The comparison of trunk muscles EMG activation between subjects with and without chronic low back pain during flexion-extension and lateral bending tasks

Effects of age/gender profiles and physical activity level on symmetry of lumbar muscle activation in pain-free older adults during various spinal movements

BACKGROUND

Back muscles simultaneously drive spinal movements and stabilize the trunk. Paraspinal muscle activity is presumed to be symmetric and gender-insensitive, and more activated with aging to protect the spine during functional tasks.

RESEARCH QUESTION

Does over-activated and asymmetric behaviors exist in the pain-free elderly population which is affected by their physical activity levels?

METHODS

Forty healthy participants (aged 64.8 ± 9.9 years, 20 males and 20 females) were recruited for this cross-sectional study. They completed the International Physical Activity Questionnaire (IPAQ) to quantify their self-reported physical activity measures including the total physical activity in MET-min/week and time spent sitting. Surface electromyographic activity of bilateral paraspinal muscles at L3 level was measured. Subjects were instructed to perform functional tasks including symmetric movements as well as right- and left-side rotation/bending. Asymmetry in muscle activation between the two sides was calculated. A multiple linear regression model was used to assess the association of muscle activations with age and gender. Pearson correlation analysis was used to verify the relationship between the asymmetry and physical activity measures.

RESULTS AND SIGNIFICANCE

The results showed a downtrend of paraspinal muscle activations with aging and the decreasing rate could differ between genders. Left-side muscle activations were generally higher than those of the right-side muscles. Muscle asymmetrical activation correlated with sitting time but not total physical activity. This study highlighted aging and gender effects on the paraspinal muscle activations as well as muscle imbalance during different movement paradigms. Future work is needed to verify the underlying mechanism for declining and asymmetrical muscle activation and its link to back disorders.

The clinical utility and reliability of surface electromyography in individuals with chronic low back pain: A systematic review

Chronic low back pain (CLBP) is a common disorder worldwide, affecting young and old adults alike. Kinematic studies of lumbar-pelvic mobility allied with surface electromyogram (sEMG) can assist in the assessment and management of CLBP. This systematic review aimed to synthesise the evidence relating to the diagnostic accuracy and reliability of the surface electromyogram in chronic low back pain patients during flexion-extension-relaxation tasks. Five databases (PubMed, Scopus, Web of Science, Embase and CINAHL) were searched for eligible studies from inception to March 2024. The risk of bias assessment for the included studies was conducted using the QUADAS-2 tool. Studies included adults (≥18 years) with CLBP > 3 months, reported diagnostic accuracy or reliability measures for sEMG during flexion-extension-relaxation tasks. Eleven studies were included in our systematic review. The risk of bias was found to be high for patient selection, reference standard and flow and timing domains with low risk of bias for the index test domain in most of the included studies. For diagnostic accuracy, six studies reported values ranging between 56-99 % indicating poor to excellent accuracy levels. Four studies reported values between 76-100 % for sensitivity and 65-100 % for specificity indicating sufficient to excellent accuracy levels. Seven studies reported moderate to excellent reliability levels, ranging between 0.66-0.99. This systematic review found the diagnostic accuracy and reliability of sEMG in CLBP patients to range from poor to excellent levels. This systematic review adds knowledge for practitioners and clinicians regarding the use of sEMG during forward, flexion and relaxation tasks/movements.

Acute effect of dry needling on trunk kinematics and balance of patients with non-specific low back pain

BACKGROUND

Limited knowledge exists about the effectiveness of dry needling (DN) concerning the torso kinematics in patients with non-specific low back pain (NS-LBP). Acute effects of DN in NS-LBP patients from a functional perspective were investigated.

METHODS

Sixteen NS-LBP patients and 11 healthy individuals (HG) were examined. NS-LBP patients received a single session of DN at the lumbar region. Baseline and immediate post-treatment measurements during flexion-extension and lateral bending of the trunk were conducted for the NS-LBP patients. HG were measured only at baseline to be used as a reference of NS-LBP patients' initial condition. Algometry was applied in NS-LBP patients. Centre of pressure, range of motion of the trunk and its' derivatives were obtained.

FINDINGS

HG performed significantly faster, smoother and with greater mobility in the performed tasks compared to the pre intervention measurements of the NS-LBP patients. For the NS-LBP patients, significant greater angular velocity in frontal plane and significant lower jerk in the sagittal plane were demonstrated post intervention. DN alleviated pain tolerance significantly at the L5 level. Regarding the effectiveness of the DN upon spine kinematics, their derivatives were more sensitive.

INTERPRETATION

It appeared that the pathological type of torso movement was acutely affected by DN. NS-LBP patients showcased smoother movement immediately after the intervention and better control as imprinted in the higher derivative of motion although range of motion did not improve. This quantitative variable may not be subjected to acute effects of DN but rather need additional time and training to be improved.

Changes in the Activity of the Erector Spinae and Gluteus Medius Muscles with the Presence of Simulated Lower Limb Dysmetria

(1) Background: Leg length discrepancy (LLD), regardless of its origin, is a very common pathology that can contribute to low back pain. Various authors have pointed out its relationship with the lack of activation of both the gluteus medius (GM) and the ipsilateral erector spinae (ES). The purpose of this study was to identify the activation of the ES and GM with different simulated LLDs, correlating this activation with LBP. In turn, we evaluated whether ES and GM activity has an effect on jumping ability using a CMJ test. (2) Method: A sample of healthy subjects was selected to whom an artificial LLD was applied using 0.5, 1, and 1.5 cm insoles. These three heights were measured using EMG while the subjects walked and performed a counter movement jump (CMJ). The measurements of the insole heights were carried out in random order using a Latin square. Muscle activation patterns were recorded for 30 s at each of the insole heights while the patients walked at 5.7 km/h and they were compared with the maximum voluntary contraction (MVC), both on the ipsilateral and contralateral sides. These muscles were then measured under the same circumstances during the performance of the CMJ. (3) Results: We found statistically significant differences in the flight heights in both the CMJ and DJ. In the comparison, significant differences were found in the flight heights of the CMJ and the DJ using the 5 mm insoles, and in the case of the DJ, also without insoles, with respect to the MVC. We found statistically significant differences in the activation of the GM with the differences in insoles, but not in the activation of the Es in relation to the different insole heights. (4) Conclusions: Insoles of different heights caused activation differences in the medius on the side where the insoles were placed. We can relate this difference in activation to LBP. In relation to the ES, no significant differences were found in the activation of the ipsilateral side of the insole.

Multifidus dysfunction and restorative neurostimulation: a scoping review

OBJECTIVE

Chronic low back pain (CLBP) is multifactorial in nature, with recent research highlighting the role of multifidus dysfunction in a subset of nonspecific CLBP. This review aimed to provide a foundational reference that elucidates the pathophysiological cascade of multifidus dysfunction, how it contrasts with other CLBP etiologies and the role of restorative neurostimulation.

METHODS

A scoping review of the literature.

RESULTS

In total, 194 articles were included, and findings were presented to highlight emerging principles related to multifidus dysfunction and restorative neurostimulation. Multifidus dysfunction is diagnosed by a history of mechanical, axial, nociceptive CLBP and exam demonstrating functional lumbar instability, which differs from other structural etiologies. Diagnostic images may be used to grade multifidus atrophy and assess other structural pathologies. While various treatments exist for CLBP, restorative neurostimulation distinguishes itself from traditional neurostimulation in a way that treats a different etiology, targets a different anatomical site, and has a distinctive mechanism of action.

CONCLUSIONS

Multifidus dysfunction has been proposed to result from loss of neuromuscular control, which may manifest clinically as muscle inhibition resulting in altered movement patterns. Over time, this cycle may result in potential atrophy, degeneration and CLBP. Restorative neurostimulation, a novel implantable neurostimulator system, stimulates the efferent lumbar medial branch nerve to elicit repetitive multifidus contractions. This intervention aims to interrupt the cycle of dysfunction and normalize multifidus activity incrementally, potentially restoring neuromuscular control. Restorative neurostimulation has been shown to reduce pain and disability in CLBP, improve quality of life and reduce health care expenditures.

Effects of sling exercises on pain, function, and corticomuscular functional connectivity in individuals with chronic low back pain- preliminary study

BACKGROUND

Individuals with chronic low back pain (CLBP) exhibit altered brain function and trunk muscle activation.

AIM

This study examined the effects of sling exercises on pain, function, and corticomuscular coherence (CMC) in healthy adults and individuals with CLBP.

METHODS

Eight individuals with CLBP and 15 healthy adults received sling exercise training for 6 weeks. Before and after training, participants performed two motor tasks: rapid arm lifts and repeated trunk flexion-extension tasks, and electromyography of the trunk muscles and electroencephalography of the sensorimotor cortex were recorded. Chi-squared test and Mann-Whitney U tests were used for between group comparison, and Wilcoxon signed-rank tests were used for pre- and post-training comparison. Spearman's Rank Correlation Coefficient (Rs) was used to identify for the relationship between motor performance and Corticomuscular coherence.

RESULTS

Sling exercises significantly improved pain (median from 3 to 1, p = .01) and Oswestry Disability Index scores (median from 2.5 to 2, p = .03) in the CLBP group. During rapid arm lifts, individuals with CLBP showed lower beta CMC of the transverse abdominis and internal oblique (Tra/IO) (0.8 vs. 0.49, p = .01) and lumbar erector spinae (0.70 vs. 0.38, p = .04) than the control group at baseline. During trunk flexion-extension, the CLBP group showed higher gamma CMC of the left Tra/IO than the control group at baseline (0.28 vs. 0.16 , p = .001). After training, all CMC became statistically non-significant between groups. The training induced improvement in anticipatory activation of the Tra/IO was positively correlated with the beta CMC (rs = 0.7851, p = .02).

CONCLUSION

A 6-week sling exercises diminished pain and disability in patients with CLBP and improved the anticipatory activation and CMC in some trunk muscles. These improvements were associated with training induced changes in corticomuscular connectivity in individuals with CLBP.

Volting, a Novel Dancing Wheelchair with Augmented Mobility: Pushing Lateral Inclinations

Wheelchair users are often perceived as someone ill and who will be limited in performing daily activities. This paradigm can be changed if instead to focus on limits, we start to think about the new possibilities that could be explored from their current mobility and technology. We present a novel dancing wheelchair with augmented mobility named Volting. Our novel wheelchair was designed to tilt the seat laterally up to 14°. This inclination is performed proportionally to the inclination of the user by a mechanism based on passive suspensions. Our system was analyzed as a double inverted pendulum and a mathematical model was developed using Euler-Lagrange equations. This analysis was used to calculate the ideal stiffness. Thus, we performed experiments with three distinct stiffness values and varying the weight of participants to analyze the behavior of our mechanism. Our results show that lateral inclinations in our wheelchair can be unstable, low sensitivity or linear tendency. The latter behavior, which is the most appropriate, was obtained using the suspension whose stiffness was close to the ideal value, thus validating our mathematical approach. Moreover, this behavior was maintained even if the user weight varies up to 10kg above the estimated value, ensuring a good performance for varying morphologies. Finally, our device was tested by a professional wheelchair dancer who shows the new possibilities of Volting in terms of mobility.

Biomechanical Consequences of Using Passive and Active Back-Support Exoskeletons during Different Manual Handling Tasks

The aim of this study was to assess, for both men and women, the consequences of using different back-support exoskeletons during various manual material tasks (MMH) on the activity of back muscles and trunk kinematics. Fifteen men and fourteen women performed MMH involving a 15 kg load (a static task, a symmetric lifting task, and an asymmetric lifting task). Four exoskeleton conditions were tested: without equipment (CON) and with three exoskeletons passive (P-EXO), and active (A-EXO1 and A-EXO2)). The electromyographic activity of the lower trapezius (TZ), latissimus dorsi (LD), erector spinae (ES), gluteus maximus (GM), and biceps femoris (BF) muscles was recorded. Trunk kinematics were evaluated to provide average thoracic, lumbar, and hip angles. The use of the P-EXO decreased the activity of LD, GM, and BF from -12 to -27% (p < 0.01) compared to CON, mostly during the static task. The A-EXO1 and A-EXO2 reduced the muscle activity of all studied muscles from -7 to -62% (p < 0.01) compared to CON and from -10 to -52% (p < 0.005) compared to the P-EXO, independently of the modalities of the experimental tasks. A statistical interaction between the sex and exoskeleton was only observed in a few rare conditions. Occupational back-support exoskeletons can reduce trunk extensor muscle activity compared to no equipment being used. However, these reductions were modulated by the exoskeleton technology (passive vs. active), design (weight and anthropomorphism), and the modalities of the task performed (static vs. dynamic). Our results also showed that the active exoskeletons could modify the trunk kinematics.

Left-Right Differential Erector Spinae Muscles Activation in Prone and Quadruped Positions

Left-right differential erector spinae (ES) muscle strengthening is required to correct ES muscle imbalances. The objective was to test the effect of 6 body positions on the differential activation of the ES muscles. In 14 able-bodied young women, using a surface electromyography system, the bilateral ES muscles activity at the third lumbar (ESL3) and the 10th (EST10) and 6th (EST6) thoracic vertebral levels was measured with the contralateral arm and leg lifted in the prone and quadruped conditions and with a single arm lifted in the quadruped position. Results showed that the activity of the ESL3 was symmetrical (P > .05) and significantly smaller than that of the thoracic ES muscles in all body positions (P < .01). The EST10 and EST6 were differentially activated in all tests (P < .001). Besides, the differential activation was higher in the contralateral-arm and -leg lift in the quadruped position than in the other positions. In conclusion, contralateral-arm and -leg lift and single-arm lift in the quadruped and prone positions are capable of differentially activating the ES muscles on one side more than the other side. Further studies are recommended to examine the effectiveness of these exercises on the correction of ES muscle imbalances in clinical populations.

Biomechanical factors associated with non-specific low back pain in adults: A systematic review

Low back pain (LBP) can result in increased direct medical and non-medical costs to patients, employers, and health care providers. This systematic review aimed to provide a better understanding of the biomechanical factors associated with chronic non-specific LBP in adults. SCOPUS, ScienceDirect, MEDLINE, and Web of Science databases were searched. In total, 26 studies were included and significant differences were noted between healthy controls and LBP patients in various motion. Biomechanical factors among adults with non-specific LBP were altered and differed as compared to healthy controls in various motion might be to compensate the pain during those motions. This review highlighted the biomechanical differences across those with non-specific LBP and healthy adults. Both groups showed a similar level of pain during functional tasks but LBP patients suffered from a moderate level of disability. Future studies should not rely on questionnaire-based pain scale only. The biomechanical factors summarized in this review can be used to diagnose non-specific LBP accurately, and as modifiable targets for exercise-based intervention.

Reliability of high-density surface electromyography for assessing characteristics of the thoracic erector spinae during static and dynamic tasks

PURPOSE

To establish intra- and inter-session reliability of high-density surface electromyography (HDEMG)-derived parameters from the thoracic erector spinae (ES) during static and dynamic goal-directed voluntary movements of the trunk, and during functional reaching tasks.

METHODS

Twenty participants performed: 1) static trunk extension, 2) dynamic trunk forward and lateral flexion, and 3) multidirectional functional reaching tasks on two occasions separated by 7.5 ± 1.2 days. Muscle activity was recorded bilaterally from the thoracic ES. Root mean square (RMS), coordinates of the barycentre, mean frequency (MNF), and entropy were derived from the HDEMG signals. Reliability was determined with intraclass correlation coefficient (ICC), coefficient of variation, and standard error of measurement.

RESULTS

Good-to-excellent intra-session reliability was found for all parameters and tasks (ICC: 0.79-0.99), whereas inter-session reliability varied across tasks. Static tasks demonstrated higher reliability in most parameters compared to functional and dynamic tasks. Absolute RMS and MNF showed the highest overall reliability across tasks (ICC: 0.66-0.98), while reliability of the barycentre was influenced by the direction of the movements.

CONCLUSION

RMS and MNF derived from HDEMG show consistent inter-session reliability in goal-directed voluntary movements of the trunk and reaching tasks, whereas the measures of the barycentre and entropy demonstrate task-dependent reliability.

Investigation of the relationship between the clinical evaluation results of lumbar region muscles with cross-sectional area and fat infiltration

BACKGROUND

The relationship between the endurance of the lumbar paraspinal muscles and morphological changes needs to be clarified. In this context, the importance can be revealed of increasing the endurance level of the paraspinal muscles in the prevention and treatment of low back diseases.

OBJECTIVE

The aim of this study was to examine the relationship between the clinical evaluation results of the cross-sectional area (CSA) and fat infiltration of the lumbar deep paraspinal muscles.

METHODS

The study included 37 patients with mechanical low back pain (mechanical), 41 patients with lumbar hernia without root compression (discopathy) and 36 healthy individuals as a control group. The functional status of the lumbar deep paraspinal muscles was evaluated clinically with muscle endurance tests. The fat infiltration and CSA of the muscles were evaluated on axial MRI sections at the L3-S1 level.

RESULTS

The mean values of the prone bridge, Biering-Sorenson, and trunk flexion tests were seen to be highest in the control group and lowest in the discopathy group (p< 0.001). In all tests, the longest test period was obtained at < 10% fat infiltration and the shortest at > 50% fat infiltration. It was observed that as the amount of fat infiltration of the muscles increased, the test times were shortened. There was no significant relationship between the endurance level and the CSA of the groups.

CONCLUSION

The study results demonstrated that the endurance of the paraspinal muscles is associated with the fat infiltration of the muscles. In patients with chronic low back pain, information about muscle morphology and degeneration can be obtained with simple endurance tests without the need for further measurements. On clinical examination, a weak endurance level of the paraspinal muscles indicates the presence of a low back problem and an increase in the amount of fat infiltration.

Trunk Dynamic Stability Assessment for Individuals With and Without Nonspecific Low Back Pain During Repetitive Movement

OBJECTIVE

This study aimed to employ nonlinear dynamic approaches to assess trunk dynamic stability with speed, symmetry, and load during repetitive flexion-extension (FE) movements for individuals with and without nonspecific low back pain (NSLBP).

BACKGROUND

Repetitive trunk FE movement is a typical work-related LBP risk factor contingent on speed, symmetry, and load. Improper settings/adjustments of these control parameters could undermine the dynamic stability of the trunk, hence leading to low back injuries. The underlying stability mechanisms and associated control impairments during such dynamic movements remain elusive.

METHOD

Thirty-eight male volunteers (19 healthy, 19 NSLBP) enrolled in the current study. All participants performed repetitive trunk FE movements at high/low speeds, in symmetric/asymmetric directions, with/without a wearable loaded vest. Trunk instantaneous rotation angle was computed for each trial to be assessed in terms of local and orbital stability, using maximum finite-time Lyapunov exponents (LyEs) and Floquet multipliers (FMs), respectively.

RESULTS

Both groups demonstrated equivalent competency in terms of trunk control and stability, suggesting functional adaptation strategies may be used by the NSLBP group. Wearing the loaded vest magnified the effects of trunk control impairment for the NSLBP group. The combined presence of high-speed and symmetrical FE movements was associated with least trunk local stability.

CONCLUSION

Nonlinear dynamic techniques, particularly LyE, are potentially effective for assessing trunk dynamic stability dysfunction for individuals with NSLBP during various activities.

APPLICATION

This work can be applied toward the development of quantitative personalized spinal evaluation tools with a wide range of potential occupational and clinical applications.

The influence of hip extensor and lumbar spine extensor strength on lumbar spine loading during a squat lift

Weakness of the hip extensors and lumbar spine extensors has been proposed to contribute to greater demands on the lumbar spine during lifting. The purpose of the current study was to examine the associations among strength of the hip and lumbar spine extensors, lumbar spine extensor moments and lumbar paraspinal muscle activation during a squat lift task. Twenty-seven healthy females participated. Strength of the hip and lumbar spine extensors was measured using a dynamometer. Lumbar spine moments and lumbar paraspinal muscle activity were quantified during the concentric phase of the squat lifting task. There was a significant positive association between lumbar extensor strength and average lumbar extensor moment during lifting (r = 0.498, p = 0.008). Similarly, hip extensor strength was positively associated with the average lumbar extension moment (r = 0.382, p = 0.049). Hip extensor strength was negatively associated with activation of the lumbar paraspinal muscles during lifting (ρ = -0.382, p = 0.049). Stronger individuals are more likely to use their hip extensors and lumbar spine extensors to perform a squat lift task. In contrast, those with lower strength employ subtle biomechanical changes to reduce lumbar spine demand.

Ultrasound Imaging Analysis of the Lumbar Multifidus Muscle Echo Intensity: Intra-Rater and Inter-Rater Reliability of a Novice and an Experienced Rater

Background and Objectives: Ultrasound echo intensity (EI) of the lumbar multifidus muscle (LMM) could offer valuable insights regarding muscle quality in people with low back pain (LBP). However, whether the rater’s experience noticeably influences the reliability and precision of LMM EI measurements has not been established. The aims of this study were to investigate the intra-rater and inter-rater reliability of LMM EI measurements, and to compare the reliability and SEM between a novice and an experienced rater. Materials and Methods: Twenty athletes (10 females, 10 males) with a history of LBP were included in this study. Transverse ultrasound images of LMM were taken at L5 in prone. LMM EI measurements were obtained bilaterally by tracing the maximum ROI representing the LMM cross-sectional area (CSA), avoiding the inclusion of bone or surrounding fascia. All measurements were performed by two novice raters and an experienced researcher. Each measurement was acquired by each rater three times for each side on three different images, and the average was used in the analyses. Raters were blinded to each other’s measurements and the participant’s clinical information. Intra-class correlation coefficients (ICCs) were obtained to assess the intra-rater and inter-rater reliability. Results: The intra-rater ICC values for the LMM measurements for the experienced rater were excellent (ICC all > 0.997). The inter-rater reliability ICC values showed moderate to excellent reliability (0.614 to 0.994) and agreement between the novice raters and the experienced rater, except for Novice 1 for the right LMM, which revealed lower ICCs and a wider 95% CI. Intra-rater and inter-rater reliability results were similar when separately looking at the right and left side of the muscle and participant gender. Conclusions: Our findings support the clinical use of ultrasound imaging for the assessment of LMM EI in individuals with LBP.

Understanding regional activation of thoraco-lumbar muscles in chronic low back pain and its relationship to clinically relevant domains

BACKGROUND

Altered regional activation of the lumbar extensors has been previously observed in individuals with low back pain (LBP) performing high-effort and fatiguing tasks. It is currently unknown whether similar alterations can be observed during low-effort functional tasks. Similarly, previous studies did not investigate whether side differences in regional activation are present in individuals with LBP. Finally, there is limited evidence of whether the extent of the alteration of regional activation is associated with clinical factors. Therefore, the aim of this study was to investigate whether individuals with LBP exhibit asymmetric regional activation of the thoraco-lumbar extensor muscles during functional tasks, and if the extent of neuromuscular control alteration is associated with clinical and psychosocial outcome domains.

METHODS

21 participants with and 21 without LBP performed five functional tasks (gait, sit-to-stand, forward trunk flexion, shoulder flexion and anterior pelvic tilt). The spatial distribution of activation of the thoraco-lumbar extensor muscles was assessed bilaterally using high-density electromyography. For each side, the distribution of electromyographic (EMG) amplitude was characterized in terms of intensity, location and size. Indices of asymmetry were calculated from these features and comparisons between groups and tasks were performed using ANOVA. The features that significantly differed between groups were correlated with self-reported measures of pain intensity and other outcome domains.

RESULTS

Indices of asymmetry did not differ between participants with and without LBP (p > 0.11). The cranio-caudal location of the activation differed between tasks (p < 0.05), but not between groups (p = 0.64). Participants with LBP showed reduced EMG amplitude during anterior pelvic tilt and loading response phase during gait (both p < 0.05). Pearson correlation revealed that greater pain intensity was associated with lower EMG amplitude for both tasks (R<-0.5, p < 0.05).

CONCLUSIONS

Despite clear differences between tasks, individuals with and without LBP exhibited similar distributions of EMG amplitude during low-effort functional activities, both within and between sides. However, individuals with LBP demonstrated lower activation of the thoraco-lumbar muscles during gait and anterior pelvic tilt, especially those reporting higher pain intensity. These results have implications in the development or refinement of assessment and intervention strategies focusing on motor control in patients with chronic LBP.

Comparison of muscle activation imbalance following core stability or general exercises in nonspecific low back pain: a quasi-randomized controlled trial

Background

Low back pain causes changes in muscle activation patterns. Knowing how different exercises may improve altered muscle activation is useful in the treatment of patients. The aim of the study was to investigate whether there was a difference in the pattern of muscle activation in chronic nonspecific low back pain sufferers following core stability exercise (CSE) and general exercise (GE).

Methods

Fifty-six non-specific chronic LBP subjects were randomly assigned to either groups (28 participants in CSE and 28 in GE group). Both groups performed 16 sessions of an exercise program for about 5 weeks. Pain, disability and trunk muscle activation patterns (using surface electromyography) were measured at baseline and post-training.

Results

After the intervention period, antagonist coactivation ratio did not change in either groups. Though all compensated imbalance ratios (residual unequal muscular activity after cancellation of directionality) decreased towards negative (imbalance to left side) only this change for total muscles ratio in GE was significant (mean difference in GE group, 0.15; 95% CI: 0.02 to 0.28; p-value of paired t-test: 0.022); (mean difference in CSE, 0.02; 95% CI: − 0.07 to 0.11; p-value of paired t-test: 0.614).. No overall significantly decrease in uncompensated imbalance ratio (absolute imbalance values without cancellation directionality) was observed. Pain and disability decreased significantly in both groups. However, there was no difference between two groups in either of the variables after the intervention.

Conclusions

Both exercise programs reduced pain and disability and made or kept trunk muscle activation imbalance to the left side. The effects of two exercises on pain, disability and antagonist coactivation or imbalance ratios were not different.

Trial registration

This study was registered in the Iranian Clinical Trial Center with the code IRCT201111098035N1, Registered Jan 21, 2013.

The effect of low back pain and lower limb injury on lumbar multifidus muscle morphology and function in university soccer players

Background

The lumbar multifidus muscle (LMM) plays a critical role to stabilize the spine. While low back pain (LBP) is a common complaint in soccer players, few studies have examined LMM characteristics in this athletic population and their possible associations with LBP and lower limb injury. Therefore, the purpose of this study was to 1) investigate LMM characteristics in university soccer players and their potential association with LBP and lower limb injury; 2) examine the relationship between LMM characteristics and body composition measurements; and 3) examine seasonal changes in LMM characteristics.

Methods

LMM ultrasound assessments were acquired in 27 soccer players (12 females, 15 males) from Concordia University during the preseason and assessments were repeated in 18 players at the end of the season. LMM cross-sectional area (CSA), echo-intensity and thickness at rest and during contraction (e.g. function) were assessed bilaterally in prone and standing positions, at the L5-S1 spinal level. A self-reported questionnaire was used to assess the history of LBP and lower limb injury. Dual-energy x-ray absorptiometry (DEXA) was used to acquire body composition measurements.

Results

Side-to-side asymmetry of the LMM was significantly greater in males (p = 0.02). LMM thickness when contracted in the prone position (p = 0.04) and LMM CSA in standing (p = 0.02) were also significantly greater on the left side in male players. The LMM % thickness change during contraction in the prone position was significantly greater in players who reported having LBP in the previous 3-months (p < 0.001). LMM CSA (r = − 0.41, p = 0.01) and echo-intensity (r = 0.69, p < 0.001) were positively correlated to total % body fat. There was a small decrease in LMM thickness at rest in the prone position over the course of the season (p = 0.03).

Conclusions

The greater LMM contraction in players with LBP may be a maladaptive strategy to splint and project the spine. LMM morphology measurements were correlated to body composition. The results provide new insights with regards to LMM morphology and activation in soccer players and their associations with injury and body composition measurements.

Assessment of Lumbar Muscles Coordinated Activity Based on High-Density Surface Electromyography: A Pilot Study

Trunk-movement involves coordinated activity of different lumbar muscles. By assessing the lumbar muscles activity, the pathogeny of some neuromuscular disease might be revealed. Surface electromyography (sEMG) could be used to measure the muscle activity, but for assessing lumbar muscles coordinated activity, there lacks of an accurate and comprehensive application of sEMG. High-density (HD) sEMG provides a potential to assess lumbar muscles coordinated activity more accurately. Thus, in this pilot study, the objective was to assess the lumbar muscles coordinated activity based on HD sEMG. By placing a 5×15 array (75 channels) of HD sEMG electrodes to the surface of the low back area, the sEMG signal from four healthy subjects could be collected. In order to analyze the lumbar muscles coordinated activity, the sEMG signal during different trunk-movements was recorded. Through calculating the root-mean-square (RMS) of each channel and interpolating the RMS value between channels, the sEMG topography could be obtained. The high activity area in the topography showed a regular distribution during different trunk-movements. It might be useful for further assessment of lumbar disease such as low back pain.

sEMG-Based Trunk Compensation Detection in Rehabilitation Training

Stroke patients often use trunk to compensate for impaired upper limb motor function during upper limb rehabilitation training, which results in a reduced rehabilitation training effect. Detecting trunk compensations can improve the effect of rehabilitation training. This study investigates the feasibility of a surface electromyography-based trunk compensation detection (sEMG-bTCD) method. Five healthy subjects and nine stroke subjects with cognitive and comprehension skills were recruited to participate in the experiments. The sEMG signals from nine superficial trunk muscles were collected during three rehabilitation training tasks (reach-forward-back, reach-side-to-side, and reach-up-to-down motions) without compensation and with three common trunk compensations [lean-forward (LF), trunk rotation (TR), and shoulder elevation (SE)]. Preprocessing like filtering, active segment detection was performed and five time domain features (root mean square, variance, mean absolute value (MAV), waveform length, and the fourth order autoregressive model coefficient) were extracted from the collected sEMG signals. Excellent TCD performance was achieved in healthy participants by using support vector machine (SVM) classifier (LF: accuracy = 94.0%, AUC = 0.97, F1 = 0.94; TR: accuracy = 95.8%, AUC = 0.99, F1 = 0.96; SE: accuracy = 100.0%, AUC = 1.00, F1 = 1.00). By using SVM classifier, TCD performance in stroke participants was also obtained (LF: accuracy = 74.8%, AUC = 0.90, F1 = 0.73; TR: accuracy = 67.1%, AUC = 0.85, F1 = 0.71; SE: accuracy = 91.3%, AUC = 0.98, F1 = 0.90). Compared with the methods based on cameras or inertial sensors, better detection performance was obtained in both healthy and stroke participants. The results demonstrated the feasibility of the sEMG-bTCD method, and it helps to prompt the stroke patients to correct their incorrect posture, thereby improving the effectiveness of rehabilitation training.

Are there differences in lifting technique between those with and without low back pain? A systematic review

Background and aims

To systemically review the literature to compare freestyle lifting technique, by muscle activity and kinematics, between people with and without low back pain (LBP).

Methods

Five databases were searched along with manual searches of retrieved articles by a single reviewer. Studies were included if they compared a freestyle lifting activity between participants with and without LBP. Data were extracted by two reviewers, and studies were appraised using the CASP tool for case-control studies.

Results

Nine studies were eligible. Heterogeneity did not allow for meta-analysis. Most studies (n = 8 studies) reported that people with LBP lift differently to pain-free controls. Specifically, people with LBP lift more slowly (n = 6 studies), use their legs more than their back especially when initiating lifting (n = 3 studies), and jerk less during lifting (n = 1 studies). Furthermore, the four larger studies involving people with more severe LBP also showed that people with LBP lift with less spinal range of motion and greater trunk muscle activity for a longer period.

Conclusions

People with LBP move slower, stiffer, and with a deeper knee bend than pain-free people during freestyle lifting tasks. Interestingly, such a lifting style mirrors how people, with and without LBP, are often told how to lift during manual handling training. The cross-sectional nature of the comparisons does not allow for causation to be determined.

Implications

The changes described may show embodiment of cautious movement, and the drive to protect the back. There may be value in exploring whether adopting a lifting style closer to that of pain-free people could help reduce LBP.

Squat Lifting Imposes Higher Peak Joint and Muscle Loading Compared to Stoop Lifting

(1) Background: Yearly, more than 40% of the European employees suffer from work-related musculoskeletal disorders. Still, ergonomic guidelines defining optimal lifting techniques to decrease work-related musculoskeletal disorders (WMSDs) has not been unambiguously defined. Therefore, this study investigates if recommended squat lifting imposes lower musculoskeletal loading than stoop lifting while using a complex full body musculoskeletal OpenSim model. (2) Methods: Ten healthy participants lifted two different weights using both lifting techniques. 3D marker trajectories and ground reaction forces were used as input to calculate joint angles, moments and power using a full body musculoskeletal model with articulated lumbar spine. In addition, the muscle activity of nine different muscles was measured to investigate muscle effort when lifting. (3) Results: Peak moments and peak joint power in L5S1 were not different between the squat and the stoop, but higher peak moments and peak power in the hip, knee, elbow and shoulder were found during squat lifting. Moment impulses in L5S1 were higher during stoop lifting. This is reflected in higher peak electromyography (EMG) but lower muscle effort in prior described muscles during the squat. (4) Conclusions: Squat lifting imposes higher peak full body musculoskeletal loading but similar low back loading compared to stoop lifting, as reflected in peak moments, peak power, and peak EMG.

Effects of lumbar extensor muscle strengthening and neuromuscular control retraining on disability in patients with chronic low back pain: a protocol for a randomised controlled trial

INTRODUCTION

Chronic low back pain (CLBP) is the leading cause of disability worldwide. However, there is no consensus in the literature regarding optimal management. Exercise intervention is the most widely used treatment as it likely influences contributing factors such as physical and psychological. Literature evaluating the effects of exercise on CLBP is often generalised, non-specific and employs inconsistent outcome measures. Moreover, the mechanisms behind exercise-related improvements are poorly understood. Recently, research has emerged identifying associations between neuromuscular-biomechanical impairments and CLBP-related disability. This information can be used as the basis for more specific and, potentially more efficacious exercise interventions for CLBP patients.

METHODS AND ANALYSIS

Ninety-four participants (including both males and females) with CLBP aged 18-65 who present for treatment to a Melbourne-based private physiotherapy practice will be recruited and randomised into one of two treatment groups. Following baseline assessment, participants will be randomly allocated to receive either: (i) strengthening exercises in combination with lumbar force accuracy training exercises or (ii) strengthening exercises alone. Participants will attend exercise sessions twice a week for 12 weeks, with assessments conducted at baseline, midway (ie, 6 weeks into the trial) and at trial completion. All exercise interventions will be supervised by a qualified physiotherapist trained in the intervention protocol. The primary outcome will be functional disability measured using the Oswestry Disability Index. Other psychosocial and mechanistic parameters will also be measured.

ETHICS AND DISSEMINATION

This study was given approval by the University of Melbourne Behavioural and Social Sciences Human Ethics Sub-Committee on 8 August 2017, reference number 1 749 845. Results of the randomised controlled trial will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12618000894291.

Impact of Lifting of Two Types of Barrels on Postural Control, Trunk Muscle Recruitment, and Kinematic Measures in Manual Workers

The aim of this study was to evaluate the impact of 2 types of beer barrels on postural control, trunk activation, and kinematic measures in adult workers. Twelve (12) males randomly performed 4 tasks on a force platform for 20 s: (1) hold an empty recyclable barrel, (2) hold a full recyclable barrel (30 L), (3) hold an empty steel barrel, and (4) hold a full steel barrel (30 L). Trunk muscular activation, force platform and kinematic measures at the trunk, hip, and knee joints were computed. The full steel barrel produced greater postural oscillation than other conditions. Higher trunk activity was also reported during the full steel barrel task. Significant kinematic changes only in the trunk were observed between the empty steel barrel and the full recyclable barrel tasks. In conclusion, the full steel barrel produced a negative impact on postural control, increasing trunk activity and changing trunk flexion angle in adult workers.

Changes in Structure and Function of the Back Muscles in Low Back Pain: Different Time Points, Observations, and Mechanisms

Spinal health depends on optimal back muscle performance, and this is determined by muscle structure and function. There has been substantial research evaluating the differences in structure and function of many back muscles, including the multifidus and erector spinae, but with considerable variation in results. Many studies have shown atrophy, fat infiltration, and connective tissue accumulation in back muscles, particularly deep fibers of the multifidus, but the results are not uniform. In terms of function, results are also somewhat inconsistent, often reporting lower multifidus activation and augmented recruitment of more superficial components of the multifidus and erector spinae, but, again, with variation between studies. A major recent observation has been the identification of time-dependent differences in features of back muscle adaptation, from acute to subacute/recurrent to chronic states of the condition. Further, these adaptations have been shown to be explained by different time-dependent mechanisms. This has substantial impact on the rationale for rehabilitation approaches. The aim of this commentary was to review and consolidate the breadth of research investigating adaptation in back muscle structure and function, to consider explanations for some of the variation between studies, and to propose how this model can be used to guide rehabilitation in a manner that is tailored to individual patients and to underlying mechanisms. J Orthop Sports Phys Ther 2019;49(6):464-476. doi:10.2519/jospt.2019.8827.

Ultrasonography of multifidus muscle morphology and function in ice hockey players with and without low back pain

OBJECTIVES

To examine the relationship between lumbar multifidus (LM) morphology, function, echo-intensity (EI) and body composition among a group of university level ice hockey players with and without low back pain (LBP).

DESIGN

Cross-sectional study.

SETTING

University Research Centre.

PARTICIPANTS

Thirty-two hockey players (18 females, 14 males) participated in this study.

MAIN OUTCOME MEASURES

Resting LM cross-sectional area (CSA) was assessed bilaterally at the L5 level in prone and standing using ultrasound imaging. The LM thickness at rest and during contraction was evaluated in addition to LM EI. Body composition measures were acquired using dual-energy X-ray absorptiometry (DEXA) and LBP history was acquired using a self-reported questionnaire.

RESULTS

LM muscle CSA was significantly associated with body composition measurements. LM EI was strongly associated with total % body fat and significantly greater in females. Resting LM muscle CSA and thickness (prone) was significantly smaller in players with LBP 4-weeks prior. LM side-to-side asymmetry (standing) was also significantly greater in players with LBP 3-months prior.

CONCLUSION

The results provide new insights with regards to LM morphology and activation in ice hockey players and revealed specific deficits in LM morphology in athletes with LBP. LM morphology was strongly associated with body composition measurements.

Have Studies that Measure Lumbar Kinematics and Muscle Activity Concurrently during Sagittal Bending Improved Understanding of Spinal Stability and Sub-System Interactions? A Systematic Review

In order to improve understanding of the complex interactions between spinal sub-systems (i.e., the passive (ligaments, discs, fascia and bones), the active (muscles and tendons) and the neural control systems), it is necessary to take a dynamic approach that incorporates the measurement of multiple systems concurrently. There are currently no reviews of studies that have investigated dynamic sagittal bending movements using a combination of electromyography (EMG) and lumbar kinematic measurements. As such it is not clear how understanding of spinal stability concepts has advanced with regards to this functional movement of the spine. The primary aim of this review was therefore to evaluate how such studies have contributed to improved understanding of lumbar spinal stability mechanisms. PubMed and Cochrane databases were searched using combinations of the keywords related to spinal stability and sagittal bending tasks, using strict inclusion and exclusion criteria and adhering to PRISMA guidelines. Whilst examples of the interactions between the passive and active sub-systems were shown, typically small sample sizes meant that results were not generalizable. The majority of studies used regional kinematic measurements, and whilst this was appropriate in terms of individual study aims, the studies could not provide insight into sub-system interaction at the level of the spinal motion segment. In addition, the heterogeneity in methodologies made comparison between studies difficult. The review suggests that since Panjabi’s seminal spinal control papers, only limited advancement in the understanding of these theories has been provided by the studies under review, particularly at an inter-segmental level. This lack of progression indicates a requirement for new research approaches that incorporate multiple system measurements at a motion segment level.

Using video rasterstereography and treadmill gait analysis as a tool for evaluating postoperative outcome after lumbar spinal fusion

BACKGROUND

The rise in the number of patients with lumbar back pain has led to an increase in the number of spinal surgeries. To avoid unfavorable outcomes, high accuracy and reliability of indication for surgery are essential. This requires critical evaluation of postoperative outcomes with its two key dimensions pain and function. While imaging findings give details about the technical dimension of the intervention, they are prone to high inter-/intra-observer variability, with limited relation to functional outcomes. Pain improvement can be directly asked from patients or documented by questionnaires. There is abundant literature on postoperative function based on questionnaires, but quantifiable data such as gait or posture analysis are scarce. Highprecision measurement tools are available and easy to implement in a clinician's work routine.

OBJECTIVE

This study evaluates whether lumbar fusion surgery changes gait and postural variables and how these changes are related to patients' descriptions of alterations in their levels of pain.

METHODS

Back profiles and gait analyses were measured by video rasterstereography and treadmill gait analysis. Measurements were recorded before surgery, at discharge, after 3 months in a longitudinal (n = 30), and after 12 months in a cross-sectional group (n = 29). A reference group was formed (n = 28). The improvement on the Numeric Pain Rating Scale was documented and compared with changes in gait and posture.

RESULTS

A significant reduction in kyphotic (52-43°, p = 0.014) and lordotic (28-11°, p < 0.001) angles was observed. The values again increased after 3 months, with a significant reduction in cadence (98-91 steps/min, p = 0.006). While improvements in pain were also obtained by surgery (p < 0.001), no clear correlation could be detected between 3-month alleviation in pain and changes in kyphotic/lordotic angle or cadence.

CONCLUSIONS

Although both methods offer high-precision measurement, changes in gait and posture were not related with the patients' reported pain relief after lumbar fusion surgery.

Intra-session and Inter-day Reliability of the Myon 320 Electromyography System During Sub-maximal Contractions

Electromyography systems are widely used within the field of scientific and clinical practices. The reliability of these systems are paramount when conducting research. The reliability of Myon 320 Surface Electromyography System is yet to be determined. This study aims to determine the intra-session and inter-day reliability of the Myon 320 Surface Electromyography System. Muscle activity from fifteen participants was measured at the anterior deltoid muscle during a bilateral front raise exercise, the vastus lateralis muscle during a squat exercise and the extensor carpi radialis brevis (ECRB) muscle during an isometric handgrip task. Intra-session and inter-day reliability was calculated by intraclass correlation coefficient, standard error of measurement and coefficient of variation (CV). The normalized root mean squared (RMS) surface electromyographic signals produced good intra-session and inter-day testing intraclass correlation coefficient values (range: 0.63–0.97) together with low standard error of measurement (range: 1.49–2.32) and CV (range: 95% Confidence Interval = 0.36–12.71) measures for the dynamic-and-isometric contractions. The findings indicate that the Myon 320 Surface Electromyography System produces good to fair reliability when examining intra-session and inter-day reliability. Findings of the study provide evidence of the reliability of electromyography between trials which is essential during clinical testing.

Electromyographic analyses of the erector spinae muscles during golf swings using four different clubs

The purpose of this study was to compare the electromyography (EMG) patterns of the thoracic and lumbar regions of the erector spinae (ES) muscle during the golf swing whilst using four different golf clubs. Fifteen right-handed male golfers performed a total of twenty swings in random order using the driver, 4-iron, 7-iron and pitching-wedge. Surface EMG was recorded from the lead and trail sides of the thoracic and lumbar regions of the ES muscle (T8, L1 and L5 lateral to the spinous-process). Three-dimensional high-speed video analysis was used to identify the backswing, forward swing, acceleration, early and late follow-through phases of the golf swing. No significant differences in muscle-activation levels from the lead and trail sides of the thoracic and lumbar regions of the ES muscle were displayed between the driver, 4-iron, 7-iron and pitching-wedge (P > 0.05). The highest mean thoracic and lumbar ES muscle-activation levels were displayed in the forward swing (67-99% MVC) and acceleration (83-106% MVC) phases of the swing for all clubs tested. The findings from this study show that there were no significant statistical differences between the driver, 4-iron, 7-iron and pitching-wedge when examining muscle activity from the thoracic and lumbar regions of the ES muscle.

Activity of Erector Spinae During Trunk Forward Bending and Backward Return: The Effects of Age

Electromyography (EMG)-based measures of the trunk muscles behavior have been used for objective assessment of biomechanical impairments in patients with low back pain (LBP); yet the literature on normal age-related differences in such measures is scant. A cross-sectional study was designed to assess age-related differences in activity of trunk extensors during forward bending and backward return. Sixty asymptomatic individuals were recruited to form five gender-balanced age groups between 20 and 70 years old. Participants completed two sets of trunk forward bending and backward return task using self-selected and fast motion paces. For bending and return phases of each task, the normalized lumbar flexion angles corresponding to different event times of erector spinae activity along with the peak normalized and non-normalized EMG activities of erector spinae were calculated. The mean normalized and non-normalized EMG activities of erector spinae during the entire task also were calculated. There was no age-related difference in normalized lumbar flexion angles corresponding to different event times of erector spinae activity. However, the peak normalized EMG activity during forward bending and backward return as well as the mean normalized EMG activity during the entire task were found to be larger in older vs. younger individuals. Given the suggested unreliability of normalized EMG in elders and considering that we did not find any age-related differences in non-normalized EMG activity of erector spinae, our results do not strongly support the existence of normal age-related differences in EMG profile of erector spinae during forward bending and backward return. Therefore, when interpreting EMG-based measures of trunk muscles behavior for identification of biomechanical impairment in patients with LBP, potential abnormalities in EMG activity of trunk muscles may not be attributed to patient's age.

The effects of neurodynamic straight leg raise treatment duration on range of hip flexion and protective muscle activity at P1

STUDY DESIGN

Randomized, single blind, same subject crossover trial.

OBJECTIVES

To compare the effects of two neurodynamic treatment doses on range of hip flexion (ROM HF) and electromyographic (EMG) activity of semitendinosus, at first onset of pain (P1).

METHODS

A total of 26 healthy participants without low back or leg pain received each treatment in a random order with at least 48 hours between sessions. Baseline ROM HF and EMG magnitude of semitendinosus at P1 were collected. Subjects then received either 361 or 362 minutes of oscillating end of range (grade IVz) straight leg raise (SLR) neurodynamic treatment and were re-assessed for baseline measures.

RESULTS

There was no significant difference between groups in EMG magnitude (P50.190) and ROM HF (P50.739) at P1. There was also no significant difference within groups in EMG magnitude at P1 (P50.182); however, there was a significant improvement in ROM HF at P1 in both groups compared to baseline readings (P50.000), with increases of 6.7u and 5.1u for the 361- and 362-minute groups, respectively.

CONCLUSION

Findings indicate that 362 minutes of oscillating grade IVz SLR neurodynamic treatment has no additional benefit over 361 minute, on ROM HF or EMG magnitude of semitendinosus at P1. Using an oscillating SLR treatment may, however, help to increase pain-free ROM HF, although further studies are necessary to confirm this.

Comparison of trunk muscle activities in lifting and lowering tasks at various heights

[Purpose] Biomechanical data for manual material handling are important for appropriate engineering design. The goal of this study was to investigate differences in trunk muscle activity in lifting and lowering tasks at various heights. [Subjects and Methods] Thirty healthy, young adult subjects performed 6 asymmetrical lifting and lowering tasks at various heights. Trunk muscle activity of the abdominal external oblique muscle (EO), rectus abdominis muscle (RA), and lumbar erector spinae muscles (ES) were recorded using surface electromyography (EMG). [Results] The EMG activities of the bilateral ES differed significantly among heights. The left EO activity in the ankle to knee lifting task was significantly increased compared with that of the knee to ankle lowering task. However, there were no significant differences in the right EO, bilateral ES, or RA between lifting and lowering tasks. [Conclusion] The results show that the optimal range for manual material handling was at trunk height, not only for lifting but also for lowering tasks.

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

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

Different coordination and flexibility of the spine and pelvis during lateral bending between young and older adults

This study examined coordination of the spine and pelvis during lateral bending of the trunk in older adults. Thirty-four healthy subjects (17 young and 17 older adults) demonstrated lateral bending at a controlled speed while holding a bar at approximately 180 degrees of shoulder flexion. Kinematic data collection was completed on the thoracic spine, lumbar spine, and pelvis. The coupling angle was calculated to examine the thorax-lumbar, lumbar-pelvis, and thorax-pelvis coordination patterns. The older adults demonstrated a reduced range of motion (ROM) of the lumbar spine, while both groups revealed similar ROM in the thorax and in the pelvis. The coupling angle between the straightening and bending phases was different only for the older adults in the thorax-lumbar (23.4±8.0 vs. -1.6±4.4, p=0.004) and the lumbar-pelvis (65.4±7.2 vs. 86.1±7.8, p=0.001) coordination. However, there was no group difference in the thorax-pelvis coordination. These findings indicate that age-related changes in the lumbar region affect coordination patterns only during the bending phase. The older adults preserved a similar pattern of movement to the young adults during the straightening phase, but the coordination variability of the coupling angles was greater for the older adults than for the young adults. This movement pattern suggests that the older adults lacked consistent trunk control in an attempt to optimize lateral bending coordination.

Trunk Postural Muscle Timing Is Not Compromised In Low Back Pain Patients Clinically Diagnosed With Movement Coordination Impairments

Trunk muscle timing impairment has been associated with nonspecific low back pain (NSLBP), but this finding has not been consistent. This study investigated trunk muscle timing in a subgroup of patients with NSLBP attributed to movement coordination impairment (MCI) and matched asymptomatic controls in response to a rapid arm-raising task. Twenty-one NSLBP subjects and 21 matched controls had arm motion and surface EMG data collected from seven bilateral trunk muscles. Muscle onset and offset relative to deltoid muscle activation and arm motion, duration of muscle burst and abdominal-extensor co-contraction time were derived. Trunk muscle onset and offset latencies, and burst and co-contraction durations were not different (p > .05) between groups. Patterns of trunk muscle activation and deactivation relative to arm motion were not different. Task performance was similar between groups. Trunk muscle timing does not appear to be an underlying impairment in the subgroup of NSLBP with MCI.

An optimization-based method for prediction of lumbar spine segmental kinematics from the measurements of thorax and pelvic kinematics

Given measurement difficulties, earlier modeling studies have often used some constant ratios to predict lumbar segmental kinematics from measurements of total lumbar kinematics. Recent imaging studies suggested distribution of lumbar kinematics across its vertebrae changes with trunk rotation, lumbar posture, and presence of load. An optimization-based method is presented and validated in this study to predict segmental kinematics from measured total lumbar kinematics. Specifically, a kinematics-driven biomechanical model of the spine is used in a heuristic optimization procedure to obtain a set of segmental kinematics that, when prescribed to the model, were associated with the minimum value for the sum of squared predicted muscle stresses across all the lower back muscles. Furthermore, spinal loads estimated using the predicted kinematics by the present method were compared with those estimated using constant ratios. Predicted segmental kinematics were in good agreement with those obtained by imaging with an average error of ~10%. Compared with those obtained using constant ratios, predicted spinal loads using segmental kinematics obtained here were in general smaller. In conclusion, the proposed method offers an alternative tool for improving model-based estimates of spinal loads where image-based measurement of lumbar kinematics is not feasible.

Changes in multifidus and abdominal muscle size in response to microgravity: possible implications for low back pain research

PURPOSE

In microgravity, muscle atrophy occurs in the intrinsic muscles of the spine, with changes also observed in the abdominal muscles. Exercises are undertaken on the International Space Station and on Earth following space flight to remediate these effects. Similar effects have been seen on Earth in prolonged bed rest studies and in people with low back pain (LBP). The aim of this case report was to examine the effects of microgravity, exercise in microgravity and post-flight rehabilitation on the size of the multifidus and antero-lateral abdominal muscles.

METHODS

Ultrasound imaging was used to assess size of the multifidus, transversus abdominis and internal oblique muscles at four time points: pre-flight and after daily rehabilitation on day one (R + 1), day 8 (R + 8) and day 14 (R + 14) after return to Earth (following 6 months in microgravity).

RESULTS

Exercises in microgravity maintained multifidus size at L2-L4, however, after spaceflight, size of the multifidus muscle at L5 was reduced, size of the internal oblique muscle was increased and size of transversus abdominis was reduced. Rehabilitation post-space flight resulted in hypertrophy of the multifidus muscle to pre-mission size at the L5 vertebral level and restoration of antero-lateral abdominal muscle size.

CONCLUSIONS

Exercise in space can prevent loss of spinal intrinsic muscle size. For the multifidus muscles, effectiveness varied at different levels of the spine. Post-mission rehabilitation targeting specific motor control restored muscle balance between the antero-lateral abdominal and multifidus muscles, similar to results from intervention trials for people with LBP. A limitation of the current investigation is that only one astronaut was studied, however, the microgravity model could be valuable as predictable effects on trunk muscles can be induced and interventions evaluated. Level of Evidence Case series.

Electromyographic activity of erector spinae and external oblique muscles during trunk lateral bending and axial rotation in patients with adolescent idiopathic scoliosis and healthy subjects

BACKGROUND

The aim of this study was to analyze electrical activity of trunk muscles in adolescent idiopathic scoliosis patients and healthy subjects during trunk lateral bending and rotation movements.

METHODS

Ten patients with right thoracic scoliosis [Cobb angle: 29.1° (10.4°)] and 10 control adolescents were studied. Electrical activities of erector spinae muscle at 6th and 10th thoracic and 3rd lumbar vertebral level, and external oblique muscles were measured bilaterally during the right and left bending from standing and prone positions, and trunk rotation in sitting position.

FINDINGS

In trunk rotation to the right, the right-side external oblique (antagonist) muscle in scoliosis group was greater than that in control group (p<0.05). In left bending from standing position, in scoliosis group, the antagonistic activity of EST6 muscle was greater than its agonistic activity (p<0.05). Also, in the right bending motion, the agonistic activity of external oblique of scoliosis group was higher than that of control group (p=0.02). During the left bending from prone position, right-side EST6 and right-side ESL3 muscles of scoliosis group were greater than that of control group (p<0.05).

INTERPRETATION

In left bending from standing position, in scoliosis group, the greater antagonistic activity of erector spinae muscle at 6th thoracic vertebral level than its agonistic activity, indicates that scoliosis is associated with asymmetrical muscle activity. Lateral bending from standing position is appropriate test to distinguish between scoliosis and control subjects. In scoliosis, the asymmetrical muscle activity is not an inherent characteristic since it was not displayed in all back motions.

Simulation of movement in three-dimensional musculoskeletal human lumbar spine using directional encoding-based neurocontrollers

Despite development of accurate musculoskeletal models for human lumbar spine, the methods for prediction of muscle activity patterns in movements lack proper association with corresponding sensorimotor integrations. This paper uses the directional information of the Jacobian of the musculoskeletal system to orchestrate adaptive critic-based fuzzy neural controller modules for controlling a complex nonlinear redundant musculoskeletal system. The proposed controller is used to control a 3D 3-degree of freedom (DOF) musculoskeletal model of trunk, actuated by 18 muscles. The controller is capable of learning to control from sensory information, without relying on pre-assumed model parameters. Simulation results show satisfactory tracking of movements and the simulated muscle activation patterns conform to previous EMG experiments and optimization studies. The proposed controller can be used as a computationally inexpensive muscle activity generator to distinguish between neural and mechanical contributions to movement and for study of sensory versus motor origins of motor function and dysfunction in human spine.

Repeatability of kinematic and electromyographical measures during standing and trunk motion: how many trials are sufficient?

Previous studies have recommended a minimum of five trials to produce repeatable kinematic and electromyography (EMG) measures during target postures or contraction levels. This study aimed to evaluate the repeatability and reliability of kinematic and EMG measures that are of primary interest in the investigation of trunk movement, and to determine the number of trials required to achieve repeatability and reliability for these measures. Thirty participants performed ten trials of upright standing and maximum trunk ranges-of-motion. Mean (upright standing) and maximum (movement tasks) kinematic and EMG measures were assessed using intraclass correlation coefficients and standard error of measurement, which were used to identify the minimum number of trials for each measure. The repeatability and reliability of the measures were generally high, with 64%, 77%, 85%, and 92% of measures producing repeatable and reliable values with two, three, four, and five trials, respectively. Ten trials were not sufficient for several upright standing angle measures and maximum twist lumbar angles. Further, several abdominal muscles during maximum flexion, as well as the left lower-thoracic erector spinae during maximum twist, required as many as five trials. These measures were typically those with very small amounts of motion, or muscles that did not act in the role of prime mover. These results suggest that as few as two trials may be sufficient for many of the kinematic and EMG measures of primary interest in the investigation of trunk movement, while the collection of four trials should produce repeatable and reliable values for over 80% of measures. These recommendations are intended to provide an acceptable trade-off between repeatable and reliable values and feasibility of the collection protocol.

Trunk muscle activation during different quadruped stabilization exercises in individuals with chronic low back pain

BACKGROUND AND PURPOSE

The aim of this study was to compare the trunk muscle activities and the local/global activity ratios of the abdominal, back and trunk muscles during stabilization exercises such as one arm raise (AR), one leg raise (LR), and opposing arm/leg raise (ALR) in patients with chronic low back pain (LBP).

METHOD

Ten individuals with chronic LBP (five men and five women) participated in this study. The external oblique abdominis, internal oblique abdominis, multifidus, thoracic part of the lumbar iliocostalis and the local/global activity ratio were assessed, while quadruped stabilization exercises were performed (AR, LR, and ALR); each exercise was carried out three times.

RESULT

One-way repeated ANOVA was used to measure the differences in the trunk muscle activity and the local/global activity ratio. Post hoc analyses were performed (α = 0.05/3 = 0.017). In the right internal oblique, muscle activity during LR was significantly greater than that during AR. In the bilateral multifidus and lumbar iliocostalis, each ALR muscle activity was significantly greater than those of AR and LR. In addition, the local/global activity ratios of the back and trunk muscle in LR and ALR were significantly greater compared with AR.

CONCLUSIONS

LR should be recommended over AR for individuals with chronic LBP. Moreover, the application of ALR should be approached carefully on the basis of progress and ability to stabilize the spine in this patient population.