EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls

The effect of an 8-week fitness regime on low back pain and core strength in high-risk professionals

BACKGROUND

Low back pain is prevalent among various populations and greatly impacts their quality of life. Professions that incorporate several working hours combined with heavy labor are the most affected. The aim of this study was to examine the effects of an 8-week core training intervention in emergency personnel.

METHODS

Sixteen randomly selected male participants; police officers (N.=8) and firefighters (N.=8) (mean age: 40.75 years; mean height: 177.69 cm; mean body mass: 85.50 kg) performed various testing procedures that assessed core muscle strength and endurance and filled the Oswestry Disability Index Questionnaire regarding the level of low back pain before and after the intervention. The 8-week intervention consisted of two 45-60-minute sessions per week that included ten core-related exercises.

RESULTS

Statistical analysis; paired samples t-test and Wilcoxon Signed-Rank Test, demonstrated significant effects in the 30-sec sit-up test, the Double Leg Lowering Test and the isometric abdominal strength measurements; P value level of significance was set at P≤0.05. All participants had minimal lower back disability before and after the intervention.

CONCLUSIONS

The results demonstrated that the prescribed regime could improve core strength and endurance in high-risk professionals. The most important finding is that training interventions for emergency personnel are most effective when they incorporate a variety of exercises that target the core musculature in all planes of movement and engage the whole range of motion.

Reduced variability of erector spinae activity in people with chronic low back pain when performing a functional 3D lifting task

BACKGROUND

Chronic low back pain (LBP) is a leading cause of disability, which is exacerbated in some by repeated lifting. Electromyography (EMG) assessments of isolated erector spinae (ES) regions during lifting identified conflicting results. Here, high-density EMG comprehensively assesses the lumbar and thoracolumbar ES activity in people with and without LBP performing a multiplanar lifting task.

METHODS

Four high-density EMG grids (two bilaterally) and reflective markers were affixed over the ES and trunk to record muscle activity and trunk kinematics respectively. The task involved cyclical lifting of a 5 kg box for ∼7 min from a central shelf to five peripheral shelves, returning to the first between movements, while monitoring perceived exertion.

RESULTS

Fourteen LBP (26.9 ± 11.1 years) and 15 control participants (32.1 ± 14.6 years) completed the study. LBP participants used a strategy characterised by less diffuse and more cranially-focussed ES activity (P < 0.05). LBP participants also exhibited less variation in ES activity distribution between sides during movements distal to the central shelf (P < 0.05). There were few consistent differences in kinematics, but LBP participants reported greater exertion (P < 0.05).

CONCLUSION

In the presence of mild LBP, participants used a less variable motor strategy, with less diffuse and more cranially-focussed ES activity; this motor strategy occurred concomitantly with increased exertion while completing this dynamic task.

Comparison of the masses and amounts of intramuscular non-contractile tissue of the lower extremity muscles, mobility and balance ability, and cognitive function between older adults with and without low back pain: A pilot study

INTRODUCTION

This study compared the masses and amounts of intramuscular non-contractile tissue of multiple lower extremity muscles measured using an ultrasound imaging device, as well as the mobility and balance ability and cognitive function between community-dwelling older adults with and without low back pain (LBP).

METHODS

Twenty-five community-dwelling older adults were classified into control (CTR) (n = 17, asymptomatic) and LBP (n = 8) groups. The current LBP status in the LBP group was as follows: duration period: 99.4 ± 81.3 months, Numerical Rating Scale: 4.8 ± 0.9, and Oswestry Disability Index: 15.3 ± 10.4%. The thicknesses and the echo intensities of various muscles (gluteus maximus, medius, and minimus; rectus femoris; vastus intermedius and lateralis; long and short heads of the biceps femoris; semitendinosus; semimembranosus; tibialis anterior; medial head of the gastrocnemius; soleus; and tibialis posterior) were measured using an ultrasound imaging device. Mobility and balance ability were assessed by measuring the usual and maximal walking speeds, timed up-and-go time, five-chair-stand time, and one-legged stance time. Mini-Mental State Examination scores were also assessed.

RESULTS

The gluteus medius muscle thickness was significantly lower in the LBP group than in the CTR group. The thicknesses and echo intensities of the other lower extremity muscles did not differ significantly between the CTR and LBP groups. The usual walking speed was also significantly slower in the LBP group than in the CTR group. Balance ability and cognitive function did not differ significantly between the two groups.

CONCLUSION

The results of the present study demonstrated lower gluteus medius muscle mass and slower usual walking speed in community-dwelling older adults with LBP compared to those in older adults without LBP; however, other variables did not differ significantly between these groups.

A Comparison of Bioelectric and Biomechanical EMG Normalization Techniques in Healthy Older and Young Adults during Walking Gait

This study compares biomechanical and bioelectric electromyography (EMG) normalization techniques across disparate age cohorts during walking to assess the impact of normalization methods on the functional interpretation of EMG data. The biomechanical method involved scaling EMG to a target absolute torque (EMGTS) from a joint-specific task and the chosen bioelectric methods were peak and mean normalization taken from the EMG signal during gait, referred to as dynamic mean and dynamic peak normalization (EMGMean and EMGPeak). The effects of normalization on EMG amplitude, activation pattern, and inter-subject variability were compared between disparate cohorts, including OLD (76.6 yrs N = 12) and YOUNG (26.6 yrs N = 12), in five lower-limb muscles. EMGPeak normalization resulted in differences between YOUNG and OLD cohorts in Biceps Femoris (BF) and Medial Gastrocnemius (MG) that were not observed with EMGMean or EMGTS normalization. EMGPeak and EMGMean normalization also demonstrated interactions between age and the phase of gait in BF that were not seen with EMGTS. Correlations showed that activation patterns across the gait cycle were similar between all methods for both age groups and the coefficient of variation comparisons found that EMGTS produced the greatest inter-subject variability. We have shown that the normalization technique can influence the interpretation of findings when comparing disparate populations, highlighting the need to carefully interpret functional differences in EMG between disparate cohorts.

Effects of high-frequency hyperthermia on the elastic modulus of the lumbar muscle in female athletes with low back pain: A randomized crossover trial

OBJECTIVE

To investigate the effects of capacitive and resistive monopolar radiofrequency (CRMF) on the shear elastic modulus of the multifidus and erector spinae muscles in female athletes with low back pain (LBP) and a history of LBP.

DESIGN

Randomized crossover trial.

SETTING

Academic institution.

PARTICIPANTS

Twenty female university athletes with LBP or a history of LBP were included.

INTERVENTIONS

All participants received CRMF, hotpack, and sham (CRMF without power) in a random order on the right side of the lumbar region. More than 2 days were allocated between the experiments to eliminate any residual effects.

MAIN OUTCOME MEASURES

The shear elastic moduli of the right multifidus and erector spinae were evaluated in the prone (rest) position while sitting with 35° trunk flexion (stretched) using shear wave ultrasound imaging equipment. The moduli were measured before, immediately after, and 30 minutes after the intervention.

RESULTS

Repeated-measures 2-way analysis of variance and post hoc analysis showed that the moduli of the CRMF group were significantly lower than those of the sham group in the stretched position immediately after intervention (P = .045). This difference diminished 30 minutes after the intervention (P = .920).

CONCLUSIONS

CRMF can be used to reduce the shear elastic modulus of the multifidus muscle in the short term. Further studies are warranted to determine how to provide longer effects.

TRIAL REGISTRATION

None.

Estimation of Ground Reaction Forces during Sports Movements by Sensor Fusion from Inertial Measurement Units with 3D Forward Dynamics Model

Rotational jumps are crucial techniques in sports competitions. Estimating ground reaction forces (GRFs), a constituting component of jumps, through a biomechanical model-based approach allows for analysis, even in environments where force plates or machine learning training data would be impossible. In this study, rotational jump movements involving twists on land were measured using inertial measurement units (IMUs), and GRFs and body loads were estimated using a 3D forward dynamics model. Our forward dynamics and optimization calculation-based estimation method generated and optimized body movements using cost functions defined by motion measurements and internal body loads. To reduce the influence of dynamic acceleration in the optimization calculation, we estimated the 3D orientation using sensor fusion, comprising acceleration and angular velocity data from IMUs and an extended Kalman filter. As a result, by generating cost function-based movements, we could calculate biomechanically valid GRFs while following the measured movements, even if not all joints were covered by IMUs. The estimation approach we developed in this study allows for measurement condition- or training data-independent 3D motion analysis.

Relationship between paravertebral muscle degeneration and spinal-pelvic sagittal parameters in patients with lumbar disc herniation

Lumbar disc herniation (LDH) is a clinically common degenerative disease of the spine, and spinal-pelvic sagittal balance and paravertebral muscle degeneration have been a research focus in recent years. To explore the relationship between the degeneration of paravertebral muscle and the changes in the spinal-pelvic sagittal parameters in LDH patients, 105 LDH patients (experimental group) and 63 healthy volunteers (control group) hospitalized in Ordos Central Hospital from January 2020 and January 2023 were included as study subjects. All the patients underwent lumbar magnetic resonance imaging and spinal X-ray using uniform criteria. The correlation between the paravertebral muscle and sagittal-pelvic sagittal parameters of the patients with LDH was obtained from two imaging examinations, and the data were organized and grouped to explore the correlation between these parameters. No significant difference in general data existed between the groups (P > 0.05). In the L4/5 LDH patients group, the ratio of fat infiltration (FIR) in the healthy side [multifidus (MF) and erector spinae (ES)] was negatively correlated with the lumbar lordosis (LL) (r = -0.461, r = -0.486, P < 0.05). The relative cross-sectional area (RCSA) of the bilateral MF was positively correlated with the pelvic tilt (r = 0.549, r = 0.515, P < 0.05). The bilateral ES RCSA was negatively correlated with the sagittal vertical axis (r = -0.579, r = -0.621, P < 0.05). A positive correlation existed between the RCSA and thoracic kyphosis in the healthy side ES (r = 0.614, P < 0.05). In the L5/S1 LDH patients group, a negative correlation existed between the FIR and LL in the healthy side ES (r = -0.579, P < 0.05). Thus, the paravertebral muscle parameters were correlated with the spinal-pelvic sagittal parameters in the patients with LDH.

Influence of Changing Hip Position on Electromyographic Activities of Selected Trunk Muscles During Bridging Exercises in Healthy Subjects: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to investigate how rectus abdominis, external oblique (EO), internal oblique (IO), erector spinae, multifidus (MF), and gluteus maximus (GMax) muscle activities change with different hip positions during back and side bridging exercises.

METHODS

Thirty-six healthy individuals participated in this cross-sectional study and performed 6 exercises including back bridging (BB) in neutral hip position, BB with internal rotation, BB with external rotation (BB + ER), side bridging with hips in neutral (SB), side bridging with hips in flexion (SB + HF), and side bridging with hips in extension (SB + HE). Muscle activity was observed using surface electromyography, normalized using maximum voluntary isometric contraction. Repeated-measures 1-way analysis of variance compared muscle readings for each position.

RESULTS

Back bridging with internal rotation showed significant differences in EO (P = .01) and IO (P < .001) compared with other BB positions. Multifidus and GMax differed significantly in BB + ER (P = .04). Side bridging exhibited significant differences in EO (P = .02; P < .001) and IO (P < .001) compared with the other 2 SB positions, with peak in SB + HF. Erector spinae, MF, and GMax also differed significantly (P < .001, P = .02, P < .001, respectively) with peak in SB + HE.

CONCLUSION

The findings revealed that EO and IO muscles were most active during BB with internal rotation, whereas the MF and GMax muscles were most active during BB + ER. In terms of SB, the EO and IO muscles were most active with either SB + HF or SB + HE, whereas the erector spinae, MF, and GMax muscles were most active with SB + HE.

Surface electromyography analysis of core stabilizing muscles during isometric shoulder contractions in athletes with low back pain

BACKGROUND

The study was carried out in the athletes with and without Low Back Pain (LBP) to determine the surface electromyography activity of core stabilizing muscles while performing isometric shoulder and trunk contractions.

STUDY DESIGN

Cross-sectional study.

METHODS

This study enlisted the participation of 40 athletes. Group A included 20 athletes (18 males and 2 females) without LBP, and Group B included 20 athletes (12 males and 8 females) with LBP. Athletes with LBP were assessed using the Modified Oswestry Disability Questionnaire (MODQ) and Visual Analog Scale (VAS) to determine their level of disability and pain severity, respectively. EMG activity of the rectus abdominis, external oblique, longissimus, and multifidus was recorded in both groups as they performed bilateral isometric shoulder and trunk contractions.

RESULTS

In the LBP group, EMG activity of the rectus abdominis and external oblique muscles was significantly lower (P < 0.05). The LBP group had significantly more multifidus activity (P = 0.03) than the NLBP group. Among all the exercises, bilateral isometric shoulder extension contraction activated the rectus abdominis, right external oblique, and longissimus group of muscles significantly more (P < 0.05) in both groups. In both groups, bilateral isometric shoulder flexion contraction resulted in significantly higher multifidus muscle activation (P = 0.002).

CONCLUSION

The activation of core stabilizing muscles was altered in athletes with LBP. When athletes are unable to contract and activate trunk muscles owing to pain, upper extremity exercises can be used to activate these muscles.

Nociceptive withdrawal reflexes of the trunk muscles in chronic low back pain

Individuals with chronic low back pain (CLBP) move their spine differently. Changes in brain motor areas have been observed and suggested as a mechanism underlying spine movement alteration. Nociceptive withdrawal reflex (NWR) might be used to test spinal networks involved in trunk protection and to highlight reorganization. This study aimed to determine whether the organization and excitability of the trunk NWR are modified in CLBP. We hypothesized that individuals with CLBP would have modified NWR patterns and lower NWR thresholds. Noxious electrical stimuli were delivered over S1, L3 and T12, and the 8th Rib to elicit NWR in 12 individuals with and 13 individuals without CLBP. EMG amplitude and occurrence of lumbar multifidus (LM), thoracic erector spinae, rectus abdominus, obliquus internus and obliquus externus motor responses were recorded using surface electrodes. Two different patterns of responses to noxious stimuli were identified in CLBP compared to controls: (i) abdominal muscle NWR responses were generally more frequent following 8th rib stimulation and (ii) occurrence of erector spinae NWR was less frequent. In addition, we observed a subgroup of participants with very high NWR threshold in conjunction with the larger abdominal muscle responses. These results suggest sensitization of NWR is not present in all individuals with CLBP, and a modified organization in the spinal networks controlling the trunk muscles that might explain some changes in spine motor control observed in CLBP.

Differences in the elastic modulus of the lumbar muscles between female athletes with and without low back pain

BACKGROUND

Low back pain is the most prevalent musculoskeletal disorder affecting performance and sports participation among athletes and is more prevalent among female athletes. Evaluating the stiffness of the lumbar muscles is important for understanding the pathophysiology of low back pain. Therefore, this study examined the differences in stiffness of the lumbar multifidus and erector spinae muscles between female university athletes with and without low back pain.

METHODS

This was a cross-sectional study. The study was conducted at a single centre, the university research laboratory. Twenty female university athletes with low back pain or a history of low back pain and 20 without low back pain participated in this study. The shear elastic moduli of the multifidus and erector spinae muscles were evaluated in the prone (to relax the muscles) and sitting with 35° of trunk flexion (to stretch the muscles) positions using shear wave ultrasound imaging equipment.

FINDINGS

The low back pain group showed significantly greater shear elastic modulus in the multifidus in both prone and sitting positions than the non-low back pain group. There were no differences in the erector spinae muscle between the two groups at either position.

INTERPRETATION

These results provide new insights into the microscopic characteristics of low back pain pathophysiology in young female athletes. Stiffness assessment using shear wave elastography will help provide a specific treatment strategy for female athletes with low back pain or a history of low back pain.

Increasing physical activity in the vehicle with an interactive seating system in a male sample

An interactive seating system (IASS) was compared to a state-of-the-art massage seating system (MS) regarding the potential of reducing health risks from prolonged sitting in the vehicle. The study investigated if the systems (1) increase heart rate, which is associated with reduced metabolic and cardiovascular risks; (2) activate muscles with the potential to reduce musculoskeletal pain; (3) influence seating comfort and discomfort. The systems were compared in a passenger scenario in a laboratory study (30 male subjects). Only the use of the IASS significantly elevated the heart rate. Muscle activity showed tendencies to increase in the lower back only while using the MS. In comparison, the IASS activated all six captured muscles. Significantly less discomfort was found for the IASS compared to the MS. In comparison to the MS, the IASS showed a substantially higher potential for reducing health risks from static sitting in the vehicle.Practitioner summary: This laboratory study compared the effects of a novel automotive interactive seating system with those of a state-of-the-art massage seating system. Muscle activity, heart rate and discomfort indicated that the IASS has a significantly higher potential to reduce health risks associated with static seating in a vehicle.Abbreviations: AB: air bladder; AC: active condition; ADSS: active dynamic seating system; CLBP: chronic lumbar back pain; ECG: electrocardiography; EMG: electromyography; IASS: interactive seating system; MS: massage seating system; PC: passive condition; PDSS: passive dynamic seating system; RMS: rootmean-square; TI: time interval.

Analysis of trunk rotation during baseball batting with lumbar disc degeneration

Lower back pain (LBP) is common among baseball players, and the occurrence of lumbar intervertebral disc degeneration is high. The dynamic load on the lumbar spine due to the postures and movements characteristic of baseball is suspected of aggravating LBP caused by degeneration, but the difference in batting action between players with and without degeneration is not known. The purpose of this study was to investigate the difference in batting motion in the presence and absence of lumbar disc degeneration (LDD). The subjects were 18 male baseball players belonging to the University League Division I: seven with disc degeneration and 11 without. The motion task analyzed tee batting. The items examined were the angles of rotation of shoulder, pelvis, hip, and twisting motion; rotation angular velocity; time to maximum angular velocity; and muscle activity potentials of the bilateral latissimus dorsi, erector spinae, multifidus, external oblique, internal oblique, rectus abdominis, and gluteus medius muscles; at each stage of batting action. There were significant differences between the shoulder and pelvis in rotation angle, time to maximum angular velocity, and muscle activity in the presence and absence of LDD, and in the time to maximum angular velocity between the shoulder and pelvis. We infer that these differences are characteristic of batting motion due to LDD.

An Evaluation of an Innovative Exercise to Relieve Chronic Low Back Pain in Sedentary Workers

OBJECTIVE

The purpose of the study was to examine the effectiveness of a novel supported dynamic lumbar extension with the abdominal drawing-in maneuver (ADIM) technique on stature change, deep abdominal muscle activity, trunk muscle fatigue, and pain intensity during prolonged sitting in chronic low back pain (CLBP) participants.

BACKGROUND

Prolonged sitting can cause trunk muscle fatigue from continuous contraction of deep trunk muscles in seated postures. Deficiency of activity of deep muscles can reduce muscular support of the spine, causing stress on spinal structures, which could result in pain.

METHOD

Thirty participants with CLBP were randomly allocated: (a) control-sitting without exercise, and (b) intervention-supported dynamic lumbar extension with the ADIM technique.

RESULTS

Compared to the intervention condition, the control condition demonstrated significantly greater deterioration in stature change, increased levels of deep trunk muscle fatigue, and an increase in pain during prolonged sitting.

CONCLUSION

The supported dynamic lumbar extension with the ADIM technique appears to provide a protective effect on detrimental stature change and deep trunk muscle fatigue. In addition, it prevented an increase in pain intensity during prolonged sitting in people with CLBP.

APPLICATION

Sedentary behavior harms health, particularly affecting the lower back. Clinicians can use the intervention to induce dynamic lumbar movement, and this exercise can maintain deep trunk muscle activity during prolonged sitting, thereby helping to prevent low back pain (LBP) problems.

Is the novel suspension exercises superior to core stability exercises on some EMG coordinates, pain and range of motion of patients with disk herniation?

Information about comparing the effectiveness of exercise methods on management of disk herniation is limited. The aim of this study was to compare the effect of two programs of suspension and core stability exercises on some electromyography (EMG) coordinates, pain and range of motion of patients with disk herniation. Thirty-two men with disk herniation participated in this clinical trial study which was randomly divided into three groups of suspension exercises (n: 12, age: 34.25 ± 8.81, BMI: 24.01 ± 2.7), core stability exercises (n: 10, age: 35 ± 10.3, BMI: 25 ± 2.27) and control (n: 10, age: 34.4 ± 6.67, BMI: 23.76 ± 1.45). Electrical activity of rectus abdominis, internal and external oblique and erector spinae muscles was masured by superficial EMG, back pain by McGill Pain Questionnaire and range of motion by Modified Schober test, one day before and immediately after of intervention period. The experimental groups performed an 8-week training period while the control group was only followed up. Data were analyzed using paired sample t test and analysis of covariance test and statistical significance was set at 0.05. Suspension group showed significant improvement in EMG of rectus abdominis, internal and external oblique muscles (respectively, p = 0.030, p = 0.017, p = 0.022) and pain (p = 0.001) compared to core stability group; but there was no significant difference between two groups in EMG of erector spinae muscle and range of motion. Changes in both training groups were significant in all variables compared to control groups (p ˂ 0.05). Our findings showed that although both exercises were effective in patients with lumbar disk herniation, but the effectiveness of suspension exercises in increasing muscle activation and reducing pain was more pronounced than core stability exercises.

Iranian Registry of Clinical Trials (IRCT): IRCT20191016045136N1.

The immediate effect of the abdominal drawing-in maneuver technique on stature change in seated sedentary workers with chronic low back pain

Many studies have measured stature change arising from loads imposed on the spine during sitting. To improve stature recovery, it is important to stabilise the lumbar spine and compensate forces from the upper body. The abdominal drawing-in maneuver (ADIM) technique has been found to mainly activate deep trunk muscles. The purpose of this study was to determine whether activation of deep trunk muscles by the ADIM technique could immediately improve stature recovery during prolonged sitting. Twenty-four patients with chronic low back pain (CLBP) were randomly allocated into different orders of experimental conditions: control (sitting without ADIM technique) and intervention conditions (sitting with ADIM technique). The latter condition required participants to complete ADIM technique for 1 min and repeat it three times throughout 41 min prolonged sitting time. Stature recovery was improved by 3.292 mm in the intervention condition compared with control condition (p-value = 0.001). Our finding demonstrated that ADIM technique improved stature recovery. Practitioner Summary: Prolonged sitting seemingly harms sedentary workers' health, particularly affecting the lower back. Activation of deep trunk muscles using abdominal drawing-in maneuver technique can promote spinal recovery. Clinicians can teach abdominal drawing-in maneuver technique to activate deep trunk muscles in chronic low back pain, thereby promoting self-management of seated stature recovery. Abbrevations: ADIM: abdominal drawing-in maneuver; RA: rectus abdominis; ICLT: iliocostalis lumborum pars thoracis; LM: lumbar multifidus; TrA: transversus abdominis; IO: internal oblique; CLBP: chronic low back pain; LBP: low back pain; RMDQ: Roland Morris disability questionnaire; NRS: numerical rating scale.

Coordination of Axial Trunk Rotations During Gait in Low Back Pain. A Narrative Review

Chronic low back pain patients have been observed to show a reduced shift of thorax-pelvis relative phase towards out-of-phase movement with increasing speed compared to healthy controls. Here, we review the literature on this phase shift in patients with low back pain and we analyze the results presented in literature in view of the theoretical motivations to assess this phenomenon. Initially, based on the dynamical systems approach to movement coordination, the shift in thorax-pelvis relative phase with speed was studied as a self-organizing transition. However, the phase shift is gradual, which does not match a self-organizing transition. Subsequent emphasis in the literature therefore shifted to a motivation based on biomechanics. The change in relative phase with low back pain was specifically linked to expected changes in trunk stiffness due to 'guarded behavior'. We found that thorax-pelvis relative phase is affected by several interacting factors, including active drive of thorax rotation through trunk muscle activity, stride frequency and the magnitude of pelvis rotations. Large pelvis rotations and high stride frequency observed in low back pain patients may contribute to the difference between patients and controls. This makes thorax-pelvis relative phase a poor proxy of trunk stiffness. In conclusion, thorax-pelvis relative phase cannot be considered as a collective variable reflecting the orderly behaviour of a complex underlying system, nor is it a marker of specific changes in trunk biomechanics. The fact that it is affected by multiple factors may explain the considerable between-subject variance of this measure in low back pain patients and healthy controls alike.

The immediate effect of the abdominal drawing-in maneuver technique on stature change in seated sedentary workers with chronic low back pain

Many studies have measured stature change arising from loads imposed on the spine during sitting. To improve stature recovery, it is important to stabilise the lumbar spine and compensate forces from the upper body. The abdominal drawing-in maneuver (ADIM) technique has been found to mainly activate deep trunk muscles. The purpose of this study was to determine whether activation of deep trunk muscles by the ADIM technique could immediately improve stature recovery during prolonged sitting. Twenty-four patients with chronic low back pain (CLBP) were randomly allocated into different orders of experimental conditions: control (sitting without ADIM technique) and intervention conditions (sitting with ADIM technique). The latter condition required participants to complete ADIM technique for 1 min and repeat it three times throughout 41 min prolonged sitting time. Stature recovery was improved by 3.292 mm in the intervention condition compared with control condition (p-value = 0.001). Our finding demonstrated that ADIM technique improved stature recovery. Practitioner Summary: Prolonged sitting seemingly harms sedentary workers' health, particularly affecting the lower back. Activation of deep trunk muscles using abdominal drawing-in maneuver technique can promote spinal recovery. Clinicians can teach abdominal drawing-in maneuver technique to activate deep trunk muscles in chronic low back pain, thereby promoting self-management of seated stature recovery. Abbrevations: ADIM: abdominal drawing-in maneuver; RA: rectus abdominis; ICLT: iliocostalis lumborum pars thoracis; LM: lumbar multifidus; TrA: transversus abdominis; IO: internal oblique; CLBP: chronic low back pain; LBP: low back pain; RMDQ: Roland Morris disability questionnaire; NRS: numerical rating scale.

Inspiratory Muscle Training in Rehabilitation of Low Back Pain: A Randomized Controlled Trial

CONTEXT

People with chronic low back pain (CLBP) suffer from weaknesses in their core muscle activity and dysfunctional breathing. Inspiratory muscle training (IMT) was recently developed to treat this condition.

OBJECTIVES

The present study was conducted to investigate the effect of IMT on core muscle activity, pulmonary parameters, and pain intensity in athletes with CLBP.

DESIGN

This study was designed as a single-blind, randomized, controlled trial.

SETTING

Clinical rehabilitation laboratory.

PARTICIPANTS

A total of 23 male and 24 female athletes with CLBP were randomly divided into the experimental and control groups.

MAIN OUTCOME MEASURES

The experimental group performed IMT for 8 weeks, 7 days per week and twice daily, using POWERbreathe KH1, beginning at 50% of maximum inspiratory pressure with a progressively increasing training load. The surface electromyography muscle activity of the erector spinae, multifidus, transverse abdominis and rectus abdominis, respiratory function and Visual Analogue Scale score were also measured before and after the intervention in both groups. The repeated-measures analysis of variance and 1-way analysis of covariance were further used to compare the intragroup and intergroup results following the intervention.

RESULTS

The findings of the study revealed that multifidus and transverse abdominis activity, as well as respiratory function, increased significantly in the IMT group (P < .05). Moreover, a descending trend was observed in the Visual Analogue Scale score in the experimental group (P < .05).

CONCLUSION

The results showed that IMT can improve respiratory function, increase core muscle activity, and, consequently, reduce pain intensity in athletes with CLBP.

What is the best method to assess the abdominal wall? Restoring strength does not mean functional recovery

BACKGROUND

Restoring the contractile function to the abdominal wall is a major goal in hernia repair. However, the core understanding is required when choosing the method for outcome assessment.

AIM

To assess the role of the anterolateral abdominal muscles on abdominal wall function in patients undergoing hernia repair by analysis of correlation between the surface electromyography activation signal of these muscles and torque produced during validated strength tests.

METHODS

Activation of the rectus abdominis, external oblique, and internal oblique/transverse abdominis muscles was evaluated by surface electromyography during two validated tests: Step: 1-A, isometric contraction in dorsal decubitus; 1-B, isometric contraction in lateral decubitus; 2-A, isokinetic Biodex testing; and 2-B, isometric Biodex testing.

RESULTS

Twenty healthy volunteers were evaluated. The linear correlation coefficient between root mean square/peak data obtained from surface electromyography signal analysis for each muscle and the peak torque variable was always <0.2 and statistically non-significant (p<0.05). The agonist/antagonist ratio showed a positive, significant, weak-to-moderate correlation in the external oblique (Peak, p=0.027; root mean square, 0.564). Surface electromyography results correlated positively among different abdominal contraction protocols, as well as with a daily physical activity questionnaire.

CONCLUSIONS

There was no correlation between surface electromyography examination of the anterolateral abdominal wall muscles and torque measured by a validated instrument, except in a variable that does not directly represent torque generation.

Role of Ultrasound in Low Back Pain: A Review

Low back pain is one of most common musculoskeletal disorders around the world. One major problem clinicians face is the lack of objective assessment modalities. Computed tomography and magnetic resonance imaging are commonly utilized but are unable to clearly distinguish patients with low back pain from healthy patients with respect to abnormalities. The reason may be the anisotropic nature of muscles, which is altered in function, and the scans provide only structural assessment. In view of this, ultrasound may be helpful in understanding the disease as it is performed in real-time and comprises different modes that measure thickness, blood flow and stiffness. By the use of ultrasound, patients with low back pain have been found to differ from healthy patients with respect to the thickness and stiffness of the transversus abdominis, thoracolumbar fascia and multifidus. The study results are currently still not conclusive, and further study is necessary to validate. Future work should focus on quantitative assessment of these tissues to provide textural, structural, hemodynamic and mechanical studies of low back pain. This review highlights the current understanding of how medical ultrasound has been used for diagnosis and study of low back pain and discusses potential new applications.

Comparison of Peak Ground Reaction Force, Joint Kinetics and Kinematics, and Muscle Activity Between a Flexible and Steel Barbell During the Back Squat Exercise

The flexible barbell is purported to improve training gains compared with an Olympic steel barbell (SB) during the back squat exercise with Division I collegiate American football programs. The two bars loaded at 30% 1-repetition maximum were compared with ten trained Division I American football players (n = 10; age = 19.5 years; body mass = 89.4 kg; body height = 182.0 cm) completing 10 repetitions of the back squat exercise. Analysis included integrated-peak values of electromyography of the rectus femoris, biceps femoris, rectus abdominis, erector spinae, external oblique, vastus lateralis, ground reaction forces, and joint kinematics and kinetics of the hip, knee, and ankle. The flexible bar elicited significant increases in peak joint kinetics (Hip Moment: 229 ± 54 Nm vs. 209 ± 52 Nm; Hip Power: 494 ± 151 W vs. 382 ± 134 W; Knee Power: 305 ± 108 W vs. 241 ± 63 W), peak vertical ground reaction forces (1195 ± 209 N vs. 1120 ± 203 N), and muscle activity (Vastus Lateralis: 75.7 vs. 66.5%, Rectus Abdominis: 190 vs. 115%, Rectus Femoris: 69.8 vs. 59.9%, External Oblique: 115 vs. 69.0%). Greater vertical ground reaction forces, hip moment, hip power, knee power, and muscle activity of the vastus lateralis, rectus abdominis, rectus femoris, and external oblique suggest the FB provides biomechanical and physiological mechanisms for training gains over the SB for 30% of 1-repetition maximum loads.

Deformations of abdominal muscles under experimentally induced low back pain

PURPOSE

Low back pain (LBP) is associated with altered motor control and muscle activity; however, it remains unknown whether these changes predispose humans to injury and pain or are the consequence of ongoing nociceptive processes. In this experimental study, we aimed to use a novel ultrasound imaging technique for the measurement of lateral abdominal wall muscle activity: the tissue deformation index (TDI).

METHODS

Forty-two healthy subjects (22.30 ± 1.49 years of age) were exposed to postural perturbation induced by rapid arm movement. Activity of three muscles, the transversus abdominis (TrA) and the internal and external oblique (EO), was recorded by ultrasound imaging (M-mode) with and without induction of LBP. Pain was induced by electrical stimulation applied bilaterally to the lumbar spine.

RESULTS

No significant differences in the TDI between right and left sides of the body (p > 0.05) were found. Generally, muscles deformed slower with pain compared to non-painful conditions; however, only EO muscle displayed a statistically significant reduction in deformation velocity (p ≤ 0.00001). TDI for EO decreased from 0.065% per ms ( ± 0.038, 95% CI 0.057-0.074) to 0.053% per ms ( ± 0.035, 95% CI 0.046-0.061). Furthermore, characteristic inter-muscular TDI gradients were observed, directed from inner towards outer muscular layers, with TrA showing the lowest TDI and EO the highest.

CONCLUSION

Experimentally induced LBP suppresses deformation of the superficial abdominal muscles and increases the variability of local/deep muscles. Further research is required to confirm these observations. These slides can be retrieved under Electronic Supplementary Material.

Muscle Activity During Aquatic and Land Exercises in People With and Without Low Back Pain

BACKGROUND

Chronic low back pain (CLBP) is the most prevalent musculoskeletal disorder. Aquatic exercises are commonly used by physical therapists for CLBP treatment and management; however, there are no data on trunk muscle activation during aquatic exercises in people with CLBP.

OBJECTIVE

We quantified activation of trunk and gluteal muscles, exercise intensity, pain, and perceived exertion in people with and without CLBP when performing water and land exercises.

DESIGN

The study used a cross-sectional design.

METHODS

Twenty participants with nonspecific CLBP and 20 healthy participants performed 15 aquatic exercises and 15 similar land exercises. Mean and peak muscle activation were measured bilaterally from erector spinae, multifidus, gluteus maximus, gluteus medius, rectus abdominis, external oblique, and internal oblique using waterproof and wireless surface electromyography. Exercise intensity (heart rate), perceived exertion (Borg scale), and, for the CLBP group, pain (visual analog scale) were recorded.

RESULTS

There were no significant between-group differences. Significant between-environment differences were found in heart rate (always higher on land), exertion (higher in the water for 3 exercises and on land for 6 exercises), and muscle activation (higher on land in 29% and in the water in 5% of comparisons). Pain levels were low, but pain was reported more than twice as frequently on land than in water (7.7% vs 3.7%, respectively).

LIMITATIONS

People with high levels of disability and CLBP classification were not included.

CONCLUSIONS

People with mild-to-moderate CLBP had similar exercise responses to healthy controls. Aquatic exercise produced sufficient muscle activation, intensity, and exertion, and should not be assumed to be less strenuous or less effective in activating trunk and pelvic muscles than exercise on land. These data can be used to inform design and prescription of rehabilitation programs and interventions.

Effects of tactile feedback on lumbar multifidus muscle activity in asymptomatic healthy adults and patients with low back pain

BACKGROUND

Reduced lumbar multifidus (LM) muscle contraction has been observed in patients with low back pain (LBP). Clinicians often use various strategies to ensure LM activation, including tactile feedback and verbal instruction. However, the effects of tactile feedback on muscle activation have not been studied previously. Therefore, the purpose of this study was to investigate whether or not tactile feedback would increase LM muscle activity in adults with and without LBP.

METHODS

Twenty asymptomatic adults and 20 patients with existing LBP completed the study. Two electromyographic (EMG) electrodes were applied to both sides of the LM at the L5 segment. EMG activity was collected three times at rest with and without tactile feedback, then five times during contralateral arm lifts with and without tactile feedback. The tactile feedback was applied by direct and continuous hand contact to the bilateral LM over the lumbosacral area. Lastly, two 5-second trials of maximum voluntary isometric contraction (MVIC) during a bilateral arm lift were performed. EMG activity collected at rest and during contralateral arm lifts was normalized to that collected during MVIC. Normalized EMG values of the right side of the asymptomatic group and the painful side of the LBP group were used for data analysis.

RESULTS

Statistical analysis showed significantly decreased LM EMG activity with tactile feedback both at rest and during contralateral arm lifts compared to LM EMG activity without tactile feedback. There was no difference in LM EMG between the asymptomatic and the LBP groups.

CONCLUSIONS

The results of the study showed that adding tactile stimulation to verbal instruction appeared to provide an inhibitory effect on LM activity in both asymptomatic healthy adults and patients with LBP. Contrary to common belief, tactical feedback via direct hand contact may reduce LM muscle recruitment, and may lessen the desired treatment effect.

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

OBJECTIVE

To 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).

DESIGN

Case-crossover study design.

SETTING

Clinical laboratory.

PARTICIPANTS

Individuals 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.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

The 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.

RESULTS

Ambulating with a LW led to (1) reduced trunk sway in the AP direction [(Z_{LW vs PD}= -2.34, P=.018); (Z_{LW vs SR}= -3.461, P=.001)]; (2) reduced erector spinae muscle activation at the left lumbar L3 level [(Z_{LW vs PD}= -2.71, P=.007); (Z_{LW vs SR}= -1.71, P=.09)]; and (3) improved gait efficiency [(Z_{LW vs PD}= -2.66, P=.008) _{Oxygen cost}; (Z_{LW 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.

CONCLUSIONS

Using 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.

Back muscle activity and sagittal spinal alignment during quadruped upper and lower extremity lift in young men with low back pain history

BACKGROUND

Quadruped upper and lower extremity lift (QULEL) is performed for selective training of the lumbar multifidus muscle in patients with low back pain (LBP) or individuals with LBP history (LBPH). However, the activities of the back muscles and sagittal spinal alignment during QULEL are not clarified in individuals with LBPH.

RESEARCH QUESTION

This study aimed to analyze the activities of the back muscles and sagittal spinal alignment during QULEL in young male with LBPH.

METHODS

The study comprised 9 asymptomatic young men and 8 young men with LBPH. The activities of the lumbar multifidus, latissimus dorsi and thoracic erector spinae, and lumbar erector spinae muscles were measured using surface electromyography. The flexion angles of the upper and lower thoracic spine, and extension angle of the lumbar spine were measured using a 6-DF electromagnetic motion tracking system. The association with LBPH was investigated using multiple logistic regression analysis with a forward selection method, with the activities of the back muscles, sagittal spinal alignment, age, body height, and body weight as independent variables.

RESULTS

Multiple logistic regression analysis (p = 0.0002) showed that the activity of the latissimus dorsi and thoracic erector spinae muscles in the side on which the lower extremity was lifted and body height were significant and independent determinants of LBPH, but other factors were not.

SIGNIFICANCE

The results of this study suggest that the activity of the latissimus dorsi and thoracic erector spinae muscles increases while there are no decrease in activity of the lumbar multifidus muscle and excessive extension of the lumbar spine during QULEL in young men with LBPH.

Postural stability and trunk muscle responses to the static and perturbed balance tasks in individuals with and without symptomatic degenerative lumbar disease

BACKGROUND

Degenerative lumbar diseases (DLDs) are characterized by motor functional deficits and postural instability. In this study, we investigated the differences in the trunk muscle responses to postural control between the presurgical DLD patients and healthy individuals while performing the static and perturbed balance tasks.

METHODS

Thirty-five DLD patients (aged 61.1 ± 8.0 years) and thirty-five asymptomatic controls (aged 62.9 ± 3.7 years) participated in this study. All participants stood on a force plate and performed the quiet standing (QS) and in situ weight-lifting (WL) tasks. The participants' performance in the QS task was tested under the eyes-open, eyes-closed, wide-base, and narrow-base conditions. Center of pressure (CoP) movements and electromyography of the erector spinae (ES) were recorded. The Mann-Whitney U test was applied for statistical analysis.

RESULTS

The DLD group showed a significantly greater CoP movements and muscle activations during the QS task. Nevertheless, smaller CoP movements were noted during the WL task in the DLD group. Under the eyes-closed and narrow-base conditions, the DLD group showed even higher muscle activations and CoP movements.

SIGNIFICANCE

The DLD patients demonstrated a poor postural control ability and tended to rely on the visual feedback and wide-base standing posture. A rigid and restricted posture was also adopted during the perturbed WL task. A high level of ES activation was required to maintain their postural steadiness. This study reveals an aberrant pattern of postural control and trunk muscle activations in symptomatic DLD patients which potentially contributes to the development of beneficial rehabilitation programs.

Trunk musculoskeletal response in maximum voluntary exertions: A combined measurement-modeling investigation

Maximum voluntary exertion (MVE) tasks quantify trunk strength and maximal muscle electromyography (EMG) activities with both clinical and biomechanical implications. The aims here are to evaluate the performance of an existing trunk musculoskeletal model, estimate maximum muscle stresses and spinal forces, and explore likely differences between males and females in maximum voluntary exertions. We, therefore, measured trunk strength and EMG activities of 19 healthy right-handed subjects (9 females and 10 males) in flexion, extension, lateral and axial directions. MVEs for all subjects were then simulated in a subject-specific trunk musculoskeletal model, and estimated muscle activities were compared with EMGs. Analysis of variance was used to compare measured moments and estimated spinal loads at the L5-S1 level between females and males. MVE moments in both sexes were greatest in extension (means of 236 Nm in males and 190 Nm in females) and least in left axial torque (97 Nm in males and 64 Nm in females). Being much greater in lateral and axial MVEs, coupled moments reached ∼50% of primary moments in average. Females exerted less moments in all directions reaching significance except in flexion. Muscle activity estimations were strongly correlated with measurements in flexion and extension (Pearson's r = 0.69 and 0.76), but the correlations were very weak in lateral and axial MVEs (Pearson's r = 0.27 and 0.13). Maximum muscle stress was in average 0.80 ± 0.42 MPa but varied among muscles from 0.40 ± 0.22  MPa in rectus abdominis to 0.99 ± 0.29 MPa in external oblique. To estimate maximum muscle stresses and evaluate validity of a musculoskeletal model, MVEs in all directions with all coupled moments should be considered.

Association of low back pain with muscle stiffness and muscle mass of the lumbar back muscles, and sagittal spinal alignment in young and middle-aged medical workers

BACKGROUND

Muscle stiffness of the lumbar back muscles in low back pain (LBP) patients has not been clearly elucidated because quantitative assessment of the stiffness of individual muscles was conventionally difficult. This study aimed to examine the association of LBP with muscle stiffness assessed using ultrasonic shear wave elastography (SWE) and muscle mass of the lumbar back muscle, and spinal alignment in young and middle-aged medical workers.

METHODS

The study comprised 23 asymptomatic medical workers [control (CTR) group] and 9 medical workers with LBP (LBP group). Muscle stiffness and mass of the lumbar back muscles (lumbar erector spinae, multifidus, and quadratus lumborum) in the prone position were measured using ultrasonic SWE. Sagittal spinal alignment in the standing and prone positions was measured using a Spinal Mouse. The association with LBP was investigated by multiple logistic regression analysis with a forward selection method. The analysis was conducted using the shear elastic modulus and muscle thickness of the lumbar back muscles, and spinal alignment, age, body height, body weight, and sex as independent variables.

FINDINGS

Multiple logistic regression analysis showed that muscle stiffness of the lumbar multifidus muscle and body height were significant and independent determinants of LBP, but that muscle mass and spinal alignment were not. Muscle stiffness of the lumbar multifidus muscle in the LBP group was significantly higher than that in the CTR group.

INTERPRETATION

The results of this study suggest that LBP is associated with muscle stiffness of the lumbar multifidus muscle in young and middle-aged medical workers.

Relative mobility of the pelvis and spine during trunk axial rotation in chronic low back pain patients: A case-control study

Background

Trunk axial rotation is a risk factor for chronic low back pain (CLBP). The characteristics of rotational mobility in the pelvis and spine among CLBP patients are not fully understood.

Purpose

The purpose of this study was to examine three-dimensional kinematic changes, and to compare the differences of rotational mobility and coupled motion, in patients with and without CLBP.

Methods

Fifteen patients with CLBP and 15 age and sex matched healthy subjects participated in this study. Each subject performed trunk rotation to maximum range of motion (ROM) in a standing position. The kinematics data was collected using a three-dimensional motion analysis system. The outcomes measured were the rotational ROM and the spine/pelvis ratio (SPR) in transvers plane at both maximum and 50% rotation position. The coupled angles in sagittal and frontal planes were also measured.

Results

No significant differences in rotational ROM of the thorax, pelvis, and spine were observed between two groups at maximum rotation position. However, there was a significant interaction between groups and rotational ROM of pelvis and spine (F = 4.57, p = 0.04), and the SPR in CLBP patients was significantly greater than that of the healthy subjects (CLBP; 0.50 ± 0.10 Control; 0.41 ± 0.12, p = 0.04). The results at 50% rotation position were similar to that at maximum rotation. This indicates a relative increase in spinal rotation in the CLBP patients during trunk rotation. Moreover, the CLBP patients exhibited a significantly higher anterior tilt of the pelvis and extension of the spine in the sagittal plane coupled with rotation.

Conclusions

CLBP patients had relative hyper rotational mobility of the spine as well as excessive spinal extension coupled with trunk rotation. These results suggest that uncoordinated trunk rotation might be a functional failure associated with CLBP.

A Randomised, Placebo-Controlled Trial of Neurodynamic Sliders on Hamstring Responses in Footballers with Hamstring Tightness

BACKGROUND

Neurodynamics intervention is known to increase apparent muscle extensibility, but information regarding hamstring responses after a neurodynamic sliders (NS) technique is scarce. The aim of this study was to evaluate the effects of NS on apparent hamstring extensibility and activity in footballers with hamstring tightness.

METHODS

Forty eligible healthy male footballers with hamstring tightness were each randomly allocated to either a 4-week NS technique or a control group (CG) receiving placebo shortwave intervention. Knee extension angles were measured with the passive knee extension test, and maximal voluntary isometric contraction (MVIC) of hamstrings was measured by a surface electromyography at baseline and after intervention sessions.

RESULTS

The results showed that NS produced a statistically and clinically significant increase in knee extension angle compared to CG (P < 0.001); however, there was no difference between the groups receiving MVIC of hamstrings. Within group comparison, NS also provided a significant increase in knee extension angle (P < 0.001), whereas the control group did not. There was no change in hamstring MVIC in either group after intervention.

CONCLUSIONS

The findings of this study reveal that four weeks of NS technique improved apparent hamstring extensibility but did not change the hamstring activity in footballers with hamstring tightness.

Comparison of the different kinematic patterns during lateral bending between subjects with and without recurrent low back pain

BACKGROUND

Lateral bending is a prerequisite for various functional activities of daily life, which require combined three-dimensional motion. Even though a number of studies have evaluated spinal kinematic changes during lateral bending, the literature reveals a lack of data based on limb dominance. The purpose of this study was to compare kinematic angular displacement of the spinal regions for dominant and non-dominant lateral bending in subjects with and without recurrent low back pain.

METHODS

Forty-four right hand dominant individuals with recurrent low back pain (43.1 [17.4] years) and without low back pain (39.7 [18.7] years) participated in this study. All participants were asked to perform trunk lateral bending to the dominant and non-dominant sides with a bar, three times repeatedly. The outcome measures included three-dimensional angular displacements for the three regions of the spine (upper thorax, lower thorax, and lumbar spine).

FINDINGS

Lumbar rotation (degrees) increased to the dominant side in the low back pain group (9.29 [1.06]) compared to the control group (6.20 [1.02]) with increased rotation in the upper thorax as well (t=-2.09, p=0.04). However, the upper thorax rotation increased in the low back pain group to the non-dominant side (t=2.08, p=0.03) and to the dominant side (t=-2.35, p=0.02). There was a group interaction with planes (F=5.82, p=0.02) during lateral bending.

INTERPRETATION

Although lower thorax motion was not different between groups, increased lumbar spine and upper thorax rotations to the dominant side in the low back pain group were evident during lateral bending. This directional asymmetry should be carefully monitored to understand increased lumbar rotation to the dominant side in subjects with recurrent low back pain. The interactions between group and plane explain compensation strategies through increased lumbar rotation to the dominant side with decreased lateral bending of the upper thorax in subjects with recurrent low back pain.

The ergonomics of laparoscopic surgery: a quantitative study of the time and motion of laparoscopic surgeons in live surgical environments

BACKGROUND

Laparoscopic surgery presents multiple ergonomic difficulties for the surgeon, requiring awkward body postures and prolonged static muscle loading that increases risk of musculoskeletal strain and injury. This prospective study quantitatively measures the biomechanical movements of surgeons during laparoscopic procedures to determine at-risk movements from prolonged static muscle loading and repetitive motions that may lead to injury.

METHODS

A total of 150 video recordings of 18 surgeons, standing at the patient's left, were captured from three fixed camera positions during live gynecological laparoscopic surgery. Postoperative processing quantified surgeon movements at the neck, shoulders and elbows using computer software to measure extreme joint angles and time spent within defined joint angle ranges.

RESULTS

Surgeons spent a median of 98 % (range 77-100 %) of surgical time with their neck rotated at 21° (range 0°-52°). The non-dominant arm was subjected to more extreme positions for significantly longer periods of time compared to the dominant, with shoulder flexion at 45°-90° for 35 vs. 0 % (p < 0.001) and elbow flexion at >120° for 31 vs. 0 % (p < 0.001) of total surgical time. Procedures involving power morcellation required significantly greater number of instrument insertion/removals-119 (range 56-182) compared with 12 (range 2-122) when morcellation was not used (p < 0.001). Shorter surgeons maintained significantly greater degrees of neck rotation when viewing the monitor (p < 0.003) and surgeons with shorter arm lengths spent longer in extreme positions with their non-dominant shoulder at >90° (p = 0.04) and elbow at >120° (p < 0.001) compared with taller surgeons. No significant correlations were found between BMI or surgical experience and more extreme joint positions.

CONCLUSIONS

Four primary areas have been identified where surgeons are consistently demonstrating movements that increase their risk of harm: (1) extended periods of neck rotation; (2) asymmetrical loading between the dominant and non-dominant shoulders; (3) power morcellation and frequent insertions/removals of laparoscopic instruments resulting in repetitions of the most extreme shoulder positions and (4) a negative correlation between height and percentage time spent in more extreme positions.

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.

Assessment of bioelectrical activity of synergistic muscles during pelvic floor muscles activation in postmenopausal women with and without stress urinary incontinence: a preliminary observational study

OBJECTIVE

Muscles such as adductor magnus (AM), gluteus maximus (GM), rectus abdominis (RA), and abdominal external and internal oblique muscles are considered to play an important role in the treatment of stress urinary incontinence (SUI), and the relationship between contraction of these muscles and pelvic floor muscles (PFM) has been established in previous studies. Synergistic muscle activation intensifies a woman's ability to contract the PFM. In some cases, even for continent women, it is not possible to fully contract their PFM without involving the synergistic muscles. The primary aim of this study was to assess the surface electromyographic activity of synergistic muscles to PFM (SPFM) during resting and functional PFM activation in postmenopausal women with and without SUI.

MATERIALS AND METHODS

This study was a preliminary, prospective, cross-sectional observational study and included volunteers and patients who visited the Department and Clinic of Urology, University Hospital in Wroclaw, Poland. Forty-two patients participated in the study and were screened for eligibility criteria. Thirty participants satisfied the criteria and were categorized into two groups: women with SUI (n=16) and continent women (n=14). The bioelectrical activity of PFM and SPFM (AM, RA, GM) was recorded with a surface electromyographic instrument in a standing position during resting and functional PFM activity.

RESULTS

Bioelectrical activity of RA was significantly higher in the incontinent group than in the continent group. These results concern the RA activity during resting and functional PFM activity. The results for other muscles showed no significant difference in bioelectrical activity between groups.

CONCLUSION

In women with SUI, during the isolated activation of PFM, an increased synergistic activity of RA muscle was observed; however, this activity was not observed in asymptomatic women. This may indicate the important accessory contribution of these muscles in the mechanism of continence.

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.

A kinematic analysis for shoulder and pelvis coordination during axial trunk rotation in subjects with and without recurrent low back pain

The purpose of this study was to compare the kinematics of the shoulder and pelvis based on range of motion (ROM), angular velocity, and relative phase (RP) values during trunk axial rotation. Nineteen subjects with recurrent low back pain (LBP) and 19 age-matched control subjects who are all right limb dominant participated in this study. All participants were asked to perform axial trunk rotation activities at a self-selected speed to the end of maximum range in a standing position. The outcome measures included ROM, angular velocity, and RP on the shoulder and pelvis in the transverse plane and were analyzed based on the demographic characteristics between groups. The LBP group demonstrated decreased ROM (p=0.02) and angular velocity (p=0.02) for the pelvis; however, there was no group difference for the shoulder girdle. The ROM difference between the shoulder and pelvic transverse planes had a significant interaction with age (F=14.75, p=0.001). The LBP group demonstrated a higher negative correlation between the shoulder (r=-0.74, p=0.001) and pelvis (r=-0.72, p=0.001) as age increased while no significant correlations were found in the control group. The results of this study indicated that there was a difference in pelvic rotation in the transverse plane between groups during axial trunk rotation. It would be important to coordinate postural stability between the shoulder and pelvic girdles during ambulation; however, the pattern of trunk movement decreased with age due to possible pelvic stiffness in subjects with recurrent LBP. Therefore, improved pelvic flexibility for coordinated trunk movement patterns would help subjects with recurrent LBP.

Axial rotation mechanics in a cadaveric lumbar spine model: a biomechanical analysis

BACKGROUND CONTEXT

Postoperative patient motions are difficult to directly control. Very slow quasistatic motions are intuitively believed to be safer for patients, compared with fast dynamic motions, because the torque on the spine is reduced. Therefore, the outcomes of varying axial rotation (AR) angular loading rate during in vitro testing could expand the understanding of the dynamic behavior and spine response.

PURPOSE

To observe the effects of the loading rate in AR mechanics of lumbar cadaveric spines via in vitro biomechanical testing.

STUDY DESIGN

An in vitro biomechanical study in lumbar cadaveric spines.

METHODS

Fifteen lumbar cadaveric segments (L1-S1) were tested with varying loading frequencies of AR. Five different frequencies were normalized with the base line frequency (0.125 Hz n=15) in this analysis: 0.05 Hz (n=6), 0.166 Hz (n=6), 0.2 Hz (n=10), 0.25 Hz (n=10), and 0.4 Hz (n=8).

RESULTS

The lowest frequency (0.05 Hz) revealed significant differences (p<.05) for all parameters (torque, passive angular velocity, axial velocity [AV], axial reaction force [RF], and energy loss [EL]) with respect to all other frequencies. Significant differences (p<.05) were observed in the following: torque (0.4 Hz with respect to 0.2 Hz and 0.25 Hz), passive sagittal angular velocity (SAV) (0.4 Hz with respect to all other frequencies; 0.166 Hz with respect to 0.25 Hz), axial linear velocity (0.4 Hz with respect to all other frequencies), and RF (0.4 Hz with respect to 0.2 Hz and 0.25 Hz). Strong correlations (R2>0.75, p<.05) were observed between RF with intradiscal pressure (IDP) and AR angular displacement with IDP. Intradiscal pressure (p<.05) was significantly larger in 0.2 Hz in comparison with 0.125 Hz.

CONCLUSIONS

Evidences suggest that measurements at very small frequencies (0.05 Hz) of torque, SAV, AV, RF, and EL are significantly reduced when compared with higher frequencies (0.166 Hz, 0.2 Hz, 0.25 Hz, and 0.4 Hz). Higher frequencies increase torque, RF, passive SAV, and AV. Higher frequencies induce a greater IDP in comparison with lower frequencies.