Electromyographic Changes in Trunk Muscles During Graded Lumbar Stabilization Exercises

The Effect of Leg Length Discrepancy on Paraspinal Muscles Activation Using Surface Electromyography

OBJECTIVE

The aim of the study is to assess the effects of leg length discrepancy on paraspinal muscle activity and kinematic variables during gait.

DESIGN

Thirty-nine healthy participants aged 5-12 yrs performed the 10-m walk test using the surface electromyography and G-walk sensor for the following conditions: (1) non-leg length discrepancy condition (leg length discrepancy 0 cm) and (2) leg length discrepancy condition with an insole on the right leg at three different heights (leg length discrepancy 0.5 cm, 1.0 cm, and 1.5 cm). The root mean square was normalized using maximal voluntary contraction and reference voluntary contraction methods (RMS_MVC and RMS_ref) and compared between the sides.

RESULTS

The mean RMS_MVC of the 12th thoracic erector spinae on the right side was significantly higher at a leg length discrepancy 0.5 cm and 1 cm. Regarding the 3rd lumbar multifidus, the mean RMS_MVC on the right side was significantly higher at a leg length discrepancy 1.5 cm. The mean RMS_ref exhibited similar patterns. Pelvic obliquity and rotation showed asymmetry at a leg length discrepancy 1.5 cm compared with a leg length discrepancy 0 cm.

CONCLUSIONS

A small leg length discrepancy significantly affected the asymmetric hyperactivation of the 3rd lumbar multifidus and 12th thoracic erector spinae muscles during gait. Considering the action of these muscles, asymmetric hyperactivation might result in rotation and bending of the lumbar spine and the bending of the thoracolumbar spine.

Rectus abdominis muscle thickness change and activation increase during planks performed on different surfaces

AIMS

The plank is a common exercise used to evaluate core function. Surface electromyography (sEMG) and ultrasound can be used simultaneously to measure muscle activity. We aimed to compare the %-thickness and %-activation during the plank performed on three surfaces and to determine agreement and relationship between rectus abdominis (RA) %-thickness of a rested tabletop position and %-activation normalized to quiet tabletop position during the plank on three surfaces.

METHODS

In this cross-sectional study, ultrasound and sEMG measured RA muscle function during the first 5-s and last 5-s of a plank performed on a table, yoga mat, and fitness ball. A repeated measures ANOVA compared differences in %-thickness change and Friedman's tests compared differences in %-activation, alpha set a priori p ≤ 0.05. Bland-Altman plots measured agreement between instruments. Spearman's rho determined relationships between instruments.

RESULTS

There was no difference between %-thickness change across surfaces during the first 5-s or last 5-s, or between %-activation during the last 5-s. The %-activation of the RA during the first 5-s performed on the fitness ball was higher than the table and yoga mat (p < 0.001). Ultrasound and sEMG had weak relationships across all surfaces (ρ = - 0.078 to 0.116).

CONCLUSION

The first 5-s of the plank performed on the fitness ball requires a greater RA activation. Ultrasound could not detect changes in %-thickness of the RA during the plank which may be influenced by the type of contraction. Comparison between these measurement tools during isometric exercise should be used with caution.

Effect of adding abdominal bracing to spinal stabilization exercise on lumbar lordosis angle, extensor strength, pain, and function in patients with non-specific chronic low back pain: A prospective randomized pilot study

TRIAL DESIGN

This study investigated the effect of adding abdominal bracing to spinal stability exercise in patients with chronic low back pain (CLBP). This prospective, randomized pilot study included 67 patients and was conducted at the sports medicine center of a single hospital.

METHODS

The abdominal bracing group (ABBG) underwent spinal stability exercise with abdominal bracing (N = 33), comprising 50 minutes training twice a week for 24 weeks. The control group performed only spinal stability exercise (N = 34) for 50 minutes twice a week for 24 weeks. The ABBG received abdominal bracing training at each session and applied abdominal bracing during the spinal stability exercise. The lumbar lordosis angle (LLA) and spine extensor muscle strength were measured. Spinal flexion angles were measured every 12° from 0° to 72°. The visual analog scale score and Oswestry disability index were measured before treatment and at 12 and 24 weeks after treatment.

RESULTS

The LLA increased over time in both the groups but was not significantly different between the groups. Spine extensor strength was improved over time in both the groups, and an interactive effect was observed at a spinal flexion angle of 60° and 72°. Pain and function were also improved over time in both the groups, but the effect was stronger in the ABBG than in the control group. In patients with CLBP, spinal stability exercise changed the LLA.

CONCLUSIONS

Although adding abdominal bracing to spinal stability exercise did not affect the changes in the LLA, abdominal bracing improved the spinal extensor strength, pain, and function in patients with CLBP. Therefore, it is recommended to add abdominal bracing to spinal stability exercise to maintain the lordosis angle and to improve CLBP symptoms.

The effectiveness of different aerobic exercises to improve pain intensity and disability in chronic low back pain patients: a systematic review

Background: Physical activity, including aerobic exercise, is highly recommended for chronic low back pain (CLBP) patients to improve pain intensity and functional disability. Objectives: To assess the effectiveness of different aerobic exercises to reduce pain intensity and functional disability in patients with CLBP. Methods: A computer-aided search was performed to find Randomised Controlled Trials (RCTs) that evaluated the effectiveness of different aerobic exercises in CLBP. Articles published between January 2007 to December 2020 were included in the review. Quality assessment using the PEDro scale, extraction of relevant information, and evaluation of outcomes were done by two reviewers independently. Results: A total of 17 studies were included that involved 1146 participants. Outcomes suggested that aerobic exercise combined with other interventions was more effective than aerobic exercise alone. Aerobic exercise with higher frequency (≥ 5 days/week) and longer duration (≥ 12 weeks) were effective to gain clinically significant (≥ 30%) improvements. Environment and using pedometer did not seem to influence the outcomes. Conclusions: Pain intensity and functional disability in CLBP patients can be minimized by prescribing aerobic exercise. However, to get better improvements, aerobic exercise should be done in combination with other interventions and at optimum frequency and duration. Further studies should emphasize examining the optimal doses and duration of different aerobic exercises.

Electromyographic and Stabilometric Analysis of the Static and Dynamic "Standing Bird Dog" Exercise

(1) Background: The "bird dog" exercise is considered one of the most effective therapeutic exercises for lumbopelvic rehabilitation and the prevention and treatment of low back pain. The "standing bird dog" (SBD) exercise, executed in a single-leg stance, constitutes a natural and challenging variation in the "bird dog"; nevertheless, this exercise has not yet been investigated. This study provides a stabilometric and electromyographic analysis of the SBD performed in static and dynamic conditions and in ipsilateral and contralateral variations; (2) Methods: A time-synchronized motion capture system, wireless electromyography sensors, and triaxial force platform were used to analyze the selected SBD exercises; (3) Results: In dynamic conditions, the gluteus maximum, multifidus, lumbar erector spinae, and gluteus medius reached a mean activation level higher than in the static condition, with peak activation levels of 80%, 60%, 55%, and a 45% maximum voluntary isometric contraction, respectively. In the static condition, balance control was more challenging in the mediolateral compared to the anteroposterior direction. In the dynamic condition, the balance challenge was higher in the anteroposterior direction and higher than the static condition in both directions; (4) Conclusions: The SBD was proved to be effective for strengthening the hip and lumbar extensor muscles and provided a powerful challenge to single-leg balance control in both mediolateral and anteroposterior directions.

Manipulating device-to-body forces in passive exosuit: An experimental investigation on the effect of moment arm orientation using passive back-assist exosuit emulator

Passive exosuits have been vastly researched in the past decade for lifting tasks to alleviate the mechanical loading on the spine and reduce the lower back muscle activities in lifting tasks. Despite promising advantages of exosuits, factors such as comfort directly influence the user's acceptability of such body-worn devices. Exosuits' routing/anchoring points, which transmit device-to-body forces, remain the leading cause of discomfort among users. In the present study, we sought to investigate the effect of the routing element, that is, the "moment arm," in altering the device-to-body forces and perceived discomfort. We first presented a simplified human-exosuit model to establish insight into the effect of the moment arm on the device-to-body forces acting at the shoulder (FS) and waist (FW). Further, an experimental investigation was conducted on 10 participants with six different exosuit moment arm configurations (C1, C2, C3, C4, C5, and C6) to investigate their effect on the device-to-body forces, perceived discomfort, and muscle activity using a passive back-assist exosuit emulator in a lifting/lowering task. Configuration C4 was found to be most beneficial in reducing device-to-body forces at the shoulder and waist by up to 44.6 and 22.2%, respectively, during lifting. Subjective scores also comprehended with the device-to-body forces, indicating that C4 produces significantly less discomfort for participants. The outcome of the study illustrates the importance of selecting an appropriate moment arm configuration for passive back support exosuits in alleviating the device-to-body forces and perceived discomfort.

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.

A Preliminary Study on the Equivalence between Standing Back-Extension and Superman Training in Lumbar Multifidus Exercise

Objective. To explore the equivalence of an easier and more convenient lumbar multifidus (LM) muscle exercise pattern among standing back-extension, static standing, and superman training. Methods. A total of 26 healthy young volunteers were enrolled, including 14 males and 12 females, aged from 22 to 44 years with an average of $31.77\pm 7.06$ years. Ultrasonography was used to measure the thickness of the left LM of the transverse process of the L5 vertebra during static standing, static prone decubitus, standing back-extension, and prone superman training. In this study, measurement data were expressed as $\text{Mean}\pm \text{SD}$ and compared using the $t$ -test. Results. The left LM thickness of the L5 vertebra was $2.92\pm 0.46$  cm during static standing and $2.78\pm 0.39$  cm during static prone decubitus, showing no statistical difference between the two groups ( $P>0.05$ ). The left LM thickness of the L5 vertebra was $3.16\pm 0.51$  cm during standing back-extension and $3.33\pm 0.41$  cm during the prone superman training, indicating no statistical difference between the two groups ( $P>0.05$ ). Conclusions. There is no significant statistical difference in the LM thickness between static standing and static prone decubitus and between standing back-extension and prone superman training, indicating the equivalence of the two methods in LM exercise, providing a simpler and easier way for clinical exercise of lumbodorsal muscles.

Asymmetrical activation and asymmetrical weakness as two different mechanisms of adolescent idiopathic scoliosis

There have been many studies on adolescent idiopathic scoliosis related abnormal muscle contractions of the spine. However, previous studies using surface electromyography to investigate paraspinal muscle asymmetry are controversial, lacking in clarity of results, and hindered by methodological limitations. The purpose of this study was to investigate the relationship between imbalance factors including surface electromyography activity according to the scoliosis curve type and leg length discrepancy and adolescent idiopathic scoliosis curve types. Seventy-nine patients with scoliosis were prospectively enrolled and were divided into five types: single thoracic, thoracolumbar, lumbar, double thoracic, and double major. Cobb angle and structural variables were measured. Surface electromyography examinations were conducted at the 7th, 12th thoracic erector spinae, 3rd lumbar erector spinae, and multifidus muscles during the superman position keeping prone spinal extension to lift the arms and legs off the floor. Whole spine radiographs were obtained to measure the Cobb angle, coronal imbalance, pelvic height and angle, and femoral head height. In the double major, thoracolumbar, and lumbar types, the mean root mean squared (RMS) EMG amplitudes were significantly higher on the convex side than the concave side (P < 0.005). In the DM type, the mean RMS EMG amplitudes of ES_T7 and ES_L3 where the apex was located were significantly higher at the convex side than those of the concave side (P < 0.005, effect size (Cohen’s d) for ES_T7/ES_L3: 0.517/0.573). The TL and L types showed a similar pattern. The mean RMS EMG amplitudes of the ES_T12 concave side and Mu_L3 and ES_L3 concave sides were significantly lower than those of the convex side in the TL and L types, respectively (P < 0.008, effect size (Cohen’s d) for ES_T12/Mu_L3/ES_L3: 0.960/0.264/0.448). Conversely, there were no significant differences in the single thoracic and double thoracic types. All structural variables (coronal imbalance, pelvic height and angle, and femur head height) were higher in the lumbar type, but only coronal imbalance was significantly different (P < 0.05). Different patterns of asymmetry of paraspinal muscles and structural variables were described based on the curvature of the spine. L type showed that EMG activity was asymmetric in the paraspinalis muscles where the apex was located and that structural asymmetry, such as coronal imbalance was significantly greater than other types. DM type showed similar paraspinalis asymmetry pattern to the ST type but there was no structural asymmetry in DM and ST types. TL type has the features of both thoracic and lumbar origins. Understanding these could contribute to the management in correcting scoliosis.

A self-oblique exercise that activates the coordinated activity of abdominal and hip muscles-A pilot study

The importance of an interaction between trunk stability muscles and hip muscle function has been suggested. However, reported exercises rarely act on the trunk and hip muscles simultaneously. Here, we devised an abdominal oblique and hip muscle exercise, the Self-oblique exercise (SOE). We examined whether SOE activated abdominal and hip muscles in the supine and half-kneeling positions, compared with abdominal crunch (AC) and plank exercises; and whether participants could modulate the exercise load. Participants were 20 healthy males with some sports experience such as football and baseball on average 10.5 ± 4.0 years. Participants applied self-pressure to their right thighs using the contralateral upper limb with 40% or 70% of the maximum force in Supine SOE and Half- kneeling SOE. The following abdominal and hip muscles were measured using surface electromyography: bilateral external obliques (EO), bilateral internal obliques (IO), right rectus abdominis, right gluteus medius (GMed), and right adductor longus (ADD). All evaluated muscle groups showed significant differences between exercises (p < 0.001). Supine SOE-70% showed 80.4% maximal voluntary contraction (MVC) for left EO (p < 0.017), 61.4% MVC for right IO (p < 0.027), 24.3% MVC for GMed (p < 0.002), and 42.4% MVC for ADD (p < 0.004); these were significantly greatest among all exercises. Muscle activity during Supine SOE-70% was greater than that during Supine SOE-40%. Similarly, Half-kneeling SOE-40% promoted abdominal and hip muscle exertion, and showed more significant activity in GMed (p < 0.006) and ADD (p < 0.001) than AC and plank. SOE could activate abdominal and hip muscles depends on the pressure applied by upper limb. Also, SOE allows participants to modulate the exercise load in a self-controlled step by step manner. Modulation of the exercise load is difficult in AC or plank compared to SOE, and AC or plank cannot obtain simultaneous oblique and hip muscle activity. SOE could be practiced anywhere, in various positions, without any tools.

Relationship between trunk muscle strength and trunk muscle mass and thickness using bioelectrical impedance analysis and ultrasound imaging

BACKGROUND

Although trunk muscles are involved in many important functions, evaluating trunk muscle strength is not an easy task. If trunk muscle mass and thickness could be used as indicators of trunk muscle strength, the burden of measurement would be reduced, but the relationship between trunk muscle strength and trunk muscle mass and thickness has not been clarified.

OBJECTIVE

The purpose of this study was to clarify the relationship between trunk muscle strength and trunk muscle mass by bioelectrical impedance analysis and trunk muscle thickness by ultrasound imaging in healthy adults.

METHODS

One hundred and twenty-one healthy university students were included in this study. Trunk flexion/extension muscle strength and trunk muscle mass by bioelectrical impedance analysis, and trunk muscle thickness by ultrasound imaging were measured.

RESULTS

Both trunk flexion strength and trunk extension strength were significantly correlated with trunk muscle mass and oblique and rectus abdominis muscle thickness. Multiple regression analysis showed that trunk extension muscle strength had an independent relationship with trunk muscle mass.

CONCLUSIONS

This study demonstrated that trunk muscle mass or trunk muscle thickness can be used as an alternative means for evaluating trunk muscle strength, making the evaluation of trunk muscles less burdensome.

The effect of lumbar stabilization and walking exercises on chronic low back pain: A randomized controlled trial

BACKGROUND

Various exercises have been proposed to mitigate chronic low back pain (LBP). However, to date, no one particular exercise has been shown to be superior. Hence, the aim of this study was to compare the efficiency between 2 exercises: the individualized graded lumbar stabilization exercise (IGLSE) and walking exercise (WE).

METHODS

A randomized controlled trial was conducted in 48 participants with chronic LBP. After screening, participants were randomized to 1 of 4 groups: flexibility exercise, WE, stabilization exercise (SE), and stabilization with WE (SWE) groups. Participants underwent each exercise for 6 weeks. The primary outcome was visual analog scale (VAS) of LBP during rest and physical activity. Secondary outcomes were as follows: VAS of radiating pain measured during rest and physical activity; frequency of medication use (number of times/day); Oswestry disability index; Beck depression inventory; endurances of specific posture; and strength of lumbar extensor muscles.

RESULTS

LBP during physical activity was significantly decreased in all 4 groups. Exercise frequency was significantly increased in the SE and WE groups; exercise time was significantly increased in the SE group. The endurance of supine, side lying, and prone posture were significantly improved in the WE and SWE groups.

CONCLUSIONS

Lumbar SE and WE can be recommended for patients with chronic LBP because they not only relieve back pain but also prevent chronic back pain through improving muscle endurance.

Proposal of a new exercise protocol for idiopathic scoliosis: A preliminary study

In clinical practice, we found a unilateral instability in patients with right thoracic scoliosis during asymmetric spinal stabilization exercise (ASSE), which can be an important clue to identify the pathophysiology of idiopathic scoliosis (IS).We investigated the relationship between unilateral postural instability and weakness of paraspinal muscles according to curve pattern. And finally, we propose the new exercise method based on the curve pattern.Combined use of prospective and retrospective clinical trials.Fifteen participants without IS and 10 patients with IS in 1 tertiary referral hospital.In 15 participants without IS, surface electromyography (sEMG) was used to evaluate the muscular activation patterns in the bilateral erector spinae (ES), rectus abdominis (RA), and external oblique (EO) muscles during ASSE. In addition, to assess the clinical effect of ASSE, Cobb angle and rotation grade were measured from 10 patients with IS.The most significant findings from the sEMG data were the increased activities of ipsilateral 7th thoracic ES during hand-up motion, ipsilateral 3rd lumbar ES during leg-up motion, and 12th thoracic and 3rd lumbar ES during side-bridging. In a radiographic analysis, specific components of ASSE that activates the concave side muscles were found to be effective for IS.The paraspinal muscle strengthening of the concave side using ASSE can improve the severity of scoliosis. Based on this research, we could propose a new exercise protocol that can be personalized according to the curve pattern.

Comparison of lumbar multifidus thickness and perceived exertion during graded superman exercises with or without an abdominal drawing-in maneuver in young adults

The present study aimed to investigate lumbar multifidus (LM) thickness and perceived exertion during graded superman exercises (GSE) or GSE with an abdominal drawing-in maneuver (GSE-AD) in young adults. Twelve young adult males and females, who were informed of the purpose and procedures of this study and then gave their voluntary consent to participate, were included in this study. All subjects randomly performed three GSE and GSE-AD over 3 days. Ultrasonography was used to measure the LM thickness to the left and right of the L5 region. Additionally, the issue of whole-body fatigue felt by the subject while performing the GSE or GSE-AD was measured using the Borg scale. The intrarater reliability of the LM measurement was found to be intraclass correlation coefficient (ICC[3,1])=0.97 (0.87-0.99) at resting and ICC(3,1)=0.94 (0.78-0.99) at contraction. Both the left and right LM showed significantly higher contraction during the grade 3 GSE (P< 0.05). The whole-body fatigue was significantly greater following GSE 2 and 3 than following GSE-AD 2 and 3 (P<0.05). In particular, GSE-AD had a significantly lower Borg score compared to GSE (P<0.05) and did not show any significant difference in muscle thickness (P>0.05). It is recommended that the abdominal drawing-in maneuver be applied with grade 3 GSE to enhance stability and reduce spinal fatigue.

The Role of a Multi-Step Core Stability Exercise Program in the Treatment of Nurses with Chronic Low Back Pain: A Single-Blinded Randomized Controlled Trial

Study Design

Single-blinded randomized controlled trial.

Purpose

To evaluate the effects of a multi-step core stability exercise program in nurses with chronic low back pain (CLBP).

Overview of Literature

CLBP is a common disorder among nurses. Considering that patient-handling activities predispose nurses to CLBP, core stability exercises suggested for managing CLBP in the general population may also be helpful in nurses. However, sufficient evidence is not available on whether a multi-step core stability exercise program affects pain, disability, quality of life, and the diameter of lateral abdominal muscles in nurses with CLBP.

Methods

In this single-blinded randomized controlled trial, 36 female nurses with CLBP were recruited. The sample was divided into two groups of 18 patients (intervention and control). Nurses in the intervention group performed core stability exercises for 8 weeks, based on a progressive pattern over time. Roland–Morris Disability Questionnaire (RDQ), quality of life (36-item Short Form Health Survey [SF-36]), ultrasound assessment of the diameter of lateral abdominal muscles, and Visual Analog Scale (VAS) score for pain were evaluated in the participants before and after the trial. Sixteen nurses (eight from each group) dropped out of the study, and analysis of covariance was used to compare outcomes for the remaining nurses in the intervention (10 nurses) and control (10 nurses) groups.

Results

The results after the trial showed significant improvements in RDQ, SF-36, and VAS score in the intervention group compared with that in the control group (p <0.005). Furthermore, the ultrasound data showed a significant increase in the left and right muscle diameter of all three abdominal muscles during the abdominal drawing-in maneuver in the intervention group compared with that in the control group (p <0.05).

Conclusions

This study showed that a multi-step core stability exercise program is a helpful treatment option for improving quality of life and reducing disability and pain in female nurses with CLBP.

The effects of pelvic diagonal movements and resistance on the lumbar multifidus

[Purpose] The purpose of this study was to compare the effects of pelvic diagonal movements, made with and without resistance, on the thickness of lumbar multifidus muscles. [Subjects and Methods] Participants in this study were healthy subjects who had no musculoskeletal disorders or lumbar-related pain. Participants were positioned on their side and instructed to lie with their hip flexor at 40 degrees. Ultrasonography was used for measurement, and the values of two calculations were averaged. [Results] The thickness of ipsilateral lumbar multifidus muscles showed a significant difference following the exercise of pelvic diagonal movements. The results of anterior elevation movements and posterior depression movements also demonstrated significant difference. There was no significant difference in lumbar multifidus muscles thickness between movements made with and without resistance. [Conclusion] These findings suggest that pelvic diagonal movements can be an effective method to promote muscular activation of the ipsilateral multifidus. Furthermore, researchers have concluded that resistance is not required during pelvic diagonal movements to selectively activate the core muscles.