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Neutral lumbar spine sitting posture in pain-free subjects
Abstract
Sitting is a common aggravating factor in low back pain (LBP), and re-education of sitting posture is a common aspect of LBP management. However, there is debate regarding what is an optimal sitting posture. This pilot study had 2 aims; to investigate whether pain-free subjects can be reliably positioned in a neutral sitting posture (slight lumbar lordosis and relaxed thorax); and to compare perceptions of neutral sitting posture to habitual sitting posture (HSP). The lower lumbar spine HSP of seventeen pain-free subjects was initially recorded. Subjects then assumed their own subjectively perceived ideal posture (SPIP). Finally, 2 testers independently positioned the subjects into a tester perceived neutral posture (TPNP). The inter-tester reliability of positioning in TPNP was very good (intraclass correlation coefficient (ICC) = 0.91, mean difference = 3% of range of motion). A repeated measures ANOVA revealed that HSP was significantly more flexed than both SPIP and TPNP (p <0.05). There was no significant difference between SPIP and TPNP (p > 0.05). HSP was more kyphotic than all other postures. This study suggests that pain-free subjects can be reliably positioned in a neutral lumbar sitting posture. Further investigation into the role of neutral sitting posture in LBP subjects is warranted.
... However, this requires sustained static exertions of the lumbar erector spinae and hip flexors, which fatigue rapidly, leading to a slumped seated posture (Park et al., 2012; . Sitters habitually assume slumped sitting postures with varying degrees of lumbar flexion (Callaghan and McGill, 2001a;O'Sullivan et al., 2010) because it increases discomfort to maintain a neutral sitting posture due to the sustained isometric muscular exertions (Vergara and Page, 2002a); 2 The large intervertebral discs that provide cushioning and flexibility between the vertebrae are squeezed at their forward edge (during slumped sitting), causing bulging on the posterior surface (Alexander et al., 2007;Nazari et al., 2012). Sustained static compression decreases fluid exchange and nutrition in the discs (Holm and Nachemson 1983), resulting in reduced load carrying capacity of the spinal segment (Owens et al., 2009) and degeneration of the lumbar disc (Huang et al., 2016;Kos et al., 2019); 3 In a flexed or slumped sitting posture, the posterior spinal ligaments and fascia are stretched to capacity (Snijders et al., 2004), leaving the sacro-iliac joints and lumbar spine unstable (O'Sullivan et al., 2006); 4 Prolonged sitting in a flexed posture causes creep and laxity, leading to inflammation in the ligaments surrounding the spine, leaving the back vulnerable to injury the following day (Solomonow, 2009); 5 When office workers maintain a static lumbar flexion position (kyphotic) for hours, it adds strain on the spine caused by the sustained posture (Le et al., 2009). ...
... When 79 men and women were allowed to self-select optimal recline angle for reading or computing in an office setting, the preferred position averaged 115 • (Gscheidle and Reed 2004b). When performing desk or computer-oriented tasks, most people work with some degree of flexion (Dowell et al., 2001;O'Sullivan et al., 2010) so from the point of view of spinal loading, a reclined posture is less damaging. However, there are drawbacks to working in a reclined posture. ...
... To summarize Part II, a review of the research on the four working postures (reclined, upright, declined sitting and standing) shows us that: 1-reclined sitting is the most comfortable position but is not ideal for performing desk-centred office work (Dowell et al., 2001;O'Sullivan et al., 2010) or incorporating increased levels of movement (Bridger 2019;Mansoubi et al., 2015). 2-Upright sitting, especially in the context of a static computer operation, has been shown in research to be the cause of the health challenges enumerated in Part I (Alexander et al., 2007;Nazari et al., 2012;Park et al., 2012;Vergara and Page, 2002;Huang et al., 2016;Kos et al., 2019). ...
... Previous research has explored spinal postural configuration by using radiography (Endo et al., 2012;Hey et al., 2017aHey et al., , 2017bRoussouly et al., 2005;Vialle et al., 2005) or body surface measurement methods (Barczyk-Pawelec and Sipko, 2017;Caneiro et al., 2010;Claeys et al., 2016;Edmondston et al., 2011a;Grimmer-Somers et al., 2008;Sheeran et al., 2018;Silva et al., 2009). In addition, habitual or self-perceived "optimal" SP have been evaluated (Barczyk-Pawelec and Sipko, 2017;Claus et al., 2016;Edmondston et al., 2007;Korakakis et al., 2017;Korakakis et al., 2019a;Korakakis et al., 2014;O'Sullivan, O'Dea, 2010, O'Sullivan et al., 2012aStraker et al., 2007;Straker et al., 2011) and gender differences have been documented in asymptomatic individuals (Endo et al., 2012;Richards et al., 2016;Sheeran et al., 2018;Straker, O'Sullivan, 2007;Straker et al., 2011). However, posture analysis has mostly been confined to discrete regions of the upper body, such as the head and thoracic region (Caneiro, O'Sullivan, 2010;Edmondston, Sharp, 2011a;van Niekerk et al., 2008), or the thoraco-lumbar and pelvic region (Claus et al., 2016;Korakakis, O'Sullivan, 2019a;O'Sullivan, O'Dea, 2010;O'Sullivan, O'Sullivan, 2012a;O'Sullivan et al., 2006) and often using relatively small sample sizes. ...
... In addition, habitual or self-perceived "optimal" SP have been evaluated (Barczyk-Pawelec and Sipko, 2017;Claus et al., 2016;Edmondston et al., 2007;Korakakis et al., 2017;Korakakis et al., 2019a;Korakakis et al., 2014;O'Sullivan, O'Dea, 2010, O'Sullivan et al., 2012aStraker et al., 2007;Straker et al., 2011) and gender differences have been documented in asymptomatic individuals (Endo et al., 2012;Richards et al., 2016;Sheeran et al., 2018;Straker, O'Sullivan, 2007;Straker et al., 2011). However, posture analysis has mostly been confined to discrete regions of the upper body, such as the head and thoracic region (Caneiro, O'Sullivan, 2010;Edmondston, Sharp, 2011a;van Niekerk et al., 2008), or the thoraco-lumbar and pelvic region (Claus et al., 2016;Korakakis, O'Sullivan, 2019a;O'Sullivan, O'Dea, 2010;O'Sullivan, O'Sullivan, 2012a;O'Sullivan et al., 2006) and often using relatively small sample sizes. ...
... Initially, participants were instructed to sit "as you usually do", avoid adjusting their contact with the seat, breath naturally and look forward at a mark on the wall 5 m away and 1.3 m from the floor. This habitual SP was covertly recorded for 30 s, as in previous studies (Edmondston et al., 2007;Korakakis et al., 2014;O'Sullivan, O'Dea, 2010). Subsequently, they were asked to respond with "yes" or "no", if they believed that the adopted posture reflects the characteristics of an "optimal" SP ("Do you believe that your current SP reflects an "optimal" SP?"). ...
Background
Notions of “optimal” posture are widespread in modern society and strongly interconnected with preconceived beliefs.
Objectives
To quantitatively evaluate spinal posture among members of the community during habitual sitting, and when asked to assume an “optimal” posture.
Design
Observational study.
Methods
Marker-based kinematic analyses of the head, spine, and pelvis were conducted on 100 individuals. Habitual sitting posture and self-perceived “optimal” posture, and whether participants believed that their habitual sitting reflected an “optimal” posture, were evaluated. The Wilcoxon signed-rank test assessed angular differences between the two postures adopted. Exploratory post-hoc analyses were conducted by using the Mann-Whitney U test to assess differences between genders.
Results
None of the participants stated that their habitual sitting was “optimal”. Statistically significant differences were observed in most of the measured angles (p < 0.001) between habitual and self-perceived “optimal” posture. In habitual sitting posture, a significant interaction with gender was found only in the thoracolumbar (p < 0.05) and pelvic (p < 0.001) angles, with small effect sizes. In self-perceived “optimal” posture females were more extended in the head, upper thoracic, lower thoracic, lumbar and pelvic (p < 0.01) regions, than the males.
Conclusions
A group of young, asymptomatic participants, consistently changed their habitual sitting posture to a more upright posture when asked to assume an “optimal” sitting posture, although the amount of change observed varied between spinal regions. These findings also highlight gender differences in not just habitual sitting posture, but also the degree to which habitual sitting posture is modified when trying to assume an “optimal” sitting posture.
... There is evidence that the 90˚sitting90˚sitting posture (knee angle and hip angle) increases the pas- sive tension of hamstring muscles, causing a posterior pelvic rotation and resulting in a kyphotic sitting posture of the lumbar spine [17][18]. However, ergonomic recommendations [19], radiographic studies [17][18], and analyses from physical therapists [20] and laypersons [21,22] indicate that a sitting posture with a slight anterior tilt of the lumbar spine and a slight lumbar lordosis of the lumbar spine reduces the incidence of low back pain most efficiently. ...
... There is a consensus among several studies [17][18][19][20][21][43][44][45][46][47][48][49] that the lumbar lordosed seated posture is optimal for favoring a neutral lumbar posture, minimizing the painful symptomatol- ogy of low back pain. It is also associated with high muscular activity and the increase in spinal load due to the posterior pelvic tilt, which is then balanced by muscle contractions in the dorsal spine, representing a dynamic posture [50]. ...
... It is also associated with high muscular activity and the increase in spinal load due to the posterior pelvic tilt, which is then balanced by muscle contractions in the dorsal spine, representing a dynamic posture [50]. This posture is obtained by positioning the lower lumbar spine in a slight forward tilt and slight lumbar lordosis, while maintaining the relaxa- tion of the muscles surrounding the thoracic spine [20]. ...
Objective
This study aimed to verify whether the saddle seat provides lower ergonomic risk than conventional seats in dentistry.
Methods
This review followed the PRISMA statement and a protocol was created and registered in PROSPERO (CRD42017074918). Six electronic databases were searched as primary study sources. The "grey literature" was included to prevent selection and publication biases. The risk of bias among the studies included was assessed with the Joanna Briggs Institute Critical Appraisal Tool for Systematic Reviews. Meta-analysis was performed to estimate the effect of seat type on the ergonomic risk score in dentistry. The heterogeneity among studies was assessed using I² statistics.
Results
The search resulted in 3147 records, from which two were considered eligible for this review. Both studies were conducted with a total of 150 second-year dental students who were starting their laboratory activities using phantom heads. Saddle seats were associated with a significantly lower ergonomic risk than conventional seats [right side (mean difference = -3.18; 95% CI = -4.96, -1.40; p < 0.001) and left side (mean difference = -3.12; 95% CI = -4.56, -1.68; p < 0.001)], indicating posture improvement.
Conclusion
The two eligible studies for this review provide moderate evidence that saddle seats provided lower ergonomic risk than conventional seats in the examined population of dental students.
... Neutral (NSP) and lordotic sitting posture (LSP) of the whole spine have been qualitatively described in the literature [10,[25][26][27], but there is limited quantitative data on defining these postures. A diversity of spinal curves from the occiput to the pelvis meet the criteria for upright spinal alignment [28], adding to the ambiguity of postural evaluation and education and questioning how clinicians prescribe upright SPs in clinical practice. ...
... From a clinical perspective, postural education typically does not focus on only one segment of the spine [10], since spinal posture is influenced by pelvic posture [32]. While at large the reliability of postural positioning has been shown to be good, most studies conducted to date assessed local lumbar or local cervico-thoracic angles without including pelvis and/or head, hampering any meaningful discussion on overall postural alignment [15,[25][26][27]33]. Given that reliability is a prerequisite of validity [29] and the posture of the upper body as one segment has only been described qualitatively, it is of clinical significance to evaluate the reliability of postural positioning and the level of reliability required to reach clinical acceptability. ...
... It has been argued that precision estimates are underestimated for data derived from three or fewer attempts, such that at least five attempts are suggested [38]. Nevertheless, many reliability studies on postural positioning have only used two attempts [33,39] while others use three or more [25,30]. ...
Purpose: To assess the reliability of postural positioning in two different sitting postures (SP), within- and between-days, as well as intra-tester and inter-tester.
Methods: Twenty six individuals were facilitated into lordotic (LSP) and neutral (NSP) SP on two different days by four physiotherapists, while kinematic data were collected. Intra-tester and inter-tester reliability were assessed using measures of relative reliability (intra-class correlation coefficients, ICC) and absolute reliability (standard error of measurement-SEM; minimal detectable change; mean difference; limits of agreement).
Results: Substantial or almost perfect relative reliability (ICC >0.67), with very good absolute reliability (SEM <2.7°) was found for both intra- and inter-tester (within- and between-day) reliability. However, likely due to methodological variation affecting head angles on Day 2, the reliability of head/neck angles were poor (ICC as low as −0.11, SEM ≤5.71°).
Conclusion: This study suggests that postural positioning of asymptomatic individuals into NSP and LSP can be performed with very good reliability for most spinal angles. Therefore, clinicians can have some confidence that positioning in SPs can be done reliably. However, while the degree of error is typically small, the small range of movement occurring at many spinal angles suggests that determining what is a clinically meaningful change in posture is difficult.
... The participants were instructed to sit ''as they usually do''. The adopted habitual SP was covertly recorded for 15 s( Edmondston et al., 2007;O'Sullivan et al., 2010). Subsequently, the subjects were instructed to move from habitual SP into what they perceived to be an ''optimal/good'' SP. ...
... Habitual SP has been described as a mid-range position ,( Dankaerts et al., 2006;O'sullivan et al., 2010), however it is sug- gested that it involves significantly more flexion than neutral up- right SP Korakakis et al., 2014;O'sullivan et al., 2010). This was confirmed in the present study as habitual SP configuration presented more flexed than both self-perceived optimal posture and instructed optimal SP in most of the measured angles. ...
... Habitual SP has been described as a mid-range position ,( Dankaerts et al., 2006;O'sullivan et al., 2010), however it is sug- gested that it involves significantly more flexion than neutral up- right SP Korakakis et al., 2014;O'sullivan et al., 2010). This was confirmed in the present study as habitual SP configuration presented more flexed than both self-perceived optimal posture and instructed optimal SP in most of the measured angles. ...
Background:
Sustained spinal flexion has been proposed to affect the properties of spinal tissues, increase postural muscle's activation latency and act detrimentally on proprioception.
Objectives:
This study evaluated the effect of flexed posture (FP) on spinal proprioception and assessed the immediate effect of spinal movement on the presumable flexion-induced proprioceptive deficit.
Design:
Clinical measurement study.
Methods:
Marker-based kinematic analyses of the head, spine, and pelvis were conducted on 50 individuals. Subjects were educated in a lordotic sitting posture (IOSP) that they reproduced immediately; after 10 and 30 min in FP; and after sagittal spinal movement. Nine sagittal angles were calculated. Absolute error (AE) and constant error (CE) were used to evaluate repositioning accuracy. Repeated measures ANOVA was used to test for significant differences in angles obtained among postures, as well as for the AE and CE calculated from the trials.
Results:
No significant differences were found in reposition error (RE) after immediate reproduction of IOSP (all p > 0.0083). Following FP AEs presented significant differences for head (4.1°), head protraction (1.9°), head tilt (2.1°), lumbar (3.2°) and pelvis angle (2.1°). CEs revealed significant differences for head protraction (-1.8°) and lumbar angle (-3.5°). No significant differences were found for AE and CE after spinal sagittal movement (all p > 0.0083).
Conclusions:
Prolonged FP can affect spinal position sense, but sagittal spinal movement can abolish the proprioceptive deficit. The significant differences documented, may be of limited clinical utility given their magnitude, and the reliability data presented may be of use in reinterpreting previously documented proprioceptive analyses.
... Therefore, medical staff should emphasize to patients with discogenic back pain the importance of maintaining a neutral posture in the lumbar spine during daily activities and exercise. Neutral posture in the lumbar spine refers to a natural and relaxed alignment with slight lumbar lordosis to produce the least amount of pressure on the spinal column, discs, and nerves [23]. In clinical practice, the importance of maintaining a neutral position for patients with lower back pain has been emphasized. ...
... Furthermore, ROM was even greater in severe disc degeneration (grade 4 or 5). These findings highlight the importance of the neutral position of the lumbar A c c e p t e d A r t i c l e spine, particularly in patients with severe intervertebral disc degeneration [23]. ...
Objective:
Precise knowledge regarding the mechanical stress applied to the intervertebral disc following each individual spine motion enables physicians and patients to understand how people with discogenic back pain should be guided in their exercises and which spine motions to specifically avoid. We created an intervertebral disc degeneration model and conducted a finite element (FE) analysis of loaded stresses following each spinal posture or motion.
Methods:
A three-dimensional FE model of intervertebral disc degeneration at L4-5 was constructed. The intervertebral disc degeneration model was created according to the modified Dallas discogram scale. The Von Mises stress and range of motion (ROM) regarding the intervertebral discs and the endplates were analyzed.
Results:
We observed that mechanical stresses loaded onto the intervertebral discs were similar during flexion, extension, and lateral bending, which were greater than those occurring during torsion. Based on the comparison among the grades divided by the modified Dallas discogram scale, the mechanical stress during extension was greater in grades 3-5 than it was during the others. During extension, the mechanical stress loaded onto the intervertebral disc and endplate was greatest in the posterior portion. Mechanical stresses loaded onto the intervertebral disc were greater in grades 3-5 compared to those in grades 0-2.
Conclusion:
Our findings suggest that it might be beneficial for patients experiencing discogenic back pain to maintain a neutral posture in their lumbar spine when engaging in daily activities and exercises, especially those suffering from significant intravertebral disc degeneration.
... A static calibration of the sitting posture was performed for each participant before testing. During the calibration, participants were seated on a desk chair without back support, upper legs horizontal, lower legs vertical, feet parallel and shoulder width apart on the ground, and arms uncrossed on the thighs ( Figure 1) (Korakakis, Giakas, Sideris, and Whiteley, 2017;O'Sullivan et al., 2010;Richards et al., 2016). Anatomical landmarks were located by manual palpation and marked by the principal researcher after degreasing the skin. ...
... Then, participants were asked to "sit as you normally do" to measure the habitual postures of the UTx and LTx. Neither further instructions, nor feedback was given (Edmondston et al., 2007;O'Sullivan et al., 2010). Hereafter a 35-min-laptop-task was performed. ...
Introduction:
Studies analyzing postures and mobility of the thoracic spine in the context of cervicogenic headache are missing. Insight in these parameters is needed since the cervical and thoracic spine are biomechanically related.
Objective:
To compare self-perceived optimal and habitual postures, active-assisted maximal range of motion, and repositioning error of the upper-thoracic and lower-thoracic spine between a cervicogenic headache-group and matched healthy control-group before and after a 30 min-laptop-task.
Methods:
A non-randomized longitudinal design was used to compare thoracic postures and mobility between 18 participants with cervicogenic headache (29-51 years) and 18 matched healthy controls (26-52 years). Outcomes were: self-perceived optimal and habitual postures, active-assisted maximal range of motion, and repositioning error of the upper-thoracic and lower-thoracic spine evaluated in sitting with a 3D-Vicon motion analysis system.
Results:
Habitual upper-thoracic postures in the cervicogenic headache-group were significantly (p = .04) less located toward the maximal range of motion for flexion compared to the control-group, self-perceived optimal upper-thoracic posture was significantly (p = .004) more extended in the cervicogenic headache-group compared to the control-group, and self-perceived optimal lower-thoracic posture could not be reestablished in the cervicogenic headache-group after the laptop-task (p = .009).
Conclusion:
Thoracic postures differ between a cervicogenic headache-group and control-group. These differences were detected by expressing the habitual thoracic posture relative to its maximal range of motion, and by analyzing the possibility of repositioning the thoracic spine after a headache provoking activity. Longitudinal studies are needed to determine the contribution of these musculoskeletal dysfunctions to the pathophysiology of cervicogenic headache.
... Sitting rest aids generally define excellent comfort in terms of use as a high level of usability, for example: subjective and objective comfort measurements to improve car seats and an assessment of the comfort questionnaire development [8][9][10], research methods for classroom seating comfort to help researchers analyse the perception of comfort (or discomfort) under dynamic conditions [11], as well as design and validation [12]. Furthermore, with regard to the resting state in the seat, some studies have compared the habitual relaxed sitting position with the neutral sitting position [13]. In addition, subjective measures have also involved the use of body mapping techniques, which aim to assess local comfort more intuitively and accurately, by providing visual recognition rather than text. ...
... Supine sitting is a relaxed and languid sitting position whereby one reclines backwards in a chair to rest. The experiment's prototype is based on a previous literature study [19], which demonstrated that people experience the most physical comfort when resting in a chair in a supine sitting position, by maintaining a neutral position, which is the most comfortable position and minimizes the range of muscle movement [13,15,18,21]. The prototype is a three-part, strip-shaped pillow that wraps around and supports the neck, underarms, waist, chest and belly like a scarf ( Fig. 2-a). ...
Employees who work long hours frequently complain of muscle fatigue caused by prolonged sitting. As a result, products that assist them when resting in a chair in a reclining position, in order to relieve fatigue and improve comfort are required. To ensure that the new product works as intended, a usability test based on prototyping must be developed. The research process was divided into three stages: firstly, the development of the perception assessment questionnaire; secondly, a validated factor analysis (CFA) was conducted on the perception assessment data of 26 subjects and the measurement model was fitted to verify the reliability and validity of the questionnaire; finally, the sEMG technique was used to verify the comfort level of 21 subjects. Based on usability experiments and an exploration of human factor relationships, this study develops a prototype testing model, which focuses on the comfort perception of body parts, as a means of promoting innovation in the design and manufacturing industry.
... Maintenance of a neutral spine posture has been suggested as an effective intervention to reduce low back discomfort in sitting. 19 Lumbar supports in automotive seating have been shown to increase lumbar lordosis, 20,21 reduce disc pressure and muscle activity, 22,23 and decrease low back pain reporting. 19 A radiographic investigation of lumbar support use confirmed improved lumbar spine posturemore lordosis-with increasing lumbar support prominence. ...
... 19 Lumbar supports in automotive seating have been shown to increase lumbar lordosis, 20,21 reduce disc pressure and muscle activity, 22,23 and decrease low back pain reporting. 19 A radiographic investigation of lumbar support use confirmed improved lumbar spine posturemore lordosis-with increasing lumbar support prominence. Lumbar lordosis angles were found to increase from 20°with 0 cm or no support to 30°with 4 cm of lumbar support prominence. ...
Background:
Recent work has demonstrated that low back pain is a common complaint following low-speed collisions. Despite frequent pain reporting, no studies involving human volunteers have been completed to examine the exposures in the lumbar spine during low-speed rear impact collisions.
Methods:
Twenty-four participants were recruited and a custom-built crash sled simulated rear impact collisions, with a change in velocity of 8 km/h. Randomized collisions were completed with and without lumbar support. Inverse dynamics analyses were conducted, and outputs were used to generate estimates of peak L4/L5 joint compression and shear.
Results:
Average (SD) peak L4/L5 compression and shear reaction forces were not significantly different without lumbar support (compression = 498.22 N [178.0 N]; shear = 302.2 N [98.5 N]) compared to with lumbar support (compression = 484.5 N [151.1 N]; shear = 291.3 N [176.8 N]). Lumbar flexion angle at the time of peak shear was 36° (12°) without and 33° (11°) with lumbar support.
Conclusion:
Overall, the estimated reaction forces were 14% and 30% of existing National Institute of Occupational Safety and Health occupational exposure limits for compression and shear during repeated lifting, respectively. Findings also demonstrate that, during a laboratory collision simulation, lumbar support does not significantly influence the total estimated L4/L5 joint reaction force.
... Although the capability to classify human postures can be considered a specific subset of the Human Activity Recognition (HAR) [3][4][5], it requires specific technological solutions, very different from HAR, and is very important in peculiar application fields. To improve the quality of life, for example, which can be significantly compromised by prolonged poor sitting and laying postures [6][7][8], causing serious health problems such as pressure ulcers, cervical and back diseases, and complex muscle and skeletal deformations. Professional vehicle drivers, like taxi/truck/farm tractor drivers, often suffer from Muscular-Skeletal Diseases (MSD) due to long time sitting [8,9]. ...
... To improve the quality of life, for example, which can be significantly compromised by prolonged poor sitting and laying postures [6][7][8], causing serious health problems such as pressure ulcers, cervical and back diseases, and complex muscle and skeletal deformations. Professional vehicle drivers, like taxi/truck/farm tractor drivers, often suffer from Muscular-Skeletal Diseases (MSD) due to long time sitting [8,9]. Furthermore, automotive applications have been pushed by updated safety protocols of autonomous vehicles, which require that the driver postures must be monitored not only to verify their readiness to take over the control in warning situations, but also for perceived (dis)comfort [10]. ...
... Although the capability to classify human postures can be considered a specific subset of the Human Activity Recognition (HAR) [3][4][5], it requires specific technological solutions, very different from HAR, and is very important in peculiar application fields. To improve the quality of life, for example, which can be significantly compromised by prolonged poor sitting and laying postures [6][7][8], causing serious health problems such as pressure ulcers, cervical and back diseases, and complex muscle and skeletal deformations. Professional vehicle drivers, like taxi/truck/farm tractor drivers, often suffer from Muscular-Skeletal Diseases (MSD) due to long time sitting [8,9]. ...
... To improve the quality of life, for example, which can be significantly compromised by prolonged poor sitting and laying postures [6][7][8], causing serious health problems such as pressure ulcers, cervical and back diseases, and complex muscle and skeletal deformations. Professional vehicle drivers, like taxi/truck/farm tractor drivers, often suffer from Muscular-Skeletal Diseases (MSD) due to long time sitting [8,9]. Furthermore, automotive applications have been pushed by updated safety protocols of autonomous vehicles, which require that the driver postures must be monitored not only to verify their readiness to take over the control in warning situations, but also for perceived (dis)comfort [10]. ...
A custom HW design of a Fully Convolutional Neural Network (FCN) is presented in this paper to implement an embeddable Human Posture Recognition (HPR) system capable of very high accuracy both for laying and sitting posture recognition. The FCN exploits a new base-2 quantization scheme for weight and binarized activations to meet the optimal trade-off between low power dissipation, a very reduced set of instantiated physical resources and state-of-the-art accuracy to classify human postures. By using a limited number of pressure sensors only, the optimized HW implementation allows keeping the computation close to the data sources according to the edge computing paradigm and enables the design of embedded HP systems. The FCN can be simply reconfigured to be used for laying and sitting posture recognition. Tested on a public dataset for in-bed posture classification, the proposed FCN obtains a mean accuracy value of 96.77% to recognize 17 different postures, while a small custom dataset has been used for training and testing for sitting posture recognition, where the FCN achieves 98.88% accuracy to recognize eight positions. The FCN has been prototyped on a Xilinx Artix 7 FPGA where it exhibits a dynamic power dissipation lower than 11 mW and 7 mW for laying and sitting posture recognition, respectively, and a maximum operation frequency of 47.64 MHz and 26.6 MHz, corresponding to an Output Data Rate (ODR) of the sensors of 16.50 kHz and 9.13 kHz, respectively. Furthermore, synthesis results with a CMOS 130 nm technology have been reported, to give an estimation about the possibility of an in-sensor circuital implementation.
... During the education of LSP the participants were instructed and facilitated to tilt their pelvis anteriorly to achieve lumbar lordosis and to retract their chin to neutrally align the head over the pelvis [35]. To achieve a NSP, participants were educated to tilt their pelvis anteriorly to obtain a neutral lordosis of the lumbar spine and relax their thorax while keeping their head neutrally aligned over the pelvis with the chin over the chest moderately retracted [36]. ...
... HSP has been described as a mid-range position [12,36], however, it involves significantly more lumbar flexion and posterior pelvis tilt than NSP and LSP [25,49]. In previous studies, LBP subgroups (flexion pattern) have displayed a more kyphotic sitting pattern towards their available end-range in both adults and adolescents [12,15]. ...
Aim: To compare repositioning error, habitual and self-perceived optimal sitting posture, between patients with low back pain presenting with a directional preference into extension and asymptomatic individuals.
Method: Fifteen patients with low back pain were matched with 15 asymptomatic individuals. Lumbo-pelvic repositioning error, pain, functional disability, and depression were evaluated. Participants reproduced two target positions (neutral and lordotic sitting postures) after slump sitting.
Results: No significant differences (all p > .05) were detected between patients with low back pain and asymptomatic individuals in error direction, magnitude and variability. Furthermore, no differences were found in habitual or self-perceived optimal posture between the patients and control groups.
Conclusions: We found no evidence of deficits in proprioception in patients with mild low back pain and directional preference into extension. While the lack of clear deficits in repositioning error is consistent with many previous studies, there are also data suggesting deficits in repositioning error among patients with low back pain. Variations in methodology, the population of patients studied, and especially their level of pain, could explain this variation. The lack of consistent deficits in repositioning error suggests other factors, across the biopsychosocial spectrum, may be more relevant in the development, and persistence, of low back pain.
... This result seems logical because those structures are just above the instable air-inflated cushion. Moreover, the link between pelvis and lumbar spine has already been demonstrated (Annetts et al., 2012;Ellegast et al., 2012;O'Sullivan et al., 2010aO'Sullivan et al., , 2010b. ...
... As expected, our EMG analysis demonstrates a decrease of the activation of the lumbar paravertebral muscles on the cushion. This result agrees with the literature that describes a diminution of the activity of those muscles on the same tilted support (Marschall et al., 1995;O'Sullivan et al., 2010aO'Sullivan et al., , 2010bO'Sullivan et al., 2012b;Sabatier, 2014), even if the cushion provides more dynamism in SP. Actually, maintaining static posture is more tiresome than maintaining dynamic posture (O' Sullivan et al., 2012b). ...
Background:
Adequate motor control is considered important for spinal stability and the prevention of low back pain in adulthood and in childhood.
Objective:
Given that the sitting position can affect proprioception, this study aimed to evaluate the influence of using at school a triangular and dynamic cushion on schoolchildren's trunk motor control.
Methods:
Thirty 8-year-old schoolchildren were randomized into a control group (n= 15) and a "cushion group" (n= 15), in which the children used the cushion for one year and a half. At the end of this period, a 3D-analysis was used to assess lumbar spine proprioception by means of a trunk repositioning task performed blindfolded in a seated position in two conditions (on a stable and on an unstable surface).
Results:
The schoolchildren in the cushion group performed better at the trunk repositioning task (p= 0.02) and hold their lumbar lordosis (p= 0.03) better than the control children, in both conditions (stable and unstable).
Conclusions:
This preliminary study suggests that daily use of a triangular dynamic cushion has a beneficial impact on children's lumbar proprioception. Further studies are needed to confirm these results and investigate the effectiveness of its use to prevent low back pain in adulthood.
... This result seems logical because those structures are just above the instable air-inflated cushion. Moreover, the link between pelvis and lumbar spine has already been demonstrated (Annetts et al., 2012;Ellegast et al., 2012;O'Sullivan et al., 2010aO'Sullivan et al., , 2010b. ...
... As expected, our EMG analysis demonstrates a decrease of the activation of the lumbar paravertebral muscles on the cushion. This result agrees with the literature that describes a diminution of the activity of those muscles on the same tilted support (Marschall et al., 1995;O'Sullivan et al., 2010aO'Sullivan et al., , 2010bO'Sullivan et al., 2012b;Sabatier, 2014), even if the cushion provides more dynamism in SP. Actually, maintaining static posture is more tiresome than maintaining dynamic posture (O' Sullivan et al., 2012b). ...
Background:
Low back pain is highly prevalent in the general population and is even reported as early as at primary school. A poor sitting position has been suggested as an etiologic factor. This study analysed, in primary schoolchildren, the influence of a triangular dynamic cushion that aims to help children maintain their physiological lumbar lordosis and to induce movement to reduce the static effect of the sitting position.
Methods:
Thirty 8-year-old children took part in this study. A 3D analysis combined with electromyography was used to evaluate the biomechanics and the related muscle activation in two sitting positions (with and without a triangular cushion on a horizontal stool) during a 15-minute working task. In addition, the force of the feet on the ground was assessed with a force plate.
Findings:
The cushion improved the trunk-thighs angle, lumbar lordosis, anterior pelvis tilt, and feet support on the ground (p<0.0001). In addition, sitting on the cushion appeared to be more dynamic (p<0.05) and induced a decrease of the lumbar paravertebral muscle activity (p<0.01).
Interpretation:
Sitting on a dynamic triangular cushion tends to favour the "ideal" siting position usually described in the literature and to decrease the level of paravertebral muscle recruitment. Seeing that sitting position is a risk factor to develop low back pain, the cushion could be a solution to prevent it.
... Przyczyną może być również nadmierne przeciążenie mięśni i więzadeł w odcinku lędźwiowym kręgosłupa, w związku z nieprawidłową postawą ciała [8]. W pasywnej pozycji siedzącej, którą można opisać jako kifotyczną, mięśnie okolicy kręgosłupa lędźwiowo-krzyżowego wykazują mniejszą aktywność, natomiast w okolicy szyjnej większą, a miednica ustawiona jest w tyłopochyleniu [4,20]. ...
... Zdolność do przyjmowania optymalnej, prawidłowej pozycji siedzącej u młodych, dorosłych osób może być istotnym czynnikiem w zapobieganiu bólu dolnego odcinka kręgosłupa. Fizjoterapeuci w większości przypadków (54.9%) wskazują, że najlepszą pozycją siedzącą jest utrzymywanie lordotycznego kształtu kręgosłupa w odcinku lędźwiowym w połączeniu z lekką kifozą [20]. Według naszej wiedzy nie ma jednak w literaturze doniesień na temat wpływu sposobu utrzymywania pozycji siedzącej w ciągu dnia na zmiany uciskowego progu bólu (UPB) tkanek miękkich. ...
... For the sitting position, the participants were instructed to sit in a neutral position on a backless wooden chair, place their feet on the ground with shoulder-width apart, the arms relaxed at their sides, the forearms on the thighs, and keep the knees and hips at 90 degrees flexion (37). The participants looked at a fixed visual sign about 1.5 meters away from the chair at eye levels (44). ...
Background
The paraspinal muscles, including multifidus (MF) and erector spinae (ES) play key roles in the stability and movement of the lumbar spine. This study aimed to determine the intra-rater reliability of the ES and MF muscle thickness measures of the rehabilitative ultrasound imaging (RUSI) in people with active extension pattern (AEP) non-specific chronic low back pain and controls.
Methods
Fifteen females with AEP and 19 controls participated in this test-retest intra-rater reliability study, including two different testing sessions performed in four to seven days apart. The primary (raw) and derived (normalized) measures of the L4 MF and ES muscles`thickness were examined in three different positions (prone, sitting, and standing) on both days. A two-way mixed average of intra-class correlation coefficient (ICC3, K) with confidence interval (CI = 95%) was used to determine the relative reliability. The standard error of measurement (SEM) and minimal detectable change (MDC) values at a CI of 95% were computed to examine the absolute reliability.
Results
The ICC values for the primary thickness of the L4 ES and MF muscles were from 0.85 to 0.91, except for MF muscle thickness in standing (ICC = 0.67) and sitting (ICC = 0.66) positions . The ICC values for derived data were lower in both groups. The SEM and MDC values were small enough to confirm the absolute reliability of the primary data.
Conclusion
This study supports the use of RUSI for examining the primary measures of the L4 MF and ES muscles in asymptomatic and AEP participants, but it should be used cautiously for assessing the derived measures.
... It is known that body posture, muscle fatigue and musculoskeletal disorder (MSD) are three main elements that are related to one another especially in a sitting condition (Abdul Hadi Abdol Rahim & Ibrahim Othman, 2010;Balasubramanian, Jagannath, & Adalarasu, 2014;Karmegam et al., 2009;Mörl & Bradl, 2013;O'Sullivan et al., 2010;O'Sullivan, McCarthy, White, O'Sullivan, & Dankaerts, 2012;Srinivasan & Balasubramanian, 2007;A. W. Stedmon, 2007;Velagapudi et al., 2010). ...
Studies concerning motorcycle have been an overwhelming area of research interest since the past few years. This trend of studies focuses on many issues relating to motorcycle including design, safety, accident preventions, fatalities statistics, ergonomics and many more. In performing these studies, researchers have used many methodologies, tools and also equipment in acquiring their data. In this study, the evolution of a new adjustable motorcycle test rig is introduced. Combination of computer aided design (CAD) and finite element analysis (FEA) software made it possible to design and simulates the test rig’s conceptual design before being fabricated. The test rig was designed to provide full adjustability for researchers to replicate established motorcyclist riding postures based on the Riding Posture Classification (RIPOC) system. The test rig setup also provides elements of environmental effects to give a more real riding experience and better fidelity to motorcyclist respondents during experiments. By having such test rig that is coupled with electronic data logger and telemetry devices, studies concerning riding postures and fatigue can be done in a much proper method and controlled experimental setup with better safety for both the respondents and researchers. Adjustable attributes provided on the test rig makes it a unique design of its own and is being patented to protect the author’s Intellectual Property Rights (IPR) on the test rig design.
... Hyper-lordosis during sitting induced consistently increased activation of the back extensor muscles and excessive compressive pressure in the facet joints of the spine (8,9). Consequently, to adopt a lumbar sitting posture that reduces passive tissue strain, slight lumbar lordosis and a relaxed thorax are important to prevent and resolve LBP during seated work (10). Studies have examined the degree of curvature of the lumbar spine according to sitting condition (11)(12)(13)(14). ...
Background: A slouched lumbar posture during sitting is risk factor for the low back pain (LBP). Various chairs have been used to maintain sagittal lumbar lordosis and sacral alignment during sitting. We aimed to demonstrate the effect of a pelvic-support chair on the lumbar lordosis and sacral tilt in patients with LBP.
Methods: We recruited 29 patients with non-specific LBP and 11 healthy subjects in South Korea from Apr 2017 to Mar 2018. The sagittal lumbosacral alignment was examined radiographically in three sitting postures: usual, erect, and sitting in a pelvic-support chair. Five angles [the lumbar lordosis, upper lumbar (ULA), lower lumbar (LLA), lumbosacral (LSA), and sacral slope (SS) angles] were compared between the subjects with LBP and healthy subjects in the three sitting conditions.
Results: There were significant differences in the lumbar lordosis, ULA, LLA, LSA, and SS according to sitting condition (P
... Tilley and Dreyfuss [56] found from a sitting observation study that passengers prefer a forward-facing and neutral straight neck position as it is the most comfortable position. Research findings in the field of psychophysiology suggest that an ideal cushion should support the body in a neutral position [57] . Bouwens et al. [50] found that neck cushions that support the neck and restrict movement in all directions to maintain a neutral posture are the most comfortable to experience. ...
Objective
: It is common for employees to complain of muscle fatigue when resting in a reclined position in an office chair. To investigate the physical factors that influence resting comfort in a supine position, a newly designed product was used as the basis for creating a prototype experiment and testing its efficacy in use. Subjective questionnaires were combined with surface EMG measurements and deep learning algorithms were used to identify body part comfort to create a hybrid approach to product usability testing.
Methods
: To facilitate the use of sEMG-based CNNs in human factors engineering, a subjective user assessment was first conducted using a combination of body mapping and an impact comfort scale to the screen which body parts have a significant impact effect on comfort when using the prototype. A control group (no used) and an experimental group (used) were then created and the body parts with the most significant effects were measured using sEMG methods. After pre-processing the sEMG signal, sMEG feature maps were obtained by mean power frequency (MPF) and linear regression was used to analyze the comforting effect. Finally, a CNN model is constructed and the sMEG feature maps are trained and tested.
Results
: The results of the experiment showed that the user's subjective assessment showed that 10 body parts had a significant effect on comfort, with the right and left sides of the neck having the highest effect on comfort (4.78). sEMG measurements were then performed on the sternocleidomastoid (SCM) of the left and right neck. Linear analysis of the measurements showed that the control group had higher SCM fatigue than the experimental group, which could also indicate that the experimental group had better comfort. The final CNN model was able to accurately classify the four datasets with an accuracy of 0.99.
Conclusion
: The results of the study show that the method is effective for the study of physical comfort in the supine sitting position and that it can be used to validate the comfort of similar products and to design iterations of the prototype.
... Since the introduction of treatment on the reclined patient in dentistry in the 1960s, dentistry has changed from being usually performed in a standing position to being executed mostly in a sitting position [3,4]. An increased working time in a sitting position may be related to an increasing number of musculoskeletal complaints (MSD), which represent a major impairment [5][6][7][8][9][10][11][12][13][14][15][16][17]. Numerous studies [5][6][7][8][9][10][11][12][13][14][15]17] have shown that between 64 and 93% of subjects surveyed (dentists, dental students, dental hygienists and dental assistants) stated that they suffer from MSD. ...
Background:
Musculoskeletal disorders (MSD) are a common health problem among dentists. Dental treatment is mainly performed in a sitting position. The aim of the study was to quantify the effect of different ergonomic chairs on the sitting position. In addition, it was tested if the sitting position of experienced workers is different from a non-dental group.
Methods:
A total of 59 (28 m/31f) subjects, divided into two dentist groups according to their work experience (students and dentists (9 m/11f) < 10 years, dentists (9 m/10f) ≥ 10 years) and a control group (10 m/10f) were measured. A three-dimensional back scanner captured the bare back of all subjects sitting on six dentist's chairs of different design. Initially, inter-group comparisons per chair, firstly in the habitual and secondly in the working postures, were carried out. Furthermore, inter-chair comparison was conducted for the habitual as well as for the working postures of all subjects and for each group. Finally, a comparison between the habitual sitting posture and the working posture for each respective chair (intra-chair comparison) was conducted (for all subjects and for each group). In addition, a subjective assessment of each chair was made. For the statistical analysis, non-parametric tests were conducted and the level of significance was set at 5%.
Results:
When comparing the three subject groups, all chairs caused a more pronounced spinal kyphosis in experienced dentists. In both conditions (habitual and working postures), a symmetrical sitting position was assumed on each chair. The inter-chair comparisons showed no differences regarding the ergonomic design of the chairs. The significances found in the inter-chair comparisons were all within the measurementerror and could, therefore, be classified as clinically irrelevant. The intra-chair comparison (habitual sitting position vs. working sitting position) illustrated position-related changes in the sagittal, but not in the transverse, plane. These changes were only position-related (forward leaned working posture) and were not influenced by the ergonomic sitting design of the respective chair. There are no differences between the groups in the subjective assessment of each chair.
Conclusions:
Regardless of the group or the dental experience, the ergonomic design of the dentist's chair had only a marginal influence on the upper body posture in both the habitual and working sitting postures. Consequently, the focus of the dentist's chair, in order to minimize MSD, should concentrate on adopting a symmetrical sitting posture rather than on its ergonomic design.
... A static calibration of the sitting posture was performed for each participant before testing started. During the calibration participants were seated on a desk chair without back support, both feet on the floor, upper legs horizontal, lower legs vertical, feet parallel and shoulder width apart on the ground, arms uncrossed on thighs ( Fig. 1) 33,40,41 . After degreasing the skin, anatomical landmarks were located by manual palpation, and marked by an experienced (> 10 years) manual therapist (= principal researcher). ...
Spinal postural variability (SPV) is a prerequisite to prevent musculoskeletal complaints during functional tasks. Our objective was to evaluate SPV in cervicogenic headache (CeH) since CeH is characterized by such complaints. A non-randomized repeated-measure design was applied to compare SPV between 18 participants with reporting CeH aged 29–51 years, and 18 matched controls aged 26–52 years during a 30-min-laptop-task. Habitual spinal postures (degrees) of the cervical, thoracic and lumbar spine were analysed using 3D-Vicon motion analysis. SPV, to express variation in mean habitual spinal posture, was deducted from the postural analysis. Mean SPV of each spinal segment was lower in the CeH-group compared to the control-group. Within the CeH-group, SPV of all except one spinal segment (lower-lumbar) was higher compared to the group’s mean SPV. Within the control-group, SPV was more comparable to the group’s mean SPV. SPV differed between groups. Averaging data resulted in decreased SPV in the CeH-group compared to the control-group during the laptop-task. However, the higher within-group-SPV in the CeH-group compared to the group’s mean SPV accentuated more postural heterogeneity. It should be further determined if addressing individual SPV is a relevant intervention.
... The best sitting posture is not definitely clarified in the literature and whether there is an ideal posture continues to be surrounded by controversy among researchers and clinicians. Qualitative assessments recommended sitting with a neutral shape of the spine, which generally is comfortable and relaxed without extreme muscle tone (80,81). Over 70% of physiotherapists considered the upright lordotic sitting posture as the optimal posture (82). ...
Background: Musculoskeletal dysfunction is one of the most important occupational health issues. Prolonged sitting may be a risk factor for low back pain (LBP) associated with reduced muscle endurance, although many people with a sedentary lifestyle and sitting-type job report
no pain and discomfort in the lumbar region. In the present study, endurance of the core muscles in individuals with sedentary jobs with nonspecific chronic LBP were compared with those without LBP.
Objective: The present study compared core muscle endurance in individuals with sedentary jobs with and without nonspecific chronic low back pain.
Methods: A total of 50 sedentary staffs were selected and divided into LBP and control group. Trunk muscle endurance was measured in seconds using the McGill’s trunk flexor endurance test, the Sorenson’s trunk extensor endurance test, and the right and left trunk flexor endurance test (Side-bridge test). Differences between the two groups were analyzed using multivariate general linear models in 2 ways ANOVA.
Results: There were no significant between-group differences in the raw endurance of the extensor, flexor, right/ left flexor muscles (P≥0.05). However, there were significant between group differences in some self-reported physical fitness subscales (P<0.05), duration of sitting
at home (P=0.035), frequency of assuming a slump sitting position (P=0.049), and sitting with leaning back to the backrest (P=0.02) at work. We developed uni- and multivariate general linear models, which showed adjustments to these parameters and unmasked fundamental
between-group differences in extensor muscle endurance.
Conclusions: Our finding does not support the popular opinion that daily sitting-while-at-work for long durations is necessarily associated with LBP. Instead, sitting posture, lower physical fitness levels, and shorter duration of sitting activities at home may be associated with reduced extensor muscle endurance in nonspecific chronic low back pain.
KEY WORDS: Core muscle; Endurance; McGill tests; Nonspecific Chronic Low Back Pain; Sedentary Occupation.
... However, this technique is limited by significant variation in patient effort/ability to flex forward, as well as by the fact that the pelvis anteverts during standing flexion, which may restrict full lumbar flexion-particularly at the most caudal segments (L4 to S1) where the majority of degenerative pathology occurs. 1 Importantly, several studies have shown a significant decrease in global lumbar lordosis with sitting compared to standing radiographs. [2][3][4][5][6] Biomechanically, it is intuitive that sitting may induce a greater flexion moment in the lumbar spine: when a person sits the pelvis retroverts, in turn the lumbar spine must go into kyphosis in order to maintain forward gaze. 5,7,8 Recently, in a study of 60 patients, Hey et al showed greater lumbar kyphosis in sitting versus standing flexion lateral lumbar X-rays. ...
Study Design
Prospective lumbar radiograph analysis.
Objective
To compare changes in lumbar lordosis in standing flexion versus seated lateral radiographs.
Methods
Standing lateral, standing flexion, and seated lateral X-rays of the lumbar spine were obtained in patients presenting with low back pain. Trauma, tumor, and revision cases were excluded. Changes in global lumbar as well as segmental lordosis were measured in each position.
Results
Seventy adult patients were reviewed. Overall, the greatest changes in lordosis were seen at L4-S1 in both the seated and flexion X-rays (12.5° and 6.3°, respectively). Greater kyphosis was seen in seated versus flexion X-rays (21.6° vs 15.8°); changes in lordosis from L1-L3 were similar in both positions, with little change seen at these levels (approximately 5° to 7°). On subgroup analysis, these differences were magnified in analyzing only patients that moved at least 20° globally, and there were no significant differences between sitting and flexion in “stiff” patients that moved less than 20° globally.
Conclusion
Greater lumbar kyphosis was seen in the seated position compared to standing flexion, especially from L4-S1. Given these results we suggest the use of seated lateral X-rays to dynamically assess the lumbar spine. These findings may also guide future research into the mechanism and clinical relevance of a stiff versus mobile lumbar spine, as well as into the sensitivity of seated X-rays in detecting instability.
... Duduk bekerja mendatangkan gangguan saat bekerja yang dikenal dengan repetitive strain injury (RSI); salah satu RSI yang sering terjadi saat duduk ialah NPB. [8][9][10][11][12] Pekerjaan yang berisiko menimbulkan NPB mekanik kronik antara lain pekerjaan yang memiliki jam kerja panjang dan mengharuskan karyawannya untuk duduk dalam waktu yang lama pada posisi duduk tertentu. Bekerja di bank merupakan salah satu pekerjaan yang berisiko terkena NPB. ...
Low Back Pain (LBP) is the most frequent musculosceletal issue found in daily work. Extenuating physical positions comprise 80-85% of the caues of LBP. In the medical world, a lot of causes of LBP do not identify the pathoanatomical disorders. These factors are e.g.: body in static position while working and the working body position leaning heavily on the vertebra (for example: sitting in a hunched position, sitting upright without back support, or working for unsually long periods of time). Until now in Manado no study has been carried out to show the correlation between LBP and the sitting position, or the duration of work. This study aimed to find out the correlation between chronic LBP and the sitting position or the duration of work among bank employees in one of the goverment banks in Manado. The results showed that there were 69 respondents involved in this study. Chronic LBP was found in 62 respondents (90%). Up stright position while sitting was the most frequent position that caused chronic LBP in 28 respondents. The average time used for working with sitting position was 7-8 hours which caused chronic LBP among 31 respondents of the group with the work time from 11.00-13.59. A P-value of 0.000 (<0.05) showed that there was a strong correlation between sitting position and chronic LBP. Duration of work also showed a strong correlation with chronic LBP with a P-value of 0.000. Conclusion: There were strong correlations beween chronic low back pain with sitting position while working and duration of work. Keywords: chronic LBP chronic, sitting position, duration of work, bank employees. Abstrak:Nyeri Punggung Bawah (NPB) merupakan gangguan muskuloskeletal yang paling sering dijumpai dalam aktivitas kerja. Faktor mekanik mencakup 80-85% dari keseluruhan penyebaNPB. Patoanatomi sering tidak dapat memberikan ketepatan diagnosis NPB oleh proses mekanik. Faktor mekanik yang mempercepat terjadinya gangguan NPB antara lain posisi badan yang cenderung statis, posisi badan yang cenderung memperberat kerja tulang-tulang vertebra seperti posisi badan membungkuk, tegak tanpa sandaran, dan waktu bekerja yang lama saat duduk. Hubungan NPB dengan posisi dan lama duduk belum pernah dilaporkan di Kota Manado. Penelitian ini bertujuan untuk mengetahui hubungan posisi dan lama duduk saat bekerja yang dapat menimbulkan NPB mekanik kronik pada karyawan bank. Hasil penelitian memperlihatkan dari keseluruhan responden yang berjumlah 69 orang, didapatkan 62 responden (90%) yang mengalami NPB mekanik kronik. Posisi duduk tegak tanpa sandaran merupakan posisi terbanyak menimbulkan NPB mekanik kronik pada 28 responden. Rata-rata lama duduk bekerja 7-8 jam menyebabkan NPB pada kelompok pukul 11.00-13.59 sebanyak 31 responden. Analisis statistik menggunakan uji chi-square memperlihatkan adanya korelasi yang kuat (P = 0,000) antara posisi duduk dan NBP mekanik kronik Lama duduk juga berkorelasi kuat dengan NBP mekanik kronik (P = 0,000). Simpulan: Terdapat hubungan yang kuat antara NBP mekanik kronik dengan posisi dan lama duduk pada karyawan bank. Kata kunci: NPB mekanik kronik, posisi duduk, lama duduk, karyawan bank.
... The purpose of posture training is to keep the body at its neural position. Several attempts have been made to define neutral of the head/neck and lumbar/low-back regions [33][34][35][36][37][38][39][40][41][42]. Many physiological landmarks such as tragus, canthus, eye socket, nation, or infraorbital notch have been used in measuring head/neck posture. ...
... Prolonged (non)occupational sitting is often proposed as a risk factor for LBP development. Although the majority of epidemiological studies do not support a causal relationship (Chen et al., 2009;Kwon et al., 2011;Roffey et al., 2010), prolonged sitting is a common aggravating factor for LBP sufferers (Astfalck et al., 2010;O'Keeffe et al., 2013;O'Sullivan et al., 2010). Furthermore, several potentially harmful mechanisms of prolonged sitting with (semi)flexion of the lumbar spine have been studied extensively over the past decades. ...
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.
... Although studies have suggested that a form of education is required for an effective rehabilitation programme for adults with NSLBP (O'Sullivan et al. 2010), literature related to including a body awareness perception component in a more formal and educative manner in exercise therapy is lacking. Furthermore, the practice of including a body awareness component with the DNS centration concept in the exercise therapy of a physiotherapy treatment for NSCLBP in Malaysia is also unknown. ...
... Moderate is maintained. 57 This posture is considered to be conducive to musculoskeletal health and prevent back pain. 38 However, none of the included studies investigated the perceived benefits of the seats as regards to the relief of musculoskeletal pain. ...
Objectives
Musculoskeletal disorders affect a high percentage of dentists, dental hygienists and therapists. Static and awkward working postures are considered as major risk factors. Proper seat selection and use of magnification loupes are promoted for their ergonomic benefits. The aim of this review was to evaluate the existing empirical evidence on the effect of the above interventions on (i) correction of poor posture and (ii) reduction in musculoskeletal pain.
Methods
The review was conducted according to the PRISMA guidelines. The review protocol was registered with PROSPERO (CRD42017058580). The Medline via Ovid, CINHAL via EBSCO, Web of Science, OpenGrey and EThOS electronic databases were searched. Prospective experimental studies were considered for inclusion. The Effective Public Health Practice Project Quality Assessment Tool (EPHPP) was used to assess the methodological quality of the included studies.
Results
Eight studies were included in the review. Four investigated the effect of loupes on posture and musculoskeletal pain, 4 the effect of the saddle seats on posture and one of the latter explored the combined effect of magnification and use of saddle seats on posture.
Conclusions
Based on a limited number of studies, the use of ergonomic saddle seats and dental loupes leads to improved working postures. The use of loupes appears to relieve shoulder, arm and hand pain. However, their effect on neck pain is scarce. None of the studies reported on the effect of the saddle seats on musculoskeletal pain. Future well-powered prospective longitudinal studies are deemed necessary to confirm the conclusions of this review.
available: http://onlinelibrary.wiley.com/doi/10.1111/idh.12327/full
... 1,2 Movement control impairment (MCI) can be defined as an impaired active movement control during functional activities. 3 MCI can also be called motor discoordination and motor control dysfunction. 4 In the clinical setting, practitioners often use the term functional (cervical, lumbar) instability to describe it. ...
Background:
The primary objective of this study was to determine the structural and known-group validity as well as the inter-rater reliability of a test battery to evaluate the motor control of the craniofacial region.
Methods:
70 volunteers without TMD and 25 subjects with TMD (Axes I) per the DC/TMD were asked to execute a test battery consisting of eight tests. The tests were videotaped in the same sequence in a standardized manner. Two experienced physical therapists participated in this study as blinded assessors. We used exploratory factor analysis in order to identify the underlying component structure of the 8 tests. Internal consistency (Cronbach α), inter-rater reliability (intraclass correlation coefficient), and construct validity (i.e. hypothesis testing-known-group validity) (receiver operating curves) were also explored for the test battery.
Results:
The structural validity showed the presence of one factor underlying the construct of the test battery. The internal consistency was excellent (0.90) as well as the inter-rater reliability. All values of reliability were close to 0.9 or above indicating very high inter-rater reliability. The Area Under the Curve (AUC) was 0.93 for rater 1 and 0.94 for rater two respectively indicating excellent discrimination between subjects with TMD and healthy controls.
Conclusions:
The results of the present study support the psychometric properties of test battery to measure motor control of the craniofacial region when evaluated through videotaping. This test battery could be used to differentiate between healthy subjects and subjects with musculoskeletal impairments in the cervical and orofacial regions. In addition, this test battery could be used to assess the effectiveness of management strategies in the craniofacial region. This article is protected by copyright. All rights reserved.
... Pelvic asymmetry has also been shown to cause higher stress on the lumbar spine in individuals with LBP [40] and changes in soft tissue tightness [41], thus making the spine susceptible to injury. Neutral sitting posture, consisting of sitting with slight lumbar lordosis and a relaxed thorax, has been proposed as an optimal seat posture at work [36,42]. Neutral sitting posture was associated with increased internal oblique and transversus abdominis muscles activity compared with slumped sitting posture [11,16]. ...
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.
... Ming [10] cites additional reasons for the development of neck pain syndromes and shoulder pain in people performing office tasks: repetition of movements, awkward or uncomfortably positioned upper limbs associated with an increased flexion or deviation of the hand, lack of workplace adjustments (no seat height adjustment, poor lighting) and individual predispositions arising from gender, age, weight, habits, the existence of possible deformation [10,11,12,13]. ...
... Ming [10] cites additional reasons for the development of neck pain syndromes and shoulder pain in people performing office tasks: repetition of movements, awkward or uncomfortably positioned upper limbs associated with an increased flexion or deviation of the hand, lack of workplace adjustments (no seat height adjustment, poor lighting) and individual predispositions arising from gender, age, weight, habits, the existence of possible deformation [10,11,12,13]. ...
Introduction. Year after year, we spend an increasing amount of time in a sitting position. Often, we sit with poor posture, as indicated by numerous pain syndromes within the musculoskeletal system. Several reports confirm that body posture and the amount of time spent in a seated position have extensive implications for our health. Previous studies and a literature review suggest there is limited knowledge regarding an ergonomic sitting position. Objective. The aim of the study was to analyze the research relating to a proper sitting position and the consequences of incorrect sitting posture. A database search was conducted in Science Direct, Scopus, PubMed, Medline, and Google Scholar. Selection was made on the basis of titles, the abstracts and full texts of the studies. No limits were applied to the date of publication.
Conclusions. Incorrect sitting posture contributes to many disorders, especially in the cervical and lumbar spine. It also determines the work of the respiratory system. Most authors suggest that maintenance of the physiological curvature of the spine is crucial for the biomechanics of the sitting position, as well as the location of the head and position of the pelvis. It raises awareness of work-related hazards and the introduction of education on the principles of proper seating. It is necessary to draw attention to the risks associated with work performed in a sitting posture, and education on the principles of ergonomical sitting.
... 25,26 The choice of the postures was based on a review of several studies examining ideal posture and subjective perception of ideal posture. 6,23,27 Table 2 contains the instructions given to the participants to execute the 5 predetermined postures, i.e. "Habitual standing posture" (HStP), "Subjectively perceived ideal standing posture" (SPIStP), "Habitual sitting posture" (HSiP), "Subjectively perceived ideal sitting posture" (SPISiP) and Adam's forward bending test. 12 Fig. 1 shows an example of a volunteer's scan while executing the HStP. ...
This work proposes a novel approach to assess spinal curvature, by using Microsoft's Kinect™ to obtain 3D reconstructed models of subject's dorsal skin surface in different postures. This method is non-invasive, radiation-free and low-cost. The trial tests here presented intended to evaluate the reliability of this approach, by assessing the tendency of 98 volunteers to present scoliosis. The shoulder height difference was calculated for each subject's scan, by quantifying the angular slope of a line crossing both scapulae. The volunteers' average age was 24.7 years. Results showed that 68.37% of the volunteers revealed differences higher than 1° between the shoulders, having that their record in what concerns to loads and lesions proved to increase the angular slope. This initial approach shall establish the grounds for assessing spinal posture in pre-clinical or industrial ergonomics scans. Further studies shall include comparison versus traditional imaging methods and experienced clinical evaluation.
... pelvis in the standing position(Roussouly et al. 2005) and also spinal-pelvic curvature in the standing and sitting positionsO'Sullivan et al. 2010;Caneiro et al. 2010). The results of these studies indicated that the adoption of habitual sitting posture gave rise to a kyphotic-type posture. ...
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 vs. 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.
... 4 Office workers, in particular, have reported a high frequency of musculoskeletal disorders, including LBP. [5][6][7][8] Currently, more than 75% of available jobs in industrial countries require employees to work in a sitting position, 9 and remaining in a sitting posture for an extended period of time has been found to be associated with LBP. [10][11][12] With the hopes of enabling a healthier workforce in the future, researchers have been investigating the potential relationship between static work postures and the development of musculoskeletal disorders 6,[13][14][15] as well as proposing various office interventions to help alleviate these musculoskeletal disorders. [16][17][18] It is generally agreed upon by ergonomists that regular movement and seat posture variation can lead to an improvement in spinal health. ...
Objective: The aim of the study was to determine whether chronic low back pain (LBP) might be attenuated through the introduction of a sit-stand workstation (SSW) in office employees. Methods: Participants were randomized to receive a SSW at the beginning or at the end of a 3-month study period. Participants responded to a short survey at the end of each workday and a comprehensive survey at weeks 1, 6, and 12. Surveys consisted of a modified brief pain inventory and the Roland Morris Disability Questionnaire. Results: Forty-six university employees with self-reported chronic LBP were enrolled. Participants who were given access to a SSW reported a significant reduction in current (P=0.02) and worst (P=0.04) LBP over time. Conclusions: Our findings support the hypothesis that chronic LBP might be improved by the introduction of a SSW in an office environment. © 2016 American College of Occupational and Environmental Medicine.
... 4 Office workers, in particular, have reported a high frequency of musculoskeletal disorders, including LBP. [5][6][7][8] Currently, more than 75% of available jobs in industrial countries require employees to work in a sitting position, 9 and remaining in a sitting posture for an extended period of time has been found to be associated with LBP. [10][11][12] With the hopes of enabling a healthier workforce in the future, researchers have been investigating the potential relationship between static work postures and the development of musculoskeletal disorders 6,[13][14][15] as well as proposing various office interventions to help alleviate these musculoskeletal disorders. [16][17][18] It is generally agreed upon by ergonomists that regular movement and seat posture variation can lead to an improvement in spinal health. ...
Objective:
The aim of the study was to determine whether chronic low back pain (LBP) might be attenuated through the introduction of a sit-stand workstation (SSW) in office employees.
Methods:
Participants were randomized to receive a SSW at the beginning or at the end of a 3-month study period. Participants responded to a short survey at the end of each workday and a comprehensive survey at weeks 1, 6, and 12. Surveys consisted of a modified brief pain inventory and the Roland Morris Disability Questionnaire.
Results:
Forty-six university employees with self-reported chronic LBP were enrolled. Participants who were given access to a SSW reported a significant reduction in current (P = 0.02) and worst (P = 0.04) LBP over time.
Conclusions:
Our findings support the hypothesis that chronic LBP might be improved by the introduction of a SSW in an office environment.
Objective: Deep learning-based CNN networks have recently been investigated to solve the problem of body posture recognition based on surface electromyographic signals (sEMG). Influenced by these studies, to develop a combined approach of
sEMG and CNNs in the study of human-product interactions and the impact of body comfort, and to compare the advantages and disadvantages of various CNNs networks.
Methods: In this study, sEMG measurements were carried out by building a prototype usability experiment, and the data were divided into four categories, with two types of datasets: training and testing. Four CNNs, LeNet-5, VGGNet-11, InceptionNet V4, and DenseNet, were used for the recognition of sEMG images.
Results: DenseNet is another type of convolutional neural network with deep layers, which has a unique advantage over other algorithms. unique advantages over other algorithms. DenseNet has fewer layers and better accuracy than InceptionNet V4, but not only does it bypass enhanced feature reuse, but its network is easier to train and has some regularisation effects, while also mitigating the problems of gradient disappearance and model degradation.
Conclusion: These findings could lead to a more appropriate CNN model and a useful tool for developing comfort judgments of surface EMG signals, furthering the development of products that come into contact with the human body without the need for routine retraining.
[Purpose] The aim of this research was to investigate the effects of three seat shapes - a standard seat with a 5° backward tilt, a seat with a 15° forward tilt, and a half-sloped seat shape (HS) with a forward-tilted front and the same angle as the standard seat at the back - on the sitting posture and trunk and lower limb muscle activities during quiet sitting and upper limb movements. [Participants and Methods] Twelve healthy adults were included in the study. We compared the number of movements during upper limb exercises (moving a water bottle back and forth and side to side with the dominant hand) during quiet sitting in the three seat shapes (standard, forward tilt, and HS), as well as the changes in the angle of the hip joint and the distance between the outside of the thigh bone and the edge of the seat. We also compared the muscle activities of the anterior deltoid, upper trapezius, external oblique, erector spinae, rectus femoris, vastus lateralis, and peroneus longus muscles as measured by surface electromyography. [Results] The HS seat resulted in less extension of the distance between the outside of the thigh bone and the edge of the seat than the standard seat, and less muscle activity in the right rectus femoris, left vastus lateralis, and right peroneus longus muscles than the forward tilt seat. [Conclusion] The results suggest that the HS seat can contribute to maintaining a posture suitable for activities.
(1) Objective: The objective of this study was to experimentally obtain the ideal pressure distribution model of buttock and thigh support for office workers in forward-leaning and upright sitting postures, reproduce the support provided by mesh materials with elastic materials, and propose an effective seat design scheme to improve the comfort of office workers. (2) Method: Based on the seven most popular mesh chairs on the market, pressure distribution experiments, and the fuzzy clustering algorithm, the relatively ideal body pressure distribution matrices were generated for office workers under two common sitting postures, and the corresponding partitioned sitting support surfaces were obtained. A prototype chair was created and validated by combining the ergonomics node coordinates and the physical properties of the materials. (3) Result: An ideal support model of four zones was constructed, and prototype pads were designed and produced according to this model. Subjects were recruited to test the ability of the prototypes to reproduce the ideal pressure distribution maps. (4) Conclusion: The four-zone ideal support model is capable of effectively representing the buttock and thigh support requirements in forward-leaning and upright sitting postures, and it is useful for the development of related products. Studying sitting postures and pressure values generated by different activities of office workers will help to refine the needs of office personnel and provide new ideas for the design of office chairs.
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.
Purpose. The awkwardly designed sewing workstations in the garment industry cause work-related musculoskeletal disorders that cause global health concerns for industrial sewing operators. This study was conducted with the aims of evaluating health risks and improvement interventions for sewing operators in Ethiopia. Materials and methods. Strain index and standardized Nordic Musculoskeletal disorder questionnaires were used for data collection. Binary and multiple logistic regression analysis were used to analyze the data and identify significant factors. Results. The study revealed that operators sitting chair design in the sewing section has significant correlation with the occurrence pain in different body parts particularly in the upper and lower back body parts with a high odds ratio of more than 93% in the low and upper back areas. Hence, the sitting chair was redesigned considering operator's anthropometric measurements and workstation requirements to improve workers safety and productivity. Conclusion. The study concludes that work related musculoskeletal disorders were significant in different body parts was crucial for appropriate intervention in redesigning the sewing workstations particularly the sitting chair to ensure health and safety of industrial sewing operators. The study therefore recommends implementation of the proposed ergonomic sitting chair to improve operators safety and productivity.
It has been shown that the type of stool influences lumbar posture and muscle activity during dental work. Studies investigating the effect on cervicothoracic muscle activity and posture are scarce though. The present study investigated the effect of different stool types on cervicothoracic muscle activity and posture during a dental procedure. Twenty five participants completed a simulated periodontal screening whilst sitting on the Ghopec, Salli MultiAdjuster saddle and A-dec dental stool. Muscle activity of M. Splenius Capitis, M. Sternocleidomastoideus, M. Trapezius Pars Descendens and M. Trapezius Pars Ascendens was measured using surface electromyography. Cervicothoracic posture was evaluated by means of a strain gauge (BodyGuard™) fixed between C5 and T2. No differences in muscle activity and posture were found between the three stools. Although the type of stool influences lumbar posture and muscle activity, it seems these differences are not continued at the cervicothoracic region.
The purposes of this study were to characterize the influence of seat back angle variations on the neck comfort of sleeping passengers without a pillow and provide suggestions for the design of economy-class seats. In this study, 17 subjects were subjected to a sleep experiment to test the effect of the backrest angle on head and neck rotation and the fatigue level of the neck muscles. The results showed that a reclined backrest (positioned at 110°) caused greater rotation of the head and neck and greater fatigue of the neck muscles than a vertical backrest. Additionally, the higher was the subject's head extended above the top of the backrest, the more complicated the head and neck rotation was and the more intense the stretching of muscles was. We conclude that, when sleeping in a sitting position without head support, passengers were more likely to experience neck muscle fatigue with the reclined backrest than with the vertical backrest. Passenger height was also found to be an important factor contributing to head and neck fatigue. On the basis of the experimental results, we offer suggestions for the design of backrests to improve passengers' sleeping experience. Our research and suggestions provide a new path for innovation in the design of economy-class seats and could help to improve the travel experience.
Various solvent extracts from two marine green algae, Codium bursa and Codium fragile collected from the North Tunisian coasts during spring and summer seasons were used to obtain high dry matter yields. The algal extracts showed the great power of in vitro cell growth inhibition against Hela cells, which was confirmed by MTT test. The comparative efficiency of different polarity solvents showed that methanolic extract with high-polarity composition had significantly more important yield than petrol ether extracts, while the higher inhibition activity was obtained with petrol ether extract from C. bursa (IC50= 115.755 μg/mL). Moreover, it showed a seasonal variation that revealed the most important activity during the season of spring as compared to summer. Flash chromatography of the petrol ether extract and GC-MS analysis of its most active fraction revealed a total of six major compounds well-known in medicinal plants: 6,10,14-trimethyl-2-pentadecanone; 2-dodecanone; 1-dodecanol; dodecyl acrylate; formic acid 3,7,11-trimethyl-1,6,10-dodecatrien-3-yl ester; and bicyclo[4.4.0]dec-2-ene-4-ol 2-methyl-9-(prop-1-en-3-ol-2-yl).
Sitting is the most common status of modern human beings. Some sitting postures may bring health issues. To prevent the harm from bad sitting postures, a local sitting posture recognition system is desired with low power consumption and low computing overhead. The system should also provide good user experience with accuracy and privacy. This paper reports a novel posture recognition system on an office chair that can categorize seven different health-related sitting postures. The system uses six flex sensors, an Analog to Digital Converter (ADC) board and a Machine Learning algorithm of a two-layer Artificial Neural Network (ANN) implemented on a Spartan-6 Field Programmable Gate Array (FPGA). The system achieves 97.78% accuracy with a floating-point evaluation and 97.43% accuracy with the 9-bit fixed-point implementation. The ADC control logic and the ANN are constructed with a maximum propagation delay of 8.714 ns. The dynamic power consumption is 7.35 mW when the sampling rate is 5 Sample/second with the clock frequency of 5 MHz.
Office goers have been compelled to or increasingly constrained to remain seated in a chair–desk complex. Assessment of seat dynamics and user-seat compatibility has been examined, using approaches such as anthropometric, biomechanical, electromyographic and stabilometric analysis, comfort rating and materials construction. This chapter describes biomechanics of sitting, analysis of sitting modes and seated features, and aspects of Balans chairs. Further, it elaborates the ergo-design characteristics of an office chair, including different chair tilting mechanisms. Methodological details of the simulated seat–desk system are included for human–seat–desk interface analysis, covering the effects of the slope of the seat pan, backrest angles, height of armrest, upright and slouch sitting, about body force distribution and muscle activation. Several general risk factors, such as seating system, repetitive use of keyboards/mouse, chair–desk with or without adjustable armrests, supported/unsupported forearm and wrist, are all interconnected and compelling components of workplace constraints in computer work. Discussion includes options of good job design, periodic task rotation, rest breaks, stretching exercises in relieving the physical and mental strain of computer operators.
Background: Assessment of, and advice about, spinal posture is common when people with spinal pain present to physiotherapists. Most descriptions regarding optimal spinal posture have been qualitative in nature. Objectives: To determine the beliefs of physiotherapists regarding optimal sitting and standing posture. Design: Online survey. Method: 544 Greek physiotherapists selected an optimal sitting (choice of seven) and standing (choice of five) posture, while providing justification for their choice. Results: Education regarding optimal sitting and standing posture was considered “considerably” or “very” important by 93.9% of participants. Three different sitting postures, and two different standing postures, were selected as the optimal posture by 97.5% and 98.2% of physiotherapists respectively. While this reflects a lack of complete consensus on optimal posture, the most commonly selected postures were all some variation of upright lordotic sitting, in contrast slouched spinal curves (sitting) or forward head posture (sitting and standing) almost never being selected as optimal. Interestingly, participants used similar arguments (e.g. natural curves, muscle activation) to justify their selection regardless of the spinal configuration of each selected posture. Conclusions: These results reinforce previous data suggesting that upright lordotic sitting postures are considered optimal, despite a lack of strong evidence that any specific posture is linked to better health outcomes. While postural re-education may play a role in the management of spinal pain for some patients, awareness of such widespread and stereotypical beliefs regarding optimal posture may be useful in clinical assessment and management.
There is certainly room for economy-class travelers to make their trips more pleasant. A travel pillow might improve comfort. In this study, the comfort expectations and experience of travel pillows were examined. Comparing these 2 aspects indicated that it is not always possible to predict the comfort experience associated with a product based on a picture, and that there is a discrepancy between expected and experienced comfort. Experienced comfort is highest for travel pillows that restrict head movements in all directions in order to maintain a neutral posture. The results of this study also support earlier studies that suggested that discomfort experience can be predicted by observing the number of participants’ in-seat movements; more movements result in higher experienced discomfort.
Aiming to find a measurement technique that allows studying the seated posture, we conducted the following systematic review. The search was made in specialized databases in the study area. The key words of the search included terms such as low back pain, sitting posture, pelvic tilt, among others. 2383 items were selected according to the review question proposed and these 228 from established inclusion criteria. They were found 17 items that allow you to identify the appropriate techniques for the stance study. The revision allowed proposing a guide for selecting a tool to evaluate the seated posture based on the benefits offered by the instrument to comply with the objectives of the study that you want to perform.
Whereas in the past dental stools typically facilitated a 90° hip angle, a number of currently available alternative designs allow for a more extended hip posture. The present study investigated the influence of different stool types on muscle activity and lumbar posture. Twenty five participants completed a simulated dental procedure on a standard stool, a saddle and the Ghopec. The latter stool comprises a seat pan consisting of a horizontal rear part for the pelvis and an inclinable sloping down front part for the upper legs, with a vertically and horizontally adjustable back rest. Lumbar posture was most close to neutral on the Ghopec, whereas sitting on a standard/saddle stool resulted in more flexed/extended postures respectively. Sitting with a 90° angle (standard stool) resulted in higher activation of back muscles while sitting with a 125° angle (saddle and Ghopec) activated abdominal muscles more, although less in the presence of a backrest (Ghopec). To maintain neutral posture during dental screening, the Ghopec is considered the most suitable design for the tasks undertaken.
Study design: Numerous authors have attempted to sub-classify low back pain in order that valid homogenous subsets of low back pain presentations might be recognised. This review systematically appraises these papers.
Methods: Medline, Embase, Cinahl, AMED and PEDro electronic databases were searched with subsequent hand searching of bibliographies. Papers were included between June 1983 and June 2003. Two reviewers independently reviewed 32 papers using a standard scoring criteria for assessment. A third reviewer mediated disagreements.
Results: Thirty-two papers were reviewed, with classification systems being grouped by method of classification. Classification has been attempted by implication of patho-anatomical source, by clinical features, by psychological features, by health and work status and in one case by a biopsychosocial weighting system. Scores were generally higher for systems using a statistical cluster analysis approach to classification than a judgemental approach. Both approaches have specific advantages and disadvantages with a synthesis of both methodologies being most likely to generate an optimal classification system.
Conclusions: The classification of NSLBP has traditionally involved the use of one paradigm. In the present era of biopsychosocial management of NSLBP, there is a need for an integrated classification system that will allow rational assessment of NSLBP from biomedical, psychological and social constructs.
Prolonged sitting with poor posture is associated with the development of lower
back pain. Ergonomic texts for physiotherapists contain diverging and confusing
views on recommended postures for the lumbar spine when seated that will
promote postural health and optimal functioning of the lumbar spine. A review of
the literature reveals that proponents of both the lordosed and kyphosed lumbar
seated position use similar arguments with contradictory conclusions. The
arguments of those advocating the kyphosed lumbar seated posture are, however,
often anecdotal and unsubstantiated by research. This paper evaluates the
con icting views and concludes that the lordosed seated posture, regularly
interspersed with movement, is the optimal sitting posture and assists in
maintaining lumbar postural health and preventing low back pain.
The role of transversus abdominis (TrA) on spinal stability may be important in low back pain (LBP). To date, there have not been any investigations into the influence of lumbo-pelvic neutral posture on TrA activity. The present study therefore examines whether posture influences TrA thickness. A normative within-subjects single-group study was carried out. Twenty healthy adults were recruited and taught five postures: (1) supine lying; (2) erect sitting (lumbo-pelvic neutral); (3) slouched sitting; (4) erect standing (lumbo-pelvic neutral); (5) sway-back standing. In each position, TrA thickness was measured (as an indirect measure of muscle activity) using ultrasound. In erect standing, TrA (mean TrA thickness: 4.63+/-1.35 mm) was significantly thicker than in sway-back standing (mean TrA thickness: 3.32+/-0.95 mm) (p=00001). Similarly, in erect sitting TrA (mean thickness=4.30 mm+/-1.58 mm) was found to be significantly thicker than in slouched sitting (mean thickness=3.46 mm+/-1.13 mm) (p=0002). In conclusion, lumbo-pelvic neutral postures may have a positive influence on spinal stability compared to equivalent poor postures (slouched sitting and sway-back standing) through the recruitment of TrA. Therefore, posture may be important for rehabilitation in patients with LBP.
Spinal posture is commonly a focus in the assessment and clinical management of low back pain (LBP) patients. However, the link between spinal posture and LBP is not fully understood. Recent evidence suggests that considering regional, rather than total lumbar spine posture is important. The purpose of this study was to determine; if there are regional differences in habitual lumbar spine posture and movement, and if these findings are influenced by LBP.
One hundred and seventy female undergraduate nursing students, with and without LBP, participated in this cross-sectional study. Lower lumbar (LLx), Upper lumbar (ULx) and total lumbar (TLx) spine angles were measured using an electromagnetic tracking system in static postures and across a range of functional tasks.
Regional differences in lumbar posture and movement were found. Mean LLx posture did not correlate with ULx posture in sitting (r = 0.036, p = 0.638), but showed a moderate inverse correlation with ULx posture in usual standing (r = -0.505, p < 0.001). Regional differences in range of motion from reference postures in sitting and standing were evident. BMI accounted for regional differences found in all sitting and some standing measures. LBP was not associated with differences in regional lumbar spine angles or range of motion, with the exception of maximal backward bending range of motion (F = 5.18, p = 0.007).
This study supports the concept of regional differences within the lumbar spine during common postures and movements. Global lumbar spine kinematics do not reflect regional lumbar spine kinematics, which has implications for interpretation of measures of spinal posture, motion and loading. BMI influenced regional lumbar posture and movement, possibly representing adaptation due to load.
General agreement among researchers suggests that poor seating posture may predispose individuals to developing low back pain. A variety of methods such as ergonomically designed chairs have been developed to assist people to maintain good posture and preserve the 'natural' lumbar curve. The aim of this study was to compare lumbar curvature on an ergonomically designed kneeling chair (EKC) with that on a standard computer chair (SCC), with reference to the standing lumbar curvature. The study used a repeated measures, within-subjects design. A convenience sample of twenty participants was recruited aged 18-35 (9 male and 11 female). Lumbar curvature was measured using the 'Middlesbrough Integrated Assessment System' (MIDAS) postural assessment tool in three different postures; sitting on a SCC, sitting on an EKC set at +20 degrees inclination and standing as the reference measurement. Results were analysed by a repeated measures oneway ANOVA (1 factor) with 3 levels followed by the Bonferroni post hoc test. The results showed a statistically significant difference between standing lumbar curvature and lumbar curvature produced by both of the chairs (p<0.05). There was also a statistically significant difference between the two seated positions (p<0.05). This study suggests that ergonomically designed kneeling chairs set at +20 degrees inclination do maintain standing lumbar curvature to a greater extent than sitting on a standard computer chair with an overall mean difference of 7.633 degrees . Further research with a greater number of subjects and on different chair designs is warranted.
To present a critical review and evaluate recent reports investigating sitting-while-at-work as a risk factor for low back pain (LBP).
The Medline, Embase and OSH-ROM databases were searched for articles dealing with sitting at work in relation to low back pain for the years 1985-97. The studies were divided into those dealing with sitting-while-working and those dealing with sedentary occupations. Each article was systematically abstracted for core items. The quality of each article was determined based on the representativeness of the study sample, the definition of LBP, and the statistical analysis.
Thirty-five reports were identified, 14 dealing with sitting-while-working and 21 with sedentary occupations. Eight studies were found to have a representative sample, a clear definition of LBP and a clear statistical analysis. Regardless of quality, all but one of the studies failed to find a positive association between sitting-while-working and LBP. High quality studies found a marginally negative association for sitting compared to diverse workplace exposures, e.g. standing, driving, lifting bending, and compared to diverse occupations. One low quality study associated sitting in a poor posture with LBP.
The extensive recent epidemiological literature does not support the popular opinion that sitting-while-at-work is associated with LBP.
Poor neck and shoulder postures have been suggested to be a cause of neck and shoulder pain in computer workers. The present study aimed to evaluate and compare the head, neck and shoulder postures of office workers with and without symptoms in these regions, in their actual work environments. The two all female subject groups reported significantly different discomfort scores across five trials repeated in a single working day. The results of repeated video capture and two-dimensional motion analysis showed that there were trends for increased head tilt and neck flexion postures in the symptomatic subjects (n = 8), compared to the asymptomatic subjects (n = 8). Symptomatic subjects also tended to have more protracted acromions compared with asymptomatic subjects and showed greater movement excursions in the head segment and the acromion. All subjects demonstrated an approximately 10% increase in forward head posture from their relaxed sitting postures when working with the computer display, but there were no significant changes in posture as a result of time-at-work.
Low back pain (LBP) has been identified as one of the most costly disorders among the worldwide working population. Sitting has been associated with risk of developing LBP. The purpose of this literature review is to assemble and describe evidence of research on the association between sitting and the presence of LBP. The systematic literature review was restricted to those occupations that require sitting for more than half of working time and where workers have physical co-exposure factors such as whole body vibration (WBV) and/or awkward postures. Twenty-five studies were carefully selected and critically reviewed, and a model was developed to describe the relationships between these factors. Sitting alone was not associated with the risk of developing LBP. However, when the co-exposure factors of WBV and awkward postures were added to the analysis, the risk of LBP increased fourfold. The occupational group that showed the strongest association with LBP was Helicopter Pilots (OR=9.0, 90% CI 4.9-16.4). For all studied occupations, the odds ratio (OR) increased when WBV and/or awkward postures were analyzed as co-exposure factors. WBV while sitting was also independently associated with non-specific LBP and sciatica. Vibration dose, as well as vibration magnitude and duration of exposure, were associated with LBP in all occupations. Exposure duration was associated with LBP to a greater extent than vibration magnitude. However, for the presence of sciatica, this difference was not found. Awkward posture was also independently associated with the presence of LBP and/or sciatica. The risk effect of prolonged sitting increased significantly when the factors of WBV and awkward postures were combined. Sitting by itself does not increase the risk of LBP. However, sitting for more than half a workday, in combination with WBV and/or awkward postures, does increase the likelihood of having LBP and/or sciatica, and it is the combination of those risk factors, which leads to the greatest increase in LBP.
Background and Purpose. Physical therapists commonly attempt to reduce and prevent low back pain by "improving" individuals' lumbar post-Lire. To investigate the physical therapy clinical practice of attempting to "improve" lumbar posture, measures of passive tissue stiffness and angular deformation during activities of daily living were used. Participants. The lumbar spine posture of 150 university students was measured as the inclinometer angle difference between L1 and S1. Eighteen female participants (6 with hypolordosis, 6 with hyperlordosis, and 6 controls without lumbar spine impairment) were recruited from this lumbar posture database. Hypolordosis and hyperlordosis were clinically classified by physical therapists. Methods. Lumbar passive tissue stiffness was measured during sitting, standing, and walking before and after a 12-week exercise program, and estimates of lumbar passive tissue strain were calculated from those measurements. Results. The neutral zone (NZ), a range of lumbar positions of low passive tissue stiffness, was identified. Prior to training, the subjects with hypolordosis had more passive tissue strain during sitting than the subjects with hyperlordosis, and the subjects with hyperlordosis stood in extension relative to their NZs while the control subjects and subjects with hypolordosis stood within their NZs. Before and after training, subjects in all 3 groups walked with lumbar spine positions within their NZs. After training, the lumbar posture of the subjects with hypolordosis and the subjects with hyperlordosis changed toward a "mean" (mid-range) lumbar posture. After the exercise program, subjects in all 3 groups stood and walked with their lumbar spines in positions within their NZs, and they sat with their lumbar spines flexed relative to their NZs. Discussion and Conclusion. Knowing that tissue failure can be related to passive tissue strain, the results of this study support the clinical practice of attempting to change individuals' posture-related lumbar spine positions during activities of daily living. Lumbar passive tissue strain, as estimated from the NZ and angular deformation during activities of daily living, can be decreased, but can also be increased, by an exercise program.
Many vibrational environments also subject the worker to awkward, asymmetric and prolonged postures. This paper reviews the epidemiological, biomechanical and physiological factors involved in working postures which could lead to musculoskeletal problems. Too little or too much sitting leads to low back pain. Sedentary postures, including driving, also lead to a higher risk of a herniated disc. In sitting the pelvis rotates and higher pressures exist in the disk. A backrest inclined to 110° or more and with a lumbar support will reduce the disk pressure. Jobs involving excessive force application will be more apt to cause muscular and ligamentous damage. However, these excessive demands can occur in whole body vibration environments too. Neck, shoulder and arm problems are usually related to posture but can occur in WBV environments. Knee problems, in the standing worker, may be due to a flexed knee posture in an attempt to attenuate vibrations. Excessive postural demands on the neck, shoulder and arm will lead to higher muscle forces and higher joint forces. Recommendations are given to reduce risk of disability.
In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
Sitting has been identified as a cause of mechanical low back pain. The purpose of this study was to use plain film x-rays to measure lumbar spine and pelvic posture differences between standing and sitting.
Eight male subjects were radiographed standing and sitting in an automobile seat. Measures of lumbar lordosis, intervertebral disk angles, lumbosacral angle, lumbosacral lordosis, and sacral tilt were completed. One-way analysis of variance (alpha = .05) was conducted on the variables stated above. A Bland-Altman analysis was conducted to assess agreement and repeatability of the lumbar lordosis angle using 2 raters.
Lumbar lordosis values in standing (average, 63 degrees +/- 15 degrees ) and sacral inclination (average, 43 degrees +/- 10 degrees ) decreased by 43 degrees and 44 degrees , respectively, in sitting. Intervertebral joint angles in sitting underwent substantial flexion (L1/L2-5 degrees [+/-3 degrees ], L2/L3-7 degrees [+/-3 degrees ], L3/L4-8 degrees [+/-3 degrees ], L4/L5-13 degrees [+/-3 degrees ], and L5/S1-4 degrees [+/-10 degrees ]). Measures of lumbar lordosis; intervertebral disk angles between L2/L3, L3/L4, and L4/L5; lumbosacral lordosis; lumbosacral angle; and sacral tilt were significantly decreased between standing and sitting (P < .001). Intervertebral disk angle between L5/S1 was not significantly different. Analysis using the Bland-Altman technique found good agreement and stable repeatability of measures with no statistical significant differences between or within raters (R1, P = .8474; R2, P = .4402; and R-R2, P = .8691).
The significant differences in lumbar and pelvic measures from standing to sitting further emphasize the range of motion experienced at vertebral levels in sitting. Based on the results of this study, interventions to return motion segments to a less flexed posture should be investigated because they may play a role in preventing injury and low back pain.
To date the influence that specific sitting posture has on the head/neck posture and cervico-thoracic muscle activity has been insufficiently investigated. Therefore the aim of this study was to investigate whether three different thoraco-lumbar sitting postures affect head/neck posture and cervico-thoracic muscle activity. Twenty (10 men, 10 women) asymptomatic subjects were placed in 3 standardized thoraco-lumbar sitting postures (lumbo-pelvic, thoracic upright and slump) to investigate their influence on cervico-thoracic muscle activity and head/neck posture. There were significant differences in lumbar and thoracic curvatures in the 3 different sitting postures (P<0.002). Slump sitting was associated with greater head/neck flexion, anterior translation of the head (P<0.001) and increased muscle activity of cervical erector spinae (CES) compared to thoracic and lumbo-pelvic sitting (P=0.001). Thoracic upright sitting showed increased muscle activity of thoracic erector spinae (TES) compared to slump and lumbo-pelvic postures (P=0.015). Upper trapezius (UT) demonstrated no significant difference in muscle activation in the 3 sitting postures (P<0.991). This study demonstrates that different sitting postures affect head/neck posture and cervico-thoracic muscle activity. It highlights the potential importance of thoraco-lumbar spine postural adjustment when training head/neck posture.
Statistical Classification Model for nonspecific chronic low back pain (NS-CLBP) patients and controls based on parameters of motor control.
Develop a Statistical Classification Model to discriminate between 2 subgroups of NS-CLBP (Flexion Pattern [FP] and Active Extension Pattern [AEP]) and a control group using biomechanical variables quantifying parameters of motor control.
It has been well documented that many CLBP patients have motor control impairments of their lumbar spine. O'Sullivan proposed a mechanism-based classification system for NS-CLBP with motor control impairments based on a comprehensive subjective and physical examination to establish the relationship between pain provocation and spinal motor control. For the FP and AEP s, 2 groups defined by O'Sullivan and under investigation is this study, the motor control impairment is considered to be the mechanism maintaining their CLBP. No previous studies have used a Statistical Model with measurements of motor control impairment to subclassify NS-CLBP patients.
Thirty-three NS-CLBP patients (20 FP and 13 AEP) and 34 asymptomatic subjects had synchronized lumbosacral kinematics and trunk muscle activation recorded during commonly reported aggravating postures and movements. Biomechanical variables were quantified and a Statistical Classification Model was developed.
The Statistical Model used 5 kinematic and 2 electromyography variables. The model correctly classified 96.4% of cases.
Selected biomechanical variables were predictors for subgroup membership and were able to discriminate the 3 subgroups. This study adds further support toward the validation of the proposed classification system.
Exploratory study of regional muscle activity in different postures.
To detail the relationship between spinal curves and regional muscle activity.
Sagittal balanced spinal posture (C7 above S1 in the sagittal plane) is a goal for spinal surgery and conservative ergonomics. Three combinations of thoracolumbar and lumbar spinal curves can be considered sagittal balanced postures: (i) flat-at both regions, (ii) long lordosis-lordotic at both regions, and (iii) short lordosis-thoracic kyphosis and lumbar lordosis. This study compares regional muscle activity between these 3 sagittal balanced postures in sitting, as well as a slump posture.
Fine-wire electromyography (EMG) electrodes were inserted into the lumbar multifidus (deep and superficial), iliocostalis (lateral and medial), longissimus thoracis, and transversus abdominis in 14 healthy male volunteers. Fine-wire or surface EMG electrodes were also used to record activity of the obliquus internus, obliquus externus, and rectus abdominis muscles. Root mean square EMG amplitude in the flat, long lordosis, short lordosis, and slump sitting postures were normalized to maximal voluntary contraction, and also to the peak activity across the sitting postures. Muscle activity was compared between postures with a linear mixed model analysis.
Of the extensor muscles, it was most notable that activity of the deep and superficial fibers of lumbar multifidus increased incrementally in the 3 sagittal balanced postures; flat, long lordosis, and short lordosis (P < 0.05). Of the abdominal muscles, obliquus internus was more active in short lordosis than the other postures (P < 0.05). Comparing the sagittal balanced postures, the flat posture showed the least muscle activity (similar to the slump posture at most muscles examined).
Discrete combinations of muscle activity supported the 3 different sagittal balanced postures in sitting, providing new detail for surgeons, researchers, and therapists to distinguish between different sagittal balanced postures.
Seated postures are achieved with a moderate amount of lumbo-sacral flexion and sustained lumbo-sacral spine flexion has been associated with detrimental effects to the tissues surrounding a spinal joint. The purpose of this study was to determine if the lower intervertebral joints of the lumbo-sacral spine approach their end ranges of motion in seated postures.
Static sagittal digital X-ray images of the lumbo-sacral region from L3 to the top of the sacrum were obtained in five standing and seated postures from 27 participants. Vertebral body bony landmarks were manually digitized and intervertebral joint angles were calculated for the three lower lumbo-sacral joints.
In upright sitting, the L5/S1 intervertebral joint was flexed to more than 60% of its total range of motion. Each of the lower three intervertebral joints approached their total flexion angles in the slouched sitting posture. These observations were the same regardless of gender. The results support the idea that lumbo-sacral flexion is driven by rotation of the pelvis and lower intervertebral joints in seated postures.
This is the first study to quantitatively show that the lower lumbo-sacral joints approach their total range of motion in seated postures. While not directly measured, the findings suggest that there could be increased loading of the passive tissues surrounding the lower lumbo-sacral intervertebral joints, contributing to low back pain and/or injury from prolonged sitting.
There is a lack of quantitative evidence for spinal postures that are advocated as 'ideal' in clinical ergonomics for sitting. This study quantified surface spinal curves and examined whether subjects could imitate clinically 'ideal' directions of spinal curve at thoraco-lumbar and lumbar regions: (i) flat - at both regions (ii) long lordosis - lordotic at both regions (iii) short lordosis - thoracic kyphosis and lumbar lordosis. Ten healthy male subjects had 3-D motion sensors adhered to the skin so that sagittal spinal curves were represented by angles at thoracic (lines between T1-T5 and T5-T10), thoraco-lumbar (T5-T10 and T10-L3) and lumbar regions (T10-L3 and L3-S2). Subjects attempted to imitate pictures of spinal curves for the flat, long lordosis, short lordosis and a slumped posture, and were then given feedback/manual facilitation to achieve the postures. Repeated measures analysis of variance was used to compare spinal angles between posture and facilitation conditions. Results show that although subjects imitated postures with the same curve direction at thoraco-lumbar and lumbar regions (slumped, flat or long lordosis), they required feedback/manual facilitation to differentiate the regional curves for the short lordosis posture. Further study is needed to determine whether the clinically proposed 'ideal' postures provide clinical advantages.
This paper presents a general statistical methodology for the analysis of multivariate categorical data arising from observer reliability studies. The procedure essentially involves the construction of functions of the observed proportions which are directed at the extent to which the observers agree among themselves and the construction of test statistics for hypotheses involving these functions. Tests for interobserver bias are presented in terms of first-order marginal homogeneity and measures of interobserver agreement are developed as generalized kappa-type statistics. These procedures are illustrated with a clinical diagnosis example from the epidemiological literature.
In a case-control study of the epidemiology of acute herniated lumbar intervertebral disc in the New Haven, Connecticut, area, it was found that driving of motor vehicles was associated with an increased risk for developing this disease. It was estimated that men who spend half or more of their time on their job driving a motor vehicle are about three times as likely to develop an acute herniated lumbar disc as those who do not hold such jobs. Persons of either sex who said that they drove a car (either away from work or at work) were more likely to develop an acute herniated lumbar disc than those who did not drive at all. These associations between driving and acute herniated lumbar disc could not be attributed to any confounding variables considered in this study.
This study compared the effects of sitting with portable supports in either a kyphotic or lordotic posture on low-back and referred pain. Two hundred ten patients with low-back and/or referred pain were randomly assigned to either a kyphotic posture or lordotic posture group. The kyphotic and lordotic postures were facilitated by the use of a flat foam cushion or lumbar roll, respectively. Pain location, back pain, and leg pain intensity were assessed over a 24-48-hour period under both standardized clinical settings and general sitting environments. When sitting with a lordotic posture, back and leg pain were significantly reduced and referred pain shifted towards the low back. This study demonstrates that in general sitting environments a lumbar roll results in: 1) reductions in back and leg pain; and 2) centralization of pain. These findings do not apply to patients with stenosis or spondylolisthesis, whose symptoms may be aggravated by use of a lumbar roll.
A series of experiments showing how posture affects the lumbar spine is reviewed. Postures which flatten (that is, flex) the lumbar spine are compared with those that preserve the lumbar lordosis. Our review shows that flexed postures have several advantages: flexion improves the transport of metabolites in the intervertebral discs, reduces the stresses on the apophyseal joints and on the posterior half of the annulus fibrosus, and gives the spine a high compressive strength. Flexion also has disadvantages: it increases the stress on the anterior annulus and increases the hydrostatic pressure in the nucleus pulposus at low load levels. The disadvantages are not of much significance and we conclude that it is mechanically and nutritionally advantageous to flatten the lumbar spine when sitting and when lifting heavy weights.
The purpose of this study was to measure and describe postural aberrations in chronic and acute low back pain in search of predictors of low back pain. The sample included 59 subjects recruited to the following three groups: chronic, acute, or no low back pain. Diagnoses included disc disease, mechanical back pain, and osteoarthritis. Lumbar lordosis, thoracic kyphosis, head position, shoulder position, shoulder height, pelvic tilt, and leg length were measured using a photographic technique. In standing, chronic pain patients exhibited an increased lumbar lordosis compared with controls (p < .05). Acute patients had an increased thoracic kyphosis and a forward head position compared with controls (p < .05). In sitting, acute patients had an increased thoracic kyphosis compared with controls (p < .05). These postural parameters identified discrete postural profiles but had moderate value as predictors of low back pain. Therefore other unidentified factors are also important in the prediction of low back pain.
A biomechanical model of the lumbar spine was used to calculate the effects of abdominal muscle coactivation on spinal stability.
To estimate the effects of abdominal muscle coactivation on lumbar spine stability, muscle fatigue rate, and lumbar spine compression forces.
The activation of human trunk muscles has been found to involve coactivation of antagonistic muscles, which has not been adequately predicted by biomechanical models. Antagonistic activation of abdominal muscles might produce flexion moments resulting from abdominal pressurization. Qualitatively, antagonistic activity also has been attributed to the need to stabilize the spine.
Spinal loads and spinal stability were calculated for maximum and submaximum (40%, 60% and 80%) efforts in extension and lateral bending using a previously published, anatomically realistic biomechanical model of the lumbar spine and its musculature. Three different antagonistic abdominal muscle coactivation patterns were imposed, and results were compared with those found in a model with no imposed coactivation.
Results were quantified in terms of the sum of cubed muscle stresses (sigma sigma m3, which is related to the muscle fatigue rate), the maximum compressive loading on the lumbar spine, and the critical value of the muscle stiffness parameter (q) required for the spine to be stable. Forcing antagonistic coactivation increased stability, but at the cost of an increase in sigma sigma m3 and a small increase in maximum spinal compression.
These analyses provide estimates of the effects of antagonistic abdominal muscle coactivation, indicating that its probable role is to stabilize the spine.
An awkward and static work posture has been recognized as a risk factor for work-related musculoskeletal problems. The objective of this study was to investigate some of the factors that can influence the posture adopted during work and in particular aspects of the task and how their influence is affected by work height. Three types of task were studied: a peg-hole assembly task, which was largely manual with very little visual component; a visual character identification task; and a combination of the two. Two levels of difficulty were included in each of the manual and visual elements. Postures of the head/neck, trunk and arm were recorded during performance of these tasks. The results showed that type and difficulty of task do influence the posture adopted, and that some of the postural responses (although complex) are predictable so that poor postures could be improved by adjusting task design in addition to workplace layout.
A two-group experimental design with repeated measures on one factor was used.
To investigate the role of paraspinal muscle spindles in lumbosacral position sense in individuals with and without low back pain.
Proprioceptive deficits have been identified in patients with low back pain. The underlying mechanisms, however, are not well documented.
Lumbosacral position sense was determined before, during, and after lumbar paraspinal muscle vibration in 23 young patients with low back pain and in 21 control subjects. Position sense was estimated by calculating the mean absolute error, constant error, and variable error between six criterion and reproduction sacral tilt angles.
Repositioning accuracy was significantly lower in the patient group than in healthy individuals (absolute error difference between groups = 2.7 degrees, P < 0.0001). Multifidus muscle vibration induced a significant muscle-lengthening illusion that resulted in an undershooting of the target position in healthy individuals (constant error = -3.1 degrees, P < 0.0001). Conversely, the position sense scores of the patient group did not display an increase in negative directional error but a significant improvement in position sense during muscle vibration (P < 0.05). No significant differences in absolute error were found between the first and last trial in the healthy individuals (P >/= 0.05) and in the patient group (P > 0.05).
Patients with low back pain have a less refined position sense than healthy individuals, possibly because of an altered paraspinal muscle spindle afference and central processing of this sensory input. Furthermore, muscle vibration can be an interesting expedient for improving proprioception and enhancing local muscle control.
Lifting dynamics and electromyographic activity were evaluated using a biomechanical model of spinal equilibrium and stability to assess cost-benefit effects of antagonistic muscle cocontraction on the risk of stability failure.
To evaluate whether increased biomechanical stability associated with antagonistic cocontraction was capable of stabilizing the related increase in spinal load.
Antagonistic cocontraction contributes to improved spinal stability and increased spinal compression. For cocontraction to be considered beneficial, stability must increase more than spinal load. Otherwise, it may be possible for cocontraction to generate spinal loads that cannot be stabilized.
A biomechanical model was developed to compute spinal load and stability from measured electromyography and motion dynamics. As 10 healthy men performed sagittal lifting tasks, trunk motion, reaction loads, and electromyographic activities of eight trunk muscles were recorded. Spinal load and stability were evaluated as a function of cocontraction and trunk flexion angle. Stability was quantified in terms of the maximum spinal load the system could stabilize.
Cocontraction was associated with a 12% to 18% increase in spinal compression and a 34% to 64% increase in stability. Spinal load and stability increased with trunk flexion.
Despite increases in spinal load that had to be stabilized, the margin between stability and spinal compression increased significantly with cocontraction. Antagonistic cocontraction was found to be most beneficial at low trunk moments typically observed in upright postures. Similarly, empirically measured antagonistic cocontraction was recruited less in high-moment conditions and more in low-moment conditions.
Prolonged sitting is generally accepted as a high risk factor in low back pain and it is frequently suggested that a lordotic posture of the lumbar spine should be maintained during sitting. We asked whether the sagittal curvature of the lumbar spine during sitting is affected by the seat tilt, backrest and the direction of the synchronised mechanism of the back and seat tilt (synchro tilt). Two office chairs were tested by multibody analysis interfacing a human model with a chair model. Results indicate that a synchronised mechanism of an office chair representing a posterior tilt of the seat while the backrest is reclined maintains an evenly distributed lumbar lordosis. The segmental angles are between 3.1 and 3.6 degrees at the lumbar vertebrae 1/2-4/5 (L1/2-L4/5). These lumbar spine segmental angles are not sensitive to the backrest height. In contrast, a synchro tilt concept with a reduction of the seat's posterior tilt while the backrest is reclined causes a strong reduction of the lumbar lordosis in backrest recline with a maximum reduction from 11.7 to 2.8 degrees in L4/5. As a consequence of these results, a synchro tilt concept with a posterior tilt of the seat while the backrest is reclined is preferable from the lumbar spine kinematics point of view.
The objective of this work is to analyze the causes of lumbar discomfort while sitting on a chair, by analyzing the relationship of lumbar curvature, pelvic inclination and their mobilities with discomfort. An experiment has been performed with healthy subjects, in which comfort, postural and mobility parameters have been measured. Their relationship has been analyzed with multivariate analysis. Factorial analysis has been used to represent all the correlated variables measured. Logistic regression and discriminant analyses have been used to classify discomfort/absence of discomfort. The results show that great changes of posture are a good indicator of discomfort, and that lordotic postures with forward leaned pelvis and low mobility are the principal causes of the increase of discomfort.
A normative, single-group study was conducted.
To determine whether there is a difference in electromyographic activation of specific lumbopelvic muscles with the adoption of common postures in a pain-free population.
Clinical observations indicate that adopting passive postures such as sway standing and slump sitting can exacerbate pain in individuals with low back pain. These individuals often present with poor activation of the lumbopelvic stabilizing musculature. At this writing, little empirical evidence exists to document that function of the trunk and lumbopelvic musculature are related to the adoption of standardized standing and sitting postures.
This study included 20 healthy adults, with equal representation of the genders. Surface electromyography was used to measure activity in the superficial lumbar multifidus, internal oblique, rectus abdominis, external oblique, and thoracic erector spinae muscles for four standardized standing and sitting postures.
The internal oblique, superficial lumbar multifidus, and thoracic erector spinae muscles showed a significant decrease in activity during sway standing (P = 0.027, P = 0.002, and P = 0.003, respectively) and slump sitting (P = 0.007, P = 0.012, and P = 0.003, respectively), as compared with erect postures. Rectus abdominis activity increased significantly in sway standing, as compared with erect standing (P = 0.005).
The findings show that the lumbopelvic stabilizing musculature is active in maintaining optimally aligned, erect postures, and that these muscles are less active during the adoption of passive postures. The results of this study lend credence to the practice of postural retraining when facilitation of the lumbopelvic stabilizing musculature is indicated in the management of specific spinal pain conditions.
Occupational low back pain (LBP) is an immense burden for both industry and medicine. Ergonomic and personal risk factors result in LBP, but psychosocial factors can influence LBP disability. Epidemiologic studies clearly indicate the role of mechanical loads on the etiology of occupational LBP. Occupational exposures such as lifting, particularly in awkward postures; heavy lifting; or repetitive lifting are related to LBP. Fixed postures and prolonged seating are also risk factors. LBP is found in both sedentary occupations and in drivers as well as those involved in manual materials handling. Any prolonged posture will lead to static loading of the soft tissues and cause discomfort. Standing and sitting have specific advantages and disadvantages for mobility, exertion of force, energy consumption, circulatory demands, coordination, and motion control. The seated posture leads to inactivity causing an accumulation of metabolites, accelerating disk degeneration and leading to disk herniation. Driver's postures can also lead to musculoskeletal problems. Workers in a driving environment are often subjected to postural stress leading to back, neck, and upper extremity pain. This exacerbates the problems due to the vibration. Prevention is by far the treatment of choice. Improved muscle function can be preventative. Poor coordination and motor control systems are as important as endurance and strength. Fixed postures should be avoided. Seats offering good lumbar support should be used in the office. A suspension seat should be used in vehicles whenever possible. Heavy and awkward lifting should be avoided and lifting aids should be made available. Workers should report LBP as early as possible and seek medical advice if they think occupational exposure is harming them. The combined effects of the medical community, labor, and management are required to cause some impact on this problem.
A cross-sectional observational design study was conducted to determine lumbar repositioning error in 15 subjects who had chronic low back pain with a clinical diagnosis of lumbar segmental instability and 15 asymptomatic participants.
To determine whether individuals with lumbar segmental instability have a decreased ability to reposition their lumbar spine into a neutral spinal position.
Proprioception of the lumbar spine has been investigated in individuals who have low back pain with variable results. The testing procedure's lack of sensitivity and the nonhomogeneity of groups may be responsible for the conflicting findings.
Repositioning accuracy of the lumbar spine was assessed using the 3Space Fastrak to determine error in 15 participants with lumbar segmental instability and 15 asymptomatic subjects. The participants were assisted into a neutral spinal sitting posture and then asked to reproduce this position independently over five trials separated by periods of relaxed full lumbar flexion.
Lumbosacral repositioning error was significantly greater in participants with lumbar segmental instability than in the asymptomatic group (t[28] = 2.48; P = 0.02. There also was a significant difference between the groups at each individual sensor.
The results of this study indicate that individuals with a clinical diagnosis of lumbar segmental instability demonstrate an inability to reposition the lumbar spine accurately into a neutral spinal posture while seated. This finding provides evidence of a deficiency in lumbar proprioceptive awareness among this population.
The intention of this paper is to introduce some of the issues surrounding the role of muscles to ensure spine stability for discussion -- it is not intended to provide an exhaustive review and integration of the relevant literature. The collection of works synthesized here point to the notion that stability results from highly coordinated muscle activation patterns involving many muscles, and that the recruitment patterns must continually change, depending on the task. This has implications on both the prevention of instability and clinical interventions with patients susceptible to sustaining unstable events.
Blinded test-retest design.
To measure the intrarater and interrater reliability of the visual assessment of cervical and lumbar lordosis.
Cervical and lumbar lordoses are frequently evaluated using visual assessment, but little attempt has previously been made to measure the reliability of visual assessment.
Twenty-eight chiropractors, physical therapists, physiatrists, rheumatologists, and orthopedic surgeons were recruited to evaluate the posture of photographed subjects (with and without back pain). Each clinician rated the lordosis of the cervical and lumbar spines as normal, increased, or decreased. Kappa coefficients (kappa) were calculated to determine intrarater and interrater reliability.
Twenty-eight clinicians evaluated photographs of 36 individuals (17 with back pain, 19 without). Mean intrarater reliability was kappa = 0.50 (95% confidence interval 0.02-0.98) and mean interrater reliability was kappa = 0.16 (95% confidence interval 0.00-0.48). No statistically significant difference existed among the five groups of clinicians or between the evaluation of the subjects with and without back pain.
Intrarater reliability of the visual assessment of cervical and lumbar lordosis was statistically fair, whereas interrater reliability was poor.
Physical therapists commonly attempt to reduce and prevent low back pain by "improving" individuals' lumbar posture. To investigate the physical therapy clinical practice of attempting to "improve" lumbar posture, measures of passive tissue stiffness and angular deformation during activities of daily living were used.
The lumbar spine posture of 150 university students was measured as the inclinometer angle difference between L1 and S1. Eighteen female participants (6 with hypolordosis, 6 with hyperlordosis, and 6 controls without lumbar spine impairment) were recruited from this lumbar posture database. Hypolordosis and hyperlordosis were clinically classified by physical therapists.
Lumbar passive tissue stiffness was measured during sitting, standing, and walking before and after a 12-week exercise program, and estimates of lumbar passive tissue strain were calculated from those measurements.
The neutral zone (NZ), a range of lumbar positions of low passive tissue stiffness, was identified. Prior to training, the subjects with hypolordosis had more passive tissue strain during sitting than the subjects with hyperlordosis, and the subjects with hyperlordosis stood in extension relative to their NZs while the control subjects and subjects with hypolordosis stood within their NZs. Before and after training, subjects in all 3 groups walked with lumbar spine positions within their NZs. After training, the lumbar posture of the subjects with hypolordosis and the subjects with hyperlordosis changed toward a "mean" (mid-range) lumbar posture. After the exercise program, subjects in all 3 groups stood and walked with their lumbar spines in positions within their NZs, and they sat with their lumbar spines flexed relative to their NZs.
Knowing that tissue failure can be related to passive tissue strain, the results of this study support the clinical practice of attempting to change individuals' posture-related lumbar spine positions during activities of daily living. Lumbar passive tissue strain, as estimated from the NZ and angular deformation during activities of daily living, can be decreased, but can also be increased, by an exercise program.
To determine the interrater reliability of common clinical examination procedures proposed to identify patients with lumbar segmental instability.
Single group repeated-measures interrater reliability study.
Outpatient physical therapy (PT) clinic and university PT department.
A consecutive sample of 63 subjects (38 women, 25 men; 81% with previous episodes of low back pain [LBP]) with current LBP was examined by 3 pairs of raters.
Not applicable.
Repeat measurements of clinical signs and tests proposed to identify lumbar segmental instability.
Kappa values for the trunk range of motion (ROM) findings varied (range,.00-.69). The prone instability test (kappa=.87) showed greater reliability than the posterior shear test (kappa=.22). The Beighton Ligamentous Laxity Scale (LLS) for generalized ligamentous laxity showed high reliability (intraclass correlation coefficient=.79). Judgments of pain provocation (kappa range,.25-.55) were generally more reliable than judgments of segmental mobility (kappa range, -.02 to.26) during passive intervertebral motion testing.
The results agree with previous studies suggesting that segmental mobility testing is not reliable. The prone instability test, generalized LLS, and aberrant motion with trunk ROM demonstrated higher levels of reliability.
A systematic biomechanical analysis involving an artificial perturbation applied to individual lumbar muscles in order to assess their potential stabilizing role.
To identify which torso muscles stabilize the spine during different loading conditions and to identify possible mechanisms of function. SUMMARY OF BACKGROUND DATA.: Stabilization exercises are thought to train muscle patterns that ensure spine stability; however, little quantification and no consensus exists as to which muscles contribute to stability.
Spine kinematics, external forces, and 14 channels of torso electromyography were recorded for seven stabilization exercises in order to capture the individual motor control strategies adopted by different people. Data were input into a detailed model of the lumbar spine to quantify spine joint forces and stability. The EMG signal for a particular muscle was replaced either unilaterally or bilaterally by a sinusoid, and the resultant change in the stability index was quantified.
A direction-dependent-stabilizing role was noticed in the larger, multisegmental muscles, whereas a specific subtle efficiency to generate stability was observed for the smaller, intersegmental spinal muscles.
No single muscle dominated in the enhancement of spine stability, and their individual roles were continuously changing across tasks. Clinically, if the goal is to train for stability, enhancing motor patterns that incorporate many muscles rather than targeting just a few is justifiable.
Low back pain (LBP) is a very common but largely self-limiting condition. The problem arises however, when LBP disorders do not resolve beyond normal expected tissue healing time and become chronic. Eighty five percent of chronic low back pain (CLBP) disorders have no known diagnosis leading to a classification of 'non-specific CLBP' that leaves a diagnostic and management vacuum. Even when a specific radiological diagnosis is reached the underlying pain mechanism cannot always be assumed. It is now widely accepted that CLBP disorders are multi-factorial in nature. However the presence and dominance of the patho-anatomical, physical, neuro-physiological, psychological and social factors that can influence the disorder is different for each individual. Classification of CLBP pain disorders into sub-groups, based on the mechanism underlying the disorder, is considered critical to ensure appropriate management. It is proposed that three broad sub-groups of CLBP disorders exist. The first group of disorders present where underlying pathological processes drive the pain, and the patients' motor responses in the disorder are adaptive. A second group of disorders present where psychological and/or social factors represent the primary mechanism underlying the disorder that centrally drives pain, and where the patient's coping and motor control strategies are mal-adaptive in nature. Finally it is proposed that there is a large group of CLBP disorders where patients present with either movement impairments (characterized by pain avoidance behaviour) or control impairments (characterized by pain provocation behaviour). These pain disorders are predominantly mechanically induced and patients typically present with mal-adaptive primary physical and secondary cognitive compensations for their disorders that become a mechanism for ongoing pain. These subjects present either with an excess or deficit in spinal stability, which underlies their pain disorder. For this group, physiotherapy interventions that are specifically directed and classification based, have the potential to impact on both the physical and cognitive drivers of pain leading to resolution of the disorder. Two case studies highlight the different mechanisms involved in patients with movement and control impairment disorder outlining distinct treatment approaches involved for management. Although growing evidence exists to support this approach, further research is required to fully validate it.
Physical therapy often is used in the management of work-related low back pain (LBP). Little information, however, is known about the types of interventions used by physical therapists in the management of this condition. The objective of this study was to describe the interventions used by physical therapists in the treatment of workers with acute or subacute LBP, with or without radiating pain below the knee.
Clinical management questionnaires for workers without and with radiating pain were returned by 190 and 139 physical therapists, respectively.
For each treatment session, therapists recorded treatment objectives, interventions, and education provided to 2 workers with LBP, 1 with radiating pain and 1 without radiating pain.
The majority of physical therapists used stretching and strengthening exercises, spinal mobilization, soft tissue mobilization and massage, manual traction, posture correction, interferential current, ultrasound, heat, and functional activities education. With radiating pain, the majority of the therapists also used cold and the McKenzie approach. Treatment objectives pursued by the majority of the therapists were decrease of pain, increase of range of motion, increase of muscle strength (force-generating capacity of muscle), decrease of muscle tension, and worker education.
Physical therapists use an array of interventions with workers with LBP. The effectiveness of most interventions reported has not been well studied.
A comparative study.
To investigate sitting postures of asymptomatic individuals and nonspecific chronic low back pain (NS-CLBP) patients (pooled and subclassified) and evaluate the importance of subclassification.
Currently, little evidence exists to support the hypothesis that CLBP patients sit differently from pain-free controls. Although classifying NS-CLBP patients into homogeneous subgroups has been previously emphasized, no attempts have been made to consider such groupings when examining seated posture.
Three angles (sacral tilt, lower lumbar, and upper lumbar) were measured during "usual" and "slumped" sitting in 33 NS-CLBP patients and 34 asymptomatic subjects using an electromagnetic measurement device. Before testing, NS-CLBP patients were subclassified by two blinded clinicians. Twenty patients were classified with a flexion motor control impairment and 13 with an active extension motor control impairment.
No differences were found between control and NS-CLBP (pooled) patients during usual sitting. In contrast, analyses based on subclassification revealed that patients classified with an active extension pattern sat more lordotic at the symptomatic lower lumbar spine, whereas patients with a flexion pattern sat more kyphotic, when compared with healthy controls (F = 19.7; df1 = 2, df2 = 63, P < 0.001). Further, NS-CLBP patients had less ability to change their posture when asked to slump from usual sitting (t = 4.2, df = 65; P < 0.001).
Differences in usual sitting posture were only revealed when NS-CLBP patients were subclassified. This highlights the importance of subclassifying NS-CLBP patients.
To test the construct validity of postural backache. To identify if individuals with backache sit for longer periods of sustained sitting and have more flexed relaxed sitting posture than individuals in a no backache group.
Following an initial questionnaire, student volunteers without a history of 'serious' back pain were classified as either postural backache group or no backache group. With the use of an activity diary that plotted activity every 5 minutes over a 3-day period, the average time spent in different postures was established. Relaxed sitting posture was evaluated using Dartfish software to analyze videotape after 10 minutes of sitting.
The most common daytime activity of both groups was sitting, with average sitting time not significantly different between groups. Periods of uninterrupted sustained sitting and uninterrupted sustained studying were significantly longer, and the degree of flexion in relaxed sitting was significantly greater in the postural backache group (all P < .024).
In a group of student volunteers, half reported postural backache. The group with backache sat for longer periods without interruption and had a more flexed relaxed sitting posture than the no backache group. These findings appear to validate McKenzie's concept of a postural syndrome.
Proprioceptive control is considered important for spinal stability and prevention of injury. However there is evidence that proprioceptive structures, that are reflexive and viscoelastic, are challenged by commonly adopted 'slouched' postures. The aim of this study was to investigate the effect of such postures on proprioceptive control. The reliability of a flexible electrogoniometer was established (ICC=0.89). Using a repeated measures design (n=32, 80% power detecting 0.5 degrees difference at 95% significance) subjects repositioned their lumbar spine immediately (3 s) and following 300 s in a 'slouched' posture, with a 15-min interval in between. Results showed a significantly reduced lumbar spine reposition sense following 300 s in a 'slouched' posture as compared with 3 s in a 'slouched' posture (P<0.001), mean difference 3.92 degrees (SD 4.35). Based on this sample, there was evidence that a 'slouched' posture, of 5 min duration, would increase reposition error by more than 2.35 degrees and less than 5.48 degrees (n=32, CI 95%). These findings support the practice of postural education to reduce potential to proprioceptive loss and injury. The electrogoniometer shows potential for use in clinical practice.
The purpose of this study was to investigate the interexaminer reliability of segmental mobility tests for the lumbar flexion and extension movement. Available reliability studies are rare and investigate total segmental mobility through several tests, making the understanding of the effect of each test more difficult. There is also a risk of creating a test situation that has less resemblance to the work situation of physiotherapists if two physiotherapists who have trained and coordinated their manual techniques together in advance are studied. Three physiotherapists with step 2 of the Swedish orthopaedic manual therapy education (OMT) performed one segmental mobility test for lumbar flexion and one for lumbar extension on twenty subjects. They were not permitted to obtain additional information, apart from a standing inspection without movements. The physiotherapists had not worked together, nor did they have a chance to coordinate their manual techniques prior to the examinations. The results showed no interexaminer reliability and suggest that future research is essential if a conclusion about lumbar intersegmental mobility tests is to be reached.
Specific strategies to optimally facilitate postural muscles to retrain postural form are advocated in the clinical management of neck pain. The purpose of this study was to compare the activation of selected cervical, thoracic and lumbar muscles during independent and facilitated postural correction in sitting in 10 subjects with chronic neck pain. Deep cervical flexor (DCF) muscle activity was recorded with custom electrodes inserted via the nose and fixed by suction to the posterior mucosa of the oropharynx. Surface electrodes were placed over the thoracic erector spinae and lumbar multifidus muscles. Root-mean-square EMG amplitude was measured for each muscle across two conditions. In the first condition, subjects were instructed to spontaneously "sit up straight" from a slumped posture without any other guidance from the therapist. In the second condition the therapist provided specific manual and verbal facilitation to assist the patient to correct to an upright pelvic position with a neutral spinal lumbo-pelvic position. Activation of the DCF and lumbar multifidus muscles (P<0.05) were significantly greater when the therapist facilitated postural correction compared to independent sitting correction. Specific postural-correction strategies result in better facilitation of key postural muscles compared to non-specific postural advice. The results of this study highlight the need for clinical skill and precision in postural training of patients with neck pain.
A cross-sectional comparative study between healthy controls and two subgroups of nonspecific chronic low back pain (LBP) patients.
To determine differences in trunk muscle activation during usual unsupported sitting.
Patients with LBP commonly report exacerbation of pain on sitting. Little evidence exists to confirm that subgroups of patients with nonspecific chronic LBP patients use different motor patterns in sitting than pain-free controls.
A total of 34 pain-free and 33 nonspecific chronic LBP subjects were recruited. Two blinded clinicians classified nonspecific chronic LBP patients into two subgroups (active extension pattern and flexion pattern). Surface electromyography (sEMG) was recorded from five trunk muscles during subjects' unsupported "usual" and "slumped" sitting.
No differences in trunk muscle activity were observed between healthy controls and nonspecific chronic LBP groups for usual sitting. When the classification system was applied, differences were identified. Compared with no-LBP controls, the active extension pattern group presented with higher levels of cocontraction of superficial fibers of lumbar multifidus (12%), iliocostalis lumborum pars thoracis (36%) and transverse fibers of internal oblique (43%). while the flexion pattern group showed a trend toward lower activation patterns (lumbar multifidus, -7%; iliocostalis lumborum pars thoracis, -6%, and transverse fibers of internal oblique, -5%). The flexion relaxation ratio of the back muscles was lower for nonspecific chronic LBP (superficial lumbar multifidus: t = 4.5; P < 0.001 and iliocostalis lumborum pars thoracis:t = 2.7; P < 0.001), suggesting a lack of flexion relaxation for the nonspecific chronic LBP.
Subclassifying nonspecific chronic LBP patients revealed clear differences in sEMG activity during sitting between pain-free subjects and subgroups of nonspecific chronic LBP patients.
A normative, single-group study was conducted.
To investigate the flexion relaxation phenomenon in the thoraco-lumbopelvic muscles among a pain-free population when moving from an upright to a slump sitting posture.
The presence of the flexion relaxation phenomenon (FRP) of the back muscles is well documented at end-range spinal flexion when standing. This phenomenon is commonly found disrupted in low back subjects. However, whether FRP occurs in sitting remains controversial.
The sample consisted of 24 healthy pain-free adults. Surface electromyography was used to measure activity in the superficial lumbar multifidus (SLM), the thoracic erector spinae (TES), and the transverse fibers of the internal oblique (IO) muscles while subjects moved from an erect to a slump sitting posture. An electromagnetic motion-tracking device simultaneously measured thoracolumbar kinematics during this task.
There was a significant decrease in both the SLM and the IO activity when moving from an erect to a slump sitting posture (P = 0.001 and P = 0.004, respectively), indicating the presence of FRP. TES activity was highly variable. While 13 subjects exhibited an increase in activity (P = 0.001), 11 demonstrated a decrease in activity (P = 0.001), indicating the presence of FRP. FRP occurred in the mid-range of spinal flexion for the SLM, IO and TES when present.
The findings show that the SLM and the IO are facilitated in neutral lordotic sitting postures and exhibit FRP at mid range flexion while moving from upright sitting to slump sitting. These findings show that FRP in sitting differs from that in standing. Variable motor patterns (activation or FRP) of the TES were observed. These findings suggest that sustaining mid to end-range flexed sitting spinal postures result in relaxation of the spinal stabilizing muscles.
A normative within-subjects single-group study.
To compare spinal-pelvic curvature and trunk muscle activation in 2 upright sitting postures ("thoracic" and "lumbo-pelvic") and slump sitting in a pain-free population.
Clinical observations suggest that both upright and slump sitting postures can exacerbate low back pain. Little research has investigated the effects of different upright sitting postures on trunk muscle activation.
Spinal-pelvic curvature and surface electromyography of 6 trunk muscles were measured bilaterally in 2 upright (thoracic and lumbo-pelvic) sitting postures and slump sitting in 22 subjects.
Thoracic, compared to lumbo-pelvic, upright sitting showed significantly greater thoracic extension (P < 0.001), with significantly less lumbar extension (P < 0.001) and anterior pelvic tilt (P = 0.03). Furthermore, there was significantly less superficial lumbar multifidus (P < 0.001) and internal oblique (P = 0.03) activity, with significantly higher thoracic erector spinae (P < 0.001) and external oblique (P = 0.04) activity in thoracic upright sitting. There was no significant difference in superficial lumbar multifidus activity between thoracic upright and slump sitting.
Different upright sitting postures resulted in altered trunk muscle activation. Thoracic when compared to lumbo-pelvic upright sitting involved less coactivation of the local spinal muscles, with greater coactivation of the global muscles. These results highlight the importance of postural training specificity when the aim is to activate the lumbo-pelvic stabilizing muscles in subjects with back pain.