Effects of non-specific low back pain on static balance in emerging adults.

BACKGROUND: Postural control impairments in middle-aged or older people with chronic low back pain (CLBP) have been extensively documented. However, little is known about changes in postural control early in the disease process which may underlie compensatory movement strategies. OBJECTIVE: Our purpose was to quantify postural sway and sensory weighting in emerging adults with and without CLBP. METHODS: Nineteen emerging adults with CLBP (age = 18-26 years (21.11 ± 1.73)) and 19 matched peers without CLBP (18-27 years (22.20 ± 1.97)) participated in a cross-sectional study. Displacement of the center of mass during Quiet stance (QS), Tandem stance (TS), and Unilateral stance (US) on 2 surfaces (stable, unstable) were used to assess postural sway. Sensory Organization Test (SOT) was used to assess sensory weighting. RESULTS: Emerging adults with CLBP showed large, significant increases in postural sway during unstable TS (p ≤ .020). Participants with CLBP relied more on somatosensory input, as evidenced by lower equilibrium scores during conditions favoring visual (p = .020) or vestibular (p < .001) input during the SOT. CONCLUSION: Emerging adults with CLBP showed postural control impairments related to altered sensory weighting. These findings provide insights into the development of CLBP and its effects on postural control. This information may aid early identification, monitoring, and treatment of individuals in the initial stages of disease development who may have unrecognized postural impairments.

Comparison of Two Static Stretching Procedures on Hip Adductor Flexibility and Strength.

It has been shown that acute static stretching (SS) may increase flexibility, improve performance and reduce the risk of muscle strains, but may also result in decreased maximal force output. Literature review revealed little research had specifically been done on the most effective ways to stretch the hip adductor muscles. The purpose was to determine the effects that an acute bout of SS (active vs passive) has on hip adductor flexibility and maintenance of strength. Randomized cross-over study using a 3 × 2 (Condition X Time) repeated measures ANOVA statistical design. Forty healthy and physically active subjects (20 male and 20 female) that screened positive for limited flexibility in hip adductor range of motion (ROM) participated. Following a warm-up, baseline maximal voluntary isometric contraction (MVC) and peak static ROM tests were administered. On separate days subjects randomly performed either 60 seconds of passive SS, active SS, or a time-matched control protocol before post measures were recorded for MVC and ROM. There was a significant time effect (p<0.001) that revealed both types of SS and control resulted in increased ROM pre-to-post (passive = 1.0; active = 1.1; control = 0.6 degrees) with no between condition differences (p=0.171). Neither type of SS resulted in reduced strength. Both methods minimally increased hip adductor flexibility without a decrease in force output. This suggests that individuals do not need to avoid SS for the hip adductors prior to engaging in physical activity for fear of a strength decrement.

Validation of an Inertial Sensor System for Physical Therapists to Quantify Movement Coordination During Functional Tasks.

Physical therapists evaluate patients' movement patterns during functional tasks; yet, their ability to interpret these observations consistently and accurately is unclear. Physical therapists would benefit from a clinic-friendly method for accurately quantifying movement patterns during functional tasks. Inertial sensors, which are inexpensive, portable sensors capable of monitoring multiple body segments simultaneously, are a relatively new rehabilitation technology. We sought to validate an inertial sensor system by comparing lower limb and lumbar spine kinematic data collected simultaneously with a commercial inertial sensor system and a motion camera system while 10 subjects performed functional tasks. Mean and peak segment angular displacement data were calculated and compared between systems. Mean angular displacement root mean square error between the systems across all tasks and segments was <5°. Mean differences in peak displacements were generally acceptable (<5°) for the femur, tibia, and pelvis segments for all tasks; however, the inertial system overestimated lumbar flexion compared to the motion camera system. These data suggest that the inertial system is capable of measuring angular displacements within 5° of a system widely accepted for its accuracy. Standardization of sensor placement, better attachment methods, and improvement of inertial sensor algorithms will further increase the accuracy of the system.

Acute changes of hip joint range of motion using selected clinical stretching procedures: A randomized crossover study.

BACKGROUND: Hip adductor flexibility and strength is an important component of athletic performance and many activities of daily living. Little research has been done on the acute effects of a single session of stretching on hip abduction range of motion (ROM). OBJECTIVES: The aim of this study was to compare 3 clinical stretching procedures against passive static stretching and control on ROM and peak isometric maximal voluntary contraction (MVC). DESIGN: Using a randomized crossover study design, a total of 40 participants (20 male and 20 female) who had reduced hip adductor muscle length attended a familiarization session and 5 testing sessions on non-consecutive days. METHOD: Following the warm-up and pre-intervention measures of ROM and MVC, participants were randomly assigned 1 of 3 clinical stretching procedures (modified lunge, multidirectional, and joint mobilization) or a static stretch or control condition. Post-intervention measures of ROM and MVC were taken immediately following completion of the assigned condition. RESULTS: An ANOVA using a repeated measure design with the change score was conducted. All interventions resulted in small but statistically significant (p < 0.05) increases (1.0°-1.7°) in ROM with no inter-condition differences except one. Multidirectional stretching was greater than control (p = 0.031). CONCLUSIONS: These data suggest that a single session of stretching has only a minimal effect on acute changes of hip abduction ROM. Although hip abduction is a frontal plane motion, to effectively increase the extensibility of the structures that limit abduction, integrating multi-planar stretches may be indicated.

Acute effects of walking with Nordic poles in persons with mild to moderate low-back pain.

Regular walking with or without Nordic poles is effective over time at reducing discomfort in individuals with chronic low back pain (LBP). Nordic pole use increases balance and stability, distributes weight through the arms and torso, and decreases loading of the spine and lower limbs. The purpose of this study was to determine if Nordic poles would reduce perceived acute discomfort while self-paced walking in individuals with LBP. We also examined whether walking with or without poles increased heart rate (HR) and ratings of perceived exertion (RPE) or speed of movement. Subjects included 20 adults (12 males, 8 females; mean age of 45.1±16.3) who were experiencing LBP of at least six months' duration (Oswestry Disability Index (ODI): mean 17 ± 8%, range 6-36% indicating minimal to moderate disability) with no current active flare-up. Participants walked a predetermined dirt-path course (805 m or 0.5 mi) with and without poles in randomized order. Data were analyzed using a 2 X 2 repeated measures ANOVA (Condition X Time), where Condition was poles vs no poles and Time was pre- and post-walk. HR and RPE increased significantly from walking the course, whereas pain did not change. There were also no differences between walking with or without poles for pain (ODI Sec #1: 0.2 points, p=0.324), HR (4 bpm, p=0.522) and RPE (0 points, p=0.759). The mean course time (sec) was slower with poles: 617±87 vs 566±65 (p<0.001). Unexpectedly, there was a noticeable drop in pain following the warm up which was done using poles (0.9 points, p<0.001). Nordic pole use is well tolerated in those with current back pain and can be encouraged, however it cannot be recommended as a superior method of addressing acute symptoms when walking.

Effects of low back pain and of stabilization or movement-system-impairment treatments on induced postural responses: A planned secondary analysis of a randomised controlled trial.

BACKGROUND: Motor retraining for non-specific chronic low back pain (LBP) often focuses on voluntary postural tasks. This training, however, may not transfer to other known postural impairments, such as automatic postural responses to external perturbations. OBJECTIVES: To evaluate the extent current treatments of motor retraining ameliorate impaired postural coordination when responding to a perturbation of standing balance. DESIGN: Planned secondary analysis of a prospectively registered (NCT01362049), randomized controlled trial with a blinded assessor. METHOD: Sixty-eight subjects with chronic, recurrent, non-specific LBP were allocated to perform a postural response task as a secondary assessment one week before and one week after receiving either stabilization or Movement System Impairment (MSI)-directed treatment over 6 weekly 1-h sessions plus home exercises. For assessment, subjects completed the Oswestry disability and numeric pain rating questionnaires and then performed a postural response task of maintaining standing balance in response to 3 trials in each of 4 randomly presented directions of linear surface translations of the platform under the subjects' feet. Integrated amplitudes of surface electromyography (EMG) were recorded bilaterally from the rectus abdominis (RA), internal oblique (IO), and external oblique (EO) muscles during the postural response task. RESULTS: No significant effects of treatment on EMG responses were evident. Oswestry and numeric pain ratings decreased similarly following both treatments. CONCLUSIONS: Stabilization and MSI-directed treatments do not affect trunk EMG responses to perturbations of standing balance in people with LBP, suggesting current methods of motor retraining do not sufficiently transfer to tasks of reactive postural control.

Detection of postural sway abnormalities by wireless inertial sensors in minimally disabled patients with multiple sclerosis: a case-control study.

BACKGROUND: Common clinical neurological exams can be insensitive to balance and mobility impairment at the early stages of multiple sclerosis (MS) and may not correspond with patient reports. Instrumented measurement of standing postural sway with inertial motion sensors may provide sensitive measures of balance impairment and better correspond with patient reports. METHODS: While wearing wireless inertial sensors, 20 subjects with MS - Expanded Disability Status Scale of less than 3.0 and a Timed 25 Foot Walk of 5 sec or less - and 20 age- and sex-matched control subjects stood with eyes open and eyes closed on a foam surface. Forty-six outcome measures of postural sway were derived. A stepwise logistic regression model determined which measures of instrumented sway provide independent predictors of group status. Subjects with MS also completed the Activities-Specific Balance Confidence (ABC) scale and the 12-Item MS Walking Scale (MSWS-12) as measures of subject-reported balance and mobility impairment. RESULTS: The regression model identified medio-lateral sway path length and medio-lateral range of sway acceleration amplitude, each in the eyes-open condition, as the only two significant independent predictors to differentiate subjects with MS from those without MS (model chi-squared = 34.55, p < 0.0001): accuracy = 87.5 %, positive likelihood ratio = 6 (2.09-17.21), negative likelihood ratio = 0.12 (0.03-0.44). Range of sway acceleration amplitude significantly correlated with both ABC (Spearman's r = -0.567, p = 0.009) and MSWS-12 scores (Spearman's r = -0.590, p = 0.006). CONCLUSIONS: Postural sway abnormalities in subjects with MS who are minimally disabled were detected using wireless inertial sensors and may signify a superior sensitivity to identify balance impairment prior to developing clinically evident disability or impaired gait speed. Further study is needed to confirm the clinical significance and predictive value of these objectively identified balance impairments.

Effects of low back pain stabilization or movement system impairment treatments on voluntary postural adjustments: a randomized controlled trial.

BACKGROUND: People with low back pain (LBP) exhibit impaired anticipatory postural adjustments (APAs). OBJECTIVE: To evaluate whether current motor retraining treatments address LBP-associated changes in movement coordination during tasks that do and do not require APAs. DESIGN: Prospectively registered randomized controlled trial with a blinded assessor. SETTING: Outcome evaluations occurred in a university laboratory; treatments were carried out in outpatient physical therapy clinics. PATIENTS: Fifteen subjects without LBP and 33 subjects with chronic, recurrent, and nonspecific LBP. INTERVENTION: Twelve subjects with LBP received stabilization treatment, 21 received movement system impairment-based treatment, for more than 6 weekly 1-hour sessions plus home exercises. MEASUREMENTS: Pre- and post-treatment, surface electromyography (EMG) was recorded bilaterally from trunk and leg muscles during unsupported and supported leg-lifting tasks, which did and did not require an APA, respectively. Vertical reaction forces under the contralateral leg were recorded to characterize the APA. Oswestry disability scores and numeric pain ratings were also recorded. RESULTS: Persons with LBP demonstrated an impaired APA compared with persons without LBP, characterized by increased premovement contralateral force application and increased postmovement trunk EMG amplitude, regardless of the task. After treatments, both groups similarly improved in disability and function; however, APA characteristics did not change (ie, force application or EMG amplitude) in either task. LIMITATIONS: Treating clinicians were not blinded to treatment allocation, only short-term outcomes were assessed, and main effects of treatment do not rule out nonspecific effects of time or repeated exposure. CONCLUSIONS: Movement impairments in persons with LBP are not limited to tasks requiring an APA. Stabilization and movement system impairment-based treatments for LBP do not ameliorate and may exacerbate APA impairments (ie, excessive force application and increased post-movement trunk muscle activation).

Altered postural responses persist following physical therapy of general versus specific trunk exercises in people with low back pain.

UNLABELLED: Interventions that target trunk muscle impairments in people with LBP have been promoted; however, the treatment effects on muscle activation impairments during postural tasks remain unclear. Thus, our objective was to evaluate the effects trunk stabilization vs. general strength and conditioning exercises on the automatic postural response in persons with chronic low back pain (LBP). Fifty-eight subjects with chronic, recurrent LBP (n = 58) (i.e., longer than six months) were recruited and randomly assigned to one of two, 10-week physical therapy programs: stabilization (n = 29) or strength and conditioning (n = 29). Pain and function were measured at 11 weeks and 6 months post-treatment initiation. To quantify postural following support surface perturbations, surface electrodes recorded electromyography (EMG) of trunk and leg muscles and force plates recorded forces under the feet, to calculate the center of pressure. Both groups demonstrated significant improvements in pain and function out to 6 months. There were also changes in muscle activation patterns immediately post-treatment, but not at 6 months. However, changes in center of pressure (COP) responses were treatment specific. Following treatment, the stabilization group demonstrated later onset of COP displacement, while the onset of COP displacement in the strengthening group was significantly earlier following treatment. Despite two different treatments, clinical improvements and muscle activation patterns were similar for both groups, indicating that the stabilization treatment protocol does not preferentially improve treatment outcomes or inter-muscle postural coordination patterns for persons with LBP. CLINICAL TRIAL REGISTRATION NUMBER: NCT01611792.

Outcomes are not different for patient-matched versus nonmatched treatment in subjects with chronic recurrent low back pain: a randomized clinical trial.

BACKGROUND CONTEXT: Classification schemas for low back pain (LBP), such as the Treatment-Based Classification and the Movement System Impairment, use common clinical features to subgroup patients with LBP and are purported to improve treatment outcomes. PURPOSE: To assess if providing matched treatments based on patient-specific clinical features led to superior treatment outcomes compared with an unmatched treatment for subjects with chronic recurrent LBP. STUDY DESIGN: This study is a randomized controlled trial. PATIENT SAMPLE: Subjects (n=124) with LBP (≥12 months) with or without recurrences underwent a standardized clinical examination to group them into one of two strata: ineligible or eligible for stabilization exercises based on the Treatment-Based Classification schema. Subjects underwent additional clinical tests to assign them to one of the five possible Movement System Impairment categories. OUTCOME MEASURES: Questionnaires were collected electronically at Week 0 (before treatment), Week 7 (after the 6-week 1-hour treatment sessions), and 12 months. Using the Oswestry disability index (0-100) and the Numeric Pain Rating Scale (0-10), the primary analysis was performed using the intention-to-treat principle. Secondary outcomes included fear-avoidance beliefs and psychosocial work-related and general health status. METHODS: After subjects were categorized based on their particular clinical features using both the Treatment-Based Classification and Movement System Impairment schemas, they were randomized into one of two treatments using a 3:1 ratio for matched or unmatched treatments. The treatments were trunk stabilization exercise or Movement System Impairment-directed exercises. RESULTS: Of the patients allocated to treatment for this study, 76 received a matched treatment and 25 received an unmatched treatment. After treatment, both groups showed a statistically significant improvement in the primary outcome measures and almost all the secondary measures; however, the matched treatment group did not demonstrate superior outcomes at Week 7 or 12 months, except on one of the secondary measures (Graded Chronic Pain Scale [Disability Scale]) (p=.01). CONCLUSIONS: Providing a matched treatment based on either the Treatment-Based Classification or the Movement System Impairment classification schema did not improve treatment outcomes compared with an unmatched treatment for patients with chronic LBP, except on one secondary disability measure.

Protocol to assess the neurophysiology associated with multi-segmental postural coordination.

Anticipatory postural adjustments (APAs) stabilize potential disturbances to posture caused by movement. Impaired APAs are common with disease and injury. Brain functions associated with generating APAs remain uncertain due to a lack of paired tasks that require similar limb motion from similar postural orientations, but differ in eliciting an APA while also being compatible with brain imaging techniques (e.g., functional magnetic resonance imaging; fMRI). This study developed fMRI-compatible tasks differentiated by the presence or absence of APAs during leg movement. Eighteen healthy subjects performed two leg movement tasks, supported leg raise (SLR) and unsupported leg raise (ULR), to elicit isolated limb motion (no APA) versus multi-segmental coordination patterns (including APA), respectively. Ground reaction forces under the feet and electromyographic activation amplitudes were assessed to determine the coordination strategy elicited for each task. Results demonstrated that the ULR task elicited a multi-segmental coordination that was either minimized or absent in the SLR task, indicating that it would serve as an adequate control task for fMRI protocols. A pilot study with a single subject performing each task in an MRI scanner demonstrated minimal head movement in both tasks and brain activation patterns consistent with an isolated limb movement for the SLR task versus multi-segmental postural coordination for the ULR task.

Shoulder functional assessments in persons with chronic neck/shoulder pain and healthy subjects: Reliability and effects of movement repetition.

OBJECTIVE: Obtaining reliable functional capacity measures from injured workers is an essential part of the return to work (RTW) process. The present study compares shoulder functional outcomes between healthy individuals and others with neck/shoulder pain, assesses reliability and examines the influence of repetitive movements on shoulder function. METHODS: Subjects performed trials of flexion and abduction active range of motion (ROM), and cumulative power output (PO) in a pushing/pulling task on the Baltimore Therapeutic Equipment Simulator II in two consecutive sessions. Tasks were assessed before and after performing a repetitive arm task, during which heart rate (HR) was recorded, until scoring 8 on the Borg CR-10 scale or on a 11-point numeric rating scale (NRS) for pain. PARTICIPANTS: Persons with chronic neck/shoulder pain (intensity ≥ 3/10 for > 3 months) (n = 16) and an age- and sex-matched control group (n = 16). RESULTS: Functional shoulder measures demonstrated strong inter-session reliability, except PO in the pain group. Average repetitive task duration was shorter in the pain group (4 min vs. 7 min). CONCLUSIONS: The protocol detected both pain- and time-related impairments, with HR and PO being sensitive to movement duration and ROM to pain.

Differences in posture-movement changes induced by repetitive arm motion in healthy and shoulder-injured individuals.

BACKGROUND: Neck/Shoulder pain is linked to movement repetition, awkward postures, prolonged maintenance of static postures, and muscular fatigue. Studies have examined the influence of pain and fatigue on movement characteristics, but few reported multi-dimensional adaptations to movement repetition. We compared the adaptations measured in three-dimensions during a repetitive reaching task in persons with chronic neck/shoulder pain and healthy subjects. METHODS: A shoulder-injured group (intensity >3/10, duration >3 consecutive months) and an age-sex-matched control group (n=16 in each) performed a repetitive reaching task to voluntary termination. Kinematics, kinetics, heart rate and muscle activity were recorded throughout. Power output on a 10-s pushing/pulling task was assessed pre- and post-reaching. Group comparisons were made in absolute time and at task end. FINDINGS: Control subjects performed the task 55% longer than the pain group; yet, both groups demonstrated task-related increased heart rate (6 beats per minute) and decreased power output (6 W). Throughout the task, the pain group demonstrated: higher supraspinatus activity, and less elbow flexion and endpoint movement. The control group increased movement amplitude of the endpoint, elbow, and shoulder, while the pain group moved the shoulder less and increased center of mass excursion to maintain the task. INTERPRETATION: Both groups adapted to the task in unique ways. The control group continually increased elbow and endpoint range of motion, bringing the arm closer to the targets, possibly to prolong task performance. The pain group used a fixed, en block arm strategy, likely to reduce the load on the injured structures; however, this may place other structures at risk for pain and injury.

Movement timing and reach to reach variability during a repetitive reaching task in persons with chronic neck/shoulder pain and healthy subjects.

Neck/shoulder pain is linked to movement repetition, awkward postures, and muscular fatigue. Studies have examined the influence of pain and fatigue on movement characteristics, but few report spatial and temporal characteristics within- and between-dynamic movements. The combined influences of fatigue and pain on these parameters are examined here. A shoulder-injured group (PAIN) (intensity >3/10, duration >3 consecutive months) and an age-sex-matched control group (CTRL) (n = 16 in each) performed a repetitive reaching task to voluntary termination. Kinematics, heart rate, and muscle activity were recorded. Group comparisons were made at the beginning and end of task. Both pain and fatigue changed movement parameters with CTRL subjects adapting to fatigue with increased arm movement, while the PAIN group increased center of mass (CoM) and minimized shoulder movement. Fatigue was associated with decreased arm relative variability, while pain caused increased arm and decreased CoM relative variability. Time to peak velocity tended to indicate increased joint coupling in the CTRL group only. Together, this suggests that despite initial differences in movement strategies, both groups tend to move toward more fixed movement strategies at the end of the task. Those of CTRL are more fixed temporally and spatially (in the arm), whereas the PAIN group adaptations are primarily spatial in nature and appear to focus on controlling CoM.

Posture-movement changes following repetitive motion-induced shoulder muscle fatigue.

Repetitive motion-induced fatigue not only alters local motion characteristics but also provokes global reorganization of movement. However, the three-dimensional (3D) characteristics of these reorganization patterns have never been documented in detail. The goal of this study was to assess the effects of repetitive reaching-induced arm fatigue on the whole-body, 3D biomechanical task characteristics. Healthy subjects (N=14) stood and performed a continuous reaching task (RRT) between two targets placed at shoulder height to fatigue. Whole-body kinematic (Vicon), kinetic (AMTI force platforms) and electromyographic (EMG, Noraxon) characteristics were recorded. Maximal voluntary isometric efforts (MVIE) of the shoulder and elbow were measured pre- and post-RRT. Post-RRT shoulder elevation MVIE was reduced by 4.9+/-8.3% and trapezius EMG amplitude recorded during the RRT increased by 46.9+/-49.9% from the first to last minute of the RRT, indicating that arm fatigue was effectively induced. During fatigued reaching, subjects elevated their shoulder (11.7+/-10.5 mm) and decreased their average shoulder abduction angle by 8.3+/-4.4 degrees. These changes were accompanied by a lateral shift of the body's center of mass towards the non-reaching arm. These findings suggest a compensatory strategy to decrease the load on the fatigued shoulder musculature.