Maintaining Lumbar Spine Stability: A Study of the Specific and Combined Effects of Abdominal Activation and Lumbosacral Orthosis on Lumbar Intrinsic Stiffness.

BACKGROUND: Two potential interventions for enhancing lumbar stability are to actively increase abdominal muscle activity, either through the abdominal drawing-in maneuver (ADIM) or bracing, and passively increase lumbar stiffness using a lumbosacral orthosis (LSO). OBJECTIVE: To compare the increase in lumbar stiffness after 2 active interventions (ADIM versus bracing) and 1 passive intervention (LSO), and to evaluate the combined effect of active (abdominal bracing) and passive interventions. METHODS: In this experimental and comparative study, lumbar stiffness, a surrogate measure of lumbar stability, was estimated in 25 healthy individuals during 7 trunk perturbation conditions: (1) control, (2) ADIM, (3) bracing at 5% of right external oblique maximal voluntary activation (5% bracing), (4) bracing at 10% of right external oblique maximal voluntary activation (10% bracing), (5) LSO, (6) LSO plus 5% bracing, and (7) LSO plus 10% bracing. Electromyographic biofeedback of the external oblique was provided on a monitor, while ultrasound was used for the ADIM to ensure a sustained contraction of the transversus abdominis. RESULTS: The ADIM, 5% bracing, and 10% bracing active interventions generated comparable lumbar stiffness. However, considering that bracing can range from 10% to 20%, it may be superior to hollowing, as further estimated with a mixed-effect statistical model. Combining bracing and an LSO resulted in an additive effect on lumbar stiffness. CONCLUSION: Bracing and ADIM produced comparable lumbar stiffness, as they were performed at the same overall abdominal activation levels (5% and 10% maximal voluntary activation). The independent effects of bracing and LSO raises the possibility of combining these interventions in some circumstances. J Orthop Sports Phys Ther 2019;49(4):262-271. Epub 18 Jan 2019. doi:10.2519/jospt.2019.8565.

Trunk postural adjustments: Medium-term reliability and correlation with changes of clinical outcomes following an 8-week lumbar stabilization exercise program.

BACKGROUND: Low back pain (LBP) has been previously associated with delayed anticipatory postural adjustments (APAs) determined by trunk muscle activation. Lumbar stabilization exercise programs (LSEP) for patients with LBP may restore the trunk neuromuscular control of the lumbar spine, and normalize APAs. This exploratory study aimed at testing the reliability of EMG and kinematics-based postural adjustment measures over an 8-week interval, assessing their sensitivity to LBP status and treatment and examining their relationship with clinical outcomes. METHODS: Muscle activation of 10 trunk muscles, using surface electromyography (EMG), and lumbar angular kinematics were recorded during a rapid arm-raising/lowering task. Patients with LBP were tested before and after an 8-week LSEP. Healthy controls receiving no treatment were assessed over the same interval to determine the reliability of the measures and act as a control group at baseline. Muscle activation onsets and reactive range of motion, range of velocities and accelerations were assessed for between group differences at baseline and pre- to post-treatment effects within patients with LBP using t-tests. Correlations between these dependent variables and the change of clinical outcomes (pain, disability) over treatment were also explored. RESULTS: Kinematic-based measures showed comparable reliability to EMG-based measures. Between-group differences were found in lumbar lateral flexion ROM at baseline (patients < controls). In the patients with LBP, lateral flexion velocity and acceleration significantly increased following the LSEP. Correlational analyses revealed that lumbar angular kinematics were more sensitive to changes in pain intensity following the LSEP compared to EMG measures. These findings are interpreted in from the perspective of guarding behaviors and lumbar stability hypotheses. CONCLUSION: Future clinical trials are needed to target patients with and without delayed APAs at baseline and to explore the sensitivity of different outcome measures related to APAs. Different tasks more challenging to postural stability may need to be explored to more effectively reveal APA dysfunction.

The effect of two lumbar belt designs on trunk repositioning sense in people with and without low back pain.

OBJECTIVES: Low back pain (LBP) has previously been associated with impaired lumbar proprioception, which may lead to and/or perpetuate joint instability as a cause of LBP. Wearing a lumbar belt (LB) may be beneficial in this regard. The primary aim was to determine the effect of 2 LB designs (extensible and non-extensible) on trunk repositioning sense in people with and without LBP. A secondary aim was to evaluate whether patients showing different clinical signs of lumbar instability differentially benefit from LBs in terms of lumbar proprioception. DESIGN: Within-group experimental study with a healthy control group. METHODS: In total, 38 patients with LBP and 19 healthy controls participated in this study. Lumbar proprioception (position sense) was measured with participants sitting in a device that allowed for generating movements in axial rotation. Three experimental conditions were compared: (1) no LB, (2) extensible LB, (3) non-extensible LB. Four repositioning errors were computed for each experimental condition: constant error (CE), absolute error (AE), variable error (VE) and total variability (E). RESULTS: CE and AE scores were higher for LBP patients than healthy controls (all P<0.001), but scores did not significantly differ by condition. Additional subgroup analyses of clinical signs of instability were inconclusive, showing the same results in LBP patients with low and high instability scores (all P<0.001). CONCLUSIONS: This study confirms a significant loss of proprioception in trunk axial rotation in patients with LBP. Wearing an LB did not improve proprioception, but the contact between the LB and the skin might depend on the movement direction. Future studies should investigate the 3 planes of motion while eliminating the effect of the vestibular system.

The effects of an 8-week stabilization exercise program on lumbar movement sense in patients with low back pain.

BACKGROUND: Lumbar stabilization exercises have gained popularity and credibility in patients with non-acute low back pain. Previous research provides more support to strength/resistance and coordination/stabilisation programs. Some authors also suggest adding strength/resistance training following motor control exercises. However, the effect of such a lumbar stabilization program on lumbar proprioception has never been tested so far. The present study investigated the effects of an 8-week stabilization exercise program on lumbar proprioception in patients with low back pain (LBP) and assessed the 8-week test-retest reliability of lumbar proprioception in control subjects. METHODS: Lumbar proprioception was measured before and after an 8-week lumbar stabilization exercise program for patients with LBP. Control subjects participated in the same protocol but received no treatment. RESULTS: The lumbar proprioception measure showed moderate reliability. Patients with LBP and control subjects demonstrated no differences in lumbar proprioception at baseline. Participants from both groups showed better proprioception following the 8-week interval, demonstrating the presence of learning between testing days. CONCLUSIONS: The improvement of lumbar proprioception seen in both groups was ascribed to motor learning of the test itself. The effect of lumbar stabilization exercises on lumbar proprioception remains unknown because the LBP group did not show lumbar proprioception impairments.

Correlation of expertise with error detection skills of force application during spinal manipulation learning.

OBJECTIVE: Most studies on spinal manipulation learning demonstrate the relevance of including motor learning strategies in chiropractic curricula. Two outcomes of practice are the production of movement in an efficient manner and the improved capability of learners to evaluate their own motor performance. The goals of this study were to evaluate if expertise is associated with increased spinal manipulation proficiency and if error detection skills of force application during a high-velocity low-amplitude spinal manipulation are related to expertise. METHODS: Three groups of students and 1 group of expert chiropractors completed 10 thoracic spine manipulations on an instrumented device with the specific goal of reaching a maximum peak force of 300 N after a brief period of practice. After each trial, participants were asked to give an estimate of their maximal peak force. Force-time profiles were analyzed to determine the biomechanical parameters of each participant and the participant's capacity to estimate his or her own performance. RESULTS: Significant between-group differences were found for each biomechanical parameter. No significant difference was found between groups for the error detection variables (p > .05). The lack of significant effects related to the error detection capabilities with expertise could be related to the specificity of the task and how the training process was structured. CONCLUSION: This study confirms that improvements in biomechanical parameters of spinal manipulation are related to expertise. Feedback based on error detection could be implemented in chiropractic curricula to improve trainee abilities in detecting motor execution errors.

The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients.

INTRODUCTION: Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control. METHODS: Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG). RESULTS: Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores. CONCLUSIONS: Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration stimulation during motor control exercises is likely to influence motor adaptation and could be considered in the treatment of cLBP. Further work is needed to clearly identify at what levels of the sensorimotor system these gains are achievable.

Multiple Venous Thromboses Presenting as Mechanical Low Back Pain in an 18-Year-Old Woman.

OBJECTIVE: The purpose of this case report is to describe a patient who presented with acute musculoskeletal symptoms but was later diagnosed with multiple deep vein thrombosis (DVT). CLINICAL FEATURES: An 18-year-old female presented to a chiropractic clinic with left lumbosacral pain with referral into the posterior left thigh. A provisional diagnosis was made of acute myofascial syndrome of the left piriformis and gluteus medius muscles. The patient received 3 chiropractic treatments over 1 week resulting in 80% improvement in pain intensity. Two days later, a sudden onset of severe abdominal pain caused the patient to seek urgent medical attention. A diagnostic ultrasound of the abdomen and pelvis were performed and interpreted as normal. Following this, the patient reported increased pain in her left leg. Evaluation revealed edema of the left calf and decreased left lower limb sensation. A venous Doppler ultrasound was ordered. INTERVENTION AND OUTCOMES: Doppler ultrasound revealed reduction of the venous flow in the femoral vein area. An additional ultrasonography evaluation revealed an extensive DVTs affecting the left femoral vein and iliac axis extending towards the vena cava. Upon follow-up with a hematologist, the potential diagnosis of May-Thurner syndrome was considered based on the absence of blood dyscrasias and sustained anatomical changes found in the left common iliac vein at its junction with the right common iliac artery. A week following discharge, she presented with chest pain and was diagnosed with venous thromboembolism. The patient was successfully treated with anticoagulation therapy and insertion of a vena cava filter. CONCLUSION: Although DVTs are common in the general population, presence in low-risk individuals may be overlooked. In the presence of subtle initial clinical signs such as those described in this case report, clinicians should keep a high index of suspicion for a DVT. Rapid identification of such clinical signs in association with a lack of objective examination findings warrants further evaluation due to potentially negative outcomes.

Sensorimotor control during peripheral muscle vibration: an experimental study.

OBJECTIVE: The aims of this study were to determine whether the application of vibration on a postural lower limb muscle altered the sensorimotor control of its joint as measured by isometric force production parameters and to compare present findings with previous work conducted on trunk muscle. METHODS: Twenty healthy adults were asked to reproduce submaximal isometric plantar flexion under 3 different conditions: no vibration and vibration frequencies of 30 and 80 Hz on the soleus muscle. Time to peak torque, variable error, as well as constant error and absolute error in peak torque were calculated and compared across conditions. RESULTS: Under vibration, participants were significantly less accurate in the force reproduction task, as they mainly undershot the target torque. Applying an 80-Hz vibration resulted in a significantly higher negative constant error than lower-frequency vibration (30 Hz) or no-vibration condition. Decreases in isometric force production accuracy under vibration influence were also observed in a previous study conducted on trunk muscle. However, no difference in constant error was found between 30- and 80-Hz vibration conditions. CONCLUSION: The results suggest that acute soleus muscle vibration interferes with plantar flexion torque generation by distorting proprioceptive information, leading to decreases in accuracy of a force reproduction task. Similar results in an isometric trunk extension force reproduction task were found with vibration applied on erector spinae muscle. However, high-frequency vibration applied on soleus muscle elicited higher force reproduction errors than low-frequency stimulation.

Trunk neuromuscular responses to a single whole-body vibration session in patients with chronic low back pain: a cross-sectional study.

OBJECTIVE: Whole-body vibration (WBV) exercise is progressively adopted as an alternative therapeutic modality for enhancing muscle force and muscle activity via neurogenic potentiation. So far, possible changes in the recruitment patterns of the trunk musculature after WBV remain undetermined. The main objective of this study was to evaluate the short-term effects of a single WBV session on trunk neuromuscular responses in patients with chronic low back pain (cLBP) and healthy participants. METHODS: Twenty patients with cLBP and 21 healthy participants performed 10 trunk flexion-extensions before and after a single WBV session consisting of five 1-minute vibration sets. Surface electromyography (EMG) of erector spinae at L2-L3 and L4-L5 and lumbopelvic kinematic variables were collected during the trials. Data were analyzed using 2-way mixed analysis of variance models. RESULTS: The WBV session led to increased lumbar EMG activity during the flexion and extension phases but yielded no change in the quiet standing and fully flexed phases. Kinematic data showed a decreased contribution to the movement of the lumbar region in the second extension quartile. These effects were not different between patients with cLBP and healthy participants. CONCLUSIONS: Increased lumbar EMG activity after a single WBV session most probably results from potentiation effects of WBV on lumbar muscles reflex responses. Decreased EMG activity in full trunk flexion, usually observed in healthy individuals, was still present after WBV, suggesting that the ability of the spine stabilizing mechanisms to transfer the extension torque from muscles to passive structures was not affected.

Trunk isometric force production parameters during erector spinae muscle vibration at different frequencies.

BACKGROUND: Vibration is known to alter proprioceptive afferents and create a tonic vibration reflex. The control of force and its variability are often considered determinants of motor performance and neuromuscular control. However, the effect of vibration on paraspinal muscle control and force production remains to be determined. METHODS: Twenty-one healthy adults were asked to perform isometric trunk flexion and extension torque at 60% of their maximal voluntary isometric contraction, under three different vibration conditions: no vibration, vibration frequencies of 30 Hz and 80 Hz. Eighteen isometric contractions were performed under each condition without any feedback. Mechanical vibrations were applied bilaterally over the lumbar erector spinae muscles while participants were in neutral standing position. Time to peak torque (TPT), variable error (VE) as well as constant error (CE) and absolute error (AE) in peak torque were calculated and compared between conditions. RESULTS: The main finding suggests that erector spinae muscle vibration significantly decreases the accuracy in a trunk extension isometric force reproduction task. There was no difference between both vibration frequencies with regard to force production parameters. Antagonist muscles do not seem to be directly affected by vibration stimulation when performing a trunk isometric task. CONCLUSIONS: The results suggest that acute erector spinae muscle vibration interferes with torque generation sequence of the trunk by distorting proprioceptive information in healthy participants.

The influence of acute back muscle fatigue and fatigue recovery on trunk sensorimotor control.

OBJECTIVE: The aim of this study was to evaluate trunk repositioning sense after an acute muscle fatigue protocol and during a 30-minute recovery period. METHODS: Twenty healthy participants were asked to reproduce a 20° and 30° angle in trunk extension. Participants were tested before and after a Biering-Sorensen fatigue protocol was performed. Movement time, peak angle variable error, constant error and absolute error in peak angle were calculated and compared between 4 temporal conditions in both 20° and 30° extensions. RESULTS: The statistical analysis revealed a main effect of angle between 20° and 30° extension condition for variable error, absolute error, and movement time. A main effect of time was also found and was characterized by a significant increase in variable error between the prefatigue condition and the first postfatigue condition. During recovery, a significant decrease in variable error was observed between the first postfatigue condition and the 30-minute postfatigue condition, indicating that the variable mean scores were similar to initial values. CONCLUSION: Lower back muscle fatigue induced changes in trunk repositioning sense indicators immediately after the fatigue protocol. However, the observed changes did not last for more than a few minutes.