Back posture and low back muscle activity in female computer workers: a field study

The impact of breaking up sitting during simulated nightshifts on musculoskeletal pain: A randomised controlled trial

OBJECTIVES

Prolonged sitting is associated with an increased risk of musculoskeletal pain, especially in nightshift workers. However, research investigating effects of breaking up sitting on musculoskeletal pain during nightshifts is lacking. This study evaluated effects of prolonged sitting or breaking up sitting with short bouts of light-intensity physical activity on pain in healthy adults during simulated nightshifts.

METHODS

An in-laboratory randomised controlled trial was undertaken with 52 healthy adults completing five simulated nightshifts. Participants were randomised to prolonged sitting (Sit9; n = 26) or breaking up prolonged sitting (Break9; n = 26). Break9 group completed 3-min walking every 30 min during nightshifts, while Sit9 group remained seated. Musculoskeletal pain intensity and sensory/affective pain experiences were assessed. Linear mixed models examined pain within nights (pre-to post-shift) and across nights (pre-shift-night-1 to pre-shift-night-5).

RESULTS

Musculoskeletal pain intensity increased within nights for both Sit9 (mean change [95%CI] points: 0.14 [0.05, 0.24]) and Break9 (0.09 [0.001, 0.19], but not across nights (Sit9: -0.13 [-0.33, 0.08]; Break9: 0.07 [-0.14, 0.29]). Sensory-pain experience improved across nights for Sit9 (-3.08 [-4.72, -1.45]), but not within nights (0.77 [-0.004, 1.55]). There was no change in affective-pain experience in either group. Between-group difference was observed favouring Sit9 for improving sensory-pain across nights (β: 3.71 [1.42, 5.99]). No other between-group difference was observed.

CONCLUSION

Both prolonged sitting and breaking up sitting were associated with a within-night increase in musculoskeletal pain intensity. Compared to prolonged sitting, breaking up sitting did not induce benefits on pain in healthy adults working simulated nightshifts.

TRIAL REGISTRATION

ACTRN12619001516178.

A week-long field study of seated pelvis and lumbar spine kinematics during office work

The study objective was to quantify "natural" seated pelvis and lumbar spine kinematics over multiple days of work at individuals' workstations. Twenty participants completed five days of their usual office work while seated time was characterized from a thigh-worn activity monitor. Seated pelvic tilt and lumbar spine flexion-extension were measured from tri-axial accelerometers. Seated time accounted for approximately 90% of participants' workdays. Sitting was characterized by posterior pelvic tilt and lumbar flexion (43-79% of maximum flexion) with an average of 9 shifts and 13 fidgets every 15 min. No significant differences emerged by sex or between days indicating that a single representative day can capture baseline sitting responses in the field. Average field kinematics tended to agree with the laboratory-collected kinematics, but postural variability was larger in the field. These kinematic values could be useful for designing interventions aimed at reducing spine flexion and increasing spine movement in occupational sitting.

Active workstations: A literature review on workplace sitting

The purpose of this paper is to further understand current literature on prolonged sitting, sitting posture and active sitting solutions. This paper is divided into three sections: The first section (Part I) is a comprehensive overview of the literature on how a static prolonged seated posture can affect: spinal health, trunk posture, contact pressure/discomfort development and vascular issues. The second section (Part II) reviews and qualitatively compares the four working postures recognized in ANSI/HFES 100-2007: reclined sitting, upright sitting, declined sitting and standing. The final section (Part III) is a summary of research on active chairs that revolves around the two types of movement patterns: 1- sustaining continual movement over a range of postures, occasionally reaching neutral lordosis, and 2- maintaining high frequency and duration of daily light contractile activity in the legs (or lower limbs).

Forced Straightening of the Back Does Not Improve Body Shape

BACKGROUND

Sitting for a long time causes various postural problems, such as slump sitting. It has been reported that employing a corrected sitting position while lifting the sternum is effective in improving this form of posture. We investigated how a corrected sitting posture with the lifting of the sternum is different from a forced position that is applied through the command and passive positions.

MATERIALS AND METHODS

The postural angle of 270 subjects aged 19-23 years was measured in the passive, forced, and corrected positions using a Saunders inclinometer and a Formetric 4D system.

RESULTS

As a result, the corrected position had a small range (min-max) at all angles, but the forced position and passive position had a large range (min-max). The lumbar lordosis angle in the corrected position showed positive values throughout its range (min-max), while the other groups showed negative values, which indicates the kyphotic position of the lumbar section. In addition, the percentage error in the corrected position was small, but it presented high values in the other groups. When comparing the average angles between the groups, there were substantial changes observed between the corrected position and the other groups. It was found that the corrected position with the sternum lifted, which is applied to improve slump sitting in the clinical environment, exhibited an angle that differed from that of the forced position and the passive position.

CONCLUSIONS

Our results suggest that a forced position on the command "scapular retraction" does not meet the clinical assumptions of posture correction, in contrast to the corrected position with the lifting of the sternum for the improvement of slump sitting. The accurate correction of the position of the sternum and sacrum improves the position of the spine in the sagittal plane, enabling physiological values for the kyphosis and lordosis angle parameters to be obtained. This approach combines the ease of execution and precision of the effect. The fact that this method does not require complex tools to accurately correct the body encourages the implementation of this solution in clinical practice.

Comparisons of lumbosacral kinematics among non-specific chronic low back pain subgroups and healthy during prolonged sitting: A cross-sectional observational study

BACKGROUND

The literature has suggested a variety of postural changes of the spine that possibly contribute to the increase in back pain during sitting in persons with non-specific chronic low back pain (NS-CLBP). However, the heterogeneity of NS-CLBP persons has made the ability to attribute pain increase to a particular sitting posture very difficult. Therefore, the purpose of this study was to compare lumbosacral kinematics and their roles in pain increase among homogenous NS-CLBP subgroups and healthy controls over a 1-h sitting period.

METHODS

Twenty NS-CLBP subjects with motor control impairment [10 classified as having flexion pattern (FP) disorder, and 10 with active extension pattern (AEP) disorder], and 10 healthy controls participated in the study. Subjects underwent a 1-h sitting protocol on a standard office chair. Lumbosacral postures including sacral tilt, third lumbar vertebrae (L3) position, and relative lower lumbar angle were recorded using two-dimensional inclinometers over the 1-h period. Perceived back-pain intensity was measured using a visual analog scale every 10 min throughout the sitting period.

RESULTS

All study groups (FP, AEP and healthy controls) significantly differed from each other in the measured lumbosacral kinematics at the beginning as well as at the end of the sitting period (p ≤ 0.05). Only the NS-CLBP subgroups showed significant changes in the lumbosacral kinematics across the 1-h sitting period (p < 0.01), and that the directions of change occurred toward end spinal postures (lumbar kyphosis for FP subgroup and lumbar lordosis for the AEP subgroup). In addition, both NS-CLBP subgroups reported a similarly significant increase in pain through mid-sitting (p < 0.001). However, after mid-sitting, the AEP subgroup reported much less increase in pain level that was accompanied by a significant decrease in the lumbar lordotic postures (p = 0.001) compared to FP subgroup.

CONCLUSION

The present study's findings suggest that each NS-CLBP subgroup presented with differently inherent sitting postures. These inherently dysfunctional postures coupled with the directional changes in the lumbosacral kinematics toward the extreme ranges across the 1-h sitting period, might explain the significant increase in pain among subgroups.

Digital therapeutics-based lumbar core exercise for patients with low back pain: A prospective exploratory pilot study

Objective

This study aimed to implement a digital therapeutics-based approach based on motion detection technology and analyze the clinical results for patients with chronic low back pain (LBP).

Methods

A prospective, single-arm clinical trial was conducted with 22 patients who performed mobile app-based sitting core twist exercise for 12 weeks. Clinical outcomes were assessed using the visual analog scale (VAS) for LBP, Oswestry Disability Index-Korean version (K-ODI), and EuroQol-5 dimension 5-level version (EQ-5D-5L) every 4 weeks after the initiation of treatment. Laboratory tests for factors associated with muscle metabolism, plain X-ray for evaluating sagittal balance, and magnetic resonance imaging for calculating cross-sectional area (CSA) of back muscles were performed at pretreatment and 12 weeks post-treatment.

Results

The study population included 20 female patients with an average age of 45.77 ± 15.45 years. The clinical outcomes gradually improved throughout the study period in the VAS for LBP (from 6.05 ± 2.27 to 2.86 ± 1.86), K-ODI (from 16.18 ± 6.19 to 8.64 ± 5.58), and EQ-5D-5L (from 11.09 ± 3.24 to 7.23 ± 3.89) (p < 0.001, respectively). The laboratory test results did not show significant changes. Pelvic incidence (from 53.99 ± 9.70° to 50.80 ± 9.20°, p = 0.002) and the mismatch between pelvic incidence and lumbar lordosis (from 8.97± .67° to 5.28 ± 8.57°, p = 0.027) decreased significantly. Additionally, CSA of erector spinae and total back muscles increased by 5.20% (p < 0.001) and 3.08% (p = 0.013), respectively.

Conclusions

The results of this study suggest that the efficacy of digital therapy-based lumbar core exercise for LBP is favorable. However, further large-scale randomized controlled studies are necessary.

Increasing movement during office work at sit-stand workstations: A novel seating device to facilitate transitions

A novel active office chair (Movably Pro) was designed to facilitate frequent sit-stand movement 1) through auditory and tactile prompts and 2) with minimal-to-no work surface adjustment when transitioning. The purpose of this study was to compare lumbopelvic kinematics, discomfort, and task performance between the novel chair and traditional sitting/standing. Sixteen participants completed three separate 2-h sedentary exposures. Although participants transitioned every 3 min between sitting and standing with the novel chair, productivity was not affected. When standing in the novel chair, the lumbopelvic angles fell in between traditional sitting and standing (p < 0.01). Movement and/or postural changes that occurred with the novel chair reduced low back and leg discomfort for pain developers (PDs) (p < 0.01). All participants classified as PDs in traditional standing were non-PDs with the novel chair. This intervention was effective in reducing sedentary time without the time loss associated with desk movement.

Innovative seated vertical lumbar traction allows simultaneous computer work while inducing spinal height changes similar to supine lying

BACKGROUND

Lumbar intervertebral disc height loss has been associated with spinal height change (SHC) and low back pain (LBP), including stenosis. Non-invasive methods to improve disc height loss require forms of lying down, which are unconducive to computer work.

OBJECTIVE

Intermittent vertical traction (VT) integrated with seated computer work may provide ergonomic alternatives for increasing SHC to promote LBP relief. The primary aim was to develop and introduce a safe VT prototype and dosage to induce and measure SHC. Prototype comfort and LBP ratings were exploratory secondary aims.

METHODS

Forty-one participants were stadiometry-measured for pre- and post-intervention SHC from seated VT at 35% body weight removed, supine lying (SL), and sitting at a computer (SIT) without VT. Pain ratings were recorded for those self-reporting LBP. VT prototype evaluations were compiled from a 3-question, 7-point Likert-style survey.

RESULTS

SHC increased by 3.9 ± 3.4 mm in VT, 1.7 ± 3.4 mm in SIT, and 4.3 ± 3.1 mm in SL (P< 0.000). Post hoc findings were significant between VT and SIT (P< 0.000), and SL and SIT (P< 0.000). VT and SL LBP ratings both decreased, but not SIT.

CONCLUSION

Intermittent seated VT is a promising alternative for postural relief during seated computer work, producing SHC similar to lying down without compromising workflow.

The influence of sedentary behaviour on lumbar-pelvic kinematics during squatting and forward bending among physically active students

Prolonged sitting may involve several mechanisms that make it a risk factor for low back pain. The aim of this study was to investigate lumbar-pelvic kinematics and multifidus muscle (MF) activity during squatting and forward bending in relation to the sedentary behaviour of physically active students. Sixty-three students were divided into two groups according to the time spent in a sitting position during the day: 'high' (>7 h/day); 'low' (≤7 h/day). Lumbar-pelvic ratios, ranges of motion, angular velocities, and MF flexion-relaxation phenomenon were investigated. Data were obtained using the optical motion analysis system, and surface electromyography. The results indicated that lumbar-pelvic ratios during both tasks and velocity of lumbar spine during squatting were significantly greater in the 'high' than in the 'low' sitting group. Muscle activity showed no differences between groups. Prolonged sitting can be considered a factor that slightly, but statistically significantly influences the lumbar-pelvic kinematics in physically active people.Practitioner summary: Lumbar-pelvic kinematics can be altered by prolonged sitting in physically active students. Lumbar-pelvic ratios during squatting and forward bending and lumbar spine velocity during squatting were significantly greater in the 'high' than in the 'low' sitting group. Sedentary behaviour should be considered during an assessment of movement patterns.Abbreviations: BMI: body mass index; ERR: extension-relaxation ratio; FRP: flexion-relaxation phenomenon; FRR: flexion-relaxation ratio; IPAQ: International Physical Activity Questionnaire; LBP: low back pain; METs: metabolic equivalent of tasks; MF: multifidus muscle; PA: physical activity; ROM: range of motion; sEMG: surface electromyography.

Alignment of the Sternum and Sacrum as a Marker of Sitting Body Posture in Children

An analysis of literature on the methods of assuming a sitting position and the results of our own research indicated the need to search for biomechanical parameters and existing relationships that would enable a description of sitting body posture. The purpose of this paper is to analyze the relationship between the alignment of the body of sternum and sacrum and the changes in the thoracic and lumbar spine curvatures in children. The study involved 113 subjects aged 9-13 years. A planned simultaneous measurement of the angle parameters of the alignment of the body of sternum and sacrum relative to the body's sagittal axis and the angle parameters of the thoracic and lumbar spine curvatures was performed during a single examination session. The proposed markers of alignment in the corrected sitting body posture are characterized by homogeneous results. A high measurement repeatability was observed when determining the corrected body posture in the study setting. It was noted that changes in the alignment of the body of sternum and sacrum resulted in changes in the thoracic kyphosis and lumbar lordosis angle values, which may be an important component of clinical observations of sitting body posture in children. Implementing the body of sternum alignment angle of about 64° relative to the body's sagittal axis in clinical practice as one of the objectives of postural education may be the target solution for sitting body posture correction in children.

Associated Risk Factors with Low Back Pain in White-Collar Workers-A Cross-Sectional Study

Objective: The purpose of the study was to compare the pressure pain threshold (PPT) of soft tissue and the curvatures of the spine in a sitting position and to estimate associated physical risk factors with low back pain (LBP) in young adults. Subjects: White-collar workers (n= 139), both women (n = 51) and men (n = 88) were separated into a control group (n = 82) and a low-intensity LBP (NRS < 3) (n = 57). Methods: The PPTs were tested utilizing the Wagner algometer. The curvatures of the spine were measured employing the photogrammetric method. In the logistic regression model, the odds ratio (OR) was estimated with ±95% confidence interval (CI) indicating the probability of the reported LBP. Results: The PPTs of soft tissue (OR = 1.1; CI = 1.02−1.19; p < 0.05) and the angle of the thoracolumbar spine in the everyday, habitual sitting position (OR = 1.19; CI = 1.05−1.34; p < 0.05) were associated with low-intensity LBP in female subjects. Additionally, the low intensity LBP were associated with the angles of the torso (OR = 1.14; CI = 1.01−1.29; p < 0.05) and the lumbosacral spine in the corrected sitting position (OR = 1.06; CI = 0.98−1.15; p > 0.05) and BMI (OR = 1.56; CI = 0.84−2.90; p > 0.05) in male subjects. Conclusion: Individual risk factors were associated with the low-intensity LBP only in females utilizing the PPT and the thoracolumbar angle in the habitual sitting position study factors. Men from the LBP group did not effectively correct the lumbosacral angle. Therefore, re-educated, self-corrected posture with specific postural training would be expected to improve proprioception in postural control capacity and result in decreasing pain.

High Density Surface Electromyography Activity of the Lumbar Erector Spinae Muscles and Comfort/Discomfort Assessment in Piano Players: Comparison of Two Chairs

Introduction: At a professional level, pianists have a high prevalence of playing-related musculoskeletal disorders. This exploratory crossover study was carried out to assess and compare quantitatively [using high density surface electromyography (HDsEMG)], and qualitatively (using musculoskeletal questionnaires) the activity of the lumbar erector spinae muscles (ESM) and the comfort/discomfort in 16 pianists sitting on a standard piano stool (SS) and on an alternative chair (A-chair) with lumbar support and a trunk-thigh angle between 105° and 135°.

Materials and Methods: The subjects played for 55 min and HDsEMG was recorded for 20 s every 5 min. For the quantitative assessment of the muscle activity, the spatial mean of the root mean square (RMS_ROA) and the centroid of the region of activity (ROA) of the ESM were compared between the two chairs. For the qualitative assessment, musculoskeletal questionnaire-based scales were used: General Comfort Rating (GCR); Helander and Zhang’s comfort (HZc) and discomfort (HZd); and Body Part Discomfort (BPD).

Results: When using the A-chair, 14 out of 16 pianists (87.5%) showed a significantly lower RMS_ROA on the left and right side (p < 0.05). The mixed effects model revealed that both chairs (F = 28.21, p < 0.001) and sides (F = 204.01, p < 0.001) contributed to the mean RMS_ROA variation by subject (Z = 2.64, p = 0.004). GCR comfort indicated that participants found the A-Chair to be “quite comfortable,” and the SS to be “uncomfortable.” GCR discomfort indicated that the SS caused more numbness than the A-Chair (p = 0.05) and indicated the A-Chair to cause more feeling of cramps (p = 0.034). No difference was found on HZc (p = 0.091) or HZd (p = 0.31) between chairs. Female participants (n = 9) reported greater comfort when using the A-Chair than the SS (F = 7.09, p = 0.01) with respect to males. No differences between chairs were indicated by the BPD assessment.

Conclusion: It is concluded that using a chair with lumbar support, such as the A-chair, will provide greater comfort, less exertion of the ESM and less discomfort than the standard piano stool.

Investigation of office workers' sitting behaviors in an ergonomically adjusted workstation

Objectives. Common ergonomic office workstations are designed for a few optimum postures. Nonetheless, sitting is a dynamic activity and the ideal sitting posture is rarely maintained in practice. Therefore, the present study aimed to investigate the sitting behavior of office workers in an actual working environment using ergonomically adjusted workstations to examine whether they promote maintaining appropriate sitting postures. Methods. Sitting behaviors (frequency of postures and position changes in different body parts) were explored among 26 office workers during a 60-min sitting duration, using the posture recording and classification method developed by Graf et al. The rapid upper limb assessment (RULA) method was also used to assess postural load. Then, the results of the RULA method were compared with the results from investigating the sitting behavior of office workers. Results. Common ergonomic workstations were effective in eliminating some awkward postures. However, some important risk factors such as holding postures with an inappropriate lumbar spine curve (86% of the observations) and maintaining a posture for a long time (for 7-12 min) were observed in the participants' sitting behaviors, while they were neglected in the RULA method. Conclusions. The common ergonomic workstations could not guarantee the users' appropriate sitting behaviors.

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 and non-computer 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.

The Intertester Reliability of a Modified Movement System Impairment Classification System Used to Evaluate Individuals With Prolonged Sitting: A Preliminary Study

OBJECTIVE

Prolonged sitting while working at a computer leads to poor sitting postures, which can aggravate low back pain in many individuals. We examined the intertester reliability of using the modified musculoskeletal impairment schema for classifying participants sitting at computers for prolonged times.

METHODS

Fifty participants were examined independently by each therapist using a test-retest design. Each therapist assigned an musculoskeletal impairment classification upon completion of the examination. The agreement percentages and the kappa coefficient were used to evaluate intertester reliability in classifying participants with prolonged sitting.

RESULTS

The percentage agreement between the 2 examiners for participants who maintained the sitting posture for prolonged times was 84%. The calculated kappa coefficient was 0.73, reflecting a substantial level of agreement.

CONCLUSIONS

The present findings provide some evidence to support the classification of individuals who sit at computers for prolonged times and participants with rotation with flexion pattern would need to manage asymmetry pattern in a subclinical group.

The inconclusiveness of research on functional pathologies of the temporomandibular system and body posture: Paths followed, paths ahead: A critical review

Objective: Literature on the functional pathologies of the temporomandibular system (FPTS) in its relationships with body posture is plagued with inconclusiveness. Despite being sometimes altogether disregarded, the issue is most relevant, due to its clinical implications. This paper aims for a deeper understanding of the origins of the inconclusiveness of research on such relationships by means of a critical analysis of the scientific literature on the subject, in order that clinicians may better treat patients with FPTS.Methods: Analysis of over 100 studies, published from 1918 through March 2018 in the PubMed database, using descriptors temporomandibular joint disorders and posture.Results: The analysis of the paths followed by researchers allowed for pinning down several methodological issues that may have led to the prevailing ambiguity on the matter.Conclusion: This review then proposes certain standardization of procedures in future studies, to be conducted by a proposed consortium of researchers.

Effect of a posture correction-based intervention on musculoskeletal symptoms and fatigue among control room operators

This study was conducted to examine the effect of a posture correction-based intervention (with a biofeedback device) on the occurrence of musculoskeletal symptoms (MSS) and fatigue among control room operators in a petrochemical plant in Iran. A total of 188 office workers (91 in the case group and 97 in the control group) participated at baseline as well as at 6- and 12-month follow-up. A questionnaire survey (including the Nordic Musculoskeletal Questionnaire and Multidimensional Fatigue Inventory) and direct observations of working postures by using the Rapid Upper Limb Assessment (RULA) method were used. The occurrence of MSS in the shoulders, upper back, neck, and low back areas, as well as the mental and physical dimensions of fatigue were found to be the most common problems. The results showed considerable improvements in working postures (in the neck, trunk, and RULA grand scores) and the occurrence of MSS (particularly in the neck, shoulders, and upper back and low back areas) and fatigue (in particular the mental and physical aspects) after the intervention. The overall mean RULA grand score for the case group was significantly decreased after the intervention (mean scores of 5.1, 4.4, and 4.6 at pre-intervention, post-intervention 1, and post-intervention 2, respectively). A total of 81 operators (89.0%) reported some kind of MSS at baseline, which were reduced to 75 operators (82.4%) and 77 operators (84.6%) at post-interventions 1 and 2, respectively. Significant differences were also found between the pre- and post-intervention scores for the physical fatigue (mean of 12.19, 10.16, and 9.99 at pre-intervention, post-intervention 1, and post-intervention 2, respectively) and mental fatigue (mean of 14.03, 12.05, and 12.16 at pre-intervention, post-intervention 1, and post-intervention 2, respectively) dimensions. The findings confirm the effectiveness of this low-cost, simple, and easy-to-use ergonomic intervention.

Reduced muscle activity variability in lumbar extensor muscles during sustained sitting in individuals with chronic low back pain

The purpose of this study was to investigate muscle activity variability within and between the right and left side of lumbar muscles in patients with chronic low back pain (cLBP) compared to healthy controls (HCs) during sustained quiet sitting. Surface electromyographic (EMG) signals were collected bilaterally from the lumbar muscles with 2 high density surface EMG grids of 9x14 electrodes. Root mean square values (RMS) over 1-sec epochs of all bipolar EMG leadings were obtained. Between-sides alternating activation was computed, as well as temporal- and spatial variability within the electrode grids through the coefficient of variation and correlations between RMS distributions. The subjective influence of sitting was evaluated by the rating of perceived exertion and the amount of LBP on a numeric pain rating scale. Compared to HCs, the patients with cLBP had lower temporal (p = 0.03) and similar spatial muscle activity variability during sitting, despite a more variable sitting position. This did not result in increased muscle fatigue indicated by EMG, but the patients with cLBP reported higher levels of RPE during- and more LBP after the sitting and as a consequence ended the sitting earlier than HCs (p < 0.01). Present findings lend support to the presence of less tolerance for low-level static muscle load in patients with cLBP.

A Validation Study of a Polymer Optical Fiber Sensor for Monitoring Lumbar Spine Movement

This study aims to investigate the validity and reliability of a novel plastic optical fiber (POF) sensor, which was developed to measure the angles of flexion, extension and lateral bend at the lumbar region. The angles of flexion, extension and lateral bend for a standing position were measured simultaneously using both the novel POF sensor of this investigation and the commercial Biometrics goniometer instrument. Each movement had two steps of bending which were 10° and 20° based on inclinometer readings. The POF sensor had good intra-rater reliability (Intraclass correlation coefficient, ICC = 0.61 to 0.83). Bland–Altman plots were used to study the agreement using these two sensors. There were proportional differences and bias between the POF sensor and Biometrics goniometer, as the zero points did not lie in the percentage difference region in the Bland–Altman plots. The proportional difference between these two likely reflects the different sizes and thus, measurement regions of the two sensors. There was also strong correlation between the two sensors (r > 0.77). Hence, the POF sensor could be of potential utility in measuring lumbar range of motion (ROM) in a manner which is minimally invasive, and where discrete sections of the spine are under specific investigation.

Influences of continuous sitting and psychosocial stress on low back kinematics, kinetics, discomfort, and localized muscle fatigue during unsupported sitting activities

Continuous seated postures may increase the risk of adverse health outcomes such as low-back pain, and this risk may be influenced by several modifying factors. In the present study, we aimed to quantify the effects of continuous sitting and psychosocial stress under an unsupported sitting condition. Fourteen participants completed continuous, 40 min. periods of computer-based tasks, involving both low and higher levels of psychosocial stress, while using a laptop computer without a desk. Continuous sitting significantly increased perceived discomfort (particularly in the upper and lower back), trunk flexion and metrics of localized muscle fatigue. A higher level of psychosocial stress increased estimated lumbosacral compression forces (by ∼12%). Only weak correlations were found between subjective and objective measures, while various fatigue metrics showed a good level of correspondence with each other. These results could support the future evaluation or design of diverse seated work configurations. Practitioner Summary: Continuous, 40 min. periods of unsupported sitting had broad impacts on subjective and objective outcomes, including discomfort, postures, spine loads and localized muscle fatigue, while psychosocial stress only had a substantial influence on lumbosacral compression. These results extend our understanding of sitting behaviors and provide information for designing future sitting environments.

Effect of gel seat cushion on chronic low back pain in occupational drivers: A double-blind randomized controlled trial

BACKGROUND

Low back pain (LBP) is an exceedingly common medical condition that results in significant medical and social burden. Sitting for a long period is a common aggravating factor for LBP. Although seat cushion is known to promote comfort, relieve pressure, and correct posture, its effect on chronic LBP has not yet been investigated. This study aimed to evaluate the clinical effect of gel seat cushion on chronic LBP in occupational drivers.

METHODS

Occupational drivers with chronic LBP lasting for >6 months were recruited. Subjects were double-blinded, randomly assigned to 2 groups (gel and foam cushion groups), and instructed to use the provided cushions while driving. Pain threshold and tissue hardness were measured at tender points using a digital algometer. Numeric pain intensity scale (NPIS), Roland-Morris Disability Questionnaire (RMDQ), and Oswestry Disability Index (ODI) were used to analyze the primary endpoint, whereas the Beck Depression Inventory and Short Form-6D were used for the secondary endpoint.

RESULTS

Of 80 enrolled subjects, 75 (gel cushion group, 40; foam cushion group, 35) were included for analysis. Both groups showed significant improvement in NPIS and ODI scores following cushion use. Results for Beck Depression Inventory and Short Form-6D scores indicated that gel cushion use was significantly helpful. Change in NPIS score was significantly greater in the gel cushion group than in the foam cushion group.

CONCLUSION

Gel cushion use may be effective in relieving LBP in occupational drivers seated for a long period compared with foam cushion use.

Acute effect of full time office work in real environment on postural actions and lumbar range of motion

INTRODUCTION

Prolonged sitting is often proposed as a risk factor for low back pain development. The purpose of this study was to evaluate the acute effect of full time office work on sensorimotor trunk functions.

METHODS

Seventeen healthy office workers participated in the study. Maximal lumbar flexion range of motion, anticipatory postural adjustments and postural reflex reactions were tested before and after full time office work in a real life environment.

RESULTS

There were longer onset latencies of postural reflexive reactions and decreased response amplitudes of anticipatory postural adjustments after full time office work, but these were significant only for the obliquus externus abdominis muscle. No changes in lumbar range of motion was found.

CONCLUSION

To our knowledge this is the first study that evaluates the effect of full time office work on postural actions and lumbar RoM. We found an absence of normal human circadian flexibility in the lumbar spine and some changes in postural actions. We propose that active trunk stiffness increase to compensate for decreased passive stiffness after prolonged seated work. Further studies are needed to confirm this assumption.

Prevalence of musculoskeletal disorders among Indian railway sahayaks

Railway sahayak or also known as coolie is one of the oldest occupations in India. This occupational group is continuously subjected to various musculoskeletal problems due to repetitive load exertion in unnatural postures. The present research aims to examine the prevalence of musculoskeletal disorders (MSDs) among Indian railway sahayaks. A cross-sectional study has been conducted on a sample of 51 male sahayaks. With a modified Nordic questionnaire, data were collected on their demographics, work, and musculoskeletal pain history. Electromyography (EMG) of the upper trapezius muscle of selected 12 healthy sahayaks having no history of neck-shoulder complaints were analyzed under different load lifting and carrying conditions. Additionally, ergonomic risk levels were recorded using Rapid Entire Body Assessment method. The questionnaire revealed that for the past 1 year prevalence, the most affected body regions of railway sahayaks were neck (47%), shoulder (51%), lower back (43%), and knee (47%). The association between age group and MSDs in different body regions were found significant (p = 0.012 for neck, p = 0.017 for shoulder, etc.). Work experience also had a significant relation to the MSDs in different body regions (p = 0.013 for shoulder,p = 0.023 for calf, etc.). Analysis of variance reveals high significance level between EMG values and tasks performed by the sahayaks. In conclusion, railway sahayaks were found to have high rate of MSDs which may be associated with lifting/carrying heavy loads in awkward postures. Ergonomic interventions must be implemented to reduce the risk level on this group of workers.

Activity Level Assessment Using a Smart Cushion for People with a Sedentary Lifestyle

As a sedentary lifestyle leads to numerous health problems, it is important to keep constant motivation for a more active lifestyle. A large majority of the worldwide population, such as office workers, long journey vehicle drivers and wheelchair users, spends several hours every day in sedentary activities. The postures that sedentary lifestyle users assume during daily activities hide valuable information that can reveal their wellness and general health condition. Aiming at mining such underlying information, we developed a cushion-based system to assess their activity levels and recognize the activity from the information hidden in sitting postures. By placing the smart cushion on the chair, we can monitor users’ postures and body swings, using the sensors deployed in the cushion. Specifically, we construct a body posture analysis model to recognize sitting behaviors. In addition, we provided a smart cushion that effectively combine pressure and inertial sensors. Finally, we propose a method to assess the activity levels based on the evaluation of the activity assessment index (AAI) in time sliding windows. Activity level assessment can be used to provide statistical results in a defined period and deliver recommendation exercise to the users. For practical implications and actual significance of results, we selected wheelchair users among the participants to our experiments. Features in terms of standard deviation and approximate entropy were compared to recognize the activities and activity levels. The results showed that, using the novel designed smart cushion and the standard deviation features, we are able to achieve an accuracy of (>89%) for activity recognition and (>98%) for activity level recognition.

[Low back pain perception from the prolonged use of a dynamic seat in sitting posture]

Objective To determine whether a tilting system located in the seat of a chair allows for performing voluntary macro-repositioning movements of the pelvis in order to reduce the perception of pain after a prolonged period in the sitting posture. Methods Eight women participated in the experiment. They were asked to sit on the chair with the tilting system and the chair without the tilting system for sixty minutes on two different days but carried out at the same time of day. Discomfort was assessed with the visual analogic scale. Results people used the tilting system to do postural changes of macro-repositioning. However, these movements were less than the movements done with the body, not using the system. Moreover, discomfort perception was the same for each chair. This might be due to the fact that total of macro-repositioning movements did not change. Conclusion Future research should evaluate the effect of tilting systems that provide macro-repositioning in a controlled form, not like in this study. Also, it is necessary to study if these types of automatic systems contribute to the reduction of the discomfort due to a prolonged period in the sitting posture.

Seat Pressure Distribution Characteristics During 1 Hour Sitting in Office Workers With and Without Chronic Low Back Pain

Background

Low back pain (LBP) is a major problem for office workers. Individuals adopting poor postures during prolonged sitting have a considerably increased risk of experiencing LBP. This study aimed to investigate seat pressure distribution characteristics, i.e., average pressure, peak pressure ratio, frequency of postural shift, and body perceived discomfort (BPD), during 1 hour of sitting among office workers with and without chronic LBP.

Methods

Forty-six participants (chronic LBP = 23, control = 23) typed a standardized text passage at a computer work station for an hour. A seat pressure mat device was used to collect the seat pressure distribution data. Body discomfort was assessed using the Body Perceived Discomfort scale.

Results

Office workers with chronic LBP sat significantly more asymmetrically than their healthy counterparts. During 1-hour sitting, all workers appeared to assume slumped sitting postures after 20 minutes of sitting. Healthy workers had significantly more frequent postural shifts than chronic LBP workers during prolonged sitting.

Conclusion

Different sitting characteristics between healthy and chronic LBP participants during 1 hour of sitting were found, including symmetry of sitting posture and frequency of postural shift. Further research should examine the roles of these sitting characteristics on the development of LBP.

Active self-correction of spinal posture in pain-free women in response to the command "straighten your back"

Evidence is limited regarding the regional changes in spinal posture after self-correction. The aim of the present study was to evaluate whether active self-correction improved standing and sitting spinal posture. Photogrammetry was used to assess regional spinal curvatures and vertical global spine orientation (GSO) in 42 asymptotic women aged 20-24 years. Upper thoracic spine angle and GSO increased in response to self-correction, while the thoracolumbar and lumbosacral angles decreased. Self-correction in the standing position resulted in decreased inclination of the upper thoracic and thoracolumbar spinal angles. Correction of sitting posture reduced the angle of the upper thoracic spine and GSO. The effects of active self-correction on spinal curvature and GSO were different for the standing versus sitting position; the greatest effects of active correction were noted in the thoracic spine. Balanced and lordotic postures were most prevalent in the habitual and actively self-corrected standing positions, whereas the kyphotic posture was most prevalent in the habitual sitting position, indicative that self-correction back posture in the standing position could be an important health-related daily activity, especially during prolonged sitting.

Objectively measured sedentary behavior and physical activity in a sample of Finnish adults: a cross-sectional study

Background

Regular physical activity (PA) confers many positive effects on health and well-being. Sedentary behavior (SB), in turn, is a risk factor for health, regardless of the level of moderate to vigorous PA. The present study describes the levels of objectively measured SB, breaks in SB, standing still and PA among Finnish adults.

Methods

This cross-sectional analysis is based on the sub-sample of the population-based Health 2011 Study of Finnish adults. The study population consisted of 18-to-85-year old men and women who wore a waist-worn triaxial accelerometer (Hookie AM 20) for at least 4 days, for at least 10 h per day (n = 1587) during a week. PA and SB were objectively assessed from the raw accelerometric data using novel processing and analysis algorithms with mean amplitude deviation as the processing method. The data was statistically analyzed using cross-tabulations, analysis of variance and analysis of covariance.

Results

The participants were on average 52 years old, 57 % being women. Participants were sedentary 59 % of their waking wear time, mainly sitting. They spent 17 % of the time standing still, 15 % in light intensity PA, 9 % in moderate PA and less than 1 % in vigorous PA. Participants aged 30–39 years had the highest number of breaks in SB per day. Younger participants (<30 years of age) had more moderate and vigorous PA than older ones (≥60 years of age), and 30–60-year-olds had the greatest amount of light PA.

Conclusions

Participants spent nearly 60 % of their waking time sedentary, and the majority of their daily PA was light. From a public health perspective it is important to find effective ways to decrease SB as well as to increase the level of PA. Our analysis method of raw accelerometer data may allow more precise assessment of dose-response relationships between objectively measured PA and SB and various indicators of health and well-being.

Is There a Relationship Between Lumbar Proprioception and Low Back Pain? A Systematic Review With Meta-Analysis

OBJECTIVE

To systematically review the relationship between lumbar proprioception and low back pain (LBP).

DATA SOURCES

Four electronic databases (PubMed, EMBASE, CINAHL, SPORTDiscus) and reference lists of relevant articles were searched from inception to March-April 2014.

STUDY SELECTION

Studies compared lumbar proprioception in patients with LBP with controls or prospectively evaluated the relationship between proprioception and LBP. Two reviewers independently screened articles and determined inclusion through consensus.

DATA EXTRACTION

Data extraction and methodologic quality assessment were independently performed using standardized checklists.

DATA SYNTHESIS

Twenty-two studies (1203 participants) were included. Studies measured lumbar proprioception via active or passive joint repositioning sense (JRS) or threshold to detection of passive motion (TTDPM). Data from 17 studies were pooled for meta-analyses to compare patients with controls. Otherwise, descriptive syntheses were performed. Data were analyzed according to measurement method and LBP subgroup. Active JRS was worse in patients compared with controls when measured in sitting (standard mean difference, .97; 95% confidence interval [CI], .31-1.64). There were no differences between groups measured via active JRS in standing (standard mean difference, .41; 95% CI, -.07 to .89) or passive JRS in sitting (standard mean difference, .38; 95% CI, -.83 to 1.58). Patients in the O'Sullivan flexion impairment subgroup had worse proprioception than the total LBP cohort. The TTDPM was significantly worse in patients than controls. One prospective study found no link between lumbar proprioception and LBP.

CONCLUSIONS

Patients with LBP have impaired lumbar proprioception compared with controls when measured actively in sitting positions (particularly those in the O'Sullivan flexion impairment subgroup) or via TTDPM. Clinicians should consider the relationship between sitting and proprioception in LBP and subgroup patients to guide management. Further studies focusing on subgroups, longitudinal assessment, and improving proprioception measurement are needed.

Perceived Risk of Low-Back Injury Among Four Occupations

OBJECTIVE

This study aimed to assess the perception of risk of low-back injury of individuals from four groups: office/administrative employees, dental workers (dentists/dental hygienists), firefighters, and undergraduate students.

BACKGROUND

The concept of worker's perception of injury risk has been used to set safe material-handling limits and to determine compliance with health and safety regulations but has not been used to identify perceptual differences among occupations or potential deficiencies in risk awareness.

METHOD

Participants (N = 232) were presented with eight images of different low-back postures/tasks and were required to rate their perceived magnitude of low-back risk on a scale from 0 (no risk) to 10 (extreme risk).

RESULTS

Office/administrative and dental workers rated postures higher than firefighters and students. Individuals from all groups perceived kyphotic postures as having a higher low-back risk than lordotic postures. Further, office and dental workers, compared to firefighters and students, perceived sitting postures to have a relatively higher level of risk, likely due to these postures being typically adopted by these individuals at work. No relationship between previous low-back pain and risk rating was observed in this study.

CONCLUSION

Low-back injury risk perception varies between occupations/groups and may be a result of different exposures.

APPLICATION

The results of this study can potentially be used to implement occupation-specific training programs to ensure that the scientific research regarding low-back injuries is being properly conveyed to employees across all sectors.

The effect of rest break schedule on acute low back pain development in pain and non-pain developers during seated work

A significant portion of the population (25-50%) is known to develop acute low back pain (LBP) within a bout of prolonged sitting. Previous research has supported the use of frequent rest breaks, from seated office work, in order to reduce self-reported LBP, however, there is limited consensus about the recommended frequency and duration of rest breaks. This may be due to the limited consideration of individual differences in acute LBP development. The purpose of this study was to examine the effect of three different standing rest-break conditions on a group of pain developers (PD) and non-pain developers (NPD) engaged in prolonged seated work. Twenty participants completed four one-hour-long bouts of seated typing: Condition A - no rest; Condition B - 5 min of standing rest every 30 min; Condition C - 2.5 min of standing rest every 15 min; Condition D - 50 s of standing rest every 5 min. Self-reported LBP, self-reported mental fatigue and 30-s samples of EMG were collected every 10 min throughout each session. Eight out of 20 participants (40%) reported LBP during Condition A (classified as PD). Only PD demonstrated clinically relevant increases in LBP across conditions where Conditions B, C, or D provided some relief, but did not restore pain scores to their original level, prior to sitting. PD and NPD developed mental fatigue equally, with Conditions B and D helping to reduce fatigue. No differences in productivity were observed between conditions or groups and no main effects were observed for muscle activity, median power frequency or co-contraction. These data suggests that frequent, short, standing rest breaks may help to reduce symptoms of LBP, however they are only a temporary solution as PD still developed clinically important LBP, even with frequent rest breaks.

Immediate effects of dynamic sitting exercise on the lower back mobility of sedentary young adults

[Purpose] The aim of this study was to investigate the effects of dynamic sitting exercises during prolonged sitting on the lower back mobility of sedentary young adults. [Subjects and Methods] Seventy-one subjects aged between 18–25 years participated in this study. Following a randomized crossover study design, subjects were randomly assigned to two groups: sitting only and dynamic sitting exercise. The dynamic sitting exercise was a combination of lower back hyperextension and abdominal drawing-in movements which were repeated 6 times in a 1-minute period and performed every 20 minutes during a 2-hour sitting session. Lumbar range of movement was measured with the modified-modified Schober test, and the pain intensity was evaluated using the visual analog scale. [Results] After the experiment, the lumbar range of movement was significantly impaired in the sitting only group; however, it was significantly improved in the dynamic sitting exercise group. There were significant differences in lumbar range of movement of both flexion and extension between the groups. No significant difference in pain intensity between the groups was found. [Conclusion] These results suggest that dynamic sitting exercises during prolonged sitting can prevent decreases in lumbar range of movement in both back flexion and extension following a 2-hour sitting period.

Perceived body discomfort and trunk muscle activity in three prolonged sitting postures

[Purpose] This study aimed to investigate the perceived discomfort and trunk muscle activity in three different 1-hour sitting postures. [Subjects] A repeated-measures design study was conducted on 10 healthy subjects. [Methods] Each subject sat for an hour in three sitting postures (i.e., upright, slumped, and forward leaning sitting postures). Subjects rated perceived body discomfort using Borg’s CR-10 scale at the beginning and after 1 hour sitting. The electromyographic activity of the trunk muscle activity was recorded during the 1-hour period of sitting. [Results] The forward leaning sitting posture led to higher Borg scores in the low back than those in the upright (p = 0.002) and slumped sitting postures (p < 0.001). The forward leaning posture was significantly associated with increased iliocostalis lumborum pars thoracis (ICL) and superficial lumbar multifidus (MF) muscle activity compared with the upright and slumped sitting postures. The upright sitting posture was significantly associated with increased internal oblique (IO)/transversus abdominis (TrA) and ICL muscle activity compared with the slumped sitting posture. [Conclusion] The sitting posture with the highest low back discomfort after prolonged sitting was the forward leaning posture. Sitting in an upright posture is recommended because it increases IO/TrA muscle activation and induces only relatively moderate ICL and MF muscle activation.

Effect of postural angle on back muscle activities in aging female workers performing computer tasks

[Purpose] This study investigated the effects of postural angle on back muscle activity during a computer task in aging women. [Subjects] Seventeen women ≥50 years old participated. [Methods] The participants were instructed to perform computer-related tasks for 20 minutes on a workstation that simulated typical office working conditions. Back posture was measured from the measured trunk and pelvic angles. Electromyography activities were recorded simultaneously from the cervical erector spinae, longissimus, and multifidus muscles. [Results] The lowest mean percentages of maximum voluntary contraction for the cervical erector spinae and longissimus muscles were obtained when the upper trunk and pelvic angles were between 0° to −5° from the sagittal plane. The back muscle activities increased as the upper trunk and pelvic angles exceeded 0°. Statistical analysis showed significant correlations between upper trunk angle and cervical erector spinae and longissimus muscle activities. Similarly, pelvic angle was significantly correlated with cervical erector spinae and multifidus muscle activities. [Conclusion] A neutral back posture minimizes muscle activities in aging women performing computer tasks.

Semi-automatic Fisher-Tippett guided active contour for lumbar multifidus muscle segmentation

Rehabilitative Ultrasound Imaging or diagnostic ultrasound is used to measure geometric properties of the lumbar multifidus muscle to infer muscle strength or degeneration for back pain therapy. For this purpose, a novel semi-automatic approach (FTS: Fisher-Tippett Segmentation) based upon the Decoupled Active Contour is proposed to reliably and quickly segment the lumbar multifidus muscle in diagnostic ultrasound. To overcome speckle or hardly visible region boundaries in ultrasound images, we first propose a novel external energy functional to explicitly consider the underlying Fisher-Tippett distribution of ultrasound data. We then introduce a user-guided Hidden Markov Model trellis formation for improved segmentation of weakly-defined regions. Extensive experiments have shown that our approach not only improves the segmentation performance when compared to existing methods, but also does not rely on sub-specialized knowledge for segmentation.

Comparison of the T10 and L4 paraspinal muscle activities over time during continuous computer work

[Purpose] This study compared the T10 and L4 paraspinal muscle activities over time during continuous computer work. [Subjects] Ten male workers participated in this study. [Methods] The T10 and L4 paraspinal muscle activities were measured using a surface EMG system after 0, 20, 40, and 80 minutes of continuous computer work. [Results] The T10 and L4 paraspinal muscle activities after 20 and 40 minutes were increased significantly compared with the initial values, while they were decreased significantly after 80 minutes compared with the initial readings. [Conclusion] This study suggests that workers using computers for short periods would benefit from back muscle stretching exercises due to increased tension in these muscles. For longer computer work, strengthening exercises would be more effective than stretching due to decreased back muscle activation.

Comparison of the Lumbar Flexion Angle and EMG Activity in Trunk Muscles in Individuals with and without Limited Hip Flexion Range of Motion during Visual Display Terminal Work with Cross-Legged Sitting

[Purpose] The purpose of this study was to compare the lumbar flexion angle and electromyography (EMG) measurements of trunk muscle activity in individuals with and without limited hip flexion range of motion (ROM) during visual display terminal (VDT) work with cross-legged sitting. [Subjects] The 15 participants included a control group with sufficient hip flexion ROM (n = 7) and an experimental group with limited hip flexion ROM (n = 8). [Methods] All subjects performed VDT work with cross-legged sitting. The lumbar flexion angle was measured using a three-dimensional motion capture system, and the trunk muscle activity was recorded using a surface EMG system during VDT work with cross-legged sitting. The differences in trunk flexion angle and trunk muscle activity between the two groups were analyzed using independent t-tests. [Results] The lumbar flexion angle was significantly greater in the experimental group than the control group, although trunk muscle activity did not differ between the two groups. [Conclusion] These findings suggest that limited hip flexion leads to greater lumbar flexion during cross-legged sitting.

Investigation of trunk muscle co-contraction and its association with low back pain development during prolonged sitting

Previous work has shown muscle activation differences between chronic low back pain patients and healthy controls in sitting postures, and between asymptomatic individuals who do (PDs: pain developers) and do not (NPDs: non-pain developers) develop transient back pain during prolonged standing (as determined using a visual analog scale). The current study aimed to investigate differences in trunk muscle co-contraction between PD and NPD individuals over 2h of prolonged sitting. Ten healthy males sat continuously for 2h while performing tasks that simulated computer-aided-drafting; four were classified as PDs, and six as NPDs. Co-contraction indices were calculated from EMG data collected from eight trunk muscles bilaterally, and compared between pain groups and over time. PDs exhibited higher levels of co-contraction than NPDs. Additionally, co-contraction tended to increase over time, and was significantly correlated to pain development. The relationship between co-contraction and back pain development may actually be circular, in that it is both causal and adaptive: high co-contraction initially predisposes to pain development, following which co-contraction further increases in an attempt to alleviate the pain, and the cycle perpetuates. Further work will be required to elucidate the exact nature of this relationship, and to confirm the generalizability to other populations.

Towards a postural indicator of back pain in horses (Equus caballus)

Postures have long been used and proved useful to describe animals' behaviours and emotional states, but remains difficult to assess objectively in field conditions. A recent study performed on horses using geometric morphometrics revealed important postural differences between 2 horse populations differing in management conditions (leisure horses living in social groups used for occasional "relaxed" riding/riding school horses living in individual boxes used in daily riding lessons with more constraining techniques). It was suggested that these postural differences may reflect chronic effects of riding techniques on the horses' kinematics and muscular development. In the present study, we tried to evaluate the interest of postural measures to assess welfare in horses. This study was separated into 2 parts. First, 18 horses coming from these 2 types of populations (leisure/riding school horses) were submitted to 2 back evaluations by 1) manual examination (experienced practitioner) and 2) sEMG measures along the spine. We then measured neck roundness on 16 of these 18 horses. The results highlighted high correlations between manual and sEMG examinations over the spine. sEMG measures at the different locations were strongly correlated all over the spine. Moreover, neck postures and muscular activities were strongly correlated, horses with concave necks having higher sEMG measures both at precise locations (i.e. cervical sites) but also when comparing neck postures to the whole spine muscular activity highlighting the functioning of horses' back as a whole. Lastly, strong differences appeared between the populations, leisure horses being evaluated as having sounder spines, exhibiting lower sEMG measures and rounder neck than the riding school horses. sEMG measures and neck "roundness" seemed therefore to be reliable indicators of back disorders, easy to evaluate in field conditions. This highlights the accuracy of using postural elements to evaluate the animals' general state and has important implications for animals' welfare evaluations.

Validation of a novel spinal posture monitor: comparison with digital videofluoroscopy

PURPOSE

A novel, minimally invasive posture monitor which can monitor lumbar postures outside the laboratory has demonstrated excellent reliability, as well as concurrent validity compared to a surface marker-based motion analysis system. However, it is unclear if this device reflects underlying vertebral motion.

METHODS

Twelve participants performed full range sagittal plane lumbo-pelvic movements during sitting and standing. Their posture was measured simultaneously using both this device (BodyGuard™) and digital videofluoroscopy.

RESULTS

Strong correlations were observed between the two methods (all r (s) > 0.88). Similarly, the coefficients of determination were high (all r (2) > 0.78). The maximum mean difference between the measures was located in the mid-range of motion and was approximately 3.4° in sitting and 3.9° in standing.

CONCLUSION

The BodyGuard™ appears to be a valid method for analysing vertebral motion in the sagittal plane and is a promising tool for long-term monitoring of spinal postures in laboratory and clinical settings in people with low back pain.

Comparing lower lumbar kinematics in cyclists with low back pain (flexion pattern) versus asymptomatic controls--field study using a wireless posture monitoring system

The aim of this study was to examine lower lumbar kinematics in cyclists with and without non-specific chronic low back pain (NS-CLBP) during a cross-sectional cycling field study. Although LBP is a common problem among cyclists, studies investigating the causes of LBP during cycling are scarce and are mainly focussed on geometric bike-related variables. Until now no cycling field studies have investigated the relationship between maladaptive lumbar kinematics and LBP during cycling. Eight cyclists with NS-CLBP classified as having a 'Flexion Pattern' (FP) disorder and nine age- and gender-matched asymptomatic cyclists were tested. Subjects performed a 2 h outdoor cycling task on their personal race bike. Lower lumbar kinematics was measured with the BodyGuard™ monitoring system. Pain intensity during and after cycling was measured using a numerical pain rating scale. The NS-CLBP (FP) subjects were significantly more flexed at the lower lumbar spine during cycling compared to healthy controls (p = 0.018), and reported a significant increase in pain over the 2 h of cycling (p < 0.001). One-way repeated measures ANOVA revealed a significant main effect for group (p = 0.035, F = 5.546) which remained just significant when adding saddle angle as a covariate (p = 0.05, F = 4.747). The difference in posture between groups did not change over time. These findings suggest that a subgroup of cyclists with NS-CLBP (FP) demonstrate an underlying maladaptive motor control pattern resulting in greater lower lumbar flexion during cycling which is related to a significant increase in pain.

Variation between seated and standing/walking postures among male and female call centre operators

Background

The dose and time-pattern of sitting has been suggested in public health research to be an important determinant of risk for developing a number of diseases, including cardiovascular disorders and diabetes. The aim of the present study was to assess the time-pattern of seated and standing/walking postures amongst male and female call centre operators, on the basis of whole-shift posture recordings, analysed and described by a number of novel variables describing posture variation.

Methods

Seated vs. standing/walking was recorded using dichotomous inclinometers throughout an entire work shift for 43 male and 97 female call centre operators at 16 call centres. Data were analysed using an extensive set of variables describing occurrence of and switches between seated and standing/walking, posture similarity across the day, and compliance with standard recommendations for computer work.

Results

The majority of the operators, both male and female, spent more than 80% of the shift in a seated posture with an average of 10.4 switches/hour between seated and standing/walking or vice versa. Females spent, on average, 11% of the day in periods of sustained sitting longer than 1 hour; males 4.6% (p = 0.013). Only 38% and 11% of the operators complied with standard recommendations of getting an uninterrupted break from seated posture of at least 5 or 10 minutes, respectively, within each hour of work. Two thirds of all investigated variables showed coefficients of variation between subjects above 0.5. Since work tasks and contractual break schedules were observed to be essentially similar across operators and across days, this indicates that sedentary behaviours differed substantially between individuals.

Conclusions

The extensive occurrence of uninterrupted seated work indicates that efforts should be made at call centres - and probably in other settings in the office sector - to introduce more physical variation in terms of standing/walking periods during the work day. We suggest the metrics used in this study for quantifying variation in sedentary behaviour to be of interest even for other dichotomous exposures relevant to occupational and public health, for instance physical activity/inactivity.

How is a box handled when all surfaces can be freely held?

In this study, we investigated how experienced and inexperienced subjects handle a box when it could be approached from any of its sides. Subjects moved a box (11 kg) either to a high (HS) or a low surface (LS). Wrist movements and grip force were synchronised and recorded, respectively, by electrogoniometers and an instrumented box. All subjects adopted a lateral-and-bottom grip, with parts of the hands simultaneously placed on the side and bottom of the box. This grip allowed the 50th percentile of wrist movements to be within safe limits, particularly in the sagittal plane. Low force was associated with lowering the box to LS and equally distributed but greater force when lifting to HS. Larger ulnar deviation was recorded when the box was lifted to HS. Only peak of wrist extension differentiated experienced from inexperienced subjects, with experienced presenting larger wrist extension. Alternative box designs are suggested to improve handling in real settings.

PRACTITIONER SUMMARY

Understanding worker preferences for box lifting behaviour can contribute to the development of new designs that facilitate the adoption of more efficient postures while reducing the risk of upper-limb musculoskeletal disorders and promoting safer manual material handling.

Towards monitoring lumbo-pelvic posture in real-life situations: concurrent validity of a novel posture monitor and a traditional laboratory-based motion analysis system

Many factors are associated with low back pain (LBP), including provocative spinal postures. Consequently, lumbo-pelvic posture is commonly assessed in LBP patients. A novel wireless monitor (BodyGuard™) can monitor lumbo-pelvic sagittal plane movements reliably, and has demonstrated concurrent validity during non-functional tasks. This study evaluated the concurrent validity of this monitor during functional tasks, as a precursor to LBP field studies. Twelve painfree participants performed a series of postural tasks (in sitting and standing) three times. Simultaneous postural measurements were obtained by the wireless monitor and a laboratory-based system (CODA™). Postural measurements were strongly correlated (r(s) = 0.88, r(2) = 0.78). The mean difference observed was small (<10% lumbo-pelvic ROM), however some tasks displayed greater error. The results support the concurrent validity of the wireless monitor for analysing lumbo-pelvic posture during functional tasks. Specific limitations of the monitor for certain postural tasks were identified, and should be considered before implementation in future field studies.

A rationale for the provision of extrinsic feedback towards management of low back pain

Low back pain (LBP) is associated with dysfunction of global and local muscle systems, feedback and feedforward postural control mechanisms. Physiotherapists include the use of feedback as part of treatment protocols. Such feedback can focus on a variety of neuromuscular impairments, although the literature related to feedback on the management of LBP has focused mainly on local muscle system impairments. Furthermore, there are various characteristics of feedback that can lead to motor control enhancement or deterioration. The aim of this manuscript is to present a rationale for feedback provision as a rehabilitation tool on the management of LBP. Feedback provision should focus on the main neuromuscular impairment presented by the patient. The suggested rationale describes decision-making stages for the use and progress of feedback interventions. Local muscle system impairment might benefit more from parameter feedback provision, while global muscle system and feedback mechanism impairments may benefit better from program feedback. The described rationale has the potential to help clinicians select the appropriate feedback for the treatment of their patients. Additionally, the presented rationale could be used by researchers to assess how different forms of feedback provision impact on clinical outcomes.