Chair Seat Research Articles

Physiological Motion Axis for the Seat of a Dynamic Office Chair.

ObjectiveThe aim of this study was to determine and verify the optimal location of the motion axis (MA) for the seat of a dynamic office chair.BackgroundA dynamic seat that supports pelvic motion may improve physical well-being and decrease the risk of sitting-associated disorders. However, office work requires an undisturbed view on the work task, which means a stable position of the upper trunk and head. Current dynamic office chairs do not fulfill this need. Consequently, a dynamic seat was adapted to the physiological kinematics of the human spine.MethodThree-dimensional motion tracking in free sitting helped determine the physiological MA of the spine in the frontal plane. Three dynamic seats with physiological, lower, and higher MA were compared in stable upper body posture (thorax inclination) and seat support of pelvic motion (dynamic fitting accuracy). Spinal kinematics during sitting and walking were compared.ResultsThe physiological MA was at the level of the 11th thoracic vertebra, causing minimal thorax inclination and high dynamic fitting accuracy. Spinal motion in active sitting and walking was similar.ConclusionThe physiological MA of the seat allows considerable lateral flexion of the spine similar to walking with a stable upper body posture and a high seat support of pelvic motion.ApplicationThe physiological MA enables lateral flexion of the spine, similar to walking, without affecting stable upper body posture, thus allowing active sitting while focusing on work.

A novel protocol to test age-related decreases in sit-to-stand movement abilities in healthy subjects

The development of simple approaches to quantitatively estimate functional motor performance in a wide range of ages is crucial for early detection of locomotive syndrome (LS). Sit-to-stand (STS) movements from a chair are important in activities of daily living (ADL), although such tasks are the most mechanically demanding among all ADL. Here, we propose a novel test to score STS abilities to estimate individual functional motor status and investigated age-related changes in STS scores as a method to evaluate reduction in performance. A total of 606 healthy subjects (average age, 48.4 years; age range, 20-87 years) without neuromusculoskeletal disorders participated in the study. We designed a test to score STS abilities, based on STS determinant variables, including seat height, foot positioning, and both-leg- or one-leg-standing tasks. STS scores ranged from 0 to 14 points, depending on the difficulty or mechanical demands of the STS task. We evaluated the STS score of the subjects divided into seven 10-year age groups. A significant and negative correlation was observed between STS scores and subject age (men: r=-0.65, P<0.001; women: r=-0.62, P<0.001). The proportion of subjects able to stand on one leg from a chair seat height of 100% of knee height decreased with age from 100% for both men and women aged 20-29 years to 0.0% and 7.1% for men and women aged 80-87 years, respectively. A large variation in STS scores was observed for subjects aged >60 years. There was a negative linear correlation between mean STS score per age group and mean age (men: R(2)=0.93, slope=-0.10, intercept=16.63 points; women: R(2)=0.92, slope=-0.08, intercept=14.76 points). The ability to perform STS was negatively correlated with age among healthy subjects aged 20-87 years. For subjects aged >60 years, STS abilities decreased, but within-group variability increased. This test was useful to identify the deterioration of functional motor performance and prevent early LS.

Ergonomic Evaluation of Console Chairs for a Weapon Locating Radar

The present study is intended to evaluate the usability of a console chair for a weapon locating radar by comparing with different kinds of chair design. Console chairs need to be ergonomically designed to reduce physical workload of operators and improve mission capability; few studies have been reported which systematically evaluate usability of military console chairs. Ergonomic design of a console chair, a bus seat, and an office chair was evaluated in terms of headrest, seatback, seatpan, armrest, and controller on a 7-point scale. Ten males in their 20s and 30s were recruited considering the demographic characteristics of console operators. The satisfaction scores of the console chair for headrest, seatback, and seatpan were significantly higher than those of the bus seat (mean difference; MD = 0.9) and office chair ( MD = 1.3). Meanwhile, the satisfaction scores of the console chair for armrest and controller were significantly lower than those of the office chair ( MD = -1.4) and bus seat ( MD = -2.2). The armrest and controller of the console chair needs ergonomic improvements for better comfort. The evaluation results of the console chair would be of use for ergonomic console chair design.

A Study on the VDT Workstations Usage for Office Workers

Objective and Background: Due to increase in Musculoskeletal Disorders (MSDs) relating to computer use, a number of ergonomics recommendations have been proposed in order to tackle this problem. However, some of these recommendations have been conflicting. Method: This study was to survey the VDT (Visual Display Terminal) use of office workers. The subjects were 452 workers at 13 places of business and the data were collected by self-administered questionnaire. Results: As a result, prevalence of self-reported MSDs of all VDT workers was 90.2% and shoulder took up 57.0% and neck 38.3% by symptom part of body. The population of computer use of more than 6h/day was 84.5%, and 33.8% also reported using the VDT 2~3h/day without the rest time. Desktop computer users were 95.6%, and a 17-inch monitor accounted for 42.0% among the desktop users. As a result of satisfaction survey on overall computer work, 21.1% of the total respondents said satisfied, desk complaint was about 24.6%, and chair complaint was 33.4%. Despite the importance of computer environment, satisfaction was from fair to uncomfortable. Conclusion and Application: In conclusion, office workers are prone to the MSDs due to their work environment. Additionally, this study found that task was a significant effect for the majority of dependent variables, and therefore, the improvement of computer workstations work environment is urgent, and the improvement of desk height adjustment, chair seat size (length, width), backrest condition, location of keyboard (mouse) and arm rest is required.

플라스틱 보조재를 갖는 영화관 의자 시트의 진동전달 특성

In the previous paper, we have reported on the development of foaming sponge seat with the auxiliary spring member and suggested new possibility of the special seat with the auxiliary plastic member for movie theater chair. In this study, we have examined the major design parameters needed in the development of a foaming sponge seat in which the mesh type plastic member are inserted to improve the vibration transfer effect of a chair seat. Through analyzing several prototypes by applying experimentation as well as the experimental modal analysis method, it was confirmed that the effect of vibration transfer can be improved through the use of a mesh type plastic member and applied to the design of practical chair seat.

Dilemmas and Delusions Bernard Shaw and Health

Beguiling a Victorian public obsessed with the pursuit of fitness, the International Health Exhibition opened in South Kensington in May 1884. Its expressed intent, to educate the public on a broad range of wellness topics, was greatly overshadowed by its dazzling display of proprietary medical commodities, salutary appliances, and faddish cures. While there were legitimate exhibits that dealt sincerely with issues of sanitation, hygiene, food, drink, and even child care, the event illuminated the extent to which personal and systemic therapeutic remedy and indeed health itself had become a lucrative industry. Less than three weeks before he joined the Fabian Society, the fledgling novelist Bernard Shaw visited one of the exhibition’s prominent attractions, Francis Galton’s Anthropometric Laboratory, to be quantified and measured. Chart 3655, created on 16 August 1884, contains the following collected data:

Intelligent Chair Sensor

In order to develop an intelligent system capable of posture classification and correction the authors developed a chair prototype equipped with air bladders in the chair's seat pad and backrest, which can in turn detect the user posture based on the pressure inside said bladders and change their conformation by inflation or deflation. Pressure maps for eleven standardized postures were gathered in order to automatically detect the user's posture, with resource to neural networks classifiers. First the authors tried to find the best parameters for the neural network classification of our data, obtaining an overall classification of around 80% for eleven standardized postures. Those neural networks were then exported to a mobile application to achieve a real-time classification of the standardized postures. Results showed a real-time classification of 93.4% for eight standardized postures, even for users that experimented for the first-time our intelligent chair. Using the same mobile application they devised and implemented two correction algorithms, acting due to conformation change of the bladders in the chair's seat when a poor seating posture is detected for certain periods of time.

OVOS DE Enterobius vermicularis EM SALAS DE ESPERA E BANHEIROS DE UNIDADES BÁSICAS DE SAÚDE (UBS) DO MUNICÍPIO DE NOVA SERRANA-MG: CONTRIBUIÇÕES PARA O CONTROLE

In this study, the presence of intestinal helminth eggs was evaluated in samples collected from five Basic Health Units (BHU) using the Graham’s technique (1941), in the city of Nova Serrana (MG). In the total of 8 collections, 40 chair seats and 40 attendance tables were sampled in the reception and, on the toilet doors, 64 internal door handles and 64 external door handles. All the slides were analyzed by light optic microscopy with 10X and 40X magnifications in the Microscopy Laboratory FUNEDI / UEMG and re-examined in the Medical Malacology and Helminthology Laboratoryof the Research Center René Rachou (FIOCRUZ-Minas). The results indicated the presence of Enterobius vermicularis eggs, mostly viable, with infection rates calculated by simple proportion. In the reception the contamination percentage was 25.0% on attendance tables and 17.9% on chair seats; in the toilets, 35.7% of internal door handles and 21.4% of external door handles presented eggs. There were no eggs and larvae of other helminths, only pollen grains, vegetable fibers and fungal spores. Lectures were held with employees of BHU to present the results and discuss measures that can be taken to prevent contamination of people who attend and work at these sites. The data showed that the BHU toilets and waiting rooms can be important vehicles of dispersal and contamination with enteroparasites. Health education measures are important and must be undertaken among the health center users and employees as they lead people to understand the problem, change their habits and discuss solutions to prevent and control this and other diseases.

보조재를 갖는 영화관 의자용 발포스펀지 시트의 진동전달 특성

This paper describes the suggestion of the special seat with the auxiliary plastic member for movie theater chair. In the previous paper, we have reported on the development of foaming sponge seat with the auxiliary spring member. And we have confirmed that it was more effective on vibration transfer than the chair seat of foaming sponge only. In this study, we have examined the major design parameters needed in the development of a foaming sponge seat in which the mesh type plastic member are inserted to improve the vibration transfer effect of a chair seat. By applying experimentation to the prototype as well as the experimental modal analysis method, we made sure that the effect of the vibration transfer could be improved through the use of a mesh type plastic member as similar as the auxiliary spring member.

The influence of chair seat height on the performance of community-dwelling older adults’ 30-second chair stand test

Although chair seat height affects the performance of sit-to-stand movement, no previous study has examined the influence of chair seat height on the 30-second chair stand test (CST). Fifty-five community-dwelling older adults (age 70.0±6.3years) performed the test from the standard height of 43cm and then from five randomly ordered seat heights from 80 to 120% of each participant's lower leg length. Chair seat height significantly influences the performance of community-dwelling older adults' 30-s CST (F=57.50, p<0.001). The mean score for standard conditions was significantly lower from those at 120, 110, and 100% conditions (p<0.05). No significant difference was observed between the standard and 80% conditions (p>0.95) and between the standard and 90% conditions (p=0.353). When comparing the scores between the randomly ordered chair seat heights, all comparisons were significantly different (p<0.001) except for the difference between the 120 and 110% conditions (p=0.104). Chair seat height's relation to the lower leg length should be considered when interpreting 30-s CST scores. Additionally, it is necessary to optimize the chair seat height when using the 30-s CST as an outcome measure for exercise intervention or to screen for people with weaker lower extremities.

A Functional PCA Model for the Study of Time Series of Pressure Maps

Principal component analysis and functional regression are combined in a model to analyze a time series of pressure maps. The model is tested measuring the pressures over a chair seat while a subject performs a combination of simple movements. A sampling rate of 3 Hz is adequate for applying the model in sitting postures. The model is able to detect patterns of movement over time, although more variables are necessary if the movements produce similar pressure distributions.

The interrelationship of the thorax and pelvis under varying task constraints

The purpose of this study was to investigate the interrelationship between the thorax and pelvis during coupled movement patterns. Fifty-seven participants were assessed using an infrared motion analysis system to track trunk movement during maximal pelvis and thorax rotations over four trunk inclinations and two pelvic constraint conditions. A repeated-measures multivariate analysis of variance investigated the effects of forward trunk inclination and pelvic constraint on thorax and pelvic rotation. Forward trunk inclination from neutral to 45° resulted in a 46% (p < 0.001) decrease in axial pelvic rotation and a 15% (p < 0.001) decrease in axial thorax rotation with an unconstrained pelvis. A constrained pelvis resulted in a 15% (p < 0.001) decrease in axial thorax rotation. An externally constrained pelvis allowed the thorax to achieve an average of 18° (SD = 2°) greater rotational range of motion across all angles. This study reinforced the importance of allowing the pelvis to rotate during whole body axial rotation tasks. Practitioner Summary: Results indicated that maximum axial trunk rotation is best achieved in a neutral posture, when the pelvis is allowed to contribute and flexion at the hips should be minimised. For example, if a recumbent task requires rotation of the torso, then the chair seat should be allowed to swivel.

영화관 의자용 음향진동자극 시트의 개발

The global movie industry is continuing rapid growth through application of the latest technology. 3D movies are being produced and shown for a more effective viewing experience. Special chairs for audiences are being experimentally manufactured and installed for the greatest viewing effect. This special chair has a structure that applies vibrating stimuli to specific parts of the body by attaching vibration transducers to theater chairs and synchronizing it with each scene of the movie. In a previous study, it has been confirmed that we can analyze the vibration transfer characteristics of sponge seats through the application of an experimental modal analysis method and obtain design variables easily. In this paper, we examine the major design parameters needed in the development of a foaming sponge seat in which auxiliary springs are inserted to improve the vibration transfer effect of a chair seat. Through analyzing several prototypes by applying experimentation as well as the experimental modal analysis method, it was confirmed that the effect of vibration transfer can be improved through the use of an auxiliary member.

Effect of Therapy Ball Seating on Learning and Sitting Discomforts among Saudi Female Students

The aim of the study was to evaluate the effect of therapy ball seating as an alternative for typical chair seating in a classroom. We evaluated the effect of ball seating on the student's sitting discomfort and academic performance using Cornell Musculoskeletal Discomfort Questionnaire and problem-based learning scales, respectively. A sample of convenience was taken. Data was collected and analyzed using t-test. Subjects experienced a major discomfort at neck and a minor discomfort at knee joint. Results showed that there was a significant improvement (P ≤ 0.05) in sitting discomfort and student's performance when seated on therapy balls compared to typical classroom chairs. This study provides evidence for the effectiveness of therapy balls as a classroom seating for students who exhibit sitting discomfort and problem-based learning.

The anthropometric match between high school learners of the Cape Metropole area, Western Cape, South Africa and their computer workstation at school

Study designDescriptive study. ObjectiveThe objective of this study was to present anthropometric data from high school students in Cape Metropole area, Western Cape, South Africa that are relevant for chair design and whether the dimensions of computer laboratory chairs currently used in high schools match linear anthropometrics of high-school students. Summary of Background Data. Learner–chair mismatch is proposed as a cause of poor postural alignment and spinal pain in adolescents. A learner–chair mismatch is defined as the incompatibility between the dimensions of a chair and the anthropometric dimensions of the learner. Currently, there is no published research to ascertain whether the furniture dimensions in school computer laboratories match the anthropometrics of the students. This may contribute to the high prevalence of adolescent spinal pain. MethodsThe sample consisted of 689 learners, 13–18 years old. The following body dimensions were measured: stature, popliteal height, buttock-to-popliteal length and hip width. These measurements were matched with the corresponding chair seat dimensions: height, depth and width. Popliteal and seat height mismatch was defined when the seat height is either >95% or <88% of the popliteal height. Buttock–popliteal length and seat depth mismatch was defined when the seat depth is either >95% or <80% of the buttock–popliteal length. Seat width mismatch is defined where the seat width should be at least 10% and at the most 30% larger than hip width. ResultsAn 89% of learners did not match the seat. Five percent of learners matched the chair depth, the majority was found to be too big. In contrast, 65% of the learners matched the chair width dimension. ConclusionsA substantial mismatch was found. The school chairs failed standard ergonomics recommendations for the design of furniture to fit the user. This study supports the conclusion that there is no one-size-fits-all solution. There is an urgent need for chairs that are of different sizes or that are adjustable.

Effects of Chair Seat Heights on Joint Moment of Lower Extremity and Muscle Activation during Sit-To-Stand Movement

Effects of Chair Seat Heights on Joint Moment of Lower Extremity and Muscle Activation during Sit-To-Stand Movement

The Importance of Work Environment Facilities

A healthful work environment brings safety to employees’ physical and mental capabilities in performing their daily routine. In order to reach the healthful work environment, providing the healthful facilities must be taking into account. The examples of facilities are chair seating and lighting. A proper chair seating and sufficient lighting play important role in ensuring employees’ welfare are protected as well their work performance goes up. The ignorance of these important healthful work environments will lead to work stress. Office ergonomics can be provided and used in any type of workplaces like permanent office, home office, virtual office, or even mobile office which the employees working at construction sites for temporary. Employees, who are spending time in office, sitting on chair, interacting with computer and switching on lamp from 8:00 a.m. till 5:00 p.m. is suggested to be provided ergonomics facilities like adjustable chair seating and appropriate lighting level. Keywords: Ergonomics, Chair Seating, Lighting, Work Stress

Influence of Therapy Ball Seats on Attentional Ability in Children with Attention Deficit/Hyperactivity Disorder

[Purpose] The aim of this study was to investigate the P300 in electroencephalography (EEG) and the reaction time in children with attention deficit hyperactivity disorder (ADHD) during an auditory oddball task when sitting on a classroom chair or therapy ball. [Subjects] Fifteen ADHD children with a mean age of 8.6 ± 2.1 years and 14 healthy children with a mean age of 8.7 ± 2.0 years were used as subjects in this study. [Methods] All subjects were asked to sit on a chair or therapy ball and perform simultaneously the auditory oddball task. A portable 40-channel EEG system and a sound operating system were employed to record and analyze the EEG and button reaction time signals. [Results] When seated on the chair, the ADHD group had a significantly longer reaction time than the control group. ADHD children seated on a therapy ball showed a significant improvement in reaction time compared with when seated on the chair. In the parietal lobe, the ADHD group had a significantly delayed P300 latency during chair seating compared with the control group. The ADHD group showed a significantly shorter P300 latency time when seated on a therapy ball. [Conclusion] The therapy ball has a significant advantage for enhancing the attentional ability in children with ADHD.

The Effect of a New Gelatinous Elastomers Cushion on Reducing Pressure and Temperature

Objective: The aim of this study was to analyze the effectiveness of a new air cell cushion (Elaston cushion) made of gelatinous elastomers, a newly developed material with a novel structure on reducing pressure and temperature. Methods: We compared the pressure and thermal responses of the Elastone cushion to three other available cushions (foam, gel-filled and air-filled villous) and four regular wooden or spongy chair seats. The skin temperature at the buttocks was also continuously measured for eight-hours sitting. Results: The Elastone cushion reduced the peak pressure (39.7 mmHg) compared with foam (60.0 mmHg), gel-filled (60.3 mmHg) and air-filled cushions (69.3 mmHg), as well as with the wooden and spongy chair seats (84.7 to 200 mmHg). The peak temperature with the Elastone cushion was 29℃. Higher temperatures were found with the gel-filled (33.8℃), air-filled (35℃) and foam (35.9℃) cushions, as well as with the wooden and spongy chair seats (34.5 to 35.9℃). Conclusion: Our findings clearly showed that the Elastone cushion was more advantageous in relieving pressure and minimizing temperature.

The influence of the flexibility of the chair seat on pressure peak and distribution of the contact area in individuals with cerebral palsy during the execution of a task

This study aimed to determine the influence of flexibility of the chair seat surface on the pressure peak and on the contact area during the execution of a task of handling an object on the seated position by individuals with spastic cerebral palsy. Ten individuals of both genders with diagnosis of spastic cerebral palsy, who had some control to voluntarily move the body and the upper limbs, participated in this study. Quantification of data was carried out in two experimental situations: (1) execution of a task of fitting with upper limbs, and with the individual placed on an adapted canvas seat; (2) execution of a task of fitting with the participant positioned on an adapted wooden seat. Data obtained were submitted to a non-parametric and descriptive statistical analysis using the Wilcoxon test. Results indicated that the use of canvas seat increased the contact area and decreased the pressure peak and the medio-lateral displacement of centre pressure on the seated posture.