People With Low Back Pain Exhibit Higher Trunk Muscle Activity and Impaired Postural Control During Static and Dynamic Functional Tasks: A Cross-Sectional Study.

The study compared superficial trunk muscle activity and postural control among an active extension subgroup of people with nonspecific chronic low back pain (AE-NSCLBP) with painfree controls during functional tasks. Thirty-two people (17 people with low back pain [LBP] and 15 painfree controls) participated in this study. Muscle activity of 5 trunk muscles and postural control were investigated during both standing tasks (eyes open/closed; single/double-leg balance) and dynamic functional tasks (spinal forward flexion and return, and a sit to stand transfer). Results showed that during single-leg standing, people with AE-NSCLBP exhibit higher muscle activity than painfree controls for 3 trunk muscles, especially with their eyes closed. There were no significant differences in muscle activity between eye conditions during double-leg standing and sit to stand transfer, forward flexion, and return from flexion. The AE-NSCLBP subgroup also demonstrated significantly impaired postural control (lower time to boundary) in 4 of 8 conditions, especially during single-leg standing and with their eyes closed. These findings show people with LBP typically demonstrated greater trunk muscle activity and poorer postural control while maintaining standing posture. This pattern was most evident when the postural challenge was higher, such as single-leg standing or with eyes closed. While this study design cannot infer causality, these findings have implications for LBP rehabilitation, particularly regarding approaches which seek to alter muscle activation among people with LBP.

The Intra-Rater Reliability of Ultrasonography for the Measurement of Lumbar Multifidus and Erector Spinae Thickness in Different Positions in People with and without Active Extension-Related Non-Specific Low Back Pain.

Background: The paraspinal muscles, including multifidus (MF) and erector spinae (ES) play key roles in the stability and movement of the lumbar spine. This study aimed to determine the intra-rater reliability of the ES and MF muscle thickness measures of the rehabilitative ultrasound imaging (RUSI) in people with active extension pattern (AEP) non-specific chronic low back pain and controls. Methods: Fifteen females with AEP and 19 controls participated in this test-retest intra-rater reliability study, including two different testing sessions performed in four to seven days apart. The primary (raw) and derived (normalized) measures of the L4 MF and ES muscles`thickness were examined in three different positions (prone, sitting, and standing) on both days. A two-way mixed average of intra-class correlation coefficient (ICC3, K) with confidence interval (CI = 95%) was used to determine the relative reliability. The standard error of measurement (SEM) and minimal detectable change (MDC) values at a CI of 95% were computed to examine the absolute reliability. Results: The ICC values for the primary thickness of the L4 ES and MF muscles were from 0.85 to 0.91, except for MF muscle thickness in standing (ICC = 0.67) and sitting (ICC = 0.66) positions . The ICC values for derived data were lower in both groups. The SEM and MDC values were small enough to confirm the absolute reliability of the primary data. Conclusion: This study supports the use of RUSI for examining the primary measures of the L4 MF and ES muscles in asymptomatic and AEP participants, but it should be used cautiously for assessing the derived measures.

Revisiting the lumbosacral orthosis from the perspective of dynamical systems theory: a preliminary randomized clinical trial on patients with chronic low back pain.

BACKGROUND: The prevalent method for investigating the effect of therapeutic interventions on walking in the individuals with chronic low back pain (CLBP) is component-level approach in which all measurements focus on the spine component alone. However, this approach cannot disclose information about the overall function of the movement system such as complex walking patterns, which, in turn, reveal the underlying movement control. OBJECTIVES: To compare the effect of 3-week wearing of lumbosacral orthosis (LSO) along with routine physical therapy with routine physical therapy alone on walking complexity in the individuals with nonspecific CLBP on the basis of the systems approach. STUDY DESIGN: Preliminary randomized clinical trial. METHODS: Twenty-four subjects were randomly allocated to two groups. The control group received the routine physical therapy for 3 weeks. The intervention group received the same program plus an LSO. Nonlinear analysis was used to quantify walking complexity, as behavior of the entire movement system, before and after the intervention and at 1-month follow-up. RESULTS: An average of 496 strides during ten minutes of walking was used for analysis. There was no significant difference (p > 0.05) in degree of walking complexity between two groups during all evaluation periods. CONCLUSIONS: The administered orthotic intervention did not alter walking complexity. This suggests that therapeutic goal of current LSOs, which is not based on the systems approach, cannot recover the emergent behavior of the movement system. This may be a potential source of controversies. CLINICAL RELEVANCE: To achieve an effective treatment, orthotists should focus on the individuals themselves, not only on their CLBP symptoms. Although the component-level approach aims to decrease the symptoms, the systems approach focuses on the whole context that fosters LBP symptoms.

Intrarater reliability of musculoskeletal ultrasound imaging of psoas major muscle in patients with subacute low back pain and healthy controls.

Background: Psoas major (PM) is a challenging muscle from the functional and anatomical point of view. The dysfunction of this muscle can result in low back pain (LBP). This study aimed to assess the intrarater reliability of ultrasound imaging (USI) of PM muscle thickness in subacute LBP patients and healthy participants without LBP in rest and during muscle contraction conditions. Methods: PM thickness was measured in all lumbar segments (L1-L5) using a USI device in 10 healthy and 10 subacute LBP participants. The intrarater data were assessed on the same day with 1- hour interval and after 7 days. Intraclass correlation coefficients (ICC), standard error of measurement (SEM), minimal detectable change (MDC), and independent t test were used for analyses. Significant level was set at 0.05. Results: PM thickness in all lumbar levels had excellent reliability (ICC range 80-98) for both groups and conditions. SEM (0.42- 2.29) and MDC (1.16-6.34) were low, and PM thickness was greater than rest in contraction condition. There were no significant differences between the 2 groups in PM thickness. Conclusion: The USI demonstrated good intrarater reliability for assessing PM thickness in patients with subacute LBP. The thickness of PM in patients with subacute LBP was similar with that in healthy participants.

The Effects of Knee Orthosis with Two Degrees of Freedom Joint Design on Gait and Sit-to-Stand Task in Patients with Medial Knee Osteoarthritis.

OBJECTIVES: Knee bracing as a conservative treatment option for patients with medial knee osteoarthritis (KOA) is of great interest to health practitioners and patients alike. Optimal orthotic knee joint structure is essential to achieve biomechanical and clinical effectiveness. Therefore, this study aimed to identify the effects of a knee orthosis with a new two-degrees-of-freedom (DOF) joint design on selected gait parameters and in a sit-to-stand task in patients with mild-to-moderate medial KOA. METHODS: This study was conducted both at the Physical Medicine and Rehabilitation Clinic in Shahid Modarres Academic Hospital and the Biomechanical Laboratory of Rehabilitation Faculty of Iran University of medical Sciences in Tehran, Iran from September 2015 to October 2017. The gait performance of 16 patients was assessed without an orthosis, using a common one-DOF (DOF) knee orthosis and using the same knee orthosis with a two-DOF orthotic joint design. The interactive shearing force between limb and brace in the shell area during a sit-to-stand test was also identified. Repeated measures analysis of variance was used to analyse the data. RESULTS: Compared with walking with no orthosis, both orthosis conditions reduced the external knee adduction moment significantly (P ≤0.05). A significant increase between the one-DOF and two-DOF conditions in terms of walking speed (P = 0.041 and P = 0.009, respectively) and stride length (P = 0.028 and P = 0.038, respectively) was observed. In a sit-to-stand test, wearing the orthosis significantly decreased knee transverse plane range of motion (P ≤0.05). There was a 41.31 ± 8.34 Newtons reduction in knee flexion constraint force. CONCLUSION: The two-DOF knee orthosis was more comfortable compared to the one-DOF knee orthosis during deep knee flexion. Otherwise, the one-DOF- and two-DOF-braces performed similarly.

Effects of Different Frequencies of Whole Body Vibration on Repositioning Error in Patients With Chronic Low Back Pain in Different Angles of Lumbar Flexion.

OBJECTIVE: This study aimed to evaluate the effect of high and low frequency of whole body vibration (WBV) on repositioning error in 3 different angles of lumbar flexion in patients with chronic low back pain. METHODS: Twenty-four participants with chronic low back pain, aged between 20 and 35 years, were included in this randomized crossover trial study. Participants were randomly assigned into 2 groups as follows: (1) low frequency/high frequency, and (2) high frequency/low frequency. Participants received high-frequency (50 Hz) and low-frequency (30 Hz) WBV in a semi-squat position for 5 minutes in 2 sessions, with 2 weeks of rest. Before and after the WBV, lumbar repositioning error in 30% and 60% of lumbar full flexion and neutral position with eyes closed when standing was evaluated using an electrogoniometer. RESULTS: The repositioning error was decreased in neutral, 30%, and 60% of lumbar flexion after the low-frequency and high-frequency WBV. Post hoc testing revealed that the effect of angle was not significant in repositioning error changes between high-frequency and low-frequency WBV (P > .05). However, the effect of low-frequency WBV on the repositioning error was significantly higher compared with high-frequency WBV (P < .05). CONCLUSION: Low-frequency WBV might induce more improvement in the accuracy of lumbopelvic repositioning compared with high-frequency WBV with the method of WBV used in this study.

The effects of familiarization with loading, weight and size of loading on neuromuscular responses during sudden upper limb loading in chronic low back pain patients.

BACKGROUND: Changes in the motor control of the spine were found in patients with chronic low back pain (CLBP). Sudden loading of the spine is supposed to be the cause of about 12% of lower back injuries. However, some aspects of this problem, such as alterations in the sensory-motor control of the spine, remain questionable. OBJECTIVE: To investigate the effects of familiarization with loading, weight and size of loading on neuromuscular responses during sudden upper limb loading in CLBP patients. METHODS: In this quasi-experimental study surface electromyography of the erector spinae (ES) and transverses abdominis/internal oblique (TrA/IO) and external oblique (EOA) muscles were recorded in 7 men and 13 women with CLBP and 20 asymptomatic subjects (10 men and 10 women) aged 18-45 years from the general community familiarization. Moreover, investigating control of the posture measurements of the center of pressure (COP) and vertical ground reaction force (GRF) or Fz were recorded using a force plate. Data were analyzed using paired t-test and independent t-test with the significance level of 0.05. RESULTS: Data analyses were performed using SPSS version 18. Some electromyography and force plate variables were significantly different for different conditions in each group and between the asymptomatic and low back pain groups (p⩽ 0.05). CONCLUSION: Several motor control changes were observed in the CLBP patients. These patients showed decreased trunk muscle activity as well as too early and too delayed responses compared to asymptomatic subjects.

Comparison of Postural Balance between Subgroups of Nonspecific Low-back Pain Patients Based on O'Sullivan Classification System and Normal Subjects during Lifting.

BACKGROUND: Balance disorder is one of the most-studied fields in low-back pain patients (LBP). However, there is insufficient information regarding the effect of LBP subgrouping on postural control. The purpose of the present study was to compare postural control between subgroups of chronic nonspecific LBP and healthy subjects during lifting. METHODS: A total of 35 men with chronic LBP (19 active extension pattern [AEP] and 16 flexion pattern [FP]) and 15 healthy controls were enrolled in this cross-sectional study. Pooled LBP was subdivided based on the O'Sullivan's classification system (OCS). The participants were asked to lift a box from the ground to the waist level and hold it for 20 seconds. The load was 10% of the subject's weight. Force plate system was used to record balance parameters, including standard deviations (SDs) of center of pressure (COP) amplitude and COP velocity in anterior-posterior and medial-lateral directions and mean total velocity. The test was divided into two static and dynamic phases. Data were analyzed using one-way analysis of variance and independent t-test. RESULTS: There were no significant differences between pooled LBP and control groups in any of the variables, except for the SD of the anterior-posterior direction velocity in the X-plane in the static phase (P=0.017). After classifying LBP, the results showed that the healthy and AEP groups were significantly different in SD of COP velocity in the frontal plane (P=0.021), mean total velocity (P=0.010), and SD of COP velocity in the sagittal plane (P=0.039). CONCLUSION: The present study showed that postural control was not different between the pooled LBP and normal groups. After classifying pooled LBP based on OCS, we found that the AEP showed different postural control as compared to healthy controls in the dynamic phase. The FP and AEP exhibited different postural control relative to the healthy controls in the static phase, and COP velocity was lower in those groups compared to the control group. The results of this study support the concept of LBP classification.

Disturbance of neck proprioception and feed-forward motor control following static neck flexion in healthy young adults.

The highly complex proprioceptive system provides neuromuscular control of the mobile cervical spine. Static neck flexion can induce the elongation of posterior tissues and altered afferent input from the mechanoreceptors. The purpose of this study was to examine the effect of prolonged static neck flexion on neck proprioception and anticipatory postural adjustments. Thirty-eight healthy participants (20 females and 18 males) between the ages of 20-35 years with no history of neck, low back, and shoulder pain enrolled in this study. Neck proprioception and anticipatory muscle activity were tested before and after 10-min static neck flexion. For assessment of neck proprioception, each participant was asked to perform 10 trials of the cervicocephalic relocation test to the neutral head position after active neck rotation to the left and right sides. Anticipatory postural adjustments were evaluated during a rapid arm flexion test. Following the flexion, the absolute and variable errors in head repositioning significantly increased (p < 0.05). The results also showed that there was a significant delay in the onset of myoelectric activity of the cervical erector spinae muscles after flexion (p = 0.001). The results of this study suggested that a 10-min static flexion can lead to changes in the neck proprioception and feed-forward control due to mechanical and neuromuscular changes in the viscoelastic cervical spine structures. These changes in sensory-motor control may be a risk factor for neck pain and injury.

The effect of static neck flexion on mechanical and neuromuscular behaviors of the cervical spine.

Occupations that involve sustained or repetitive neck flexion are associated with a higher incidence of neck pain. Little in vivo information is available on the impact of static neck flexion on cervical spinal tissue. The aim of this study was to assess changes in mechanical and neuromuscular behaviors to sustained neck flexion in healthy adults. Sixty healthy subjects aged 20-35 years participated in this study. The participants were exposed to static neck flexion at a fixed angle of full flexion for 10 min. Mechanical and neuromuscular responses of the cervical spine to sudden perturbations were measured pre- and post-exposure. Magnitude of load-relaxation during flexion exposure, stiffness, peak head angular velocity, and reflexive activities of cervical muscles were recorded. Effective neck stiffness decreased significantly, especially in female participants (P = 0.0001). The reflexive response of the cervical erector spinae muscles to head perturbation delayed significantly (P = 0.0001). Peak head angular velocity was significantly increased after exposure to neck flexion for 10 min, especially in female participants (P = 0.001). In the present study, static flexion resulted in changes in mechanical and neuromuscular behavior of the cervical spine, potentially leading to decreased stiffness of the cervical spine. The results confirm the importance of maintaining a correct head and neck position during work and improving the work environment to reduce the cervical spinal load and work-related neck pain.

The Ratio of Lumbar to Hip Motion during the Trunk Flexion in Patients with Mechanical Chronic Low Back Pain According to O'Sullivan Classification System: A Cross-sectional Study.

BACKGROUND: Static and dynamic postures of lumbopelvic in low back pain (LBP) are considered as two important aspects of clinical assessment and management of LBP. Thus, the focus of the current study was to compare the posture and compensatory strategy of hip and lumbar region during trunk flexion between LBP subgroupsand health subjects. LBP cases are subdivided into active extension pattern (AEP) and flexion pattern (FP) based on O'Sullivan's classification system (OCS). METHODS: This work was a cross-sectional study involving 72 men, 21 low back pain patients with FP and 31 low back pain patients with AEP and 20 healthy groups. Lumbar and hip angles during trunk flexion were measured by a 3D motion analysis system in neutral standing posture and end-range of trunk flexion. The participants were asked to full bend without any flexion of the knees. The bending speed was preferential. Hip and lumbar ranges of motion were divided into four quartiles (Q). The quartiles were compared between groups. Data analysis was performed using one-way analysis of variance (ANOVA) and independent t-test. RESULTS: There was no statistically significant difference in lumbar lordosis in standing and full trunk flexion positions between the healthy groups and heterogeneous LBP groups. In addition, there was not any statistically significant difference between the healthy group and the homogenous LBP group (FP and AEP). Moreover, no statistically significant difference was observed in hip angles during standing between the healthy group and the heterogeneous LBP group, and between the healthy group and the homogenous LBP group (FP and AEP). In full trunk flexion position, there was statistically significant difference in hip angles between the healthy group and the heterogeneous LBP group (P=0.026). In this position, the difference in hip angles between the healthy group and FP group was statistically significant (P<0.05). In the second Q, there was no significant difference between the healthy group and the heterogeneous LBP group (P=0.062), however, there was a significant difference between FP group and the healthy group in the fourth Q of the total hip range of motion. There was no statistically significant difference between the healthy group and the heterogeneous LBP group (P=0.054) but there was a difference between FP group and the healthy group. Lumbar/hip motion ratio (L/H ratio) was different between and within the subgroups in the second Q. CONCLUSION: This study supported the subgrouping of LBP and showed that the difference between subgroups could be determined effectively through subdividing the total range of lumbar and hip motions into smaller portions. It is possible that the neuromuscular system selects different strategies to compensate and prevent further injury of the chain components (muscle, joint, nerve and etc.). LEVEL OF EVIDENCE: IV.

A Preliminary Study of the Objective Measurement of Compliance Rates for Semirigid Lumbar-Support Use in Patients with Chronic Nonspecific Low Back Pain: How Important Is the Compliance Rate?

STUDY DESIGN: Clinical pilot study. PURPOSE: To objectively evaluate the compliance rate of lumbar-support use in patients with chronic nonspecific low back pain, as well as to assess low back pain intensity, disability, and fear-avoidance beliefs. OVERVIEW OF LITERATURE: Wearing time is an important factor in the assessment of the efficacy of lumbar-support use in patients with chronic nonspecific low back pain. Previous studies have measured lumbar-support wearing time based on subjective assessment, and these evaluations are not easily verifiable and are usually overestimated by subjects. METHODS: Twelve subjects with chronic nonspecific low back pain who had been wearing semirigid lumbar supports for 6 weeks were evaluated. Compliance was objectively monitored using temperature sensors integrated into the semirigid lumbar supports. Subjects wore their lumbar supports for 8 hour/day on workdays and 3 hour/day on holidays during the first 3 weeks. During the next 3 weeks, subjects were gradually weaned off the lumbar supports. Pain intensity was measured using a numerical rating scale. The Oswestry disability index was used to assess the subjects' disability. Fear-avoidance behavior was evaluated using a fear-avoidance beliefs questionnaire. RESULTS: The mean compliance rate of the subjects was 78.16%±13.9%. Pain intensity was significantly lower in patients with a higher compliance rate (p=0.001). Disability index and fear-avoidance beliefs (functional outcomes) significantly improved during the second 3-weeks period of the treatment (p<0.001, p=0.02, respectively). CONCLUSIONS: The compliance rate of patients wearing lumbar supports is a determining factor in chronic low back pain management. Wearing semirigid lumbar supports, as advised, was associated with decreased pain intensity, improved disability index scores, and improved fear-avoidance beliefs in patients with chronic nonspecific low back pain.

Effect of movement control and stabilization exercises in people with extension related non -specific low back pain- a pilot study.

BACKGROUND: Exercise is considered an effective treatment strategy for non-specific chronic low back pain (NSCLBP).background In spite of the wide use of exercise protocols, it is not clear what type of exercise is more effective in decreasing pain, disability and normalizing muscle activation patterns in people with chronic low back pain. OBJECTIVES: To assess the effects of two exercise protocols (stabilization vs movement control) on pain and disability scores and the flexion relaxation ratio (FRR) of lumbar multifidus (LM) and iliocostalis lumbarum pars thoracic (ICLT) in people with extension related non-specific chronic low back pain. STUDY DESIGN: Pilot randomized control trial. METHODS: 32 subjects with active extension pattern chronic low back pain (stabilization group = 16, movement control group = 16) participated in this study. Treatment groups received 4 weeks of exercise therapy. Outcomes were based on pain score (Numeric rating Scale-NRS), disability (Oswestry Disability Index- ODI) and FRR of the LM and ICLT. RESULTS: Four people dropped out of the study in each group for reasons unrelated to the protocols of the study. Pain and disability reduced in both groups, with no significant difference between the groups. The FRR of LM did not change in either treatment group after treatment. However, the FRR of ICLT was significantly increased after treatment in the movement control group. CONCLUSION: Both movement control and stabilization exercises reduced pain and disability in the short-term among people with extension pattern NSCLBP, with no difference in effectiveness between the groups. However, movement control exercises were more effective in normalizing back muscle activation patterns than stabilization exercises.

Can lumbosacral orthoses cause trunk muscle weakness? A systematic review of literature.

BACKGROUND: Wearing lumbosacral orthosis (LSO) is one of the most common treatments prescribed for conservative management of low back pain. Although the results of randomized controlled trials suggest effectiveness of LSO in reducing pain and disability in these patients, there is a concern that prolonged use of LSO may lead to trunk muscle weakness and atrophy. PURPOSE: The present review aimed to evaluate available evidence in literature to determine whether LSO results in trunk muscle weakness or atrophy. STUDY DESIGN: This is a systematic review. METHODS: A systematic search of electronic databases including PubMed, Scopus, ScienceDirect, and Medline (via Ovid) followed by hand search of journals was performed. Prospective studies published in peer-reviewed journals, with full text available in English, investigating the effect of lumbar orthosis on trunk muscle activity, muscle thickness, strength or endurance, spinal force, and intra-abdominal pressure in healthy subjects or in patients with low back pain, were included. Methodological quality of selected studies was assessed by using the modified version of Downs and Black checklist. This research had no funding source, and the authors declare no conflicts of interest-associated biases. RESULTS: Thirty-five studies fulfilled the eligibility criteria. The mean and standard deviation of the quality score was 64±9.7%. Most studies investigating the effect of lumbar orthosis on electromyographic activity (EMG) of trunk muscles demonstrated a decrease or no change in the EMG parameters. A few studies reported increased muscle activity. Lumbosacral orthosis was found to have no effect on muscle strength in some studies, whereas other studies demonstrated increased muscle strength. Only one study, which included ultrasound assessment of trunk muscle stabilizers, suggested reduced thickness of the abdominal muscles and reduced cross-sectional area of the multifidus muscles. Out of eight studies that investigated spinal compression load, the load was reduced in four studies and unchanged in three studies. One study showed that only elastic belts reduced compression force compared to leather and fabric belts and ascribed this reduction to the elastic property of the lumbar support. CONCLUSION: The present review showed that the changes in outcome measures associated with muscle work demands were inconsistent in their relation to the use of lumbar supports. This review did not find conclusive scientific evidence to suggest that orthosis results in trunk muscle weakness.

Goal equivalent manifold analysis of task performance in non-specific LBP and healthy subjects during repetitive trunk movement: Effect of load, velocity, symmetry.

Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions. Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP). Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading; each at two levels. A goal function for the task was defined as maintaining a constant movement time at each cycle. Given the GEM, flexibility index and performance index were calculated respectively as amounts of goal-equivalent variability and the ratio of goal-equivalent to non-goal-equivalent variability. CNSLBP group was as similar as healthy individuals in both flexibility index (p=0.41) and performance index (p=0.24). Performance index was higher in asymmetric (p<0.001), high velocity (p<0.001), and loaded (p=0.006) conditions. Performance and flexibility in using motor abundance were influenced by repeated trunk flexion/extension conditions. However, these measures were not significantly affected by CNSLBP.

Effect of static neck flexion in cervical flexion-relaxation phenomenon in healthy males and females.

INTRODUCTION: Neck pain is a common musculoskeletal disorder, especially among skilled workers who must keep their necks in a flexed position frequently during the day. The present study investigated changes in cervical flexion-relaxation phenomenon parameters after sustained neck flexion. METHODS: The participants were 40 healthy subjects grouped by gender (20 females, 20 males). They were exposed to static neck flexion at the full angle of cervical flexion for 10 min. Each subject underwent three trials of cervical flexion and re-extension before and after this period. Differences in onset and cessation angle of flexion-relaxation phenomenon, maximum neck flexion angle, amplitude of neck muscle activation and flexion-relaxation ratio were evaluated. RESULTS: The maximum neck flexion angle significantly increased after sustained flexion. The onset of flexion-relaxation was significantly delayed during flexion, but cessation angle remained unchanged. Myoelectric activity of the cervical erector spinae muscles increased significantly after maintaining flexion, especially in female subjects. The flexion-relaxation ratio also decreased significantly. CONCLUSION: It was concluded that 10 min of static flexion results in a delay in flexion-relaxation phenomenon and a shortened silence period. Also the cervical erector spinae muscles are required to be active longer and generate more activity. These neuromuscular changes may be a risk factor for neck pain.

MR defecography: a diagnostic test for the evaluation of pelvic floor motion in patients with dyssynergic defecation after biofeedback therapy.

BACKGROUND: Dyssynergic defecation is a major cause of chronic functional constipation as a common digestive complaint. We clinically evaluated the effects of biofeedback therapy on the pelvic floor motion indices through magnetic resonance (MR) defecography, quality of life and depression in patients with dyssynergic defecation. METHODS: In this clinical trial study, among patients referring to the Colorectal Clinic of Hazrat Rasoul Hospital, 22 subjects were randomly assigned into two equal groups (n= 11) to receive either standard only or biofeedback and standard therapy. Dynamic changes of the pelvic floor were measured by MR defecography. During the simulated defecation, two MR defecography dynamic indices including abnormal anorectal angle change and perineal descent were measured before and after treatment. The effects of biofeedback therapy on patients' symptoms, quality of life and severity of depression were assessed and compared with the standard therapy. Statistical analysis was carried out using independent _t-test and Mann-Whitney test. RESULTS: Paradox index (p< 0.001), perineal descent index (p< 0.001), depression (p< 0.1), physical function (p< 0.001), vitality (p< 0.001) and role emotion (p< 0.001) significantly improved in the biofeedback therapy group in contrast to the standard therapy SDT group. CONCLUSION: Biofeedback therapy appears to be effective in improving symptoms of functional constipation and dysfunction of pelvic floor motion as well as patient's quality of life and depression state. MR defecography is able to show the changes in dynamic indices of the pelvic floor through biofeedback therapy.

The effects of arm movement on reaction time in patients with latent and active upper trapezius myofascial trigger point.

BACKGROUND: Myofascial pain syndrome is a significant source of mechanical pain. The aim of this study was to investigate the effects of arm movement on reaction time in females with latent and active upper trapezius myofascial trigger point. METHODS: In this interventional study, a convenience sample of fifteen women with one active MTP, fifteen women with one latent MTP in the upper trapezius, and fifteen normal healthy women were participated. Participants were asked to stand for 10 seconds in an erect standing position. Muscle reaction times were recorded including anterior deltoid (AD), cervical paraspinal (CP) lumbar paraspinal (LP), both of upper trapezius (UT), sternocleidomastoid (SCM) and medial head of gastrocnemius (GcM). Participants were asked to flex their arms in response to a sound stimulus preceded by a warning sound stimulus. Data were analyzed using one-way ANOVA Test. RESULTS: There was significant differences in motor time and reaction time between active and control groups (p< 0.05) except for GcM. There was no significant difference in motor time between active and passive groups except for UT without MTP and SCM (p< 0.05). Also, there were no significant differences in motor times between latent MTP and control groups. Furthermore, there was no significant difference in premotor times between the three groups. CONCLUSION: The present study shows that patients with active MTP need more time to react to stimulus, but patients with latent MTP are similar to healthy subjects in the reaction time. Patients with active MTP had less compatibility with environmental stimulations, and they responded to a specific stimulation with variability in Surface Electromyography (SEMG).

Changes in postural and trunk muscles responses in patients with chronic nonspecific low back pain during sudden upper limb loading.

BACKGROUND: Alterations in the neuromuscular control of the spine were found in patients with chronic low back pain (CLBP). Sudden loading of the spine is assumed to be the cause of approximately 12% of lower back injuries. However, some aspects of this problem, such as alterations in the sensory-motor control of the spine, remain questionable. This study investigated postural and neuro- motor changes in trunk muscles during sudden upper limb loading in patients with CLBP. METHODS: Electromyography of the erector spinae (ES) and transverses abdominis/internal oblique (TrA/IO) and external oblique (EOA) muscles were recorded in 20 patients with CLBP and 20 asymptomatic individuals with eyes open (EO) and eyes closed (EC) conditions. Moreover, measurements of the center of pressure (COP) and vertical ground reaction force (GRF) or Fz were recorded using a force plate. Data were analyzed using paired t-test and independent t-test at the significance level of 0.05. RESULTS: In patients with CLBP, decreased electrical activity of the ES muscle was observed under both the EO and EC conditions and that of the TrA/IO muscle was observed under the EO condition (p< 0.05). Other findings included a shorter peak latency of the ES muscle in the EO condition and a greater increase in the peak latency of the ES muscle following the EC condition (p< 0.05). No significant differences were observed in COP and GRF measurements between the groups. CONCLUSION: Electrical muscle activity may indicate less stiffening or preparatory muscle activity in the trunk muscle of patients with CLBP. Altered latency of the muscle may lead to microtrauma of lumbar structures and CLBP.

Lumbopelvic muscle activation patterns in three stances under graded loading conditions: Proposing a tensegrity model for load transfer through the sacroiliac joints.

PURPOSE: According to the conventional arch model of the pelvis, stability of the sacroiliac joints may require a predominance of form and force closure mechanisms: the greater the vertical shear force at the sacroiliac joints, the greater the reliance on self-bracing by horizontally or obliquely oriented muscles (such as the internal oblique). But what happens to the arch model when a person stands on one leg? In such cases, the pelvis no longer has imposts, leaving both the arch, and the arch model theory, without support. Do lumbopelvic muscle activation patterns in one-legged stances under load suggest compatibility with a different model? This study compares lumbopelvic muscle activation patterns in two-legged and one-legged stances in response to four levels of graded trunk loading in order to further our understanding the stabilization of the sacroiliac joints. METHODS: Thirty male subjects experienced four levels of trunk loading (0%, 5%, 10% and 15% of body weight) by holding a bucket at one side, at three conditions: 1) two-legged standing with the bucket in the dominant hand, 2) ipsilateral loading: one-legged standing with the bucket in the dominant hand while using the same-side leg, and 3) contralateral loading: one-legged standing using the same leg used in condition 2, but with the bucket in the non-dominant hand. During these tasks, EMG signals from eight lumbopelvic muscles were collected. ANOVA with repeated design was performed on normalized EMG's to test the main effect of load and condition, and interaction effects of load by condition. RESULTS: Latissimus dorsi and erector spinae muscles showed an antagonistic pattern of activity toward the direction of load which may suggest these muscles as lateral trunk stabilizers. Internal oblique muscles showed a co-activation pattern with increasing task demand, which may function to increase lumbopelvic stability (P < 0.05). No unilateral pattern of the internal obliques was observed during all trials. CONCLUSIONS: Our results suggest that the lumbopelvic region uses a similar strategy for load transfer in both double and single leg support positions which is not compatible with the arch analogy. Our findings are more consistent with a suspensory system (wire-spoke wheel model). If our proposed model holds true, the pelvic ring can only be integrated by adjusting tension in the spokes and by preserving rim integrity or continuity. Thus, we propose that in order to restore tension integrity throughout the pelvic ring, efforts to unlock restrictions, muscular correction of positional faults and lumbopelvic or even respiratory exercises following sacroiliac joint dysfunctions must be taken into consideration. Our hypothetical model may initiate thinking and act as a guide to future work based on a biomechanical approach to the problem of sacroiliac joint dysfunction.