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Background Low Back Pain (LBP) is the most common musculoskeletal disorder in the world. Medical students, particularly those who use computers for study purposes, are more vulnerable to LBP due to prolonged sitting times and improper sitting posture during lectures. However, prior research showed that the prevalence of LBP among medical students appeared lower when they were enrolled during online pandemic learning. Hence, this research is performed to determine the correlation between the duration of sitting and sitting posture on the incidence of LBP among medical students in Universitas Sumatera Utara, Indonesia. Methods A cross-sectional study with an analytical descriptive design was conducted in September 2023 among randomly selected 147 medical students at Universitas Sumatera Utara, Indonesia. The inclusion criteria of the research sample are students with BMI< 23 kg/m2 while the exclusion criteria are students who have abnormalities and a history of trauma or spinal fractures. Data was obtained from filling out questionnaires of The Pain and Distress Scale (PAD) and Body Awareness of Postural Habit in Young People (BAPHY). A Chi-square test and logistic regression were used to analyze data with a p-value < 0.05 was regarded as statistically significant. Results The study’s findings revealed that 40.1% of students reported having LBP problems, 72.1% reported sitting for more than seven hours each day, and 33.3% reported having a bad sitting posture. Chi-square analysis revealed a significant correlation between sitting duration and posture on complaints of lower back pain (RR = 1.69, p = 0.041 and RR = 1.69, p = 0.009). At a risk of 2,438 times, sitting posture is the main factor contributing to LBP among medical students at Universitas Sumatera Utara, Indonesia. Conclusions This research showed a significant correlation between duration and sitting posture on the incidence of low back pain.

Purpose: This study examines the impact of dynamic neuromuscular stabilization (DNS) on chest mobility, upright sitting height, and quality of life (QoL) in obese women. DNS exercises are used to assess and activate the spinal stabilizers to improve the performance of the posture and respiratory systems. Methods: In this semi-experimental study, 60 participants were randomly assigned to two groups as follows: The DNS group (n=30) and the control group (n=30). To start, in a random order, each participant completed a pre-test of the upper chest mobility, lower chest mobility, upright sitting height, and QoL. The DNS protocol was then implemented, with participants undergoing training six times a week for six weeks. After the completion of training, a post-test was conducted to measure all parameters. The data was analyzed using descriptive statistical analysis and repeated measures analysis of variance in the SPSS software, version 23. Results: In the DNS group, significant improvements were observed in the post-test compared to the pre-test for upper chest mobility (2.1±1.6 vs 3.7±1.8 cm, P

Purpose: This study examines the impact of dynamic neuromuscular stabilization (DNS) on chest mobility, upright sitting height, and quality of life (QoL) in obese women. DNS exercises are used to assess and activate the spinal stabilizers to improve the performance of the posture and respiratory systems. Methods: In this semi-experimental... [ABSTRACT FROM AUTHOR]

Abstract The number of people who need to use wheelchair for proper mobility is increasing. The integration of technology into these devices enables the simultaneous and objective assessment of posture, while also facilitating the concurrent monitoring of the functional status of wheelchair users. In this way, both the health personnel and the user can be provided with relevant information for the recovery process. This information can be used to carry out an early adaptation of the rehabilitation of patients, thus allowing to prevent further musculoskeletal problems, as well as risk situations such as ulcers or falls. Thus, a higher quality of life is promoted in affected individuals. As a result, this paper presents an orderly and organized analysis of the existing postural diagnosis systems for detecting sitting anomalies in the literature. This analysis can be divided into two parts that compose such postural diagnosis: on the one hand, the monitoring devices necessary for the collection of postural data and, on the other hand, the techniques used for anomaly detection. These anomaly detection techniques will be explained under two different approaches: the traditional generalized approach followed to date by most works, where anomalies are treated as incorrect postures, and a new individualized approach treating anomalies as changes with respect to the normal sitting pattern. In this way, the advantages, limitations and opportunities of the different techniques are analyzed. The main contribution of this overview paper is to synthesize and organize information, identify trends, and provide a comprehensive understanding of sitting posture diagnosis systems, offering researchers an accessible resource for navigating the current state of knowledge of this particular field.

The number of people who need to use wheelchair for proper mobility is increasing. The integration of technology into these devices enables the simultaneous and objective assessment of posture, while also facilitating the concurrent monitoring of the functional status of wheelchair users. In this way, both the health personnel and the user can be provided with relevant information for the recovery process. This information can be used to carry out an early adaptation of the rehabilitation of patients, thus allowing to prevent further musculoskeletal problems, as well as risk situations such as ulcers or falls. Thus, a higher quality of life is promoted in affected individuals. As a result, this paper presents an orderly and organized analysis of the existing postural diagnosis systems for detecting sitting anomalies in the literature. This analysis can be divided into two parts that compose such postural diagnosis: on the one hand, the monitoring devices necessary for the collection of postural data and, on the other hand, the techniques used for anomaly detection. These anomaly detection techniques will be explained under two different approaches: the traditional generalized approach followed to date by most works, where anomalies are treated as incorrect postures, and a new individualized approach treating anomalies as changes with respect to the normal sitting pattern. In this way, the advantages, limitations and opportunities of the different techniques are analyzed. The main contribution of this overview paper is to synthesize and organize information, identify trends, and provide a comprehensive understanding of sitting posture diagnosis systems, offering researchers an accessible resource for navigating the current state of knowledge of this particular field. [ABSTRACT FROM AUTHOR]

المخلص: أهداف البحث: يرتبط السلوك الخامل المرتفع بوظائف الأوعية الدموية المركزية المعاكسة والخلل الإدراكي. التدخلات لتخفيف الآثار السلبية للجلوس في مكان العمل مثيرة للاهتمام، ومع ذلك، فإن الأدلة التي تدعي فعالية مثل هذه التدخلات لا تزال تظهر. تهدف تجربة التقاطع العشوائية الحالية إلى استكشاف فعالية الجلوس لفترات طويلة مع أو بدون فواصل النشاط البدني على وظائف الأوعية الدموية المركزية والطرفية والمعرفية لدى البالغين. طرق البحث: أكمل واحد وعشرين من البالغين الأصحاء أربع ساعات من محاكاة ظروف العمل في ثلاث زيارات تجريبية: (1) الجلوس دون انقطاع؛ (2) يقطع الجلوس ثلاث دقائق سيرا على الأقدام كل ساعة؛ (3) يقطع الجلوس ثلاث دقائق من صعود السلم كل ساعة. تم قياس قطر الشريان السباتي والسطحي والسرعة ومعدل القص وتدفق الدم باستخدام الموجات فوق الصوتية المزدوجة عند 50 ميجاهرتز في ثلاث نقاط زمنية (الساعة صفر والثانية والرابعة) بينما تم تقييم الوظائف التنفيذية باستخدام إريكسن فلانكر المعتمدة على الحاسوب كل ساعة. النتائج: كان الانخفاض في أوقات رد الفعل (-30.59٪) والدقة (-10.56٪) أثناء ظروف الجلوس غير المنقطعة ذات دلالة إحصائية، بينما كان الانخفاض أقل أثناء الجلوس المتقطع بثلاث دقائق من المشي كل ساعة والجلوس بثلاث دقائق من صعود السلم كل ساعة. لم يلاحظ وجود فروق ذات دلالة إحصائية في وظائف الشريان السباتي والشريان الفخذي السطحي مع توقف الجلوس لمدة ثلاث دقائق من المشي كل ساعة والجلوس بثلاث دقائق من صعود السلم كل ساعة تدخل. الاستنتاجات: تم العثور على فواصل النشاط البدني متفاوتة الشدة أثناء الجلوس لفترات طويلة لتحسين أوقات رد الفعل. ومع ذلك، يجب تأكيد الفوائد الوعائية لفواصل النشاط البدني من خلال الدراسات المستقبلية في الوقت الفعلي. Abstract: Objectives: High sedentary behaviour is associated with adverse effects on central vascular function and cognitive function. Although interventions to mitigate the adverse effects of workplace sitting are intriguing, evidence of the efficacy of such interventions remains lacking. This randomised cross-over trial was aimed at exploring the effectiveness of prolonged sitting, with or without physical activity breaks, on central, peripheral vascular and cognitive function in adults. Methods: Twenty one healthy adults completed 4 h of simulated work conditions in three experimental visits: (1) uninterrupted sitting (SIT); (2) sitting interrupted by 3 min of walking every hour (LIT); and (3) sitting interrupted by 3 min of stair climbing every hour (MIT). Carotid (CA) and superficial femoral artery (SFA) diameter, velocity, shear rate and blood flow were measured with Duplex ultrasound at 50 MHz at three time points (hours 0, 2 and 4), and executive function was assessed with the computer based Eriksen Flanker task every hour. Results: The decreases in reaction time (−30.59%) and accuracy (−10.56%) during SIT conditions were statistically significant, and less of a decrease was observed under LIT and MIT conditions. No significant differences in CA and SFA function were observed with LIT and MIT interventions. Conclusion: Physical activity breaks of varying intensity during prolonged sitting improve reaction time. However, the vascular benefits of physical activity breaks should be confirmed in the future through long term studies in natural environment.

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Purpose: To verify the effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance. Methods: Thirty healthy subjects were evaluated. The Conformat was used to analyze the center of sitting pressure (COSP), and the three-dimensional motion analysis system was used to analyze changes in head and trunk postures while subjects remained in a sitting position with and without sole-ground contact. The parameters of masticatory performance and movement were calculated as follows. For evaluating masticatory performance, the amount of glucose extraction (AGE) during chewing of a gummy jelly was measured. For evaluating masticatory movements, the movement of the mandibular incisal point was recorded using the Motion Visi-Trainer V1, and parameters of the stabilities of movement path and rhythm were calculated. Results: Head and trunk sway values and the displacement of COSP were significantly smaller with sole-ground contact than those without sole-ground contact. The masticatory movement path with sole-ground contact showed less variation in the opening distance and more stable movement path compared to those without sole-ground contact. The AGE was significantly greater with sole-ground contact than that without sole-ground contact. Conclusion: Sitting posture with and without sole-ground contact affects chewing stability and masticatory performance. [ABSTRACT FROM AUTHOR]

Cervical spinal cord injury (SCI) leads to impaired trunk motor control, negatively impacting the performance of activities of daily living in the affected individuals. Improved trunk control with better sitting posture has been previously observed due to neuromuscular electrical stimulation and transcutaneous spinal stimulation, while improved postural stability has been observed with spinal cord epidural stimulation (scES). Hence, we studied how trunk-specific scES impacts sitting independence and posture. Fourteen individuals with chronic, severe cervical SCI with an implanted neurostimulator performed a 5-min tall-sit task without and with trunk-specific scES. Spine posture was assessed by placing markers on five spine levels and evaluating vertical spine inclination angles. Duration of trunk manual assistance was used to assess independence along with the number of independence changes and average independence score across those changes. With scES, the sacrum-L1 inclination and number of independence changes tended to decrease by 1.64 ± 3.16° (p = 0.07; Cohen's d = 0.53) and 9.86 ± 16.8 (p = 0.047; Cohen's d = 0.59), respectively. Additionally, for the participants who had poor sitting independence without scES, level of independence tended to increase by 12.91% [0%, 31.52%] (p = 0.38; Cohen's d = 0.96) when scES was present. Hence, trunk-specific scES promoted improvements in lower spine posture and lower levels of trunk assistance. [ABSTRACT FROM AUTHOR]

Objective: The effectiveness of the Tipton chair on the thoracic and lumbar spine of students was evaluated in the straight upright position and careful study postures. Materials & Methods: This study was performed on 30 students (20 women and 10 men) who had no history of musculoskeletal disorders. Evaluation of changes in the angles of the thoracic and lumbar spinal was performed using an electrogoniometer on the normal and Tipton chair in the two postures of straight upright and careful study. The participants were evaluated in each posture on each chair for five minutes. Considering the resting time and questionnaire completion, the study took 30 minutes for each person. The data recorded by the electrogoniometer were analyzed through repeated measures statistical test and data of the system usability scale (SUS) questionnaire by the paired t-test in SPSS software, version 25. Results: The mean range of changes in the angles of the thoracic spine in the sagittal plane showed that the variable of chair type was not significant (P=0.072), but the variable of posture was (P=0.013). Also, regarding the mean range of change in thoracic lateral flexion, the interaction of chair and posture (P=0.048) and the chair variable with (P=0.003) had a significant difference. This difference was about a 28% reduction in the mean range of changes in the lateral flexion of the thoracic spine in the upright posture and a 10% reduction in the careful study posture in the Tipton chair compared to the normal chair. While the posture variable had no significant difference (P=0.705). Also, the mean range of changes in lumbar flexion extension showed that the chair variable (P=0.003) had a significant difference. This significant difference was about a 16% reduction in the mean range of changes in the flexion extension of the lumbar spine in the upright posture and a 43% reduction in the careful study posture in the Tipton chair compared to the normal chair. While the variable of posture (P=0.162) did not have significant differences. The study's results on lateral lumbar flexion also showed that both variables of chair and posture had a significant difference (P=0.009). The mean range of changes in lumbar lateral flexion angles in both upright and careful posture in the Tipton chair was reduced by 28% compared to the normal chair. Analysis of SUS questionnaire scores for the Tipton and normal chairs showed a significant difference between these two chairs (P=0.000). In addition, the average scores of the SUS questionnaire were 78.6 for the Tipton chair and 65.9 for the normal chair, which shows an increase of 19%. Conclusion: The results of the present study showed that the Tipton chair could reduce the average range of body angles in the thoracic and lumbar spine. Also, the study results indicated an increase in user satisfaction with the Tipton chair compared to the normal chair, in which the level of satisfaction of women is higher than men. It can be due to the difference in anthropometric dimensions between women and men.

Cervical Spondylosis (CS) is a chronic spinal condition in which the spine gradually stiffens and can finally become completely inflexible. It is arduous to diagnose in early stages and leads to delay in medication. The risk level of Cervical Spondylosis can be reduced if it is detected in primary care. Based on this objective, a system is designed and developed to diagnose and predict the severity of cervical spondylosis in early stages. Different machine learning techniques are evaluated for this and results indicate that machine learning techniques can provide a low cost and accurate mechanism for early stage spondylosis detection.

Objective The effectiveness of the Tipton chair on the thoracic and lumbar spine of students was evaluated in the straight upright position and careful study postures. Materials & Methods This study was performed on 30 students (20 women and 10 men) who had no history of musculoskeletal disorders. Evaluation of changes in the angles of the thoracic and lumbar spinal was performed using an electrogoniometer on the normal and Tipton chair in the two postures of straight upright and careful study. The participants were evaluated in each posture on each chair for five minutes. Considering the resting time and questionnaire completion, the study took 30 minutes for each person. The data recorded by the electrogoniometer were analyzed through repeated measures statistical test and data of the system usability scale (SUS) questionnaire by the paired t-test in SPSS software, version 25. Results The mean range of changes in the angles of the thoracic spine in the sagittal plane showed that the variable of chair type was not significant (P=0.072), but the variable of posture was (P=0.013). Also, regarding the mean range of change in thoracic lateral flexion, the interaction of chair and posture (P=0.048) and the chair variable with (P=0.003) had a significant difference. This difference was about a 28% reduction in the mean range of changes in the lateral flexion of the thoracic spine in the upright posture and a 10% reduction in the careful study posture in the Tipton chair compared to the normal chair. While the posture variable had no significant difference (P=0.705). Also, the mean range of changes in lumbar flexion extension showed that the chair variable (P=0.003) had a significant difference. This significant difference was about a 16% reduction in the mean range of changes in the flexion extension of the lumbar spine in the upright posture and a 43% reduction in the careful study posture in the Tipton chair compared to the normal chair. While the variable of posture (P=0.162) did not have significant differences. The study's results on lateral lumbar flexion also showed that both variables of chair and posture had a significant difference (P=0.009). The mean range of changes in lumbar lateral flexion angles in both upright and careful posture in the Tipton chair was reduced by 28% compared to the normal chair. Analysis of SUS questionnaire scores for the Tipton and normal chairs showed a significant difference between these two chairs (P=0.000). In addition, the average scores of the SUS questionnaire were 78.6 for the Tipton chair and 65.9 for the normal chair, which shows an increase of 19%. Conclusion The results of the present study showed that the Tipton chair could reduce the average range of body angles in the thoracic and lumbar spine. Also, the study results indicated an increase in user satisfaction with the Tipton chair compared to the normal chair, in which the level of satisfaction of women is higher than men. It can be due to the difference in anthropometric dimensions between women and men. [ABSTRACT FROM AUTHOR]

Cervical spinal cord injury (SCI) leads to impaired trunk motor control, negatively impacting the performance of activities of daily living in the affected individuals. Improved trunk control with better sitting posture has been previously observed due to neuromuscular electrical stimulation and transcutaneous spinal stimulation, while improved postural stability has been observed with spinal cord epidural stimulation (scES). Hence, we studied how trunk-specific scES impacts sitting independence and posture. Fourteen individuals with chronic, severe cervical SCI with an implanted neurostimulator performed a 5-min tall-sit task without and with trunk-specific scES. Spine posture was assessed by placing markers on five spine levels and evaluating vertical spine inclination angles. Duration of trunk manual assistance was used to assess independence along with the number of independence changes and average independence score across those changes. With scES, the sacrum-L1 inclination and number of independence changes tended to decrease by 1.64 ± 3.16° (p = 0.07; Cohen’s d = 0.53) and 9.86 ± 16.8 (p = 0.047; Cohen’s d = 0.59), respectively. Additionally, for the participants who had poor sitting independence without scES, level of independence tended to increase by 12.91% [0%, 31.52%] (p = 0.38; Cohen’s d = 0.96) when scES was present. Hence, trunk-specific scES promoted improvements in lower spine posture and lower levels of trunk assistance.

[Purpose] To evaluate the efficacy of the "forward-tilting posture" (the trunk tilted forward against a table) in a wheelchair in relieving gluteal pressure. [Participants and Methods] Thirty-six healthy adults were instructed to sit in a wheelchair assuming the following three postures: (1) both feet placed on the foot support with the trunk upright ("basic sitting posture"), (2) both feet placed on the foot support with the trunk tilted forward against a table ("forward-tilting posture A"), and (3) both feet placed on the floor with the trunk tilted forward against a table ("forward-tilting posture B"). A seat-type sensor pad placed on a wheelchair cushion was used to measure the maximum gluteal pressure and gluteal contact area. [Results] The maximum gluteal pressures in "forward-tilting postures A" and "forward-tilting postures B" were significantly lower than those in the basic sitting posture. The maximum gluteal pressure in "forward-tilting posture B" was significantly lower than that in "forward-tilting posture A". The gluteal contact area in "forward-tilting posture B" was significantly larger than that in "forward-tilting posture A". [Conclusion] The study results indicate that the "forward-tilting posture" in a wheelchair effectively relieves gluteal pressure., Competing Interests: There are no conflicts of interest to declare., (2024©by the Society of Physical Therapy Science. Published by IPEC Inc.)

[Purpose] This study aimed to investigate the influence of seat-forward tilt angles on improving upper limb dexterity in seated tasks and to contribute to the development of seating strategies. [Participants and Methods] Seventeen healthy men (age, 20.0 ± 0.5 years; height, 175.1 ± 4.9 cm; and body weight, 63.8 ± 6.7 kg) participated in this study. The forward tilt angles of the seat were set at 0°, 15°, and 30°, with knee pads used in all conditions. The Purdue Pegboard task was used to assess upper limb dexterity, with participants inserting pins into holes in the board for 60 s. Additionally, a visual analog scale was used to evaluate the perceived ease of the task. [Results] The Purdue Pegboard task scores were 30.0 ± 2.5, 30.6 ± 2.7, and 32.5 ± 2.9 for the 0°, 15°, and 30° conditions, respectively. The visual analog scale scores were 75.3 ± 9.8, 76.4 ± 14.6, and 84.1 ± 11.1 for the 0°, 15°, and 30° conditions, respectively. Both measurements showed significantly higher values under the 30° condition than under the other two conditions. [Conclusion] These results suggest that a tilt angle of 30° provides the most significant ease and upper limb dexterity., Competing Interests: The authors declare no conflicts of interest. The authors are responsible for the content and writing of this manuscript., (2024©by the Society of Physical Therapy Science. Published by IPEC Inc.)

Purpose: To statistically analyse sitting posture using anthropometrics data among college students in Malaysia. Design/methodology/approach: This study was conducted among 52 college students consisting of males and females. Data were analysed using a common statistical tool which is the Statistical Package of Sosial Science (SPSS). Findings: Preliminary analysis of data indicated that there are wider differences in standard deviation of eye sitting height compared to the previous study conducted. Research limitations/implications: This study was conducted at only one higher learning institution/college located at East Cost of Malaysia. Practical implications: The larger value of standard deviation discovered as statistical analysis performed using combined data among male and female participants suggested that data should be segregated. Originality/value: Result obtained could be used as a preliminary guideline to design any related item in related to sitting posture. [ABSTRACT FROM AUTHOR]

Cervical Spondylosis (CS) is a chronic spinal condition in which the spine gradually stiffens and can finally become completely inflexible. It is arduous to diagnose in early stages and leads to delay in medication. The risk level of Cervical Spondylosis can be reduced if it is detected in primary care. Based on this objective, a system is designed and developed to diagnose and predict the severity of cervical spondylosis in early stages. Different machine learning techniques are evaluated for this and results indicate that machine learning techniques can provide a low cost and accurate mechanism for early stage spondylosis detection. [ABSTRACT FROM AUTHOR]

Abstract Background Musculoskeletal pains are among evident health problems in children and adolescents. Backpack carrying behaviors and the sitting postures are among behavioral factors associated with musculoskeletal pain in schoolchildren. Therefore, this study aims to identify the factors related to these important musculoskeletal behaviors, using Health Promotion Models. Methods In this cross-sectional study, a questionnaire was created based on PRECEDE Model and Health Belief Model and was administered to 673 Iranian students, whom were selected randomly from elementary schools of Hamadan, Iran, in 2018. Results The findings of the study revealed that proper sitting postures and backpack carrying were 42 and 33%, respectively. The findings also showed that predisposing factors including perceived susceptibility (p

Background: Inappropriate sitting posture leads to musculoskeletal problems and is reported to be linked with the individual's confidence. This study explores the importance of recommended sitting posture on student, health, and sleep. Methods: 70 volunteer adolescent students aged 18–26 years were enrolled in this study. Instructions and sensitization lectures about the study were conducted and obtained informed consent. The students were asked to wear an upper scapular brace from 8.30 a.m. to 4.30 p.m. daily/31 days and advised to maintain the optimal sitting posture as per occupational health guidelines. The effect of the upper scapular brace and optimal sitting on posture from the various body angles were measured at sitting and standing. Pittsburgh Sleep Quality Index (PSQI), Simple lifestyle indicator questionnaires (SLIQ), Happiness index (HI) responses was collected and analysed. Measured multitasking tests and anthropometric variables like Height, Weight, and BMI before and after the intervention and effect sizes (Cohen's d) was calculated. Used an alpha level (P

In the context of extra-terrestrial missions, the effects of hypogravity (0 < G < 1) on the human body can reduce the well-being of the crew, cause musculoskeletal problems and affect their ability to perform tasks, especially during long-term missions. To date, studies of the effects of hypogravity on human movement are limited to experiments on the lower limbs. Here, we extend the knowledge base to the upper limbs, by conducting experiments to evaluate the effect of hypogravity on upper limb physical fatigue and mental workload in participants. Our hypothesis was that hypogravity would both increase participant productivity, by reducing overall physical fatigue expressed in Endurance Time, and reduce mental workload. Task Intensity-Endurance time curves are developed especially in seated positions, while performing static, dynamic, repetitive tasks. This experiment involved 32 healthy participants without chronic problems of the musculoskeletal system aged 33.59 ± 8.16 years. Using the collected data, fatigue models were constructed for tasks of varying Intensity. In addition, all participants completed the NASA – Task Load Index subjective mental workload assessment, which revealed the level of subjective workload when executing different tasks. We found two trends in the empirical fatigue models associated with the difference between the strength capabilities of males and females. The first is a significant positive (p = 0.002) relation between Endurance time and gravity level (⅙ G Moon, ⅓ G Mars, 1G) with negative coefficient for males and females for a static task. And there is marginal relation (p < 0.1) between overall mental workload and gravity level with a positive coefficient for males and females for the same task. The same trend was observed for dynamic and repetitive tasks. We concluded that the Task Intensity-Endurance Time model, adapted to hypogravity in combination with subjective mental assessment, is useful to human fatigue investigation. The combination of these methods used for ergonomic analysis and digital human modeling, could improve worker productivity. Finally, this study may help prepare astronauts for long-term missions on the Moon and Mars and improve our understanding of how we can prevent musculoskeletal disorders caused by hazardous manual handling under such extreme environments. [ABSTRACT FROM AUTHOR]

Flexible pressure monitoring device can help correct the sitting posture and prevent health problems (e.g., deformity of spinal column and musculoskeletal disease). Currently, most measurement systems hinder their wide applications owing to the high cost or low accuracy. In this study, a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently. The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics, which possesses high resolution (2. 26 sensors/cm²), high sensitivity (0.701 kPa-1) and fast response (≤35 ms). It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns. The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis. The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly. [ABSTRACT FROM AUTHOR]

While multiple previous studies have proposed utilizing an ambient display for providing real-time posture feedback to seated computer workers, it is not well understood how effective ambient feedback is in supporting the users' dual task of computer work and posture monitoring/rectification. The objective of the current study was to evaluate an ambient display for real-time posture feedback in comparison with typical conditions, an on-screen display and no display condition, in terms of the dual task performance. The ambient and the on-screen display were also compared in terms of perceived detection efficiency and user acceptance measures. A total of 24 participants performed the dual task in each of the three display conditions (the ambient, on-screen and no display conditions). The dependent measures for the dual task performance were the number of typed answers and the occurrence rate of high-risk postures; and, for the subjective evaluation, two detection efficiency measures (visibility and understandability) and four user acceptance measures (performance expectancy, effort expectancy, attitude toward using technology and social influence) were employed. The study demonstrated that both the ambient and the on-screen displays enhanced the dual task performance with respect to the no-display condition and the ambient display was superior to the on-screen display in the subjective experience measures.

In the context of extra-terrestrial missions, the effects of hypogravity (0 < G < 1) on the human body can reduce the well-being of the crew, cause musculoskeletal problems and affect their ability to perform tasks, especially during long-term missions. To date, studies of the effects of hypogravity on human movement are limited to experiments on the lower limbs. Here, we extend the knowledge base to the upper limbs, by conducting experiments to evaluate the effect of hypogravity on upper limb physical fatigue and mental workload in participants. Our hypothesis was that hypogravity would both increase participant productivity, by reducing overall physical fatigue expressed in Endurance Time, and reduce mental workload. Task Intensity-Endurance time curves are developed especially in seated positions, while performing static, dynamic, repetitive tasks. This experiment involved 32 healthy participants without chronic problems of the musculoskeletal system aged 33.59 ± 8.16 years. Using the collected data, fatigue models were constructed for tasks of varying Intensity. In addition, all participants completed the NASA – Task Load Index subjective mental workload assessment, which revealed the level of subjective workload when executing different tasks. We found two trends in the empirical fatigue models associated with the difference between the strength capabilities of males and females. The first is a significant positive (p = 0.002) relation between Endurance time and gravity level (⅙ G Moon, ⅓ G Mars, 1G) with negative coefficient for males and females for a static task. And there is marginal relation (p < 0.1) between overall mental workload and gravity level with a positive coefficient for males and females for the same task. The same trend was observed for dynamic and repetitive tasks. We concluded that the Task Intensity-Endurance Time model, adapted to hypogravity in combination with subjective mental assessment, is useful to human fatigue investigation. The combination of these methods used for ergonomic analysis and digital human modeling, could improve worker productivity. Finally, this study may help prepare astronauts for long-term missions on the Moon and Mars and improve our understanding of how we can prevent musculoskeletal disorders caused by hazardous manual handling under such extreme environments.

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

Background: Musculoskeletal pains are among evident health problems in children and adolescents. Backpack carrying behaviors and the sitting postures are among behavioral factors associated with musculoskeletal pain in schoolchildren. Therefore, this study aims to identify the factors related to these important musculoskeletal behaviors, using Health Promotion Models.Methods: In this cross-sectional study, a questionnaire was created based on PRECEDE Model and Health Belief Model and was administered to 673 Iranian students, whom were selected randomly from elementary schools of Hamadan, Iran, in 2018.Results: The findings of the study revealed that proper sitting postures and backpack carrying were 42 and 33%, respectively. The findings also showed that predisposing factors including perceived susceptibility (p < 0.05, β = 0.219), perceived severity (p < 0.05, β = 0.166), perceived barriers (p < 0.05, β = - 0.191), perceived self-efficacy (p < 0.05, β = 0.188) and also enabling factors (p < 0.05, β = 0.329) were significantly related to sitting behaviors. Moreover, backpack carrying behaviors had significant relationships with predisposing factors of perceived susceptibility (p < 0.05, β = 0.198), perceived barriers (p < 0.05, β = - 0.258), perceived self-efficacy (p < 0.05, β = 0.185) and reinforcing factors (p < 0.05, β = 0.208).Conclusions: It seems necessary for future preventive programs to take factors of musculoskeletal pains among children and adolescents into account. [ABSTRACT FROM AUTHOR]

Background: Spinal load and muscle activity in occupation settings is an area of increasing concern. Regarding technological advancements, in diverse occupations the spinal loads have increased through constrained seated postures. Back belts are consequently used in prophylactic and conservative management of occupational low back pain (LBP) in two distinct settings, prevention in industry, and treatment in LBP management. Industrial sites utilize belts for LBPprophylaxis on a large scale with their design and user experience (UE) influencing both the effectiveness and the workers’ compliance. This pilot study aims at determining the effectiveness of the new Tehran Back Belt (TBB) and assesses both UE and biomechanical effect (BE) on paraspinal muscle activity in healthy subjects. Methods: A pretest-posttest study. Stage-1, design and fabrication of the TBB. Stage-2, the UE of the designed belt evaluated in healthy volunteers (n=30) via a checklist. The BE was determined from the level of lumbar extensor and trunk flexor muscle activity gauged during two test conditions of sitting posture (with and without belt) over 35-minute periods. Results: Most subjects (>90%) reported high ‘ease of use’ and ‘comfort’ while wearing the TBB.The BE statistical analysis showed significantly reduced EMG activity levels for the longissimus(P = 0.012, η2=0.24), rectus abdominis (P=0.024, η2=0.18) and internal oblique (P=0.001,η2=0.44) muscles in belt-use conditions. Conclusion: Decreased muscle activity while using the TBB is potentially advantageous for workers as spinal muscle activity is significantly reduced. Further investigations for longer duration effects and during real work office-based activities are warranted.

Sitting comfortably in a vehicle, office or at home, besides design characteristics, requires excellent physical support of the material to the exposed body segments. An uncomfortable seat can cause well-known pain such as lower back pain, which is nowadays become as "chronical" pain among all the seated workers. This systematic review protocol is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) Statement and presents a methodology to find possible evidence of critical values of the applied pressure which can cause a negative impact on the soft tissues of the seated person. Furthermore, if it is possible to correlate obtained critical values with the time spent in the sitting position. Based on this, the main databases (Scopus, PubMed and Science Direct) will be searched using the same keywords combination for all of them. Afterwards, articles selection process, data extraction, and validation will be approved independently by the reviewers and collected data will be summarized in a spreadsheet table. Outcomes of the selected articles will be examined in the details and will be analyzed in order to extract the main results.

Human posture detection allows the capture of the kinematic parameters of the human body, which is important for many applications, such as assisted living, healthcare, physical exercising and rehabilitation. This task can greatly benefit from recent development in deep learning and computer vision. In this paper, we propose a novel deep recurrent hierarchical network (DRHN) model based on MobileNetV2 that allows for greater flexibility by reducing or eliminating posture detection problems related to a limited visibility human torso in the frame, i.e., the occlusion problem. The DRHN network accepts the RGB-Depth frame sequences and produces a representation of semantically related posture states. We achieved 91.47% accuracy at 10 fps rate for sitting posture recognition.

Purpose: To evaluate the mechanical accuracy and the robustness of position alignment under x-ray-based image guidance of a treatment chair with six degrees of freedom (6DTC) which was developed for patient treatment in an upright posture at fixed horizontal beam lines in particle (proton, carbon ion, or others) radiotherapy facilities.Method and Material: The positional accuracy including translational and axial rotational accuracy of the 6DTC was evaluated by using a Vicon Motion Capture System (VMCS). Stability of the chair rotation isocenter was determined by a CCD camera with an in-house developed software. The tests were carried out to examine two key motion components of the 6DTC: a floor/rail-mount 360°-rotating platform and a 6-degree-of-freedom (6DOF) platform. The measurement results were compared to that of a commercial clinical robot couch. The accuracy of position alignment, simulating the actual clinical protocol, through an Image-guided Radiation Therapy (IGRT) system was studied at the pre-treatment position and beam specific treatment position.Results: The translational accuracy was 0.12 mm (SD 0.07 mm) for the 6DOF platform. The rotational accuracy was 0.04° (SD 0.03°) and 0.02° (SD 0.02°) for the 6DOF platform and the 360° -rotating platform, respectively. The displacement between the chair rotation center and the room isocenter center was no more than 0.18 mm in all three rotational axes. Combined with an x-ray-based IGRT system, the treatment alignment test with a rigid phantom yielded a total positional accuracy of 0.23 mm (SD 0.17 mm) and 0.14° (SD 0.14°) at treatment position.Conclusions: On the basis of the rigid phantom study, the 6DTC showed comparable accuracy to the robot treatment couch. Combining with the IGRT, the 6DTC can provide position alignment with submillimeter accuracy for rigid phantom in upright posture.

Inadequate initial management of unstable pelvic injuries is usually associated with a fracture non-union and/or mal-union. Complete clinical and imaging evaluation is mandatory for a correct preoperative planning. Among other symptoms, sitting discomfort may arise from asymmetry of the ischial tuberosities or pressure from a prominent bony projection. Conventional radiographs are usually taken with the individual in a supine position and not in position where the symptoms are referred. We attempted to define a new radiological projection different than the regular pelvis views to study the position of pelvis of a normal person in sitting position. The second objective was to demonstrate its utility in the evaluation of a pelvic deformity. Fifteen healthy individuals were evaluated with a radiological projection in a sitting position. One patient with a vertically migrated pelvis nonunion was also evaluated with the same radiological protocol. In each volunteer's radiological study, a parallel line could be drawn between the sitting table and both distal aspects of the ischial tuberosities, sacral alas and superior aspect of the iliac wings. A plumb line perpendicular to the above mentioned ones could be drawn uniting the vertebras' spinous processes. A 90⁰ line intersection confirms the absence of deformity. In the pathological case, a pseudo scoliosis of the thoracolumbar spine is detected trying to compensate the pelvis obliquity and maintain equilibrium. We determined normal and pathological radiological features in the sitting imbalance of the pelvic in the anteroposterior plane of the pelvis. The study helps to understand the biomechanics and compensation of the pelvis to define surgical indications and predict post correction anatomy. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the mechanical accuracy and the robustness of position alignment under x-ray-based image guidance of a treatment chair with six degrees of freedom (6DTC) which was developed for patient treatment in an upright posture at fixed horizontal beam lines in particle (proton, carbon ion, or others) radiotherapy facilities. Method and Material: The positional accuracy including translational and axial rotational accuracy of the 6DTC was evaluated by using a Vicon Motion Capture System (VMCS). Stability of the chair rotation isocenter was determined by a CCD camera with an in-house developed software. The tests were carried out to examine two key motion components of the 6DTC: a floor/rail-mount 360°-rotating platform and a 6-degree-of-freedom (6DOF) platform. The measurement results were compared to that of a commercial clinical robot couch. The accuracy of position alignment, simulating the actual clinical protocol, through an Image-guided Radiation Therapy (IGRT) system was studied at the pre-treatment position and beam specific treatment position. Results: The translational accuracy was 0.12 mm (SD 0.07 mm) for the 6DOF platform. The rotational accuracy was 0.04° (SD 0.03°) and 0.02° (SD 0.02°) for the 6DOF platform and the 360° -rotating platform, respectively. The displacement between the chair rotation center and the room isocenter center was no more than 0.18 mm in all three rotational axes. Combined with an x-ray-based IGRT system, the treatment alignment test with a rigid phantom yielded a total positional accuracy of 0.23 mm (SD 0.17 mm) and 0.14° (SD 0.14°) at treatment position. Conclusions: On the basis of the rigid phantom study, the 6DTC showed comparable accuracy to the robot treatment couch. Combining with the IGRT, the 6DTC can provide position alignment with submillimeter accuracy for rigid phantom in upright posture. [ABSTRACT FROM AUTHOR]

• This work addresses recognition of human activities with different time duration. • A method based on adaptive sliding time windows is proposed. • A MGD-based dynamic time window adjustment algorithm is proposed. • The proposed adaptive sliding window method improves the recognition accuracy. The incessant diffusion of smart wearable devices and Body Area Networks (BANs) systems is pushing more and more researches on human activity recognition. Previous studies usually adopted fixed time window or chose an optimal window size depending on the characteristics of the activity. In this paper, we propose an adaptive time window-based algorithm of activity recognition, which addresses the problem of different types of activities having different time duration that usually causes poor recognition results. Multivariate Gaussian Distribution (MGD) method was used to detect the signal difference between each determined time window and the defined activity characteristics, and we more accurately define the time window size for each activity. To evaluate the proposed algorithm, we focused on the activities performed by wheelchair users in their daily life, so as to provide them with better healthcare services. We construct two different datasets, respectively considering static and dynamic wheelchair user activities on different ground surfaces. Then, we use time window expansion and contraction method to determine and dynamically adjust the window size for each activity. Different comparison criteria such as recognition precision and F-score were used to evaluate our algorithm. Experiment results revealed that, according to F-score, the proposed algorithm performs 15.3% better than traditional methods in static conditions. In dynamic scenarios we observed 6.4% and 24.5% improvements on flat and rough floors, respectively. [ABSTRACT FROM AUTHOR]

Objected to influences of impact to the whole body with sitting posture, the inverse dynamical analysis is carried out. Firstly by using the high-speed video camera, the images of the marked points on the body and the impact platform are captured and then the marked points' displacement can be obtained. Taking those displacements as input parameters, the inverse dynamical composition are continued with AnyBody Modeling System and responses are obtained and the impact transfer performance of the vertical direction in the human body with sitting posture and the muscle activities could be confirmed. From the sitting musculoskeletal model, it is concluded that acting forces of the joints and the mechanism performance of those parts of the body could be computed with different impact loadings, which would be conducive to understand the impact influence for the most parts of the body; especially for those parts that could be not tested. The study could be better for the reasonable countermeasures with certain postures for random impacting loadings. [ABSTRACT FROM AUTHOR]

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.

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.

PURPOSE This study investigated the association between the modifiable risk factors and spinal deformations in children. METHODS Children (152 boys, 153 girls) were recruited to participate in the study. Physical activity level, sitting time, and posture were assessed with a questionnaire. Spinal parameters such as scoliosis angle (SA), pelvic oblique (PO), and pelvic torsion (PT) were measured with the Formetric 4D. Children were classified as uncrossed and cross-legged sitting groups according to postures, as sedentary, moderately-active, and highly-active groups according to physical activity levels, and as low, mid, and high groups according to sitting time. Logistic regression was used to determine the odds ratio (OR) and 95% confidence interval (95% CI) of pelvic deformations. RESULTS Children with cross-legged sitting posture had significantly higher values in SA and PO than children with uncrossed sitting posture. Significant differences in SA, PO, and PT were found between the activity-based subgroups and a significant difference in PT between the sitting time-based subgroups. Compared with uncrossed sitting children (reference, OR=1), cross-legged sitting children had a significantly risk (OR=3.153, 95% CI=1.707-5.822) of PO deformation. Compared with highly active children (reference, OR=1), sedentary children had a significantly higher risk (OR=4.115, 95% CI=1.496-11.321) of PO deformation. In addition, moderately- active and sedentary children had significantly higher risks (OR=3.987 and 95% CI=2.044-7.777 and OR=5.806 and 95% CI=2.675-12.601, respectively) of PT deformation as compared with highly-active children (reference, OR=1). CONCLUSIONS The current findings suggest that crossed-legged sitting posture and decreased physical activity are two of modifiable risk factors for spinal deformations in children.

Objected to influences of impact to the whole body with sitting posture, the inverse dynamical analysis is carried out. Firstly by using the high-speed video camera, the images of the marked points on the body and the impact platform are captured and then the marked points’ displacement can be obtained. Taking those displacements as input parameters, the inverse dynamical composition are continued with AnyBody Modeling System and responses are obtained and the impact transfer performance of the vertical direction in the human body with sitting posture and the muscle activities could be confirmed. From the sitting musculoskeletal model, it is concluded that acting forces of the joints and the mechanism performance of those parts of the body could be computed with different impact loadings, which would be conducive to understand the impact influence for the most parts of the body; especially for those parts that could be not tested. The study could be better for the reasonable countermeasures with certain postures for random impacting loadings.

Background: Spinal load and muscle activity in occupation settings is an area of increasing concern. Regarding technological advancements, in diverse occupations the spinal loads have increased through constrained seated postures. Back belts are consequently used in prophylactic and conservative management of occupational low back pain (LBP) in two distinct settings, prevention in industry, and treatment in LBP management. Industrial sites utilize belts for LBP prophylaxis on a large scale with their design and user experience (UE) influencing both the effectiveness and the workers' compliance. This pilot study aims at determining the effectiveness of the new Tehran Back Belt (TBB) and assesses both UE and biomechanical effect (BE) on paraspinal muscle activity in healthy subjects. Methods: A pretest-posttest study. Stage-1, design and fabrication of the TBB. Stage-2, the UE of the designed belt evaluated in healthy volunteers (n = 30) via a checklist. The BE was determined from the level of lumbar extensor and trunk flexor muscle activity gauged during two test conditions of sitting posture (with and without belt) over 35-minute periods. Results: Most subjects (>90%) reported high 'ease of use' and 'comfort' while wearing the TBB. The BE statistical analysis showed significantly reduced EMG activity levels for the longissimus (P = 0.012, η² = 0.24), rectus abdominis (P = 0.024, η². = 0.18) and internal oblique (P = 0.001, η².44) muscles in belt-use conditions. Conclusion: Decreased muscle activity while using the TBB is potentially advantageous for workers as spinal muscle activity is significantly reduced. Further investigations for longer duration effects and during real work office-based activities are warranted. [ABSTRACT FROM AUTHOR]

• Sitting posture affected the thermal insulation of modern office chairs. • Leaning forwards reduced the chair insulation by 0.09 clo. • Facemasks provide small, but not insignificant thermal insulation of 0.05 clo. • The insulation of contemporary office chairs matched those of earlier studies. This study experimentally explored the variability in thermal insulation with different sitting postures and a contemporary selection of chair designs. Also, the insulating effect of three different types of facemasks was evaluated. Measurements were made with a thermal manikin seated in a well-controlled climate chamber at three different room temperatures: 20 ± 0.2 °C, 25 ± 0.2 °C and 30 ± 0.2 °C. Two sitting postures were investigated: back in contact with the chair backrest or not, i.e. leaning slightly forwards. The selected chairs had effective thermal insulation around 0.14–0.17 clo when the manikin was seated with the back in contact with the chair backrest, except the applied executive chair, which provided 0.26 clo. On average, leaning forwards reduced the clothing insulation by 0.09 clo. The tested facemasks all provided the same marginal insulation I clu of 0.05 clo. The measured chair insulation values were well aligned with those from earlier studies. The study confirms that chair insulation is a parameter that should be carefully evaluated and considered when assessing thermal comfort. [ABSTRACT FROM AUTHOR]

Selected anthropometric measures of two hundred primary school pupils in Ibadan North Local Government Area of Oyo State were used to design classroom desks and tables. The relevant anthropometric measures were popliteal height, buttock-popliteal length, elbow rest height, hip breadth, shoulder height and elbow-hand grip. The pupils with age range from 5 to 14 years (mean = 9.8 years, SD = 2.9 years) were grouped into three age groups of 5-8 years, 9-12 years and 13-14 years. From the data obtained; 5th, 10th, 50th, 75th, 90th and 95th percentiles were computed. In addition, 2-Tail Paired samples T-Test was conducted for the measurements of the male and female pupils for the three- age groups at 0.05 level of significance. Based on the anthropometric data obtained, this paper proposes furniture design dimensions for seat height (32.0 cm, 37.3 cm and 40.3 cm for 5-8 years, 9 to 12 years and 13-14 years respectively). It proposes seat depth (33.0 cm, 38.0 cm and 41.0 cm for 5-8 years, 9 to 12 years and 13-14 years respectively) and seat width (30.0 cm, 31.0 cm and 31.0 cm for 5-8 years, 9 to 12 years and 13-14 years respectively). Moreover, it proposes backrest height (upper) (39.0 cm, 43.0 cm and 44.0 cm for 5-8 years, 9 to 12 years and 13-14 years respectively) and arm rest (12.0 cm, 13.0 cm and 15.0 cm for 5-8 years, 9 to 12 years and 13-14 years respectively). It also proposes desk height (42.0 cm, 49.0 cm and 53.3 cm for 5- 8 years, 9 to 12 years and 13-14 years respectively.

Purpose: To verify the effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance., Methods: Thirty healthy subjects were evaluated. The Conformat was used to analyze the center of sitting pressure (COSP), and the three-dimensional motion analysis system was used to analyze changes in head and trunk postures while subjects remained in a sitting position with and without sole-ground contact. The parameters of masticatory performance and movement were calculated as follows. For evaluating masticatory performance, the amount of glucose extraction (AGE) during chewing of a gummy jelly was measured. For evaluating masticatory movements, the movement of the mandibular incisal point was recorded using the Motion Visi-Trainer V1, and parameters of the stabilities of movement path and rhythm were calculated., Results: Head and trunk sway values and the displacement of COSP were significantly smaller with sole-ground contact than those without sole-ground contact. The masticatory movement path with sole-ground contact showed less variation in the opening distance and more stable movement path compared to those without sole-ground contact. The AGE was significantly greater with sole-ground contact than that without sole-ground contact., Conclusion: Sitting posture with and without sole-ground contact affects chewing stability and masticatory performance.

Sitting on a chair in an awkward posture or sitting for a long period of time is a risk factor for musculoskeletal disorders. A postural habit that has been formed cannot be changed easily. It is important to form a proper postural habit from childhood as the lumbar disease during childhood caused by their improper posture is most likely to recur. Thus, there is a need for a monitoring system that classifies children's sitting postures. The purpose of this paper is to develop a system for classifying sitting postures for children using machine learning algorithms. The convolutional neural network (CNN) algorithm was used in addition to the conventional algorithms: Naïve Bayes classifier (NB), decision tree (DT), neural network (NN), multinomial logistic regression (MLR), and support vector machine (SVM). To collect data for classifying sitting postures, a sensing cushion was developed by mounting a pressure sensor mat (8 × 8) inside children's chair seat cushion. Ten children participated, and sensor data was collected by taking a static posture for the five prescribed postures. The accuracy of CNN was found to be the highest as compared with those of the other algorithms. It is expected that the comprehensive posture monitoring system would be established through future research on enhancing the classification algorithm and providing an effective feedback system. [ABSTRACT FROM AUTHOR]

Background: The forward head rounded shoulder (FHRS) sitting posture has been associated with decreased shoulder complex muscle strength and function. Upon clinical observation, the adverse effects of the FHRS sitting posture on shoulder complex isometric muscle strength is also present when testing controls for scapular position. Hypothesis/Purpose: The purpose of the study was to assess the effect of various sitting postures on shoulder external rotator muscle isometric strength when the strength testing controls for scapular position. Study Design: A cohort study, with subjects serving as their own controls. Methods: One hundred subjects ages 20-26 participated in the study. Each subject was placed in a neutral cervical sitting (NCS) posture which was maintained for five minutes after which the strength of the dominant shoulder external rotators was immediately tested with the glenohumeral joint in the neutral position using a Micro-FET3 Hand Held Muscle Testing Dynamometer (HHMTD). Each subject was returned to the NCS posture for subsequent external rotator strength testing after five minutes in a FHRS sitting posture, five additional minutes in the NCS posture and five minutes in a retracted cervical sitting (RCS) posture resulting in each subjects' external rotator strength being tested on four occasions. Subjects were randomized for order between the FHRS and RCS postures. Results: Mean strength values for each condition were normalized to the mean strength value for the 1st NCS condition for each subject. A statistically significant decline in shoulder external rotator strength following the FHRS sitting posture occurred compared to the appropriate postural conditions (p<.05). A frequency analysis revealed that 36% of the subjects demonstrated greater than 10% decline in external rotator strength following five minutes in the FHRS sitting posture. The average percentage of strength decline in those with greater than a 10% reduction in external rotator strength was 19%. Sixty-four percent of the subjects experienced less than a 10% decline in shoulder external rotator strength in response to the FHRS sitting posture. Conclusion: Shoulder external rotator strength declined 8% following five minutes in the FHRS sitting posture. A sub-population of 36% demonstrated an average decline of 19% in shoulder external rotator strength following five minutes in the FHRS sitting posture. The strength decline appears to resolve over the short-term by returning to the NCS posture. Level of Evidence: Level III [ABSTRACT FROM AUTHOR]

Background: Upright and slouched sitting are frequently adopted postures associated with increased intradiscal pressure, spinal height loss and intervertebral disc pathology.Objectives: To examine the effects of two sustained propped slouched sitting (PSS) postures on spinal height after a period of trunk loading.Methods: Thirty-four participants without a history of low back pain (LBP) were recruited (age 24.4 ± 1.6 years). Subjects sat in (1) PSS without lumbar support and (2) PSS with lumbar support for 10 min, after a period of trunk loading. Spinal height was measured using a stadiometer.Results: Mean spinal height increase during PSS without lumbar support was 2.94 ± 3.63 mm and with lumbar support 4.74 ± 3.07 mm.Conclusions: Both PSS with and without lumbar support significantly increased spinal height after a period of trunk loading (p < 0.001). Such PSS postures can provide a valuable alternative to upright sitting and may be recommended for recovering spinal height in the working environment following periods of loading. [ABSTRACT FROM AUTHOR]