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Seeking the Optimal Posture of the Seated Lumbar Spine

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Abstract

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.
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... The design was built on a 520 mm × 520 mm seat cushion from the manufactu Octaspring (Figure 8a). Pynt et al. [15] explain that in the sitting position, the sitting bo (ischial tuberosities) support most of the body weight. Therefore, two modules w In the second experiment, we investigated the relations among the displacement, the velocity of the displacement, and the received phototransistor sensor signals via Action Compression. ...
... The design was built on a 520 mm × 520 mm seat cushion from the manufacturer Octaspring (Figure 8a). Pynt et al. [15] explain that in the sitting position, the sitting bones (ischial tuberosities) support most of the body weight. Therefore, two modules were placed in the area where the sitting bones were expected. ...
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Sitting comfort is an important factor for passengers in selecting cars, airlines, etc. This paper proposes a soft robotic module that can be integrated into the seat cushion to provide better comfort experiences to passengers. Building on rapid manufacturing technologies and a data-driven approach, the module can be controlled to sense the applied force and the displacement of the top surface and actuate according to four designed modes. A total of 2 modules were prototyped and integrated into a seat cushion, and 16 subjects were invited to test the module’s effectiveness. Experiments proved the principle by showing significant differences regarding (dis)comfort. It was concluded that the proposed soft robotics module could provide passengers with better comfort experiences by adjusting the pressure distribution of the seat as well as introducing a variation of postures relevant for prolonged sitting.
... The long-standing doctrine of an optimal seating posture that is "as upright as possible" has been highly disputed. The principle of "dynamic sitting" has been slowly substituted, where sitting positions were identified as to continuously change (Dieen et al., 2001;Pynt et al., 2001). However, O'Sullivan in his systematic review concluded that dynamic sitting approaches are not effective as a stand-alone management approach for LBP (O'Sullivan et al., 2012). ...
... Another important finding is that this motif has a positive effect on LBP. These results are consistent with the ideas presented in some review articles of LBP (Dieen et al., 2001;Pynt et al., 2001). Therefore, it suggests that the healthy sitting posture (1) is best thought of as an active, not a static phenomenon, regularly interspersed with moving, (2) is the optimal sitting posture, and (3) helps with lumbar postural health and LBP prevention. ...
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Background: Low back pain (LBP) is a common health problem — sitting on a chair for a prolonged time is considered a significant risk factor. Furthermore, the level of LBP may vary at different times of the day. However, the role of the time-sequence property of sitting behavior in relation to LBP has not been considered. During the dynamic sitting, small changes, such as slight or big sways, have been identified. Therefore, it is possible to identify the motif consisting of such changes, which may be associated with the incidence, exacerbation, or improvement of LBP. Method: Office chairs installed with pressure sensors were provided to a total of 22 office workers (age = 43.4 ± 8.3 years) in Japan. Pressure sensors data were collected during working days and hours (from morning to evening). The participants were asked to answer subjective levels of pain including LBP. Center of pressure (COP) was calculated from the load level, the changes in COP were analyzed by applying the Toeplitz inverse covariance-based clustering (TICC) analysis, COP changes were categorized into several states. Based on the states, common motifs were identified as a recurring sitting behavior pattern combination of different states by motif-aware state assignment (MASA). Finally, the identified motif was tested as a feature to infer the changing levels of LBP within a day. Changes in the levels of LBP from morning to evening were categorized as exacerbated, did not change, or improved based on the survey questions. Here, we present a novel approach based on social spider algorithm (SSA) and probabilistic neural network (PNN) for the prediction of LBP. The specificity and sensitivity of the LBP inference were compared among ten different models, including SSA-PNN. Result: There exists a common motif, consisting of stable sitting and slight sway. When LBP level improved toward the evening, the frequency of motif appearance was higher than when LBP was exacerbated ( p < 0.05) or the level did not change. The performance of the SSA-PNN optimization was better than that of the other algorithms. Accuracy, precision, recall, and F1-score were 59.20, 72.46, 40.94, and 63.24%, respectively. Conclusion: A lower frequency of a common motif of the COP dynamic changes characterized by stable sitting and slight sway was found to be associated with the exacerbation of LBP in the evening. LBP exacerbation is predictable by AI-based analysis of COP changes during the sitting behavior of the office workers.
... Finally, the focus of the present study is on sizes; however, the literature recommends considering the shapes of the subjects (Branton, 1984;Nijholt et al., 2016;Wang et al., 2018), their seating posture (lordosis and kyphosis lumbar seated position) (Pynt et al., 2001), the type of chair (dynamic and static chairs) (van Dieën et al., 2001), and the proportions of the chair (Kelly, 2005) to accommodate a maximum number of users. In addition to the anthropometry of the user, these design considerations affect the percentage of accommodation level. ...
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... Based on this, the concept of "dynamic sitting", where sitting position is continuously altered, has gradually replaced the prior belief that an ideal sitting position requires an upright 90-90-90 approach that included 90 degrees of knee, torso-thigh and elbow angles ( emp et al., 2016). As a result, postural variability, including ICMs (macro-movements) (Davis et al., 2009;Vergara and Page, 2002;Pynt et al., 2001;Srinivasan and Mathiassen, 2012), small micro-movements (Dunk & Callaghan., 2010) and postural changes (transitions) between sitting and standing ( enaidy et al., 1994;arakolis et al., 2016;Liao and Drury, 2000;McLean et al., 2001) have been proposed as strategies to reduce low back discomfort associated with prolonged sitting. ICMs, besides providing nourishment for the nucleus pulposus and the intervertebral discs (Callaghan and Mc ill, 2001;Corlett, 2006;Holm and Nachemson, 19 2), provides periodic breaks for the muscles reducing the likelihood of fatigue (Todd et al., 2007). ...
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Sedentary behavior has increased steadily over prior decades, primarily due to increased computer use at work and at home. The total sedentary time per day has been associated with increased risk of cardiometabolic diseases ; increased sitting time at work has been associated with musculoskeletal discomfort particularly in the low back. Office workers spend many hours sitting, thus efforts to increase movement through changes of posture (sit to stand) or moving while sitting have been proposed as ways to mitigate the negative effects of prolonged sitting. Yet, few studies have investigated differences in the movement patterns of office workers while sitting performing their actual work. Therefore, the aim of this study was to characterize movement patterns during a prolonged sitting bout and to determine their association with musculoskeletal pain. Twenty-eight office workers participated in this field study that used a pressure sensitive mat to quantify seat pan pressure (4 regions) and trunk sway parameters over a 2-hour bout of computer work. Data were stratified by brea ers who stood up at least once within the 2-hour test and prolongers who remained sitting throughout the test. Overall, there was a decreasing trend in trunk sway parameters (mean COP position, sway path, sway area, sway velocity, maximum displacement, and in-chair movements) over time (p < 0.05), with significant changes in sitting strategies. There were significant differences in trunk sway parameters and perceived musculoskeletal discomfort between brea ers and prolongers with brea ers having more consistent movement while sitting over the prolonged sitting bout (p < 0.05) and lower discomfort ratings. This may indicate that interrupting prolonged bouts of sitting with short periods of standing can maintain sitting movement patterns and reduce the development of musculoskeletal discomfort. Trunk sway monitoring and promoting periodic standing may be useful tools for maintaining in chair movements that may reduce or prevent the onset of musculoskeletal discomfort during prolonged sitting.
... In contrast, maintaining the natural curvature of the lumbar spine while sitting is known to reduce intradiscal pressure, ligament tension, and thus disc degeneration. 4 Haddad et al. ...
Chapter
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