Sitting Positions Research Articles

Ergonomics Optimization of Heavy Commercial Vehicle

Optimize the cab seat height of the heavy commercial vehicle and the maneuverability of the shift lever. Method: The mathematical model of human sitting posture and upper limb operation were established. The Chinese human body size was corrected by the combination of height growth rate and height linear ratio. Under the constraint of sitting posture, the H-point fitline model of the 5th, 50th and 95th percentile male drivers in China was obtained, and the optimal H-point range and SgRP point height were determined. The problem of high seat height has been optimized. At the same time, a operating lever layout position model is established; The actual measurement was made in the Class A vehicle, and the shift lever arrangement position was redefined. Conclusion: The height adaptability of the seat is improved; the operating comfort of the shift lever is improved; the visible area of the instrument panel becomes larger, and the 10th percentile male driver in China has a larger blind spot.

Relationship between Movements of the Head and Neck and Spinal Alignment in a Sitting Posture

Relationship between Movements of the Head and Neck and Spinal Alignment in a Sitting Posture

Relationship between muscle thickness and spinal column alignment in the standing and sitting positions

The trunk muscles play a role in posture maintenance, but whether they are related to spinal alignment in different postures has only been investigated in young adults and not in the elderly who show age-related changes in the spine. This study aimed to determine the relationship between changes in spinal alignment and muscle thickness in three postures in healthy elderly subjects. Spinal mouse measurements of Spinal alignment and ultrasound measurements of the trunk muscles were performed in the standing, upright and slump sitting positions on healthy elderly individuals living in the community. Results showed significant differences in the sacral tilt, lumbar curvature, and overall tilt angles in the slump sitting position for spinal alignment, and significant differences were noted in muscle thickness between standing and upright sitting, standing and slump sitting, and standing and slump sitting, and upright and slump sitting for the spinal proprioceptive muscle (second lumbar level). In conclusion, there was no correlation between the two changes. It was suggested that the spine be viewed as a whole and not in parts, with muscle thickness changes. Keywords: Spine, postural difference, posture holding muscle.

Effect of low back pain on the muscles controlling the sitting posture.

[Purpose] The purpose of the current study was to reveal the association between posture control and muscle activity by measuring the trunk and hip joint muscle activities in the upright and slump sitting positions in both the healthy participants and patients with recurrent lower back pain. [Participants and Methods] We recruited eleven patients of recurrent lower back pain and ten healthy participants. During the maintenance of the two types of posture, upright and slump, we collected the surface electromyography data. We assessed the following muscles: rectus abdominis, external oblique, thoracic erector spinae, lumbar erector spinae, internal oblique, lumbar multifidus, iliacus, serratus anterior, rectus femoris, tensor fascia latae, and gluteus maximus. We studied the differences in spinal–pelvic curvature and muscle activity between the upright and slump positions in each group. [Results] In the healthy group, comparison of the muscle activity in upright and slump positions for both the trunk (external oblique, internal oblique, lumbar erector spinae, and lumbar multifidus), and the hip muscles (iliacus and gluteus maximus) showed a significant decrease in activity in the slump position. In the group with recurrent lower back pain, although the external oblique, lumbar erector spinae and lumbar multifidus showed reduced activity in slump position, these values were smaller when compared to those in the healthy group. [Conclusion] This study aimed to clarify the relationship between posture (upright and slump) and the activity of the trunk and hip joint muscles in the healthy participants and the patients with recurrent lower back pain. The results indicated that postural changes caused by recurrent lower back pain significantly affected the activity of the muscles involved in controlling the posture.

Multifidus Thickness Comparison between the Effectiveness of Abdominal Bracing and Maximum Expiration Maneuvers in Lumbo-Pelvic Upright Sitting Posture

Multifidus Thickness Comparison between the Effectiveness of Abdominal Bracing and Maximum Expiration Maneuvers in Lumbo-Pelvic Upright Sitting Posture

Comparison of three sitting positions for combined spinal - epidural anesthesia: a multicenter randomized controlled trial

Background and objectivesThe aim of this prospective, multi-centered and multi-arm parallel randomized trial was to test the hypothesis that modified sitting positions including hamstring stretch position (HSP) and squatting position (SP) would reduce needle - bone contact events and increase the success rate of combined spinal - epidural anesthesia (CSEA) compared to traditional sitting position (TSP) in patients undergoing total knee or hip arthroplasty. Patients and methodsThree hundred and sixty American Society of Anesthesiologists (ASA) I-III patients, aged between 45-85 years were randomly allocated to one of three groups using computer-generated simple randomization: group TSP (n = 120), group HSP (n = 120), and group SP (n = 120). Primary outcome measures were the number of needle-bone contact and success rates. Secondary outcome measure was the ease of interspinous space identification. ResultsSeven patients in group SP and four of HSP could not tolerate their position and were excluded. Number of needle-bone contact, success rates, and grade of interspinous space identification were similar between groups (p = 1.000). Independent of positioning, the success rates were higher in patients whose interspinous space was graded as easy compared to difficult or impossible (p < 0.001). Success rates reduced, interspinous space identification became more challenging, and number of needle – bone contact increased as patient’s body mass index (BMI) increased (p < 0.001). ConclusionSP and HSP may be used as alternatives to the TSP. BMI and ease of interspinous space identification may be considered important determinants for CSEA success.

Stretching is Superior to Brisk Walking for Reducing Blood Pressure in People With High-Normal Blood Pressure or Stage I Hypertension.

Aerobic exercise is recommended for reducing blood pressure; however, recent studies indicate that stretching may also be effective. The authors compared 8 weeks of stretching versus walking exercise in men and women with high-normal blood pressure or stage 1 hypertension (ie,130/85-159/99mmHg). Forty men and women (61.6y) were randomized to a stretching or brisk walking exercise program (30min/d, 5d/wk for 8wk). Blood pressure was assessed during sitting and supine positions and for 24 hours using a portable monitor before and after the training programs. The stretching program elicited greater reductions than the walking program (P < .05) for sitting systolic (146 [9] to 140 [12] vs 139 [9] to 142 [12]mmHg), supine diastolic (85 [7] to 78 [8] vs 81 [7] to 82 [7]mmHg), and nighttime diastolic (67 [8] to 65 [10] vs 68 [8] to 73 [12]mmHg) blood pressures. The stretching program elicited greater reductions than the walking program (P < .05) for mean arterial pressure assessed in sitting (108 [7] to 103 [6] vs 105 [6] vs 105 [8]mmHg), supine (102 [9] to 96 [9] vs 99 [6] to 99 [7]mmHg), and at night (86 [9] to 83 [10] vs 88 [9] to 93 [12]mmHg). An 8-week stretching program was superior to brisk walking for reducing blood pressure in individuals with high-normal blood pressure or stage 1 hypertension.

Muscle length influence on rectus femoris damage and protective effect in knee extensor eccentric exercise.

This study tested the hypothesis that the magnitude of rectus femoris (RF) damage and the repeated bout effect (RBE) would be greater after knee extensor eccentric exercise performed in a supine (long RF lengths) than a sitting (short RF lengths) position, and the muscle length effects would be more prominent at the proximal than distal RF. Young untrained men were placed to one of the two groups (n = 14 per group). S group performed the knee extensor eccentric exercise in the sitting position for the first bout and the supine position for the second bout, and L group performed the exercise in the supine position for two bouts, with 4 weeks between bouts. Dependent variables included evoked and maximal voluntary isometric contraction (MVC) torque, electromyography (EMG) during MVC, muscle soreness, and shear modulus, which were measured before and 1‐3 days after each exercise bout. After the first bout, L group in comparison with S group showed greater (P < .05) changes in hip flexor MVC torque (average of 1‐3 days post‐exercise: −11.1 ± 9.4% vs −5.0 ± 7.5%), proximal RF EMG (−22.4 ± 16% vs −9.0 ± 21.9%), and proximal RF shear modulus (33.2 ± 22.8% vs 16.9 ± 13.5%). No significant differences between groups were evident for any of other variables after the first bout including knee extensor MVC torque, and for the changes in all variables after the second bout. These results supported the hypothesis that RF damage would be greater for the spine than sitting position especially at the proximal region, but did not support the hypothesis about the RBE.

INFLUENCE OF DIFFERENT SITTING POSITIONS ON THE MAXIMAL RESPIRATORY PRESSURES IN HEALTHY INDIVIDUALS OF VARIOUS AGE GROUPS: AN EXPERIMENTAL STUDY

Background: Variation in the position of the body influences the orientation and length of the muscle. The ability of the respiratory muscles to generate force depends upon its length. There is a dearth of literature about the effect of pressures generated by the respiratory muscles due to the different sitting positions. Purpose of the study: Due to the importance of body positioning in the optimization of breathing exercises, a need was felt to compare maximal respiratory pressures of the respiratory muscles in different sitting positions and identify a suitable position in which respiratory muscles work the best. Participants: Total 144 participants were included in the study according to the inclusion and exclusion criteria. Participants were divided into age groups of 18-40years, 41-60years and 60years and above. Equal representation was given to sample number and gender in each group. Method: MIP and MEP were measured in three different sitting positions i.e. upright sitting position, forward leaning position and semi fowlers position by using the Micro RPM (Micro Medical/Care Fusion, Kent, United Kingdom). The best of the three measurements was taken. Results: There is a significant difference in the values of MIP and MEP in different sitting positions in all the age groups with p-value &lt; 0.05. In each age group it was found that the values of MIP was better in upright sitting position as compared to forward leaning position (p-value &lt;0.01) with no difference found in the values of MIP between the upright sitting position and semi-fowlers position (p-value &gt; 0.05). The values for MEP was found to be increased in forward leaning position as compared to upright sitting position and semi-fowlers position p-value &lt;0.05 Conclusion: The present study concluded that, there is a significant influence of different sitting positions on the maximal respiratory pressures in healthy individuals of various age groups. Implication: The results of this study can be used to make a good clinical decision about which sitting position should be adapted while giving the various types of breathing exercises to the patient. KEY WORDS: Maximal respiratory pressures, MIP, MEP, body positioning, sitting positions, breathing exercises.

Multifidus Thickness Comparison between the Effectiveness of Abdominal Bracing and Maximum Expiration Maneuvers in Lumbo-Pelvic Upright Sitting Posture

Background: Trunk flexor-extensor muscles’ co-activation and upright posture are important for spinal stability. Abdominal bracing and maximal expiration are being used as exercises to excel torso co-contraction. However, no study has on comparison of the effect of this exercise on multifidus in the upright sitting posture.Objectives: This study aims to verify the effectiveness of abdominal bracing and expiration maneuvers in lumbo-pelvic upright sitting.Design: Cross-sectional study.Methods: Eighteen healthy women were recruited for this study. The multifidus muscle thickness of all subjects was measured in three sitting conditions (lumbo-pelvic upright sitting, lumbo-pelvic upright sitting with abdominal bracing, and lumbo-pelvic upright sitting with maximum expiration) using ultrasound. One-way repeated measure analysis of variance was used for the evaluation.Results: Compared to lumbo-pelvic upright sitting, lumbo-pelvic upright sitting with abdominal bracing and lumbo-pelvic upright sitting with maximum expiration were associated with significantly increment of muscle thickness. There was no significant difference in muscle thickness between lumbo-pelvic upright sitting with abdominal bracing and lumbo-pelvic upright sitting with maximum expiration.Conclusion: Abdominal bracing and maximum expiration could be beneficial to increasing lumbar multifidus thickness in lumbo-pelvic upright sitting.

Notions of “optimal” posture are loaded with meaning. Perceptions of sitting posture among asymptomatic members of the community

BackgroundNotions of “optimal” posture are widespread in modern society and strongly interconnected with preconceived beliefs. ObjectivesTo quantitatively evaluate spinal posture among members of the community during habitual sitting, and when asked to assume an “optimal” posture. DesignObservational study. MethodsMarker-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. ResultsNone 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. ConclusionsA 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.

Smart-Cover: A real time sitting posture monitoring system

Prolonged asymmetrical sitting is common and can exacerbate musculoskeletal back pain and spinal deformities. Monitoring sitting posture can help maintain correct posture and prevent health problems. Currently posture is assessed by expert clinicians using subjective visual observation. More objective methods involve the use of a gold-standard motion capture system in Laboratories, which is expensive and not widely available. We develop a Smart-Cover, an automatic system to provide real time visualization and information about sitting posture. A Sitting Pressure Sensor (SPS) is built using Velostat, conductive fabric and foam to collect pressure distribution information within the seat surface. The data are collected from 10 healthy young subjects where each subject sits for 30 min and are transferred to a cloud server using Internet-of-Things (IoT). A rule-based classifier is used to provide timely notification to users about sitting duration and level of asymmetry. A new end-point device application is developed to show sitting balance. Dial based displays show level of asymmetry, active and static sitting, and daily summary score. Our system is user friendly, inexpensive, automatic and quantitative method for evaluating posture in real time, which has the capability of providing quantitative information about sitting behaviour. The results show that our system can be used for objective monitoring of sitting posture which has medical and social benefits. Smart-Cover can support the management of patients during their rehabilitation by monitoring pressure areas and balance when seated. In addition, it offers users at home, schools and offices the means to improve their sitting posture.

Modeling and Optimization of Spine and Lower Extremities of a Motor Cycle Rider

Motorcycle riders have to maintain almost a constant sitting posture in the seat with restricted provision for movement while riding which may eventually lead to rider discomfort and fatigue. This article focuses on the biomechanics modeling of the lower extremities and spine of a motorcycle rider. The proposed biomechanics model involves the five segments including the Pelvis, Femur, Tibia-Fibula, Foot, and the Spine of the rider. A custom-made python program is developed in which eight physical dimensions and weight of the rider has to be provided as input. Dimensions of the various motorcycles can be stored as a library. As a case study of the modeling, the comfort of a selected subject on two well-known vehicles in India is conducted. This model can be extended for calculating fatigue load experienced by the rider for the various dimensions and alterations of the vehicle. This model can also be used to customize the vehicle dimensions to increase the comfort of the rider. Validation study for modeling the real-time subjects using surface electromyography (sEMG) signals is needed which is the future scope of the work.

ERGONOMIC EVALUATION OF STUDY DESKS AND CHAIRS USING ANTHROPOMETRY AND BIOMECHANICAL APPROACH AT AN-NURIYAH ISLAMIC BOARDING SCHOOL BONTOCINI JENEPONTO REGENCY

School is one of the places to study. Therefore, it requires facilities to support the sustainability of the process of teaching and learning to teach such as study desks and study chairs. However, when the activity of writing is performed using study desks and chairs, students tend to lean to the front, slouch and dangle their feet. Evaluation of the products ergonomically has to be adjusted with the usage in order that they are not going to cause various negative impacts for students that will take place in both the short term and the long one. As a consequence, this study is important to carry out to minimize the mismatch of study desks and chairs with students and to obtain the redesigned results of study desks and study chairs ergonomically. The anthropometric approach was used for the dimensions of the human body in the design of study desks and chairs. In addition, the biomechanical approach was utilized to evaluate good sitting position for students. The evaluation was observed from the calculation of compression pressure, which is the load that occurs in the neck and lumbar. The results of the design of the proposed study desks and chairs are more ergonomic and can accommodate anthropometric users; hence, parts of the study desks and chair can minimize the complaints perceived by students. Through the biomechanical approach, the results obtained the angle surface of the table of 200, the slope of the seat rest of 100º and the seat slope of 50º

A Smart System for Sitting Posture Detection Based on Force Sensors and Mobile Application

The employees’ health and well-being are an actual topic in our fast-moving world. Employers lose money when their employees suffer from different health problems and cannot work. The major problem is the spinal pain caused by the poor sitting posture on the office chair. This paper deals with the proposal and realization of the system for the detection of incorrect sitting positions. The smart chair has six flexible force sensors. The Internet of Things (IoT) node based on Arduino connects these sensors into the system. The system detects wrong seating positions and notifies the users. In advance, we develop a mobile application to receive those notifications. The user gets feedback about sitting posture and additional statistical data. We defined simple rules for processing the sensor data for recognizing wrong sitting postures. The data from smart chairs are collected by a private cloud solution from QNAP and are stored in the MongoDB database. We used the Node-RED application for the whole logic implementation.

Differences in standing and sitting spinopelvic sagittal alignment for patients with posterior lumbar fusion: important considerations for the changes of unfused adjacent segments lordosis

ObjectiveThis study aimed to describe the changes in spinopelvic sagittal alignment in the sitting position after posterior lumbar fusion, and to identify the factors influencing unfused adjacent segment lordosis.MethodsConsecutive patients with lumbar degenerative disease who underwent posterior lumbar interbody fusion between December 2010 and April 2012 were recruited. Lateral full spine radiographs were obtained in the standing, erect sitting, and natural sitting positions. Spinopelvic parameters were measured preoperatively and at the final follow-up.ResultsThe data of 63 patients were analyzed in this study. The average age was 61.6 ± 11.0 years. When changing from standing to sitting at the final follow-up, all spinopelvic sagittal parameters with the exceptions of pelvic incidence and thoracic kyphosis were significantly altered. The most noticeable changes occurred in the natural sitting position, with the spine slumped toward achieving a C-shaped sagittal profile. Multiple linear regression analysis revealed that when changing to a natural sitting position, age and fusion levels reflected the changes in lumbar lordosis (ΔLL), age and lumbosacral fusion reflected the changes in upper residual lordosis (ΔURL).ConclusionThe most noticeable changes in spinopelvic sagittal alignment occurred in the natural sitting position after lumbar fusion. Age, fusion levels, and lumbosacral fusion significantly influenced the differences in LL and URL between the standing and natural sitting position. These characteristics should be fully considered when planning spinal realignment surgery and investigating the etiological factors of junctional complications.

The effectiveness of cement augmentation in kyphosis correction of dynamically loaded osteoporotic vertebral fractures: A retrospective case series

BackgroundOsteoporotic fracture of vertebrae is the presentation of osteoporosis, in most elderly patients and treatment of these fractures aims in pain relief, correction of kyphosis and management of osteoporosis. The purpose of the study is to evaluate the clinical usefulness of cement augmentation and the ability of cement augmented vertebrae to withstand physiological axial load. Materials and methodsWe did a retrospective analysis of all patients (62 patients and 67 vertebrae) from 2015 to 2019 in whom a stand-alone percutaneous cement augmentation was done for primary osteoporotic vertebral fractures. The kyphotic angle (KA), wedge angle (WA) and anterior vertebral height (AVH) were measured in radiographs taken pre-operatively and post-operatively in slump sitting and supine position. The mobility of the vertebra was determined radiologically by the difference in KA, WA and AVH in two positions (slump sitting and supine) and were compared. Functional outcome was analyzed using VAS scores for back pain. ResultsThe mean age group was 67.66 + 11.49 years, with thoracolumbar region being the most commonly involved. There was a significant improvement in back pain scores post cement augmentation from a pre-operative VAS of 6.91 ± 1.7 to a post-operative VAS score of 1.74 ± 1.1. The kyphotic deformity parameters like KA, WA and AVH also improved post cement augmentation. The difference of KA, WA and AVH between sitting and supine position preoperatively were 4.85 ± 6.87degrees, 2.61 ± 6.35 degrees and 0.26 ± 0.47 cm. The difference of post-operative KA, WA and AVH in two different positions was 1.02 ± 0.76 degrees, 0.05 ± 0.21 degrees and 0.03 ± 0.04 and were statistically significant than pre-operative measurements. ConclusionThe cement augmentation technique in addition to pain relief, it also improves the kyphotic deformity of the fractured vertebrae. The kyphotic deformity correction achieved by the procedure remain sustained even in physiological axial loading of the cement augmented vertebra.

Evaluating the Changes in the Functional Status of the Musculoskeletal System before and after an Intervention among Sewing Machine Operators with Partial Work Ability

Musculoskeletal disorders are the most common occupational diseases in Estonia and in the European Union as a whole. Sewing machine operators’ work is very monotonous, in continuous sitting position, with repetitive one-side movements of the upper limbs and legs. Working in an awkward posture and doing the same movements for a long period of time increases the risk of musculoskeletal system disorders, and in longer perspective, could cause work disability. The aim of the study was to analyse the prevalence of musculoskeletal disorders, intensity and duration of pain in a different body regions and to assess the changes of the functional status of the musculoskeletal system before and after the intervention among workers with partial work ability. The target group was 57 sewing machine operators, who were presented with an anonymous online questionnaire and agreed to participate in the intervention program. The study group was 12 sewing machine operators with partial work ability. RULA (Rapid Upper Limb Assessment) method was used for evaluating ergonomic workstations. The pain assessment was studied by NPRS, Numeric Pain Rating Scale. Online questionnaires were based on BQ (Baecke Physical Activity Questionnaire) and NMQ (The Nordic Musculoskeletal Questionnaire). The results showed that musculoskeletal status among workers with partial work ability improved after the intervention. Associations between individual and job related factors and musculoskeletal pain were observed. The research allows to make actual proposals for workplace layout of sewing machine operators, to provide ergonomic deployment and offer suitable exercise movements for rest breaks.

Trunk Posture Adaptations during Sitting on Dynamic Stool: A Validation Study

Back pain is a complex condition that results from multiple factors including sitting issues such as the chair type and spinal sitting posture. The physiological spinal curvature on the sagittal plane represents a typical feature of good body posture. Sitting postures matching the physiological shape of the spine on the sagittal plane during standing are deemed advantageous from a postural point of view. The aim of this study was to validate a novel dynamic stool by comparing trunk posture adaptations on the sagittal plane during dynamic sitting vs. conventional sitting (standard stool) in healthy people. In total, 100 healthy adults were included. Age, sex and body mass index were recorded. Thoracic kyphosis and lumbar lordosis were measured with the IncliMed® goniometer during standing posture, conventional sitting posture (standard stool) and dynamic sitting posture (novel dynamic stool). Sitting posture was maintained for 2 min before evaluation. Thoracic kyphosis and lumbar lordosis were significantly different between standing vs. sitting (dynamic and conventional) posture (p &lt; 0.001) and between dynamic vs. conventional sitting posture (p &lt; 0.001). Sitting on the novel dynamic stool tested in this study was shown to provide a greater match of thoracic kyphosis and lumbar lordosis with the physiological spinal curvature on the sagittal plane during standing than conventional sitting.

Severity evaluation of obstructive sleep apnea based on speech features.

There are upper airway abnormalities in patients with obstructive sleep apnea (OSA), and their speech signal characteristics are different from those of unaffected people. In this study, the severity of OSA was evaluated automatically by machine learning technology based on the speech signals of Chinese people. In total, 151 adult male Mandarin native speakers who had suspected OSA completed polysomnography to assess the severity of the disease. Chinese vowels and nasal sounds were recorded in sitting and supine positions, and the accuracy of predicting the apnea-hypopnea index (AHI) of the participants using a machine learning method was analyzed based on features extracted from the speech signals. Among the 151 participants, 75 had AHI > 30 events/h, and 76 had AHI ≤ 30 events/h. Various features including linear prediction cepstral coefficients (LPCC) were extracted from the data collected from participants recorded in the sitting and supine positions and by using a linear support vector machine (SVM); we classified the participants with thresholds of AHI = 30 and AHI = 10 events/h. The accuracies of the classifications were both 78.8%, the sensitivities were 77.3% and 79.1%, and the specificities were 80.3% and 78.0%, respectively. This study constructed a severity evaluation model of OSA based on speech signal processing and machine learning, which can be used as an effective method to screen patients with OSA. In addition, it was found that Chinese pronunciation can be used as an effective feature to predict OSA.