Erector Spinae Muscle Activity Research Articles

Immediate Changes in Gluteus Maximus and Erector Spinae Muscle Activities During Prone Hip Extension After the Abdominal Drawing-in Exercise in Female Adults With Weak Abdominal Muscles and Normal Female Adults

Immediate Changes in Gluteus Maximus and Erector Spinae Muscle Activities During Prone Hip Extension After the Abdominal Drawing-in Exercise in Female Adults With Weak Abdominal Muscles and Normal Female Adults

Comparison of Trunk Muscle Activity Between Traditional Plank Exercise and Plank Exercise With Isometric Contraction of Ankle Muscles in Subjects With Chronic Low Back Pain.

Choi, JH, Kim, DE, and Cynn, HS. Comparison of trunk muscle activity between traditional plank exercise and plank exercise with isometric contraction of ankle muscles in subjects with chronic low back pain. J Strength Cond Res 35(9): 2407-2413, 2021-This study aimed to compare the effects of 4 different ankle conditions on the activities of rectus abdominis (RA), external oblique (EO), transversus abdominis/internal oblique (TrA/IO), and erector spinae (ES) muscles during plank exercise in subjects with chronic low back pain (CLBP). Twenty-two subjects with CLBP participated in this study. The subjects performed the traditional plank and plank with 3 different ankle muscle contraction types (isometric contraction of ankle dorsiflexor, plantarflexor, and without ankle muscle contraction). Surface electromyography was used to measure the activities of RA, EO, TrA/IO, ES, tibialis anterior, and gastrocnemius muscles. A 1-way repeated-measures analysis of variance was used to assess the statistical significance of activities of the RA, EO, TrA/IO, and ES muscles. The activities of RA, EO, and TrA/IO muscles were significantly greater in the plank with isometric contraction of ankle dorsiflexor (PlankDF) than in the other 3 plank exercises. No significant difference in the activity of ES muscles was revealed during the 4 plank exercises. The activities of all abdominal muscles during PlankDF were significantly higher than those during the traditional plank, as well as during the plank with isometric contraction of ankle plantarflexor (PlankPF) and the plank without ankle muscular contraction (Plankw/o), and more than 60% of maximal voluntary isometric contraction was observed. Thus, PlankDF could be applied not only as a rehabilitation strategy for patients with decreased core stability owing to weakness of abdominal muscles but also as fitness program for improving core strength.

The utility of Sysmex XN body fluid mode for cell count in body fluids

While using their smartphone, users tend to adopt awkward neck and shoulder postures for an extended duration. Such postures impose the risk of MSDs on those body parts. Numerous studies have been undertaken to examine neck posture; however, few studies have investigated shoulder postures. This study examined various shoulder postures during smartphone use and their effect on neck and shoulder kinematics, muscle loading, and neck/shoulder discomfort. Thirty-two asymptomatic young adult smartphone users randomly performed texting tasks for 3 min at four different shoulder flexion angles (15°, 30°, 45°, and 60°), while maintained a neck posture in the neutral position (0° neck flexion angle). Measures were taken of neck and shoulder muscle activity of the cervical erector spinae (CES), anterior deltoid (AD), upper trapezius (UT) and lower trapezius (LT), and kinematic data (angle, distance and gravitational moment). Results showed AD and LT muscle activity significantly increased when the shoulder flexion angle increased with an opposite effect on CES and UT. A recommended shoulder posture was identified as 30° flexion, as this yielded the best compromise between activation levels of the four muscles studied. This angle also induced the lowest neck/shoulder discomfort score. The findings suggest smartphone users hold their device at approximately 30° shoulder flexion angle with their neck in a neutral posture to reduce the risk of shoulder and neck musculoskeletal disorders when smartphone texting.Smartphone use in the manufacturing and service industries is an integral part of work and useful means of communication tool. Awkward postures during extensive smartphone use impose an increased risk of both neck and shoulder musculoskeletal disorders. Shoulder flexion angles need consideration when making recommendations about safe work postures during smartphone use.

Effects of abdominal drawing-in maneuver with pressure biofeedback, foam-roller and quadruped on lumbopelvic stability and muscle activities in lumbar rotation syndrome.

The abdominal drawing-in maneuver (ADIM) exercise has been commonly applied to recover lumbopelvic stability and normal movement in the clinical field. Although many researchers investigated its effects using several methods, there is further need for comparing those methods. The purpose of this study was to assess the effects of ADIM with three different methods including a pressure biofeedback unit, a foam-roller, and the quadruped posture on lumbopelvic rotation and muscle activities. Twenty-five healthy participants (14 males, 11 females) who volunteered for this study were randomly divided into three intervention groups. We obtained pre- and postintervention data through application of a three-dimensional motion analysis system and a surface electromyography. Results showed that lumbopelvic rotation degree was significantly decreased in all groups (P<0.05). The muscle activities of external oblique, internal oblique of left side, and gluteus maximus were significantly increased (P<0.05). The muscle activities of erector spinae and biceps femoris were not significantly different (P>0.05). The muscle activity of internal oblique of the right side showed significant differences (P<0.05), between ADIM with pressure biofeedback group and ADIM with foam-roller group, and ADIM with foam-roller group and ADIM with quadruped group. Three kinds of ADIM were effective to recover lumbopelvic stability. This study suggests that the proper method of ADIM should be applied to a given patient considering abilities to maintain equilibrium and to control muscular strength.

Comparison of two mobilization techniques in management of chronic non-specific low back pain

AimThe aim of the study was to compare between the effects of Maitland's postero-anterior (PA glide) mobilization and Mulligan's sustained natural apophyseal glide (SNAG) on pain, mobility, muscle activation and functional disability in subjects with chronic, non-specific low back pain. MethodsThe study was a two arm repeated measure design with random allocation of subjects (n = 33). Subjects in group 1 received Maitland's PA glide mobilization and those in group 2 received Mulligan's SNAG. Along with the respective mobilization technique, individualized exercises were common for subjects in both the groups. Subjects in both groups received treatment for 4 days a week for 4 weeks. The outcome measures were numeric pain rating scale (NPRS) scores, lumbar flexion and extension range of motion, erector spinae muscle activity and Oswestry low back pain disability questionnaire score. ResultsThe outcome measure scores showed statistical significance in time effect on NPRS (p = 0.001); lumbar flexion and extension range of motion (p = 0.001); erector spinae muscle activity (0.001); Oswestry low back pain disability questionnaire score (p = 0.001); group effect on lumbar flexion (p = 0.03) and extension range of motion (p = 0.05); and interaction effect (time x group) on lumbar flexion (p = 0.003) and extension range of motion (p = 0.002); and, erector spinae muscle activity (p = 0.05) at the 3rd lumbar vertebral level. ConclusionThe addition of Maitland or Mulligan mobilization techniques of the spine does not show a difference in the improvement of symptoms associated with chronic non-specific low back pain.

The effects of Gyrotonic expansion system exercise and trunk stability exercise on muscle activity and lumbar stability for the subjects with chronic low back pain.

The Gyrotonic expansion system comprises three-dimensional (3D) spinal motion that not only improves functional spinal motion but also increases muscular strength and flexibility around the spine. This study aimed to demonstrate the clinical effect of Gyrotonic exercise on patients with chronic low back pain by comparing between Gyrotonic and trunk stability exercises. This study included 26 subjects with chronic low back pain patients and who were randomly assigned to the Gyrotonic exercise group or trunk stability exercise group. Each group performed their exercises 3 times a week for 4 weeks. All subjects were measured before and after the exercise for muscles activity of the erector spinae (ES), rectus abdominis (RA), external oblique (EO), and internal oblique (IO) using surface electromyography. Lumbar stability was measured using a 3D spine tester, and functional disability was measured using the Korean Oswestry disability index. In the Gyrotonic exercise group, ES and EO muscle activity significantly increased (P<0.05). In the trunk stability exercise group, ES, EO, and RA muscle activity significantly increased (P<0.05). No differences in muscle activity were found between the groups. Both groups showed significant improvements in lumbar stability and functional disability but no significant differences were noted between the groups. Gyrotonic exercise and trunk stability exercise are encouraged owing to their positive effects on muscle activity, lumbar stability, and functional ability in patients with chronic low back pain. We suggest that Gyrotonic exercise is one of the effective exercise for mitigating chronic low back pain caused by spinal instability.

Changes in the Flexion-Relaxation Response After Percutaneous Endoscopic Lumbar Discectomy in Patients with Disc Herniation

Previous studies of percutaneous endoscopic lumbar discectomy (PELD) to treat lumbar disc herniation (LDH) have shown good clinical results. However, limited information has been reported regarding postoperative improvement in back muscle function. We aimed to determine whether changes in neuromuscular patterns, assessed using the flexion-relaxation phenomenon (FRP), could be observed after PELD. A total of 30 patients participated in the present study. The patients' muscle functions were evaluated before and after PELD using surface electromyography and self-report measures. The evaluated action included 3 repetitions of a trunk flexion and extension movement. The association between the FRP measures and patient-reported outcomes was evaluated. At 4 weeks after PELD, the patients had significantly lower visual analog scale and Quebec Back Pain Disability Scale (QBPDS) scores and significantly increased gross range of motion. Also, we observed a reduction in erector spinae muscle activation at L3 in the maximum voluntary flexion phase. Normalized electromyographic root-mean-square values were significantly reduced in the maximum voluntary flexion phase and significantly increased in the extension phase. Postoperatively, 60% of the patients successfully achieved flexion-relaxation compared with 7% of the patients preoperatively. A significant correlation was found between the FRP measures and patient-reported outcomes, except for the Fear-Avoidance Beliefs Questionnaire scale. PELD for individuals with LDH appears to normalize paraspinal muscle activation during lumbar flexion-extension movement. The gross range of motion and disability-related limitations of physical activity also improved.

Lumbar Muscle Activation Pattern During Forward and Backward Walking in Participants With and Without Chronic Low Back Pain: An Electromyographic Study

ObjectiveThe purpose of this study was to investigate the electromyographic activity of lumbar multifidus (MF) and erector spinae (ES) muscle during forward walking (FW) and backward walking (BW) in participants with and without chronic low back pain (CLBP). MethodsTwenty-one patients with CLBP were recruited from outpatient department of Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia. Twenty-one age-matched healthy controls without CLBP were recruited from community. Maximum voluntary isometric contraction (MVIC) was quantified for MF and ES using standard guidelines. Electromyographic activity of MF and ES was recorded using surface electrodes during FW and BW on a motorized treadmill, which was later normalized by respective MVIC’s of each muscle. ResultsMuscle activity (in percentage MVIC) was determined to be higher for both the muscles during BW. Activity of MF muscle was significantly higher in CLBP patients compared with healthy controls (P < .04). Electromyographic activity of MF and ES was significantly increased during BW (MF: P < .001; ES: P < .001) compared with FW in both healthy and CLBP groups. ConclusionBW leads to greater activation of the paraspinal muscles. Along with global extensor (ES), activity of core extensor (MF) is also higher during BW than FW in both healthy participants and CLBP patients. BW is a more favorable aerobic activity to enhance lumbar paraspinal recruitment. These findings may have important clinical implications in the rehabilitation of CLBP.

Investigation of the EMG activity of erector spinae and trapezius muscles during Islamic prayer (Salat).

This study aimed to investigate the electrical activity of two muscles located at the dorsal surface during Islamic prayer (Salat). Specifically, the electromyography (EMG) activity of the erector spinae and trapezius muscles during four positions observed while performing Salat, namely standing, bowing, sitting and prostration, were investigated. Seven adult subjects with an average age of 28.1 (± 3.8) years were included in the study. EMG data were obtained from their trapezius and erector spinae muscles while the subjects maintained the specific positions of Salat. The EMG signal was analysed using time and frequency domain features. The results indicate that the trapezius muscle remains relaxed during the standing and sitting positions while the erector spinae muscle remains contracted during these two positions. Additionally, during the bowing and prostration positions of Salat, these two muscles exhibit the opposite activities: the trapezius muscle remains contracted while the erector spinae muscle remains relaxed. Overall, both muscles maintain a balance in terms of contraction and relaxation during bowing and prostration position. The irregularity of the neuro-muscular signal might cause pain and prevent Muslims from performing their obligatory prayer. This study will aid the accurate understanding of how the back muscles respond in specific postures during Salat.

Age-related changes in upper body contribution to braking forward locomotion in women

IntroductionGait termination is a transitory task that requires the lower body to produce braking forces and inhibit forward propulsion. However, it is still unknown whether the upper body plays an active role in braking of gait and whether this mechanism is impaired with ageing. Research questionDo older women exhibit an impaired control of upper body segments during gait termination with respect to young women? MethodsTen young and 10 older women performed three gait termination trials at comfortable speed while fixing the gaze on a visual target. A 3D motion analysis system was used to measure head, trunk and pelvis angular displacement and velocity, and estimate neck, waist and hip moments through Plug-in Gait modeling. Cross-correlation analysis of kinematic waveforms between paired adjacent segments (head-trunk and trunk-pelvis) was performed to investigate upper body coordination. Surface EMG activity of erector spinae (L3), sternocleidomastoid and neck extensor muscles was recorded. Statistics was carried out by MANOVA. ResultsOlder participants exhibited delayed peak extensor torques of neck, waist and hip compared to young participants, along with lower progression speed. Both groups showed a slight flexion of the trunk counteracted by a backward tilt of head and pelvis during braking. In addition, older women displayed a peculiar upper body coordination pattern, with the head coupling with trunk motion, as shown by cross-correlation. Older women displayed shorter lumbar erector spinae onset latency relative to last heel contact than young (16 ± 68 ms vs 92 ± 37 ms). SignificanceThe upper body plays an active role in the braking of gait and this mechanism is impaired in older women. Moreover, the age-related coupling of head and trunk motion may produce an unbalancing effect on whole-body stability during the braking mechanism, thus leading to a higher risk of falls.

The influence of hip mobility and quadriceps fatigue on sagittal spinal posture and muscle activation in rugby scrum performance

Rugby Union scrumming puts the spine under a high degree of loading. The aim of the current study was to determine how sagittal hip range of motion and quadriceps fatigue influence force output, spinal posture, and activation of the trunk and quadriceps muscles in rugby scrumming. Measures of sagittal hip flexion/extension range of motion were collected from 16 male varsity and club first XV level participants. Sagittal spine motion (electromagnetic motion capture), trunk and quadriceps activation (electromyography), and applied horizontal compressive force (force plate) were measured during individual machine scrumming. Participants performed a 5-trial scrum block involving 5 s of contact with 1–2 min recovery between each trial. They then performed a fatiguing protocol (wall sit to failure) and immediately returned to the scrum machine to perform another five trials. Though there was no significant influence of fatigue on the horizontal compressive force applied during contact (P = .83), there was a 52% increase in cervical flexion (P < .001), as well as decreased (18–23% lower) abdominal and erector spinae muscle activation (P < .05). Furthermore, quadriceps activation decreased (12–25% lower) over the course of the initial scrum block but increased (13–15% higher) in the post fatigue block (P < .05). Although athletes were able to maintain force output following the fatiguing wall sit task, there is the potential that they may be at an increased risk of spinal injury due to the combination of increased flexion and high-applied compressive force; a combination which has been shown to increase the likelihood of intervertebral disc herniation.

Postural and Metabolic Benefits of Using a Forearm Support Walker in Older Adults With Impairments

ObjectiveTo investigate the postural and metabolic benefits a walker with adjustable elbow support (LifeWalker [LW]) can provide for ambulation in population with impairment. The clinical outcomes from the elbow support walker will be compared with standard rollator (SR) and participants predicate device (PD). DesignCase-crossover study design. SettingClinical laboratory. ParticipantsIndividuals aged between 18 and 85 years using a rollator walker as primary mode of assistance and certified as medically stable by their primary physician. Participants (N=30; 80% women [n=24]) recruited from a convenient sample provided voluntary consent and completed the study. InterventionNot applicable. Main Outcome MeasuresThe trunk anterior-posterior (AP) sway (during the 10-meter walk test), oxygen consumption (during the 6-minute walk test), the mean forearm load offloaded to the elbow support as percentage of body weight, and mean peak hand grip load (during the 25-meter walk test) were measured. ResultsAmbulating with a LW led to (1) reduced trunk sway in the AP direction [(ZLW vs PD= −2.34, P=.018); (ZLW vs SR= −3.461, P=.001)]; (2) reduced erector spinae muscle activation at the left lumbar L3 level [(ZLW vs PD= −2.71, P=.007); (ZLW vs SR= −1.71, P=.09)]; and (3) improved gait efficiency [(ZLW vs PD= −2.66, P=.008) Oxygen cost; (ZLW Vs. SR= −2.66, P=.008) Oxygen cost]. Participants offloaded between 39% and 46% of their body weight through the elbow support armrest while ambulating with the LW. Irrespective of the walker used, participants exerted ∼5%-6% of their body weight in gripping the walker handles during walking. ConclusionsUsing the forearm support-based LW led to upright body posture, offloaded portions of body weight from the lower extremity, and improved gait efficiency during ambulation in comparison to the SR and the participants’ own PD. Further studies focusing on population-specific benefits are recommended.

The relationship between functionality and erector spinae activity in patients with specific low back pain during dynamic and static movements

BackgroundAlterations in the activity of the lumbar erector spinae (LES) muscles on both sides of the spine have been inconsistently reported in patients with specific low back pain (sLBP) after measuring the muscular activity with surface electromyography (sEMG). It also remains unclear whether these alterations in LES activity can be related to the functional level of patients with sLBP. Research questionThis study investigated the LES activity in patients with sLBP during activities of daily living (ADL) which included dynamic and static movement tasks. Moreover, the alterations in LES activity were correlated with the first seven questions of the Zurich Claudication Questionnaire (ZCQ-SS). MethodsThirty patients with specific LBP and twenty healthy subjects were recruited to perform five ADLs including ‘static waist flexion’, ‘sit to stand’,’ 30-seconds standing’, ‘6-minutes walking’ and ‘climbing stairs’. sEMG sensors were mounted on the left and right LES muscles. The integrated EMG (IEMG) was calculated from the preprocessed sEMG data as statistical comparison criteria. ResultsLES activity was significantly higher in patients during ‘sit to stand’,’ 30-seconds standing’ and ‘climbing stairs’ and significantly lower during ‘static waist flexion’ compared to healthy controls. All tasks showed a significant correlation with the ZCQ-SS score except for ‘6-minutes walking’, whereby LES activity and ZCQ-SS score correspondingly increased during ‘sit to stand’ and ‘climbing stairs’ and the LES activity decreased with an increasing ZCQ-SS score during ‘static waist flexion’ and’ 30-seconds standing’. SignificanceThere was a high correlation between alterations in LES activity and the level of functionality in LBP patients. However, the LES activity showed an opposite behavior during static and dynamic movement tasks. The methodology presented can be a useful tool for quantifying improvements in functionality after rehabilitation processes.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P10. Infant positioning impacts neck and back muscle activity: a pilot study exploring implications for spinal development

BACKGROUND CONTEXT Since 1992, pediatricians have recommended that all infants be placed to sleep in the supine or side-lying position to reduce the risk of Sudden Infant Death Syndrome (SIDS). Although this policy successfully reduced the incidence of SIDS by nearly 50%, questions regarding the positional impact on musculoskeletal and motor development have since surfaced. Studies have linked prone positioning to extensor muscle development and motor milestone achievements, and some believe a link can be made between infant positioning and idiopathic infantile scoliosis. Recently, a relationship between muscle forces and spinal curvatures, particularly hyperkyphosis, was found in fetal chicks, leading to more questions regarding the role of the paraspinal muscles in early spinal development/deformity. PURPOSE The purpose of this pilot study is to examine relationships between infant positions and neck or back muscle activity using electromyography (EMG). STUDY DESIGN/SETTING Electromyographic research study. PATIENT SAMPLE Healthy infants aged 2-7 months. OUTCOME MEASURES Normalized mean EMG data. METHODS Seven healthy infants (mean 5.2 months, 5 male) were enrolled in the study. Surface EMG recorded muscle activity of bilateral cervical paraspinal and erector spinae muscles during five 30-second tasks: laying prone, laying supine, held in arms, held in a baby carrier, and in a car seat. EMG data was normalized to the prone task, and paired t-tests were used to compare to the prone position (p RESULTS Infants exhibited significantly more erector spinae activity during prone positioning compared to all other tasks, and twice as much compared to the supine position (p CONCLUSIONS This first look at the muscle activity of healthy infants in common positions supports the importance of prone time in neck and back development. Prone time significantly increases erector spinae activity. As subject enrollment continues, the in-carrier position may show comparable neck muscle activity to the prone position, as the baby must support the weight of the head while upright.

O 053 - Femoral deformities affect gait performance more than hip muscle weakness

Alterations in the activity of the lumbar erector spinae (LES) muscles on both sides of the spine have been inconsistently reported in patients with specific low back pain (sLBP) after measuring the muscular activity with surface electromyography (sEMG). It also remains unclear whether these alterations in LES activity can be related to the functional level of patients with sLBP.This study investigated the LES activity in patients with sLBP during activities of daily living (ADL) which included dynamic and static movement tasks. Moreover, the alterations in LES activity were correlated with the first seven questions of the Zurich Claudication Questionnaire (ZCQ-SS).Thirty patients with specific LBP and twenty healthy subjects were recruited to perform five ADLs including ‘static waist flexion’, ‘sit to stand’,’ 30-seconds standing’, ‘6-minutes walking’ and ‘climbing stairs’. sEMG sensors were mounted on the left and right LES muscles. The integrated EMG (IEMG) was calculated from the preprocessed sEMG data as statistical comparison criteria.LES activity was significantly higher in patients during ‘sit to stand’,’ 30-seconds standing’ and ‘climbing stairs’ and significantly lower during ‘static waist flexion’ compared to healthy controls. All tasks showed a significant correlation with the ZCQ-SS score except for ‘6-minutes walking’, whereby LES activity and ZCQ-SS score correspondingly increased during ‘sit to stand’ and ‘climbing stairs’ and the LES activity decreased with an increasing ZCQ-SS score during ‘static waist flexion’ and’ 30-seconds standing’.There was a high correlation between alterations in LES activity and the level of functionality in LBP patients. However, the LES activity showed an opposite behavior during static and dynamic movement tasks. The methodology presented can be a useful tool for quantifying improvements in functionality after rehabilitation processes.

Motor adaptations to trunk perturbation: effects of experimental back pain and spinal tissue creep.

In complex anatomical systems, such as the trunk, motor control theories suggest that many motor solutions can be implemented to achieve a similar goal. Although reflex mechanisms act as a stabilizer of the spine, how the central nervous system uses trunk redundancy to adapt neuromuscular responses under the influence of external perturbations, such as experimental pain or spinal tissue creep, is still unclear. The aim of this study was to identify and characterize trunk neuromuscular adaptations in response to unexpected trunk perturbations under the influence of spinal tissue creep and experimental back pain. Healthy participants experienced a repetition of sudden external trunk perturbations in two protocols: 1) 15 perturbations before and after a spinal tissue creep protocol and 2) 15 perturbations with and without experimental back pain. Trunk neuromuscular adaptations were measured by using high-density electromyography to record erector spinae muscle activity recruitment patterns and a motion analysis system. Muscle activity reflex attenuation was found across unexpected trunk perturbation trials under the influence of creep and pain. A similar area of muscle activity distribution was observed with or without back pain as well as before and after creep. No change of trunk kinematics was observed. We conclude that although under normal circumstances muscle activity adaptation occurs throughout the same perturbations, a reset of the adaptation process is present when experiencing a new perturbation such as experimental pain or creep. However, participants are still able to attenuate reflex responses under these conditions by using variable recruitment patterns of back muscles. NEW & NOTEWORTHY The present study characterizes, for the first time, trunk motor adaptations with high-density surface electromyography when the spinal system is challenged by a series of unexpected perturbations. We propose that the central nervous system is able to adapt neuromuscular responses by using a variable recruitment pattern of back muscles to maximize the motor performance, even under the influence of pain or when the passive structures of the spine are altered.

Changes in Lumbopelvic Movement and Muscle Recruitment Associated with Prolonged Deep Squatting: A Pilot Study.

This study examined the changes in spinal kinematics and muscle recruitment of the lumbopelvic region associated with prolonged squatting. Eight subjects with chronic nonspecific low back pain (LBP) and eight asymptomatic subjects (AS) performed squat-to-stand and reverse movements, before and immediately after 15 min deep-squatting. Within-group and between-group differences in lumbopelvic kinematics and electromyographic activity acquired in lumbar erector spinae (ES), gluteus maximus (GM), and vastus lateralis (VL) were analyzed. During squat-to-stand after squatting, the LBP group showed slower then faster lumbar movement in the second and third quartiles, respectively. In the second quartile, the AS group moved with a significantly greater lumbar angle. However, significantly greater bilateral GM activity (+4–4.5%) was found in the LBP group only. A more profound decrease in bilateral ES activity (−10%) was also shown in the LBP group, yet this was nonsignificant compared to the AS group (−4%). In the third quartile, only the LBP group moved with a significantly greater lumbar angle, together with a significant increase in bilateral ES (+6–8%) and GM muscle (+2–3%) activity. The findings of the altered pattern of joint kinematics and recruitment of the key lumbopelvic muscles displayed in the LBP group inform on the possible mechanisms that may contribute to the increased risk of developing lumbar dysfunctions for people who work in prolonged squatting postures.

Disturbance of neck proprioception and feed-forward motor control following static neck flexion in healthy young adults

The highly complex proprioceptive system provides neuromuscular control of the mobile cervical spine. Static neck flexion can induce the elongation of posterior tissues and altered afferent input from the mechanoreceptors. The purpose of this study was to examine the effect of prolonged static neck flexion on neck proprioception and anticipatory postural adjustments. Thirty-eight healthy participants (20 females and 18 males) between the ages of 20–35 years with no history of neck, low back, and shoulder pain enrolled in this study. Neck proprioception and anticipatory muscle activity were tested before and after 10-min static neck flexion. For assessment of neck proprioception, each participant was asked to perform 10 trials of the cervicocephalic relocation test to the neutral head position after active neck rotation to the left and right sides. Anticipatory postural adjustments were evaluated during a rapid arm flexion test. Following the flexion, the absolute and variable errors in head repositioning significantly increased (p < 0.05). The results also showed that there was a significant delay in the onset of myoelectric activity of the cervical erector spinae muscles after flexion (p = 0.001). The results of this study suggested that a 10-min static flexion can lead to changes in the neck proprioception and feed-forward control due to mechanical and neuromuscular changes in the viscoelastic cervical spine structures. These changes in sensory-motor control may be a risk factor for neck pain and injury.

Effect of leg weight shifting on muscle activation of the trunk and lower extremity during trunk flexion and extension performance

Objective: To investigate the effect of performing three different toe touch (TT) task condition on the activities of four different muscles using surface electromyography (sEMG) in healthy young adults. Design: Cross-sectional study. Methods: A total of 20 healthy young adults (6 males, 14 females) voluntarily participated in this study. All subject randomly performed three different TT task conditions as follows: general toe-touch (GTT) task, one side toe touch (TT) task during weight bearing, and one side foward toe touch (FTT) task during weight bearing. The muscle activities of erector spinae (ES), gluteus maximus (GM), hamstring (HAM), tibialis anterior (TA) muscles during the TT task were measured using sEMG. Subject performed each of the three conditions three time in random order and mean values were obtained. Results: With the trunk flexion period, the TT and FTT showed significantly greater muscle activity in the GM, HAM and TA compared to the GTT task (p<0.05). The TT position showed significantly greater HAM muscle activity than the GTT position. The dominant and nondominant ES muscle activity was significantly greater in the FTT compared to the GTT position (p<0.05). The dominant GM, HAM, and TA was significantly greater in the TT and FTT compared to the GTT position (p<0.05). Although the dominant ES was significantly greater in the TT and FTT compared to the GTT position (p<0.05), the dominant GM muscle activity was signifcantly greater in the TT compared with the GTT position (p<0.05). Conclusions: These findings may be applicable within the clinical field for selective trunk and lower extremity muscle activation and basic biomechanics purpose.

Effect of Modified Bridge Exercise on Muscle Activity of Erector Spinae, Gluteus Maximus and Biceps Femoris Muscle in Patients with Chronic Low Back Pain

Effect of Modified Bridge Exercise on Muscle Activity of Erector Spinae, Gluteus Maximus and Biceps Femoris Muscle in Patients with Chronic Low Back Pain