Back Rest Research Articles

Toward the Design of an Ultra-Light Car Seat With a Reclining Back Rest

To reduce the weight of a seat of a city car (A-segment), a car seat was developed. First, a questionnaire was used to define the main functions the occupants prefer to have in the seat. The reclining and forward afterwards movement of the seat were seen as most important. Therefore, a reclining mechanism was built into the lightweight chair. This seat was tested by 39 participants and compared with a benchmark seat of the Toyota Aygo. It was clear that comfort testing is difficult comparing a full developed car seat with a prototype, which still needs development. Nevertheless, the comfort was comparable between the two seats and the shoulder space of the new seat was appreciated. The conclusion is that it is possible to develop a lighter weight car seat, which has the main features preferred by occupants, but further development is needed.

Relationships between working from home, sitting postures and low back pain during COVID-19: A survey of frequent computer users.

To investigate the effects of working from home on musculoskeletal pain. An e-survey of computer workers was conducted. Multinomial logistic regression modelling examined relationships between work location (work or home office desk, dining table, other), sitting posture (diagrams with descriptors), depressive symptoms (CESD -10), sleep quality (good/average vs poor) and pain (low back pain [LBP]), other pain without LBP, asymptomatic). Of 634 respondents, most (91%, n = 578) worked partially at home and had pain (91%, n = 576; 342 LBP, 234 other pain, 58 asymptomatic). Sitting posture ("trunk a little bent forward" vs "straight up, back against back rest": OR = 2.9; 95% CI 1.3-6.5, p = .008), being female (2.2; 1.2-4.1, p = .008), and depressive symptoms (3.4; 1.7-6.6; p < .001) were associated with LBP. Poor sleep quality related to LBP but correlated with depressive symptoms. Working from home and location were not associated with pain. Sitting postures, but not working from home, are associated with LBP.

To Find Out the Effect of Varying the Back Rest Angles on Drivers Posture While in a Static Condition

Abstract : A total of 32 male subjects, with a mean age of 26, were recruited for the study on the basis of inclusion and exclusion criteria .Before included in the study , the consent form were taken from all the subjects. They were recruited from different hospitals of Dehradun. 32 male subjects were taken for photographs with car seats adjusted at three different angles. Subjects were asked to assume their comfortable sitting posture, while resting their backs on the car seat, holding the steering wheel and looking directly though the wind shield. Photographs were taken of each subject at three different backrest angles; 110°, 120°, and 130°. Each photo was analyzed using corel-draw software, to calculate the craniovertebral angle, craniohorizontal angle, and sagittal shoulder posture. The result, CHA vs CVA (p=0.001), CVA vs SSP (p=0.045) and SSP vs CHA (p= 0.001) was found to be significant. Similarly, post hoc analysis for multiple comparisons test was applied for 130°. The result, CHA vs CVA (p=0.001), CVA vs SSP (p=0.042) and SSP vs CHA (p=0.001)) was found to be significant.

Does a reclined backrest with less legroom meet the same comfort as a fixed backrest with 80 mm more leg room?

BACKGROUND: In vehicles there is often limited space for seats. This might mean that reclining the back rest reduces the legroom. The second row in a cargo van has this problem and in this limited space an upright seat and a reclined seat with less legroom was developed and tested. OBJECTIVE: The research question of this study is: Does a reclined backrest with less leg room result in the same comfort and/or discomfort as an upright backrest with more leg room? METHODS: Twenty participants are asked to sit 45 minutes in the upright seat with 8 cm more legroom and 45 minutes in the reclined seat. Ten participants started in the upright seat and ten in the reclined. Participants had to complete a comfort and discomfort questionnaire every 15 minutes and a qualitative interview was conducted after experiencing both seats. RESULTS: For comfort no statistically significant differences were found between both seats. For discomfort statistically significant differences were found where discomfort was lower in the reclined seat. Half of the participants preferred the upright and half the reclined seat. The interviews showed that the reclined position was more related to relaxation. CONCLUSIONS: This study indicates that a more reclined back rest results in less discomfort, but that does not lead to a clear preference of participants. The reclined position is associated with relaxing, and this study indicates that for the relaxing state the more reclined seat is preferred. For more active situations the upright posture seems better.

Work-Related Risk Factors Contributing to De-Quervain's Tenosynovitis among Carpenters in Punjab

Purpose: De Quervain's Tenosynovitis is inflammation of extensor pollicis brevis and abductor pollicis longus tendons that run from the side of the wrist to the base of the thumb. To see the frequency of De Quervain’s Tenosynovitis and work related risk factors in carpenters of Punjab, Pakistan&#x0D; Methodology: It was a cross-sectional study. Sample size of the research was 492. Study was conducted at the province Punjab, Pakistan. Inclusion criteria of the study were carpenters of age between twenty to fifty years having experience of more than 2 years. Data was collected to the selected population, through convenient sampling technique. Duration of the study was 8 months. Outcome measures of the study were Finkelstein test, Visual analogue scale and a structured questionnaire. The collected data was analyzed by using SPSS version 25.&#x0D; Findings: Out of 492 participants, De-Quervain's Tenosynovitis was found to be present in 46% of carpenters Punjab. 25.6% of the participants had moderate, while 22.3% had extreme discomfort in lower back. 19.91% reported not to have an enough space for work. 55.69% didn’t take adequate breaks while working. 69.91% reported to have no back rest while working, 63% reported not use any wrist support or brace while working and 35.36% reported not to have any proper training for this work.&#x0D; Conclusion: De Quervain’s Tenosynovitis is prevalent in carpenters of Punjab, Pakistan. Work-related discomfort was found in various regions of body including eyes, neck, shoulders, arms, wrist and hand. Contributing work-related risk factors for De Quervain's Tenosynovitis among carpenters encompass insufficient training, absence of wrist support, and inadequate breaks during work.

Prevalence of De-Quervain’s Tenosynovitis in Tailors of Multan (Punjab)

Purpose: De Quervain's Tenosynovitis is inflammation of extensor pollicis brevis and abductor pollicis longus tendons that run from the side of the wrist to the base of the thumb. To see the frequency of De Quervain’s Tenosynovitis and work related risk factors in tailors of Multan, Pakistan&#x0D; Methodology: It was a cross-sectional study. Sample size of the research was 246. Study was conducted at the city of Pakistan, Multan. Inclusion criteria of the study were tailors of age between twenty to fifty years having experience of more than 3 years. Data was collected to the selected population, through convenient sampling technique. Duration of the study was 8 months. Outcome measures of the study were Finkelstein test, Visual analogue scale and a structured questionnaire. The collected data was analyzed by using SPSS version 25.&#x0D; Findings: Out of 246 participants, 72.3% were males and 27.6% were females. Prevalence of De Quervain's Tenosynovitis was found to be 64% in tailors of Multan through Finkelstein test. 25.6% of the participants had moderate, while 22.3% had extreme discomfort in lower back. 35.3% reported to have mild discomfort in arms. 52.4% had mild to moderate discomfort in wrist or hand. 19.91% reported not to have an enough space for work. 44.30% did not have adjustable chairs. 69.91% reported to have no back rest while sewing, 63% reported unavailability of foot rest and 64.63% had no arm rest while sewing.&#x0D; Recommendations: De Quervain’s Tenosynovitis is prevalent in tailors of Multan, Pakistan. Work-related discomfort was found in various regions of body including eyes, neck, shoulders, arms, wrist and hand. Chairs with no adjustable height, unavailability of arm and foot rest and no back support were associated work related risk factors in tailors.

Kajian Penerapan GMP dan WISE Guna Peningkatan Higienitas Produk dan Produktivitas Pada UKM Amplang Samarinda

Hygiene and product safety were the main issue that need to be assured by food industries, including amplang industries in Samarinda. Furthermore, workers safety was also important for improving small industries’ productivity. This paper aimed to evaluate application of Good Manufacturing Practise (GMP) and Work Improvements in Small Medium Entreprise (WISE) in two small industries that produce amplang. GMP is a system that ensures products are consistently produced and controlled according to set quality standards. (i.e., BPOM standard). WISE is a programme to assist micro, small and medium-sized enterprises improve working conditions and productivity using simple, effective and affordable techniques. The GMP study showed that SME Y had GMP value higher than SME X (i68% and 55%). These two SMEs have used clean water to produce amplang and store raw materials, end products and hazardous materials properly. The drawbacks of these two SMEs are the need to improve recording and documentation as well as make SOPs for product withdrawals from the market. UKM X needs to make SOPs for the cleanliness of the production area and improve product labels. The results of the WISE study of these two SMEs have not provided appropriate PPE for workers and have not promoted occupational health. Procedure for mitigating fire hazard had not developed although fire was one of the risk factors in these two SMEs. Evacuation path had not been provided and even, SME X had not provided the fire extinguishers. Furthermore, ergonomic work station obliged to design especially for workers who sit cross-legged, designing cross-legged chair with back rest.

"Design and Development of Infant Bed Using Bamboo and Bamboo Charcoal Fabric"

The aim to produce infant bed by using bamboo and bamboo charcoal fabrics. This baby bed will be highly Anti-Microbial smooth, soft, herbal smell and back rest material will be having the cooling property and fragrance with more comfortless for the babies. Baby bedding is also known as bed cloths, is the material laid above matters for warmth, protection of matters and it is washable and comfort for sleeping. It improve more absorbency and implement natural printing and antimicrobial finish. The treated fabric will be analysed by comfort properties like air permeability and wicking property. The finished fabric is tested, further to develop the end product and the result shows that end product is more comfortable for the usage

The Impact of Chair Design on Trunk Sway Parameters During Computer-Based Tasks Over a Prolonged Bout of Sitting

Prolonged sedentary behavior has increased due to computer use for work and leisure activities. Prolonged bouts of sitting have been associated with health risks such as low back pain. Prior studies have suggested that chair design characteristics, such as the presence of arm or back rests, are associated with sitting posture, movement patterns, and low back pain. The purpose of this within-subjects study was to examine the effects of armrest adjustments and tilt mechanisms on user-chair interfacial pressure variables and micromotion while performing computer tasks. Preliminary findings indicate that proper armrest adjustments increased average displacement and in-chair movements (p &lt; 0.04) which may reduce low back pain while sitting. Further research is needed to understand the temporality of these relationships over long bouts of sitting.

Association of Mid-sagittal Anteroposterior Diameter of Lumbar Canal in Patients with Low Back Pain using MRI: A Cross-sectional Study from West Bengal, India

Introduction: Lumbar spinal canal stenosis is the progressive narrowing of spinal canal that causes compression of nerve roots before their exit. The presenting symptoms of spinal canal stenosis includes bilateral lower extremity pain, altered sensation in both legs and poorly localised weakness and generally associated with low back pain. Determination of normal diameter and its variation with development of low back pain could prove useful in determining the aetiology and outcome of congenital or acquired causes of stenosis like spondylolisthesis, Paget’s disease, fluorosis, etc. Aim: To measure and compare the mid-sagittal anteroposterior diameter of lumbar canal in symptomatic cases with low back pain and asymptomatic subjects using Magnetic Resonance Imaging (MRI). Materials and Methods: The present study was a hospitalbased cross-sectional, observational study involving Out Patient Department (OPD) patients of Bangur Institute of Neurosciences, Kolkata, West Bengal, India, was undertaken from May 2012 to July 2012. The study participants were selected by systematic random sampling. Total number of 102 cases were investigated in this study. Out of these, 52 cases were symptomatic patients of low back pain and rest 50 cases were asymptomatic. MRI was done to estimate the mid-sagittal anteroposterior diameter at different levels of lumbar canal. Unpaired t-test was used as test of significance using Statistical Package for the Social Sciences (SPSS) version 19.0. A p-value &lt;0.05 was considered as statistically significant. Results: In this study, in the asymptomatic group, the anteroposterior diameter at the intervertebral disc level -between L1-L2-18.364±1.4351 mm, L2-L3-17.470±1.3298 mm, L3- L4-16.670±1.6042 mm, L4-L5-15.200±1.8906 mm, L5-S1- 14.196±2.1092 mm. Mean diameter of central lumbar vertebral was found to be lower in symptomatic cases with low back pain at different vertebral levels and the difference was found to be statistically significant between symptomatic and asymptomatic subjects. It was found that age of presentation did not show any statistical significance with the presence of low back pain. Conclusion: The lumbar vertebral canal diameter was found to be significantly lower in subjects with low back pain than subjects having no complaints.

Monitoring of Occupant States in Autonomous Vehicles Using Capacitance-Sensing Imaging

The increasing popularity of autonomous vehicles has heightened the need to deploy robust systems that guarantee the safety and comfort of vehicle occupants. Such systems are required to monitor the presence and posture of occupants in real-time. This paper proposes a novel system that combines capacitive sensing with machine learning to achieve real-time occupant detection and posture recognition. The main constituent of the system is a capacitance-sensing mat that spans both the seat base (SB) and the backrest (BR) of a typical vehicle seat. The mat is connected to a sensing circuitry that continuously monitors variations in capacitance inside the mat to generate grayscale capacitance-sensing images (CSIs). The CSIs are real-time pictorial representations of the variations in capacitance caused within the mat due to changes in the position and the posture of occupants. The real-time CSIs then serve as inputs to a k-nearest-neighbors-based (k-NN) classifier that is capable of identifying different posture classes. The classifier is pre-trained using a previously acquired database consisting of a collection of CSIs belonging to known posture classes. Subsequently, the performance of the classifier is validated, and the system is deployed for real-time occupant detection and posture recognition.

Analysis of the Thermal Comfort and Energy Performance of a Thermal Chair for Open Plan Office

The aim of this work is to analyse the thermal comfort and energy performance of a thermal heating chair for open plan office using field experiments, thermal comfort survey and energy simulations. A comprehensive review on the development of thermal chairs was carried out to highlight the present research gaps. The study developed a thermal chair prototype with controllable heating pads, incorporated into the back of the seat and back rest fabric. The field test was carried out in an office building in the UK during the winter. The study showed that the users set the thermal chair temperature between 29-45 °C. The field survey results of the thermal satisfaction survey showed that 19 out of 44 participants felt satisfied before using the device. While after using the thermal chair, the number of satisfied respondents increased to 34. The work also utilised Building Energy Simulation to further assess the thermal comfort and energy performance of the thermal chair. Three cases were simulated: non heated office chair with the zone thermostat maintained at 22 °C, non heated office chair with the zone thermostat at 16-20 °C and thermal chair with the zone thermostat at 16-20 °C.

Investigating the influence of seating area design and enclosure on the seat-dip effect using scale model measurements

The low-frequency attenuation in the direct sound due to the concert hall seats, i.e., the seat-dip effect, is studied with the help of a scale model comprising an adjustable seating area and an enclosed box. More particularly, different seat underpass sizes and floor raking angles are studied, and the results are averaged over multiple source positions. With the measurements on the seating area only, the main seat-dip frequency is found to depend on the seat back rest height, and on the degree of obstruction of the seat underpass. The attenuation bandwidth is found to depend mainly on the floor raking. The differences become less clear when seating area is enclosed by concert hall walls and ceiling because the early reflections from the concert hall geometry compensate the low-frequency attenuation in the direct sound. In addition, the low frequencies below the main seat-dip frequency are found to increase in the presence of unobstructed seat underpasses, and such seats are recommended for the maximal bass response in a concert hall.

Revolving Stool with Back Rest an Ergonomic Intervention for Women in Jaggery Ball Making Agro Based Enterprise

Revolving Stool with Back Rest an Ergonomic Intervention for Women in Jaggery Ball Making Agro Based Enterprise

Risk factors of occupation related back pain and neck pain among patients attending tertiary care hospital, Ahmedabad, India.

SummaryIntroductionNeck/back pain is one of the common health problems associated with significant impact on health resulting in sickness absenteeism. Neck/back pain is one of important causes of disability adjusted life years worldwide. The objectives of study were: To identify various occupations related risk factors and their possible role in occurrence of back pain/neck pain and visual analogue scale(VAS) assessment of their perceived pain.MethodsThe study was conducted at one of the tertiary care hospital at Ahmedabad city, India. All patients above age of 18 years attending physiotherapy department for treatment of back pain/neck pain and gave consent were taken as study participants. Information about certain body postures in their lifestyle or at workplace which can have effects on back pain/neck pain were asked. VAS for perceived pain was anchored by “no pain” (score 0) and “pain as bad as it could be” (score 100). Data were entered in MS Excel and analyzed by frequency, contingency coefficient and Goodman and Kruskal’s Gamma test.Results and ConclusionTotal of 512 participants were included in study, among which(10.3%)and 392 (76.6%) participants had neck pain and back pain alone, respectively, while 67 (13.1%) participants had both neck and back pain. Age, marital status, socioeconomic class, body mass index and type of occupation revealed statistically significant association with severity of pain. Among participants with prolonged computer usage, back rest fitting to natural back curve and adjustable height of chair were significant factors for occurrence of neck pain. Various body postures like prolonged sitting/ standing, frequent bending at waist/knee, pulling/pushing heavy objects, frequent weight lifting > 10 kg and repetitive movements of back/neck revealed as statistically significant risk factors for back/neck pain.

Evaluation of Whole-Body Vibration (WBV) of Dozer Operators Based on Job Cycle

Dozer operators are frequently exposed to high levels of occupational vibration. So far, no study reported component wise evaluation of dozer cycle of operation. In the present study, WBV data were collected by placing the trial accelerometer at operator’s seat-surface and at seat-back. Frequency-weighted root mean square (RMS), vibration dose value (VDV) and crest factor were collected for each dozer for two phases’ forward motion and return motion. All the dozers under study were found to be in severe zone with respect to measured RMS, during forward motion and return motion, irrespective of type of measurements (i.e., seat-surface and seat-back). As per VDV, out of eight dozers three dozers were found to be in caution zone during forward motion and three in return motion. According to EU Directive 2002 (as per RMS), all the dozers under study have reported exposure action value above 0.5 m/s2. Further, out of eight dozers, four dozers have shown exposure limit value above 1.15 m/s2 for seat-surface measurements and three dozers for seat-back measurements. Vibration mitigation strategies should be adapted not just based on intensity of vibration but also with respect to dominant axis of vibration. Considering the severe health risk due to the translational vibration (i.e., in x-direction), the vibration risk in the forward x-direction can be reduced by using seat belt; similarly in rear x-direction it can be attenuated by placing lumber-assisted back rest.

Sewing shirts with injured fingers and tears: exploring the experience of female garment workers health problems in Bangladesh

BackgroundThe ready-made garment industry in Bangladesh not only contributes to the nation’s economic development, but has created income opportunities for women, benefiting their whole family. However, these benefits come at considerable cost to the women. This research examines how the work environment and gendered family role in this conservative society affect the health of the female industrial workers.MethodsA qualitative study employed in-depth interviews (n-20) and focus group discussions with female garment workers (n-4) in two cities of Dhaka district. Further, key informant interviews (n = 4) with factory doctors, along with eight workplace observations were conducted to explore the lived experience of female workers’ health issues. Interview transcripts were coded in Atlas-ti, 5.2. The data were analysed using thematic analysis approach. The themes are illustrated with case narratives.ResultsThe female workers reported that their work has led to back and joint pain, continuous headache, eye pain and difficulty in breathing associated with inhaling fabric dust. Inadequate lighting, constantly sitting in one position without back rest and continuous noise from hundreds of machines makes them feel permanently tired. Further, the female workers reported that working in the factory and meeting the expectations of the families at home has doubled their workload. The doctors indicated that the physical work environment, their low job status and the nature of the job affect the health of female workers.ConclusionThis study found that female workers in the ready-made garment industry face a high risk of health problems. Both government and non-government organizations need to be better involved in designing interventions targeting these women, to protect them from such health risks. In addition, recognition by the whole society of the important role the women play in the economy is needed, so that support by both family and society can be improved.

Whole-body vibration exposure among tractor drivers

A total of 450 experimental runs were performed at three speed levels, i.e., 5.6, 7.4 and 9.3 m/s as well as three sitting postures, i.e., lean forwards (LF), vertical erect with no back rest (VE-NB) and lean with back rest (L-WB). Majority of vibration levels were exceeding ISO 2631-1 1997 exposure action value. Vibration transmission was highest for posture LF followed by VE-NB and L-WB at 7.4 and 9.3 m/s, whereas VE-NB at 5.6 m/s followed by LF and L-WB. Subjective comfort responses are significant at 5% level for neck, shoulder and lower back with mean daily exposure levels. 1/3rd octave band showed dominant frequencies of 3.15 and 4 Hz that could affect health and safety of drivers due to existing natural frequencies of various body parts. It is recommended that tractors need more design efforts to damp vibration transmission along z axis so as to enhance ride comfort level.

Analysis of Ergonomic Office Chair for Information Technology Work Environment - A Case Study in Indian Context

Information technology industry is one of the fastest growing industries in India. The normal working hours as per Factories Act 1948 is not more than 9 hours per day. In the IT industry an individual spends most of the working time in front of computer system. Reports suggest that continuous sitting in the same postures has been the reason for many musculoskeletal disorders (MSDs) and repetitive strain injuries (RSIs) amongst the employees in this sector. Ergonomic design of the work station influences the working capability & health condition of the employees. The main objective of this paper is to propose an ergonomically designed office chair. The work focuses on the design and analysis of Office chair which is ergonomically structured according to Indian Anthropometric data. The three dimensional model of the ergonomic office chair was developed and the structural analysis of the chair was carried out using simulations tool under quasi-static loading and dynamic loading conditions. The static structural deformation and stress was observed to be within the limits having a Factor of safety (FOS) of 15. The cyclic loading was considered for fully reversed condition with load limits of +1200 N to -1200 N in sitting position. Back rest was considered as flexural load of +200N to -200N fully reversed. It was observed that the fatigue life of the designed chair is 1x106 and hence the design is considered to be safe for cyclic loading condition.

Development of automatic weaving technique of tapered circular tubular woven graft: a preliminary validation

The tapered circular tubular (TCT) woven fabric has been applied successfully as the components in vascular prostheses. The application of tapered tubular woven fabric based on the existing weaving technology requires the densification of a large end to ensure porosity uniformity through the tapered tubule. Although the previously proposed equal-cover-factor (ECF) design technique overcame some disadvantages of the conventional densification methods, such as the protruding portions of the dropped yarns as well as the change of both fabric porosity and tensile strength, the off-loom weft density significantly deviates from the on-loom value. On the basis of ECF design technique and the basic shed geometry, this study rebuilt the relative motion relationship among the front rest, the cloth fell, the back rest, and the take-up length, and modified the weft density on loom to achieve continuous weaving process of TCT fabric as well as the uniform porosity. And then, a computerized weaving procedure based on the rebuilt relationship was developed to automatically weave TCT fabric with different weaves on the customized shuttle loom. As a result, the uniform porosity of those samples validated the proposed weaving techniques.