taken bilaterally of multifidus, erector spinae, and psoas at several segmental levels (L3 upper and L4 upper and lower endplate) and during several conditions: 1) at rest, 2) upon trunk-extension exercise without pain, and 3) upon trunk-extension exercise with experimental induced pain at the clinical pain-side (1.5-ml intramuscular hypertonic saline injections in erector spinae). Following experimental pain induction, muscle activity levels similarly reduced for all three muscles, on both painful and nonpainful sides, and at multiple segmental levels (P = 0.038). Pain intensity and localization from experimental LBP were similar as during recalled clinical LBP episodes. In conclusion, unilateral and unisegmental experimental LBP exerts a generalized and widespread decrease in lumbar muscle activity during remission of recurrent LBP. This muscle response is consistent with previous observed patterns in healthy people subjected to the same experimental pain paradigm. It is striking that similar inhibitory patterns in response to pain could be observed, despite the presence of preexisting alterations in the lumbar musculature during remission of recurrent LBP. These results suggest that motor output can modify along the course of recurrent LBP.

Multivariable modeling of factors associated with spinal pain in young adolescence.

PURPOSE: To investigate the factors related to the 1-month period prevalence of low back pain (LBP), neck pain (NP) and thoracic spine pain (TSP) in young adolescents, thereby considering potential correlates from the physical, sociodemographic, lifestyle, psychosocial and comorbid pain domains. METHODS: In this cross-sectional baseline study, 69 factors potentially associated with spinal pain were assessed among 842 healthy adolescents before pubertal peak growth. With consideration for possible sex differences in associations, multivariable analysis was used to simultaneously evaluate contributions of all variables collected in the five domains. RESULTS: A significantly higher odds of LBP was shown for having high levels of psychosomatic complaints (odds ratio: 4.4; 95 % confidence interval: 1.6-11.9), a high lumbar lordotic apex, retroversed pelvis, introverted personality, and high levels of negative over positive affect. Associations with a higher prevalence and odds of NP were found for psychosomatic complaints (7.8; 2.5-23.9), TSP in the last month (4.9; 2.2-10.8), backward trunk lean, high levels of negative over positive affect and depressed mood. Having experienced LBP (2.7; 1.3-5.7) or NP (5.5; 2.6-11.8) in the preceding month was associated with a higher odds of TSP, as were low self-esteem, excessive physical activity, sedentarism and not achieving the Fit-norm. CONCLUSIONS: Psychosomatic symptoms and pain comorbidities had the strongest association with 1-month period prevalence of spinal pain in young adolescents, followed by factors from the physical and psychosocial domains. The role that "physical factors" play in non-adult spinal pain may have been underestimated by previous studies.

Disc herniations in astronauts: What causes them, and what does it tell us about herniation on earth?

PURPOSE: Recent work showed an increased risk of cervical and lumbar intervertebral disc (IVD) herniations in astronauts. The European Space Agency asked the authors to advise on the underlying pathophysiology of this increased risk, to identify predisposing factors and possible interventions and to suggest research priorities. METHODS: The authors performed a narrative literature review of the possible mechanisms, and conducted a survey within the team to prioritize research and prevention approaches. RESULTS AND CONCLUSIONS: Based on literature review the most likely cause for lumbar IVD herniations was concluded to be swelling of the IVD in the unloaded condition during spaceflight. For the cervical IVDs, the knowledge base is too limited to postulate a likely mechanism or recommend approaches for prevention. Basic research on the impact of (un)loading on the cervical IVD and translational research is needed. The highest priority prevention approach for the lumbar spine was post-flight care avoiding activities involving spinal flexion, followed by passive spinal loading in spaceflight and exercises to reduce IVD hyper-hydration post-flight.

Optimal Normalization Tests for Muscle Activation of the Levator Scapulae, Pectoralis Minor, and Rhomboid Major: An Electromyography Study Using Maximum Voluntary Isometric Contractions.

OBJECTIVE: To identify maximum voluntary isometric contraction (MVIC) test positions for the deeper-lying scapulothoracic muscles (ie, levator scapulae, pectoralis minor, rhomboid major), and to provide a standard set of a limited number of test positions that generate an MVIC in all scapulothoracic muscles. DESIGN: Cross-sectional study. SETTING: Physical and rehabilitation medicine department. PARTICIPANTS: Healthy subjects (N=21). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mean peak electromyographic activity from levator scapulae, pectoralis minor, and rhomboid major (investigated with fine-wire electromyography) and from upper trapezius, middle trapezius, lower trapezius, and serratus anterior (investigated with surface electromyography) during the performance of 12 different MVICs. RESULTS: The results indicated that various test positions generated similar high mean electromyographic activity and that no single test generated maximum activity for a specific muscle in all subjects. The results of this study support using a series of test positions for normalization procedures rather than a single exercise to increase the likelihood of recruiting the highest activity in the scapulothoracic muscles. CONCLUSIONS: A standard set of 5 test positions was identified as being sufficient for generating an MVIC of all scapulothoracic muscles: seated T, seated U 135°, prone T-thumbs up, prone V-thumbs up, and supine V-thumbs up. A standard set of test positions for normalization of scapulothoracic electromyographic data that also incorporates the levator scapulae, pectoralis minor, and rhomboid major muscles is 1 step toward a more comprehensive understanding of normal and abnormal muscle function of these muscles and will help to standardize the presentation of scapulothoracic electromyographic muscle activity.

Fiber Typing of the Erector Spinae and Multifidus Muscles in Healthy Controls and Back Pain Patients: A Systematic Literature Review.

OBJECTIVE: Understanding the changes in muscle fiber typing is relevant in the context of muscle disorders because it provides information on the metabolic profile and functional capacity. The aim of this study was to systematically review the literature comparing muscle fiber typing in the back muscles of healthy subjects with low back pain (LBP) patients. METHODS: Predefined keywords regarding muscle fiber typing and back muscles were combined in PubMed and Web of Science electronic search engines from inception to August 2014. Full-text articles were independently screened by 2 independent, blinded researchers. Full texts fulfilling the predefined inclusion criteria were assessed on risk of bias by 2 independent researchers, and relative data were extracted. Data were not pooled because of heterogeneity in biopsy locations and population. RESULTS: From the 214 articles that were identified, 18 met the inclusion criteria. These articles evaluated the muscle fiber type distribution or proportional fiber type area between muscles, muscle layers, men, and women or healthy subjects and LBP patients. Regarding muscle fiber type distribution, findings in healthy subjects and LBP patients show no or inconclusive evidence for intermuscular and interindividual differentiation. Studies evaluating the proportional fiber type area also suggest little intermuscular differentiation but provide plausible evidence that the proportional area occupied by type I fibers is higher in women compared to men. The evidence for differentiation based on the presence of low back pain is conflicting. CONCLUSION: This study found that the evidence regarding muscle fiber typing in back muscles is either inconclusive or shows little differences. The most plausible evidence exists for differentiation in proportional fiber type area depending on sex.

Effect of Pain Induction or Pain Reduction on Conditioned Pain Modulation in Adults: A Systematic Review.

OBJECTIVE: Pain facilitation as well as pain inhibition might be present in chronic pain patients. A decreased efficacy of pain inhibition can be measured by conditioned pain modulation (CPM). The use of the CPM paradigm in scientific research has boosted over the last few years and is recognized for its high clinical relevance in chronic pain patients. It is, however, unclear whether the presence of pain and possible modulations of pain influences the efficacy of endogenous pain inhibition, measured by CPM. This systematic literature study aimed to provide an overview of the effects of clinical pain and experimental pain induction or pain reduction on CPM in adults. METHODS: A systematic literature search was conducted in the databases "Pubmed" and "Web of Science". Only full texts of original studies regarding the effect of clinical pain and experimentally induced pain and pain reduction on CPM in adults were included. The included articles were scored on methodological quality and through a CPM paradigm. RESULTS: Twelve articles of good to moderate quality were included in this review. Some pain inhibitory medication and oral contraceptives inhibit the CPM mechanism. Removing chronic pain by surgery results in an improved CPM response. This effect is not observed when removing acute pain. CONCLUSION: Analgesic medication and oral contraceptives might inhibit the CPM response, whereas there is limited evidence that pain-relieving surgery improves CPM in chronic pain patients. However, the results merely suggest that decreased CPM values (as in chronic pain patients) can improve after elimination of pain.

Classification system of the sagittal standing alignment in young adolescent girls.

PURPOSE: The purpose of this cohort study was to classify sagittal standing alignment of pre-peak height velocity (pre-PHV) girls, and to evaluate whether identified subgroups were associated with measures of spinal pain. This study further aimed at drawing attention to similarities and differences between the current postural classification and a previous system determined among pre-PHV boys. METHODS: 557 pre-PHV girls [mean age, 10.6 years (SD, 0.47 years)] participated in the study. Three gross body segment orientation parameters and five specific lumbopelvic characteristics were quantified during habitual standing. Postural subgroups were determined by cluster analysis. Logistic regression was applied to assess the relationship between postural subgroups and spinal pain measures (pain and seeking care, assessed by self-administered questionnaire). Chi-square statistics, independent samples T test, and distribution-based methods were used for comparison with postural categorization in pre-PHV boys. RESULTS AND CONCLUSION: Among pre-PHV girls, clinically meaningful posture clusters emerged both on the gross body segment and specific lumbopelvic level. The postural subtypes identified among pre-PHV girls closely corresponded to those previously described in pre-PHV boys, thereby allowing the use of the same, working nomenclature. In contrast to previous findings among pre-PHV boys, no associations between posture clusters and spinal pain measures were significant in girls at pre-PHV age. When comparing discrete 'global' alignment scores across corresponding posture types, some intriguing differences were found between genders which might involve different biomechanical loading patterns. Whether habitual posture forms a risk factor for developing spinal pain up to adulthood needs evaluation in prospective multifactorial follow-up research.

Posture class prediction of pre-peak height velocity subjects according to gross body segment orientations using linear discriminant analysis.

BACKGROUND/PURPOSE: Measurement and classification of standing posture in the sagittal plane has important clinical implications for adolescent spinal disorders. Previous work using cluster analysis on three gross body segment orientation parameters (lower limbs, trunk, and entire body inclination) has identified three distinct postural groups of healthy subjects before pubertal peak growth: "neutral", "sway-back", and "leaning-forward". Although accurate postural subgrouping may be proposed to be crucial in understanding biomechanical challenges posed by usual standing, there is currently no objective method available for class assignment. Hence, this paper introduces a novel approach to subclassify new cases objectively according to their overall sagittal balance. METHODS: Postural data previously acquired from 1,196 pre-peak height velocity (pre-PHV) subjects were used in this study. To derive a classification rule for assigning a class label ("neutral", "sway-back", or "leaning-forward") to any new pre-PHV subjects, linear discriminant analysis was applied. Predictor variables were pelvic displacement, trunk lean and body lean angle. The performance of the newly developed classification algorithm was verified by adopting a cross-validation procedure. RESULTS: The statistical model correctly classified over 96.2% of original grouped subjects. In the cross-validation procedure used, over 95.9% of subjects were correctly assigned. CONCLUSIONS: Based on three angular measures describing gross body segment orientation, our triage method is capable of reliably classifying pre-PHV subjects as either "neutral", "sway-back", or "leaning-forward". The discriminant prediction equations presented here enable a highly accurate posture class allocation of new cases with a prediction capability higher than 95.9%, thereby removing subjectivity from sagittal plane posture classification.