Low Back Muscle Activity Research Articles

Effects of time-dependent acupuncture on back muscle endurance in women with chronic nonspecific low back pain: A randomized crossover trial.

Chronic nonspecific low back pain (CNLBP) is a leading cause of disability and remains a major burden for many public health systems. Acupuncture is a nonpharmacological treatment for CNLBP that can be effective in improving low back pain; nevertheless, its effect on improving back muscle endurance in patients with CNLBP and its duration of effect have not been studied. The goal of this study was to assess the impact of acupuncture on lower back muscle activity in CNLBP patients. This was a single-blind, randomized, crossover experimental study. Thirty female patients were randomized into Group A (15 patients) or Group B (15 patients). Patients in Group A were assigned to receive real acupuncture (RA) in the first phase and sham acupuncture (SA) in the second phase, while those in Group B received SA first and then RA, with a 1-week washout period between phases. Two-way repeated ANOVA was used to evaluate the effect of group and time on isokinetic parameters, Surface electromyography (sEMG) data, and blood data. Significant interaction effects were identified between group * time on the isokinetic parameters of the lumbar extensor muscles, sEMG values of the erector spinae, blood lactate levels, and blood ammonia levels (all p< 0.05). Compared with those of the SA group, the isokinetic parameters of the lumbar extensor muscles, sEMG values of the erector spinae, blood lactate levels, and blood ammonia levels of the RA group were significantly different (all p< 0.05). RA improves lumbar extensor endurance in patients with CNLBP and lasts approximately 9 minutes. RA can improve blood circulation to reduce blood lactic acid and blood ammonia produced during exercise.

How Effective Are Forecasting Models in Predicting Effects of Exoskeletons on Fatigue Progression?

Forecasting can be utilized to predict future trends in physiological demands, which can be beneficial for developing effective interventions. This study implemented forecasting models to predict fatigue level progression when performing exoskeleton (EXO)-assisted tasks. Specifically, perceived and muscle activity data were utilized from nine recruited participants who performed 45° trunk flexion tasks intermittently with and without assistance until they reached medium-high exertion in the low-back region. Two forecasting algorithms, Autoregressive Integrated Moving Average (ARIMA) and Facebook Prophet, were implemented using perceived fatigue levels alone, and with external features of low-back muscle activity. Findings showed that univariate models without external features performed better with the Prophet model having the lowest mean (SD) of root mean squared error (RMSE) across participants of 0.62 (0.24) and 0.67 (0.29) with and without EXO-assisted tasks, respectively. Temporal effects of BSIE on delaying fatigue progression were then evaluated by forecasting back fatigue up to 20 trials. The slope of fatigue progression for 20 trials without assistance was ~48-52% higher vs. with assistance. Median benefits of 54% and 43% were observed for ARIMA (with external features) and Prophet algorithms, respectively. This study demonstrates some potential applications for forecasting models for workforce health monitoring, intervention assessment, and injury prevention.

Evaluation of a passive back-support exoskeleton during in-bed patient handling tasks

This study evaluated the effects of a back-support exoskeleton on the trunk and hip joint angles, lower back muscle activity and heart rate during four patient handling tasks: assisting a patient from sitting to lying, laterally repositioning the patient and turning the patient in two directions. Eight participants performed these tasks with and without the exoskeleton. Results demonstrated a significant reduction in the lower back muscle activity, but less pronounced effects for other tasks involving minimal trunk flexion. Hip flexion angles were reduced for all tasks when the exoskeleton was worn. The amount of reduction in the muscle activity and changes in the trunk and hip angles varied by task. The exoskeleton did not affect the heart rate across all tasks. The exoskeleton appeared to be more effective in tasks requiring substantial trunk flexion, indicating its potential benefits for reducing lower back muscle strain during such activities.

A mixed methods approach to describe the efficacy of lift assist device use to reduce low back musculoskeletal disorder risk factors during three common patient extrication scenarios

This mixed-method study evaluated the efficacy of lift assist device use (Binder®, Eagle®, Maxi Air®) relative to manual lifting/care-as-usual in reducing low back muscle activity and perceived exertion during simulated patient extrication tasks. User feedback was recorded to identify factors that might influence use. Twenty paramedics performed a floor to stretcher lift, lateral transfer, and confined space extrication care-as-usual and with lift assist devices. Use of a lift assist reduced low back muscle activity during floor to stretcher and confined space tasks by 34–47%. Paramedics perceived exertion decreased from ‘somewhat hard’ to ‘light’ or ‘very light’ when using an assistive device. Paramedics noted that ease of use, patient comfort, task time, patient acuity, among other considerations would influence use decisions. Lift assist devices were efficacious at reducing low back muscle activity and perceived exertion during floor to stretcher and patient extrication tasks.

A randomized controlled trial investigating the impact of a single flash cupping session on patients with chronic lower back pain using multichannel surface electromyographic assessment.

Chronic lower back pain (CLBP) is one of the most common disorders worldwide. Flash cupping has the ability to relieve CLBP; nevertheless, its impact on CLBP and the likely mechanism of action have not been studied. The goal of this study was to assess the impact of a single, brief cupping session on CLBP and low back muscle activity using multichannel surface electromyography (sEMG). In this randomized controlled trial, 24patients with CLBP were enrolled and randomly assigned to the control group (treated by acupuncture) and cupping group (treated by acupuncture and flash cupping). Acupuncture was applied on the shen shu (BL23), dachang shu (BL25), and wei zhong (BL40) acupoints in both the groups. A brief cupping treatment was applied to the shen shu (BL23), qihai shu (BL24), dachang shu (BL25), guanyuan shu (BL26), and xiaochang shu (BL27) acupoints on both sides of the lower back in the cupping group. The numeric rating scale (NRS) was used to assess therapy efficacy for lower back pain (LBP) before and after treatment. Surface EMG data collected during symmetrical trunk flexion-extension movements were utilized to measure lower back muscle activity and the effectiveness of LBP therapy. There was no statistically significant difference (P= 0.63) in pain intensity between the two groups before and after treatment. There was a statistically significant difference (P= 0.04) between the control group and the cupping group in the sEMG topographic map parameter CoGx-To-Midline. This study established a connection between the action mechanism of flash cupping and enhanced horizontal synchronization of lower back muscular activity.

Chronic low back pain and muscle activity in women during the sit-to-stand task: A cross-sectional study

IntroductionThe ability to stand up and sit down is important. Due to the large number of repetitions of these activities during the day and the demand that the task requires, it is cited as painful in the presence of low back pain (LBP). Individuals with LBP present alterations in muscle activation, however, this statement needs to be verified during everyday situations like the sit-to-stand task (STST). Therefore, the objective was to evaluate the muscle recruitment of women with and without LBP during the STST. Methods35 women were evaluated, and allocated into the control group (CG n = 15) and the low back pain group (LBPG n = 20). The protocol consisted of clinical evaluation and the sit-to-stand task (STST). Electromyographic signals of the lumbar multifidus (LM), internal oblique (IO) and external oblique (EO), rectus abdominis (RA), and lumbar iliocostalis (LI) were carried out concomitantly with the STST. To verify normality, the Shapiro-Wilk test was used. For the characterization of the sample, the MANOVA test was chosen and the MANCOVA test was also chosen to compare the characteristics of the participants. ResultsRegarding the data analysis of the electromyographic signals, higher values were seen in the RA (moments 2 and 3) in the LBPG in the STST. ConclusionThe present study showed that women with chronic LBP present higher muscle activation of the rectus abdominis in the sit-to-stand task.

스마트 자동차 좌석을 이용한 엉덩이의 동적 균형조절이 코어 등근육 활성도에 미치는 효과

Sitting in a car seat for a long time causes fatigue in muscles such as trapezius and paraspinal muscles, which increases muscle fatigue and tension and eventually causes in degenerative spinal changes and pain. Therefore, the authors attempt to investigate the effect of trapezius and lower back muscle activity changes on whether fatigue may be improved by balancing the buttock contact pressure in the sitting position. The purpose of this study was to assess the electrophysiologic effect of dynamic balance control for the trapezius and lower core back muscles through wireless surface electromyographic evaluation using the smart car seat equipped with an ICT-based air bladder. Surface electromyography (sEMG) was measured for each 32 participant’s trapezius and lumbar back muscles in three phases: 1) initial on standing, 2) seated for 25 minutes without balancing ischial pressure, 3) seated for 25 minutes with balancing ischial pressure, and then sEMG was measured for 1 minute on the standing of three individual phases. In the trapezius and low back muscles, the sEMG value of the three-phase MVIC showed a statistically significant increase in the left side compared to the right side (p0.0001). % MVIC difference increased in unbalanced seating (7.32±0.83) compared to the initial measure (7.24±1.72). However, it decreased with balancing seating(6.73±1.81, p=0.049). There was no statistically significant difference in the overall %MVIC differences between both lower back muscles among three phases (p=0.35), but the balanced seating showed a slightly increased % MVIC difference (p=0.10) in contrast to that of the trapezius. Balanced control of hip pressure using automatic logic control of ICT-based smart car seats has the effect of reducing the left-right difference in muscle activity of upper core muscles compared to that of non-balanced seating. Conclusively, it is believed that the difference in the left and right imbalances in the activity of trapezius can be alleviated through the pressure balance seating at the driver’s seat, and the effect of improving muscle fatigue can be expected. Nevertheless, driving in a sitting position, regardless of balance control, the lower core muscles continue to increase the activity of the lumbar muscles, which inevitably causes pain, discomfort, and fatigue over time. Wireless bio-sensing and balanced seat control using ICT-integrated smart car seats can be used as important application science fields that can improve muscle fatigue and degenerative spinal changes associated with professional workers.

Effects of a Core Strengthening Program on Muscle Activity Patterns, Strength, and Endurance in People with and without a History of Low Back Pain: A Randomized Controlled Trial

Background of Study: Altered patterns of abdominal and low back muscle activity have been reported in people in the sub-acute phase of low back injury. Specifically, higher overall muscle activity and less ability to match activity to task demands have been found. Objective: This study determined if an 8-week group exercise intervention would alter muscle activity, strength, and endurance in people with/without a history of low back pain (LBP). Method: In this randomized controlled trial 46 participants (age 19-55) with a history of LBP were randomized to exercise (LBPEx, n=24) and no-exercise (LBPCon, n=22) groups. 27 participants without a history of LBP (NoLBP) also exercised. 17 LBPEx and 19 NoLBP participants completed the intervention. 19 LBPCon were tested at 8-week follow-up. The exercise intervention was an 8-week, choreographed, 30-minute group exercise intervention (Les Mills CoreTM) focused on building core strength, stability, and endurance. Pre and post-intervention surface electromyograms from abdominal and low back muscles were recorded during a trunk stability task (TST), and analyzed using Principal Component Analysis to extract patterns corresponding to overall amplitude and relative activation during the TST loading phase. Abdominal and back extensor strength and endurance were also measured. Results: It was found that overall abdominal activity decreased for left anterior external oblique (p=0.019 for TST level 3), left lateral external oblique (p=0.012 for TST level 3), and right posterior external oblique (p=0.035 for TST level 3) in LBPEx and for right lateral external oblique (p=0.009 for TST level 2 and p=0.004 for TST level 3) and left posterior external oblique (p=0.014 for TST level 2 and p=0.011 for TST level 3) in NoLBP during the TST. Abdominal strength and endurance, and back extensor endurance increased for LBPEx and NoLBP (p0.05). Back extensor strength increased for NoLBP (p0.05). Relative abdominal activation during the TST level 2 loading phase increased for right upper rectus abdominus (p=0.05), right lateral external oblique (p=0.002), and left posterior external oblique (p=0.006) for NoLBP, and for left anterior external oblique (p=0.042) for LBPEx. Conclusion: Les Mills CoreTM is readily available and may be recommended as a safe, accessible, and effective intervention to increase abdominal strength and endurance, and back extensor endurance, even for people with a history of LBP.

Evaluation of vertical and multi-axial suspension seats for reducing vertical-dominant and multi-axial whole body vibration and associated neck and low back joint torque and muscle activity

The primary aim of this laboratory-based human subject study was to evaluate the biomechanical loading associated with mining vehicles’ multi-axial whole body vibration (WBV) by comparing joint torque and muscle activity in the neck and low back during three vibration conditions: mining vehicles’ multi-axial, on-road vehicles’ vertical-dominant, and no vibration. Moreover, the secondary aim was to determine the efficacy of a vertical passive air suspension and a prototype multi-axial active suspension seat in reducing WBV exposures and associated biomechanical loading measures. The peak joint torque and muscle activity in the neck and low back were higher when exposed to multi-axial vibration compared to the vertical-dominant or no vibration condition. When comparing the two suspension seats, there were limited differences in WBV, joint torque, and muscle activity. These results indicate that there is a need to develop more effective engineering controls to lower exposures to multi-axial WBV and related biomechanical loading. Practitioner Summary: This study found that mining vehicles’ multi-axial WBV can increase biomechanical loading in the neck and back more so than on-road vehicles’ vertical-dominant WBV. While a newly-developed multi-axial active suspension seat slightly reduced the overall WBV exposures, the results indicate that more effective engineering controls should be developed. Abbreviation: APDF: amplitude probability density function; Aw: weighted average vibration; BMI: body mass index; C7: The 7th cervical vertebra; EMG: electromyography; ES: erector spinae; IRB: institutional review board; ISO: International Organization for Standardization; L5/S1: the fifth lumbar vertebra (L5)/the first sacral vertebra(S1); MSDs: musculoskeletal disorders; MVC: maximum voluntary contraction; PSD: power spectral density; RVC: reference voluntary contraction; SCM: sternocleidomastoid; SD: standard deviation; SPL: splenius capitis; TRAP: trapezius; VDV: vibration dose value; WBV: whole body vibration

Effects on variation in shoulder, forearm and low back muscle activity from combining seated computer work with other productive office tasks: results from a simulation study

The effect on muscle activity variation of combining different office tasks is not known. We recorded electromyography from the upper trapezius (UT), wrist extensor (WE) and lumbar erector spinae (LES) in 24 office workers during five productive tasks, and breaks. Minute-to-minute variance was then estimated, by simulations, in a reference ‘job’ consisting of 85% sitting computer work and 15% breaks, and in ‘jobs’ where sitting computer work was replaced by different proportions of the other office tasks and breaks. Replacing sitting computer work with sitting non-computer work increased estimated variance by, in median, 23% (UT), 19% (WE) and 0% (LES). Replacing it with other tasks, in particular, standing computer work and non-desk work, was less effective in increasing variance. Thus, some combinations of office tasks have a slight potential to increase muscle activity variation in the shoulder and lower arm, but not the lumbar back, while others will be ineffective. Practitioner summary: The need for exposure variation is often emphasised in office ergonomics. We estimated the effect on muscle activity in the shoulder, forearm and lumbar back of combining sitting computer work with other available tasks and breaks, finding that introduction of sitting non-computer tasks and non-desk work slightly increased variation; other tasks were essentially non-effective.

Differences in myoelectric activity of the lumbar muscles between recurrent and chronic low back pain: a cross-sectional study

BackgroundAltered lower back muscle activity is proposed as a contributing factor to the reoccurrence and chronicity of low back pain (LBP). This study compared lumbar muscle activity during trunk extension in patients with continuous chronic LBP (CLBP), non-continuous CLBP, recurrent LBP (RLBP) and healthy subjects.MethodsIn 75 subjects (16 continuous CLBP, 15 non-continuous CLBP, 23 RLBP, 21 healthy controls), surface electromyographic (EMG) activity of the lumbar erector spinae (ES), multifidus (MF), latissimus dorsi (LD) and gluteus maximus (GM) was recorded during the concentric, holding and eccentric phase of a modified Biering Sorenson exercise.ResultsContinuous CLBP patients showed higher EMG activity in the ES and MF muscles compared to healthy controls in the concentric (p = 0.011; p = 0.009 respectively) and the holding phase (p = 0.015; p = 0.013). Higher EMG activity was observed in continuous CLBP compared to RLBP in the ES and MF muscles in the holding phase (p = 0.035; p = 0.037), and in the MF in the concentric phase (p = 0.046), but not in the ES (p = 0.062). No differences in muscle activity were established in either the concentric, holding, and eccentric phase for the LD and GM muscles. No differences were found between non-continuous CLBP and the other groups.ConclusionsAn enhanced muscle activity of the lumbar muscles during the concentric and holding phase was observed during trunk extension in patients with continuous CLBP compared to patients with RLBP and healthy subjects. No differences between groups are present in the GM and LD muscles during concentric and holding phases and for any muscle in the eccentric phase.

Investigating the effect of a passive trunk exoskeleton on local discomfort, perceived effort and spatial distribution of back muscles activity

This study aimed at determining the effect of a passive exoskeleton on local perceived discomfort, perceived effort and low back muscles’ activity. Thirteen volunteers performed two simulated working tasks with and without the exoskeleton. In the static task, the exoskeleton decreased the lumbar perceived discomfort, the perceived effort and the level of low back muscles’ activity (∼10%) while increasing discomfort in the chest and feet. The percent decrease in EMG amplitude was correlated with the percent increase in perceived effort with exoskeleton. For the dynamic task, the exoskeleton increased the discomfort in the chest and decreased the level of back muscle activity (∼5%). Current findings suggest exoskeleton is effective in reducing the back load while increasing the perceived discomfort at non-targeted body regions in both working tasks. The concurrent increase of discomfort in non-targeted areas probably led to a higher perceived effort despite the reduction of low back muscle activity. Practitioner summary: This study provided insights into exoskeleton effects on local discomfort, perceived effort and muscle activity. Overall, the potential benefits of passive exoskeleton should be considered alongside its adverse effects on the non-targeted body regions that can lead to an increase of perceived effort despite the reduction of back muscle activity.

The effects of different seat suspension types on occupants' physiologic responses and task performance: implications for autonomous and conventional vehicles

This study evaluated whole body vibration (WBV), non-driving task performance, muscle activity, and self-reported discomfort and motion sickness between different seat suspension systems in a simulated vehicle environment. In a repeated-measures laboratory experiment where field-measured 6-degree-of-freedom (6-DOF) passenger vehicle vibration was replicated on a 6-DOF motion platform, we measured WBV, non-driving task (pointing, typing, web-browsing, and reading) performance, low back (erector spinae), shoulders (trapezius) and neck (splenius capitis and sternocleido-mastoid) muscle activity, and self-reported discomfort and motion sickness from three different seats: a vertical (z-axis) active suspension, multi-axial active suspension [vertical (z-axis) + lateral (y-axis)], and a static suspension-less seat (current seat type in all passenger cars). Both the vertical and multi-axial active suspension seats significantly reduced the vertical WBV exposure (p < 0.0001). However, no significant differences were found in non-driving task performance (p > 0.30), muscle activity (p > 0.22), self-reported discomfort (p > 0.07), and motion sickness (p = 0.53) across three different seats. These findings indicate that the active suspension seats may have potential to future reduce the vertical and total WBV exposures, respectively. However, none of the suspension seats demonstrate any significant benefits on the non-driving task performance, muscle activity, self-reported discomfort and motion sickness measures in a simulated vehicle environment.

The impact of a progressive sit-stand rotation exposure duration on low back posture, muscle activation, and pain development

This study evaluated early and frequent seated breaks from standing work to reduce low back pain (LBP) in known pain developers (PD). Twenty-four participants, classified as either PD or non-PD during a separate 2-hour standing session, performed 124 minutes of standing work with seated breaks at a 3:1 stand-sit ratio with increasing durations from 3:1 minute to 48:16 minutes. Back pain and spine posture measures showed no differences between PD and non-PD. Females had greater left glutaeus medius activation (8.4%MVC) than males (4.5%MVC) and greater glutaeus medius co-contraction. This protocol was successful at reducing LBP in PD to the level of non-PD, with mean pain scores (13 mm) only slightly exceeding the clinical LBP threshold of 10 mm. Early and frequent breaks within the first hour of standing work appear to be an effective solution to reduce the LBP that often occurs at the beginning of standing work. Practicioner Summary: Sit-stand workstations may be an effective solution to reduce static occupational low back postures. This experimental study demonstrated that early and frequent seated breaks from standing work may be an effective solution to reduce tissue aggravation that often occurs within the first 45 minutes of a standing work exposure. Abbreviations: LBP: low back pain; PD: pain developer; NPD: non-pain developer; VAS: visual analog scale; EMG: electromyography; LES: lumbar erector spinae; TES: thoracic erector spinae; GMD: glutaeus medius; IOB: internal oblique; MVC: maximum voluntary contraction; CCI: co-activation coefficient; FDA: functional data analysis

Changes in Low Back Muscle Activity and Spine Kinematics in Response to Smartphone Use During Walking.

Within-subject design of an experimental study. The aim of this study was to determine the effects of smartphone use on the activity level of the lumbar erector spinae muscles and spine kinematics during walking. Using a smartphone while walking makes the user hold the phone steady and look downward to interact with the phone. Walking with this non-natural posture of the head and the arms may alter the spine kinematics and increase the muscular load on the low back extensor muscles. Twenty healthy young individuals participated in the laboratory experiment. Each participant walked on a treadmill in five different conditions: normal walking without using a phone, conducting one-handed browsing while walking, two-handed texting while walking, walking with one arm bound, and walking with both arms bound. Spine kinematics variables and the myoelectric activity levels of the lumbar erector spinae muscles were quantified and compared between the five walking conditions. Participants walked with significantly (P < 0.05) more thoracic kyphosis and lumbar lordosis when using a phone compared to when walking without using the phone. The median level of muscle activity was also 16.5% (browsing) to 31.8% (texting) greater for the two smartphone use conditions than for the normal walking condition, and the differences were significant (P < .05). Between the normal walking and the two bound arm walking conditions, no significant difference in the muscle activity was found. Study results show that the concurrent use of a smartphone while walking could pose a larger muscular load to the lumbar erector spinae muscles than that of normal walking. Habitual use of a smartphone while walking could be a risk factor for low back musculoskeletal problems.Level of Evidence: N/A.

The Effects of Aquatic Stabilization Exercise on Low Back Muscle Activity, Static Balance and Body Mass Index of Overweight Adults

The Effects of Aquatic Stabilization Exercise on Low Back Muscle Activity, Static Balance and Body Mass Index of Overweight Adults

Assessing potential trade-offs between the lower back and shoulders: influence of lift training intervention on joint demands

Background. Many of the approaches available for modifying manual materials handling (MMH) exertion emphasize lower back protection but often do not consider how interventions affect other body regions. This study focused on the influence of lift training on resultant joint moments and muscular demand trade-offs between the lower back and shoulders during MMH tasks. Methods. Three recommended lifting techniques (straddle lift, pivot technique and tripod lift) were compared to a priori (untrained) self-selected lifting techniques. Results. Mean and cumulative resultant moments indicated that using the lifting techniques evaluated in this investigation protected the shoulders more than the lower back. Mean and peak shoulder muscle activity also decreased following training (p < 0.05). Although there were no peak and mean changes to lower back muscle activity (p>0.05), there was a significant decrease in cumulative lower back muscle activity (p < 0.05). Reported perceived exertion values decreased following training across the lifting techniques for all evaluated body regions (p < 0.05). Conclusion. Overall, the recommended MMH techniques protected both the lower back and the shoulders, and no exposure trade-offs between them were identified.

Air-assisted devices reduce biomechanical loading in the low back and upper extremities during patient turning tasks

This laboratory study evaluated different assistive devices for reducing biomechanical loading during patient turning tasks. Twenty caregivers (18 females and 2 males) performed standardized patient turning tasks with two simulated patients (body mass: 74 kg and 102 kg). The turning tasks were performed in two turning directions (toward vs. away relative to caregivers) using five device conditions: draw sheet, friction-reducing turning sheet, air-assisted transfer device, air-assisted turning device, and no assistive device. Low back and upper extremity muscle activity, trunk and shoulder postures, low back moment, and self-reported usability ratings were evaluated. While all assistive devices reduced trunk flexion, both air-assisted transfer and turning devices reduced the trunk flexion (p's < 0.001) and muscle activity (p's < 0.001) in the erector spinae and triceps compared to no assistive device condition. These results suggest that the air-assisted devices have potential as an effective intervention to considerably reduce physical risk factors associated with caregivers' musculoskeletal disorders in low back and upper extremities.

Effect of dry-electrode-based transcranial direct current stimulation on chronic low back pain and low back muscle activities: A double-blind sham-controlled study.

Dry-electrode-based transcranial direct current stimulation is a new type of non-invasive brain stimulation system which relieves chronic low back pain and improves related muscle movement, in a way that overcomes the drawback of conventional systems. To investigate the effectiveness of dry-electrode-based transcranial direct current stimulation in relieving chronic low back pain and altering pain-related low back muscles movement, by using pain assessment tool and surface electromyographic topography. We conducted a prospective, double-blind, randomized, sham-controlled study. 60 patients with non-specific chronic low back pain were randomly and evenly allocated into tDCS and sham groups. Each group accepted a single 20-minute stimulation at 2 mA on the primary motor cortex. Numeric rating scale for pain intensity assessment and root-mean-square difference parameter from surface electromyographic topography were measured before and after stimulation. The current direction in brain using finite element method was simulated to verify the current distribution under dry stimulation electrode. After stimulation, the pain intensity in the tDCS group significantly decreased, while it did not show evident change in the sham group. However, change of root-mean-square difference parameters between tDCS and sham groups showed no significant difference. Simulation results based on finite element method showed most of current focused on primary motor cortex while peak value of current density was 0.225 A/m2. Dry-electrode-based transcranial direct current stimulation can lower pain perception in patients with chronic low back pain. The analgesic mechanism can affect the top-down modulation pathway of pain.

Robotic Surgery Is Less Physically Demanding Than Laparoscopic Surgery: Paired Cross Sectional Study.

To study musculoskeletal workload in experienced surgeons during laparoscopic surgery (LS) compared with robotic assisted laparoscopy (RALS). 70-90% of surgeons who regularly perform LS report musculoskeletal symptoms, mainly in neck and shoulders. Data regarding the potential ergonomic benefits of RALS in a clinical setting is very limited. Twelve surgeons with advanced experience in both LS and RALS each performed 2 hysterectomies on the same day. LS was performed standing, RALS sitting, the latter allowing forearm and head support. Bipolar surface electromyogram (EMG) was recorded from several muscles and was expressed relative to EMG during maximum contractions (%EMGmax). Gaps per minute plus static (p0.1), mean (p0.5), and peak (p0.9) muscle activation were calculated. Perceived exertion was rated before and just after each surgery. Neck muscle activity (p0.1 4.7 vs. 3.0%EMGmax, p0.5 7.4 vs. 5.3%EMGmax, p0.9 11.6 vs. 8.2%EMGmax, all P < 0.05) and static shoulder muscle activity (p0.1 5.7 vs. 2.8%EMGmax, P < 0.05) were higher for LS than for RALS. Both a higher level of gaps during RALS and a lower rating of perceived exertion, also for the legs, after RALS supported these observations. However, low back muscle activity was higher for RALS. RALS is significantly less physically demanding than LS, and also feels less strenuous for the surgeons. However, for both types of surgeries, there still is room for improvement of working conditions. To further optimize these, we suggest a scheme to regularly observe and advise the surgeons.