Effects of combined anodal transcranial direct current stimulation and motor control exercise on cortical topography and muscle activation in individuals with chronic low back pain: A randomized controlled study.

BACKGROUND: Aberrant movement in chronic low back pain (CLBP) is associated with a deficit in the lumbar multifidus (LM) and changes in cortical topography. Anodal transcranial direct current stimulation (a-tDCS) can be used to enhance cortical excitability by priming the neuromuscular system for motor control exercise (MCE), thereby enhancing LM activation and movement control. This study aimed to determine the effects of a 6-week MCE program combined with a-tDCS on cortical topography, LM activation, movement patterns, and clinical outcomes in individuals with CLBP. METHODS: Twenty-two individuals with CLBP were randomly allocated to the a-tDCS group (a-tDCS; n = 12) or sham-tDCS group (s-tDCS; n = 10). Both groups received 20 min of tDCS followed by 30 min of MCE. The LM and erector spinae (ES) cortical topography, LM activation, movement control battery tests, and clinical outcomes (disability and quality of life) were measured pre- and post-intervention. RESULTS: Significant interaction (group × time; p < 0.01) was found in the distance between LM and ES cortical locations. The a-tDCS group demonstrated significantly fewer discrete peaks (p < 0.05) in both ES and LM and significant improvements (p < 0.05) in clinical outcomes post-intervention. The s-tDCS group demonstrated a significant increase (p < 0.05) in the number of discrete peaks in the LM cortical topography. No significant changes (p > 0.05) in LM activation were observed in either group; however, both groups demonstrated improved movement patterns. DISCUSSION: Our findings suggest that combined a-tDCS with MCE can separate LM and ES locations over time while s-tDCS (MCE alone) reduces the distance. Our study did not find superior benefits of adding a-tDCS before MCE for LM activation, movement patterns, or clinical outcomes.

Ultrasound characteristics of soft tissues near sacroiliac joints and in the lumbar region of patients with ankylosing spondylitis.

AIMS: To investigate the musculoskeletal morphomechanical properties (i.e., the thickness and elastic modulus) and the total count of power Doppler signals near the sacroiliac joints in patients with ankylosing spondylitis (AS) and non-AS individuals. MATERIAL AND METHODS: Twenty participants with AS [median age (interquartile range): 31.7 (11.04) years] and 19 controls [36.3 (10.5) years] with no AS history were recruited. Bilateral ultrasound image acquisition was performed, including the short posterior sacroiliac ligament, interosseous sacroiliac ligament, long posterior sacroiliac ligament, iliolumbar ligament, proximal piriformis muscle, and sacrotuberous ligament. The intraclass correlation coefficients (ICC) of ultrasound parameters, laboratory test results of human leukocyte antigen B27, C-reactive protein, and erythrocyte sedimentation rate, and self-reported physical and disease activity scores were also obtained. RESULTS: The ligaments and piriformis muscle were thicker and stiffer (greater elastic modulus) in participants with AS than in non-AS participants (all p<0.01). The measurements showed good or excellent reliability (all ICC(3,1) >0.85). The numbers of power Doppler signals detected in the iliolumbar ligament, proximal piriformis muscle, and sacrotuberous ligament were higher in participants with AS than in non-AS participants (all p<0.001). A correlation was identified between disease duration and the elastic modulus of the piriformis muscle (r=0.640, p=0.003). CONCLUSION: We conclude that the ligaments and proximal piriformis muscle of AS participants have increased thickness, elastic modulus, and power Doppler signal than those of non-AS individuals. These reliable findings may serve as potential markers for the early diagnosis of AS and for assessing medication effects.

Cortical excitability and multifidus activation responses to transcranial direct current stimulation in patients with chronic low back pain during remission.

Evidence indicates that patients with chronic low back pain (CLBP) have lumbar multifidus muscle (LM) activation deficit which might be caused by changes in cortical excitability. Anodal transcranial direct current stimulation (a-tDCS) can be used to restore cortical excitability. This study aimed to (1) determine the immediate effects of a-tDCS on the cortical excitability and LM activation and (2) explore the relationship between cortical excitability and LM activation. Thirteen participants with CLBP during remission and 11 healthy participants were recruited. Cortical excitability (peak-to-peak motor evoked potential amplitude; P2P and cortical silent period; CSP) and LM activation were measured at pre- and post-intervention. We found significant difference (P < 0.05) in P2P between groups. However, no significant differences (P > 0.05) in P2P, CSP and LM activation were found between pre- and post-intervention in CLBP. The CLBP group demonstrated significant correlation (P = 0.05) between P2P and LM activation. Although our finding demonstrates change in P2P in the CLBP group, one-session of a-tDCS cannot induce changes in cortical excitability and LM activation. However, moderate to strong correlation between P2P and LM activation suggests the involvement of cortical level in LM activation deficit. Therefore, non-significant changes could have been due to inadequate dose of a-tDCS.

The role of an active muscular subsystem in prone instability test during rest and leg raise conditions.

BACKGROUND: Clinicians commonly used prone instability test (PIT) by assessing the posterior-to-anterior (PA) displacement to identify lumbar instability. Most studies focusing on passive subsystem found greater mobility in lower lumbar (L4-L5) than upper lumbar (L1-L3) spine. However, there is still a lack of evidence to demonstrate the role of active subsystem. Additionally, it is unclear whether sex affects PA displacements. AIM: To determine differences in displacement among five lumbar segments, between two testing positions (rest and leg raise), and between male and female during PIT in individuals with chronic non-specific low back pain (CNLBP). DESIGN: A cross-sectional study design. SETTING: Spine biomechanics laboratory. POPULATION: Individuals with CNLBP. METHODS: An electromagnetic tracking system was used to measure PA displacement with sensors attached at T12, S2 and a hand-held dynamometer. Participants were asked to perform PIT, while a 100N force was applied to each lumbar segment during resting and leg raise positions. RESULTS: Significantly less PA displacement (P<0.05) was seen in lower compared to upper lumbar spine and in leg raise compared to rest at L1 to L4. No significant interaction of sex with different lumbar levels and conditions (P>0.05) during PIT was found. CONCLUSIONS: Although previous studies have reported that the lower lumbar spine had greater mobility, the lower amount of displacement during the rest position suggests the role of an active subsystem contributing to lumbar stability regardless of sex. CLINICAL REHABILTATION IMPACT: A reduction in displacement during the leg raise position across L1 to L4 suggesting an interaction of stabilizing subsystems of the spine to provide lumbar stability.

The use of statistical parametric mapping to determine altered movement patterns in people with chronic low back pain.

Kinematics studies have generally focused on the quantity of movement using discrete parameters such as maximum and minimum angles to compare between people with chronic low back pain (CLBP) and healthy individuals. However, discrete parameters cannot be used to fully describe movement patterns and segmental contributions. This study aimed to explore the use of Statistical Parametric Mapping (SPM) to characterize quality of movement by examining if differences in movement patterns exist between groups, and within-group segmental contributions, during active movement tests. Twenty-one individuals with CLBP and nine healthy individuals were recruited. Inertial Measurement Unit (IMUs) were attached at thoracic (T3) and lumbar (L1) spine, and pelvis (S1) to collect active trunk flexion, extension, rotation, and lateral bend. SPM was used to analyze between-group movement patterns and within-group segmental contributions. SPM revealed no significant differences (P > 0.05) between groups. However, a greater lumbar contribution (P < 0.001) was observed during 10-40% of flexion followed by a greater pelvic contribution (P < 0.001) during 60-90% of flexion, while a greater lumbar than thoracic contribution (P < 0.001) was observed during flexion and the return to upright position in individuals with CLBP. Individuals with CLBP used a greater thoracic contribution compared to lumbar contribution (P < 0.001) during rotation, while a greater lumbar contribution compared to pelvic contribution was observed (P < 0.001) during lateral bending. Our findings suggest that SPM approach was able to detect differences in thoracic, lumbar, and pelvic velocity contributions and timings between segments in individuals with CLBP. These findings may help improving inter-rater reliability of clinical observations.

Neuromuscular responses to combined neuromuscular electrical stimulation and motor control exercises in a patient with recurrent low back pain: A single subject research report.

BACKGROUND: Previous studies have demonstrated changes in lumbar multifidus muscle (LM) contractility after motor control exercises (MCE), and it has been hypothesized that adding neuromuscular electrical stimulation (NMES) may help to re-activate motor units. OBJECTIVE: To present the effects of combined NMES and MCE on LM contractility, spatial and temporal motor unit recruitment, and movement control in a patient with recurrent low back pain (rLBP). METHODS: Motion tracking system was used to measure quality of movement (smoothness) during an active forward bend, while ultrasound imaging and decomposition electromyography were used to measure the LM contractility and motor unit recruitment during the Sorensen test. These data were collected pre and post intervention. Perceived improvement was also recorded. RESULTS: Improved movement smoothness post intervention was found, with increases in LM contractility from 68.1% to 97.7%, and from 74.2% to 86.7% on the right and left sides, respectively. Number of motor unit increased from 14 to 18 units, while mean firing rate decreased from 10.9 to 7.1 pulses/second post intervention. The patient also reported a perceived improvement of +2 on the Global Rating of Change (GROC). However, this change was not greater than +3 to be considered as minimal clinically important difference. CONCLUSION: These findings indicate improvements in movement control, LM contractility, and changes in spatial and temporal motor unit recruitment in the study patient, suggesting the potential clinical utility and the need for further research on combined NMES and MCE in the treatment of patients with rLBP.

Multifidus Muscle Contractility Deficit Was Not Specific to the Painful Side in Patients with Chronic Low Back Pain During Remission: A Cross-Sectional Study.

Purpose: Morphology studies demonstrated that patients with chronic low back pain (CLBP) have bilateral multifidus muscle (LM) atrophy. This atrophy should result in LM contractility deficit bilaterally. Additionally, a recent study showed the effect of sex on LM thickness. Researchers proposed percentage LM contractility (LMCONT) as standardization to enable the comparison across participants. This study aimed to determine side-to-side difference in LMCONT and to determine the difference in LMCONT between males and females. Patients and Methods: Twenty-five healthy individuals (NoLBP group; 10 males and 15 females) and 35 with CLBP (CLBP group; 16 males and 19 females; 23 unilateral pain and 12 bilateral pain) were recruited. Ultrasound imaging was used to measure LM thickness at rest, during maximum voluntary isometric contraction, and during combined maximum voluntary isometric contraction with electrical stimulation. These data were used to calculate LMCONT. For unilateral CLBP, right and left LMCON were renamed to painful and non-painful sides. Results: Data demonstrated no significant difference (p > 0.05) between right (87.3 ± 13.7%) and left (87.2 ± 14.0%) in NoLBP, right (71.2 ± 15.7%) and left (76.5 ± 19.7%) in bilateral CLBP, and painful (70.3 ± 17.5%) and non-painful (77.7 ± 18.4%) in unilateral CLBP. No difference (p > 0.05) was found between males and females in both NoLBP (male 84.8 ± 6.5%, female 88.9 ± 15.4%) and CLBP groups (male 76.3 ± 15.5%, female 71.9 ± 14.0%). Conclusion: The findings suggested that LM contractility deficit in CLBP is not specific to painful side. No effect was found of sex on LM contractility. Therefore, we can use averaged LM activation across painful and non-painful sides and across males and females to compare between NoLBP and CLBP groups.

Individuals With Impaired Lumbopelvic Control Demonstrate Lumbar Multifidus Muscle Activation Deficit Using Ultrasound Imaging in Conjunction With Electrical Stimulation: A Cross-sectional Study.

OBJECTIVE: To determine lumbar multifidus (LM) muscle activation deficits in individuals with impaired lumbopelvic control (iLPC) based on musculoskeletal ultrasound in conjunction with electrical stimulation approach and the correlation between back extension force and LM activation. DESIGN: A cross-sectional study design. SETTING: A university laboratory. PARTICIPANTS: Fifty participants (25 iLPC and 25 no low back pain [NoLBP]) were recruited from the university physical therapy clinic and surrounding areas. MAIN OUTCOME MEASURES: The musculoskeletal ultrasound was used to measure LM thickness at rest, maximum voluntary isometric contraction (MVIC), and electrical stimulation combined with MVIC, and a handheld dynamometer was used to record force during MVIC and electrical stimulation combined with MVIC. These data were used to derive LM activation (LMACT) and percentage force generation (ForceGEN). RESULTS: The iLPC group had significantly lower LMACT (17%) than the NoLBP group (P<.05). No significant difference was seen in ForceGEN between the NoLBP and iLPC groups (P>.05). No significant correlation was seen between LMACT and ForceGEN (P>.05). CONCLUSIONS: The findings support the utility of our protocol to determine LM activation deficits. The lower LM activation in iLPC group suggests that individuals with iLPC were unable to fully recruit the motor units available in LM. Force generation measurements may not be an appropriate approach to determine such deficits in LM.

The inter-rater reliability of clinical observation of prone hip extension and association between aberrant movement and chronic low back pain.

BACKGROUND: Clinical observation of aberrant movement patterns during prone hip extension (PHE) is commonly used in clinical practice to identify patients with low back pain. It could be clinically useful to identify individuals with chronic low back pain during remission (CLBPremission) to provide proactive intervention to prevent exacerbation of low back symptoms. OBJECTIVES: This study aimed to establish inter-rater reliability of clinical observation of PHE and association between aberrant movement pattern and CLBPremission. DESIGN: A cross-sectional study. METHOD: Twenty-six participants with CLBPremission and 18 participants without history of low back pain (NoLBP) performed 3 repetitions of active PHE, while 2 examiners concurrently observed and independently rated the movements as "presence" or "absence" of aberrant movement. Kappa statistics were used to establish inter-rater reliability based on rating data from 2 examiners, while chi-square tests were used to determine the association between aberrant movement and CLBPremission based on ratings (presence and absence) and known groups (CLBPremission and NoLBP). RESULTS: Kappa values ranged from fair to moderate (Kappa = 0.36-0.58). Result also demonstrated a significant association (P < 0.05) between presence of aberrant movement and CLBPremission. Findings indicate fair to moderate inter-rater reliability which are sufficient for clinical practice. The findings also indicated presence of aberrant movement patterns during active PHE was associated with CLBPremission. CONCLUSIONS: These findings suggested the usefulness of clinical observation of aberrant movement pattern during PHE to identify CLBPremission. The detection of aberrant movement would help clinicians to provide preventive program to minimize the risk of recurrent episodes of low back symptoms.

Patients with low back pain use stiffening strategy to compensate for movement control during active prone hip rotation: A cross-sectional study.

BACKGROUND: New motor adaptation to pain theory suggests that patients with low back pain (LBP) use the lumbopelvic stiffening strategy by redistribution of within and between muscle activities to protect painful structure. This could result in an altered postural control of the lumbopelvic region during active prone hip rotation (PHR). OBJECTIVE: To investigate coordination and timing of lumbopelvic and hip movements, and smoothness of the lumbopelvic control during PHR between participants with and without LBP. METHODS: Eight participants with LBP and eight participants without LBP were recruited. The electromagnetic tracking system was used to record kinematic data during PHR. Cross-correlation between hip rotation and lumbopelvic movement in the transverse plane was calculated. Correlation at zero time-lag, time-lag, correlation at time-lag, and maximal lumbopelvic motion were derived. Frequency of movement disruption was identified. An independent t-test was used in conjunction with the effect size and 95% minimal detectable difference (MDD95) to determine the difference in kinematic parameters. RESULTS: Participants with LBP demonstrated a significant delay (exceeding MDD95) in lumbopelvic motion while nonsignificant frequency of disrupted motion on the painful side PHR demonstrated a trend with a large effect size that exceeded MDD95. There were trends with moderate to large effect sizes and differences exceeding MDD95 in delay of lumbopelvic motion with greater movement disruption on the nonpainful side in participants with LBP. CONCLUSION: Participants with LBP used a lumbopelvic stiffening strategy for postural control to protect painful structures; however, the stiffening might complicate efforts to smoothly control lumbopelvic movement.

Combined neuromuscular electrical stimulation with motor control exercise can improve lumbar multifidus activation in individuals with recurrent low back pain.

Motor control exercise (MCE) is commonly prescribed for patients with low back pain. Although MCE can improve clinical outcomes, lumbar multifidus muscle (LM) activation remains unchanged. Neuromuscular electrical stimulation (NMES) can be used to re-activate motor units prior to MCE which should result in increased LM activation. Therefore, this study aimed to explore the immediate effects of NMES combined with MCE on LM activation and motor performance. Twenty-five participants without low back pain (NoLBP) and 35 participants with movement control impairment (MCI) were recruited. Participants with MCI were further randomized to combined NMES with MCE (COMB) or sham-NMES with MCE (MCE) group. Ultrasound imaging was used to measure LM thickness at rest, maximum voluntary isometric contraction (MVIC), and NMES with MVIC. These data were used to calculate LM activation. Quadruped rocking backward was used to represent motor performance. LM activation and motor performance were measured at baseline and after one-session of intervention. Results showed that both COMB and MCE groups had significantly lower (P < 0.05) LM activation compared with NoLBP group at baseline. Additionally, both COMB and MCE groups demonstrated significant improvement (P < 0.05) in motor performance while COMB group demonstrated significantly greater improvement (P < 0.05) in LM activation compared with MCE group. Individuals with MCI still have persisting LM activation deficit. Our key findings suggest that combined NMES and MCE may have better ability to improve LM activation in individuals with MCI. These findings would support the utility of NMES to induce a priming effect before MCE.

Using neuromuscular electrical stimulation in conjunction with ultrasound imaging technique to investigate lumbar multifidus muscle activation deficit.

Lumbar multifidus muscle (LM) activation deficit has been proposed as a potential underlying mechanism responsible for recurrence episode of low back pain (LBP). The quantification of voluntary LM activation can provide a better understanding of the role of muscle activation deficit in LBP. The objective of this technical report is to propose a new approach using neuromuscular electrical stimulation (NMES) in combination with the ultrasound imaging technique (USI) to investigate the ability of individual to voluntarily activate the LM. We recruited ten participants with a recurrent LBP (rLBP) and twelve participants with no history of LBP (NoLBP). Theoretically, the superimposition of NMES on the LM during maximum voluntary isometric contraction (MVIC) should activate all motor units available in the LM. The percentage of LM activation (%LM) can be calculated by the changes of LM thickness during MVIC, divided by the changes of LM thickness during the combination of MVIC and NMES. This %LM was used to compare between groups. The individuals with rLBP had significantly lower %LM (p < 0.05) compared with the NoLBP counterpart (%LM = 72.4 and 92.9, respectively). Results demonstrate that this new approach can potentially differentiate %LM among individuals with rLBP and NoLBP. This new approach can be potentially used to 1) determine the extent of LM activation deficit, 2) identify the existence of muscle activation deficit in the LM, and 3) objectively measure the effect of the intervention designed to address the LM activation deficit.

Association between lumbopelvic motion and muscle activation in patients with non-specific low back pain during forward bending task: A cross-sectional study.

BACKGROUND: Evidence suggests patients with non-specific low back pain (NSLBP) have altered lumbar and pelvic movement patterns. These changes could be associated with altered patterns of muscle activation. OBJECTIVE: The study aimed to determine: (1) differences in the relative contributions and velocity of lumbar and pelvic movements between people with and without NSLBP, (2) the differences in lumbopelvic muscle activation patterns between people with and without NSLBP, and (3) the association between lumbar and pelvic movements and lumbopelvic muscle activation patterns. METHODS: Subjects (8 healthy individuals and 8 patients with NSLBP) performed 2 sets of 3 repetitions of active forward bending, while motion and muscle activity data were collected simultaneously. Data derived were lumbar and pelvic ranges of motion and velocity, and ipsilateral and contralateral lumbopelvic muscle activities (internal oblique/transverse abdominis (IO/TA), lumbar multifidus (LM), erector spinae (ES) and gluteus maximus (GM) muscles). RESULTS: Lumbar and pelvic motions showed trends, but exceeded 95% confidence minimal detectable difference ( MDD 95 ) , for greater pelvic motion ( p = 0 . 06 ) , less lumbar motion ( p = 0 . 23 ) among patients with NSLBP. Significantly less activity was observed in the GM muscles bilaterally ( p < 0 . 05 ) in the NSLBP group. A significant association ( r = - 0 . 8 , p = 0 . 02 ) was found between ipsilateral ES muscle activity and lumbar motion, while moderate, but statistically non-significant associations, were found between GM muscle activity bilaterally and lumbar velocity ( ipsilateral: r = - 0 . 6 , p = 0 . 14 ; contralateral: r = - 0 . 6 , p = 0 . 16 ) in the NSLBP group. CONCLUSION: Findings indicated patients had greater pelvic contribution, but less lumbar contribution which was associated with less activation of the GM bilaterally.

Effect of increased relative stiffness of the lumbar spine on hamstring muscle stretching in individuals with a history of low back pain suspected to have a clinical lumbar instability: A randomized crossover design.

BACKGROUND: Theoretically, lumbopelvic stabilization techniques during hamstring muscle stretching could increase lumbar stiffness relative to hamstring muscle in individuals with a history of low back pain and suspected clinical lumbar instability. However, evidence to support this theory is limited. This study aimed to 1) determine changes in lumbopelvic, lumbar, and hip motions, and hamstring muscle length after stretching exercises with lumbopelvic stiffening or relaxing techniques, and 2) compare those changes between techniques. METHODS: This study used a randomized crossover design. Thirty-two participants with a history of low back pain and bilateral hamstring muscle tightness were recruited. The order of the first technique was randomly assigned. After a 2-day washout, participants were crossed over to the second technique. Motion data during active forward trunk bending and bilateral hamstring muscle length during passive knee extension were collected pre- and post-intervention. FINDINGS: Significant increases (P < 0.05) were found in bilateral hamstring muscle length for both techniques. However, stiffening technique demonstrated a significant decrease in lumbar motion (P < 0.05) and increase in hip motion (P < 0.05), while relaxing technique demonstrated trends showing increases in lumbar and hip motions (P = 0.134 and 0.115, respectively). The findings showed significantly greater improvement (P < 0.05) in lumbar and hip motions with stiffening technique. INTERPRETATION: The findings suggest increased relative stiffness of the lumbar spine during hamstring muscle stretching can specifically lengthen bilateral hamstring muscle and decrease excessive lumbar motion. This stiffening technique may prevent excessive movement of the lumbar spine, thereby reducing the risk of recurrent low back pain.

Individuals With and Without Low Back Pain Use Different Motor Control Strategies to Achieve Spinal Stiffness During the Prone Instability Test.

BACKGROUND: The prone instability test is used to identify individuals with low back pain (LBP) who would benefit from trunk stabilization exercises. Although activity from muscles during the leg-raising portion of the prone instability test theoretically enhances spinal stiffness and reduces pain, evidence for this is lacking. OBJECTIVES: To compare and contrast (1) pain and stiffness changes between prone instability testing positions, and (2) muscle activation patterns during the prone instability test leg raise in individuals with and without LBP. METHODS: Participants with (n = 10) and without (n = 10) LBP participated in this laboratory case-control study. Spinal stiffness was measured using a beam-bending model and 3-D kinematic data. Stiffness changes were compared across the test positions and between groups. Surface electromyographic data were collected on trunk and limb musculature. Principal-component analysis was used to extract muscle synergies. RESULTS: Spinal stiffness increased across testing positions in all participants (P<.05). Participants with LBP experienced reduced pain during the test (P<.001). No between-group difference was found in spinal stiffness during leg raising during the test (P>.05). Participants without LBP used 3 muscle synergies during the leg raise and participants with LBP used 2 muscle synergies. CONCLUSION: Spinal stiffness increased in all participants; however, participants without LBP demonstrated a muscle synergy pattern where each synergy was associated with a distinct function of the prone instability test. Participants with LBP used a more global stabilization pattern, which may reflect a maladaptive method of enhancing spinal stability. J Orthop Sports Phys Ther 2019;49(12):899-907. Epub 3 Aug 2019. doi:10.2519/jospt.2019.8577.

One session of motor control exercise improves joint position sense assessed by an iPhone application: a randomized controlled trial.

[Purpose] To establish the test-retest reliability of an iPhone application and determine the immediate effect of motor control exercise (MCE) on lumbar position sense. [Participants and Methods] This study used a two-arm, randomized controlled trial design with a blinded assessor. Sixty healthy participants were randomized into the exercise or control group. The exercise group underwent 30-min MCE, whereas the control group rested for 15 min. Lumbar motion measured by two iPhones with goniometer application was used to determine the test-retest reliability. Absolute repositioning errors (pre- and post-test) from the control and exercise groups were used to determine the immediate effect of MCE on lumbar position sense. [Results] The test-retest reliability was 0.67-0.95. A significant interaction effect was found for Angle*Time, main effect of Angle, and main effect of Time. Post-hoc comparison showed a significant improvement in position sense at 45° and 60° in the exercise group. [Conclusion] The findings suggest that a mobile phone application has the ability to detect changes in lumbar position sense between sessions that exceed measurement error following MCE. One session of specific MCE can improve lumbar position sense at high lumbar flexion.

Lumbar Multifidus and Erector Spinae Muscle Synergies in Patients with Nonspecific Low Back Pain During Prone Hip Extension: A Cross-sectional Study.

BACKGROUND: Prone hip extension is used to clinically assess movement control in patients with nonspecific low back pain (LBP). Excessive lumbopelvic movements and altered muscle activation patterns are common in patients with nonspecific LBP. However, no evidence exists regarding lumbar multifidus and lumbar erector spinae muscle synergy patterns in patients with nonspecific LBP during this clinical test. OBJECTIVE: To determine the difference in lumbopelvic motion and change in muscle synergy between patients with nonspecific LBP and healthy individuals. DESIGN: A cross-sectional study design. SETTING: University physical therapy clinic and laboratory. PARTICIPANTS: Seven patients with nonspecific LBP (age [mean ± SD] 29 ± 5 years, 43% female, body mass index [BMI] of 25 ± 2 kg/m2 , Numeric Pain Rating Scale 6 ± 2; Oswestry Disability Index 20% ± 8%) and seven age-, sex-, and BMI-matched healthy individuals (mean age 28 ± 5 years, 43% female, BMI of 22 ± 2 kg/m2 ) were recruited. METHODS: Each participant performed six repetitions of prone hip extension on each side; kinematic and electromyographic data were collected simultaneously. MAIN OUTCOME MEASUREMENTS: Kinematic data were used to represent lumbopelvic motion, whereas electromyography (EMG) data were used to represent muscle activity. A paired t-test was used to determine the difference in lumbopelvic motion. Principal component analysis and two-way repeated-measures analysis of variance were used to extract muscle synergies and identify differences in muscle synergy patterns between and within groups. RESULTS: Results demonstrated no significant group difference (P > .05) in amount of lumbopelvic motion. However, healthy individuals synergistically activate lumbar multifidus and lumbar erector spinae with 81.0% variance accounted for (VAF). Patients with nonspecific LBP had an altered synergy with independent activation of lumbar multifidus on the painful side with 32.0% VAF and the lumbar multifidus on the nonpainful side, and both lumbar erector spinae with 52.2% VAF synergistically activated. CONCLUSIONS: These findings suggest that clinicians should focus on muscle activation patterns rather than the amount of lumbopelvic motion during clinical observation of prone hip extension. LEVEL OF EVIDENCE: Level III.

Reduced instantaneous center of rotation movement in patients with low back pain.

PURPOSE: The instantaneous center of rotation (ICR) can be used to investigate movement coordination and control in patients with low back pain (LBP). Tracking of the ICR in LBP patients has not been systematically investigated. This study aimed to (1) determine the within-session measurement error of ICR parameters, and (2) characterize the change in ICR among three groups of participants (no history of LBP = HC; history of LBP = HLBP; and current LBP = LBP). METHODS: Ninety-three participants (HC = 31; HLBP = 33; and LBP = 29) were recruited. Participants performed two sets of three repetitions of an active forward bend, while their lumbar and pelvic movements were recorded with an electromagnetic tracking system. Total ICR displacement and the radius of the bounding sphere containing the ICR were derived during the forward bending and the return to upright phases. Intra-class correlation coefficients (ICC3,3) and minimal detectable difference (MDD) were used to determine measurement error and interpret findings of the group analysis. One-way ANOVAs and post hoc Bonferroni comparisons were used to determine differences among groups. RESULTS: ICC3,3 demonstrated excellent within-session test-retest reliability of the ICR parameters (ICC3,3 = 0.86-0.97). The MDD values were 0.20-3.40 mm. Comparisons between the HC and LBP groups and between the HLBP and LBP groups showed significant differences (p < 0.05) for all ICR parameters, with medium effect sizes (0.51-0.66), except for total displacement during forward bending between the HC and LBP groups. CONCLUSION: Less ICR displacement and variability in patients with LBP may indicate coping strategies to stiffen the lumbar spine. This could result from patients with LBP adopting a strategy of increased muscle activation to provide spinal stability during functional tasks.

Kinematic characterization of clinically observed aberrant movement patterns in patients with non-specific low back pain: a cross-sectional study.

BACKGROUND: Clinical observation of aberrant movement patterns during active forward bending is one criterion used to identify patients with non-specific low back pain suspected to have movement coordination impairment. The purpose of this study was to describe and quantify kinematic patterns of the pelvis and trunk using a dynamics systems approach, and determine agreement between clinical observation and kinematic classification. METHOD: Ninety-eight subjects performed repeated forward bending with clinical observation and kinematic data simultaneously collected. Kinematic data were plotted using angle-angle, coupling-angle, and phase-plane diagrams. Accuracy statistics in conjunction with receiver operating characteristic curves were used to determine agreement between clinical observation and kinematic patterns. RESULTS: Kinematic patterns were consistent with clinical observation and definitions of typical and aberrant movement patterns with moderate agreement (kappa = 0.46-0.50; PABAK = 0.49-0.73). Early pelvic motion dominance in lumbopelvic coupling-angle diagram ≥59° within the first 38% of the movement represent observed altered lumbopelvic rhythm. Frequent disruptions in lumbar spine velocity represented by phase-plane diagrams with local minimum occurrences ≥6 and sudden decoupling in lumbopelvic coupling-angle diagrams with sum of local minimum and maximum occurrences ≥15 represent observed judder. CONCLUSION: These findings further define observations of movement coordination between the pelvis and lumbar spine for the presence of altered lumbopelvic rhythm and judder. Movement quality of the lumbar spine segment is key to identifying judder. This information will help clinicians better understand and identify aberrant movement patterns in patients with non-specific low back pain.