Evaluation of a prototype multi-posture office chair

Office chairs have often been designed to promote a single ‘correct’ rather rigid and upright posture, yet it is acknowledged that allowing changes in posture is good ergonomics practice. The present study investigated office worker's preferences for a standard shaped typist's chair (ST) and a prototype multi-posture (PMP) office chair designed to allow its users a variety of sitting positions. Forty-two (22 male and 20 female) telesales personnel (12), clerical staff (12) and researchers (18) used ST or PMP in their workplace for the first week of a 2-week study (with an even number in each work area). The PMP chair was introduced to participants with a brief lecture on how to use it and with an information booklet. Following this, each participant completed a chair comfort questionnaire. In the second week, participants swapped chairs and again completed the chair comfort questionnaire. At the end of the second week participants were also asked to complete a separate questionnaire about the usability of the information booklet that accompanied the PMP chair. Statistically significant differences in subject's rating of the two chairs were observed in 7 out of 19 questions. On a 100 mm scale, the ST chair was rated as having a greater mean overall acceptability, desirability and suitability for body build than the PMP chair. Participants also claimed to achieve better posture in the ST chair, that they tipped forward less and were more satisfied with its width. Although the participants generally preferred the ST chair, the PMP chair received more favourable ratings among the researchers who were quite mobile in their work, and in whom there was a trend for less neck, shoulder and upper back discomfort. More participants reported an overall preference for the PMP chair. The findings suggest that a more aesthetically acceptable PMP chair should be developed, peoples' reasons for preferring a more traditionally designed chair should be explored, and that the effect of postural stability education on personal preconceptions should be examined to obtain an optimal combination of healthy sitting habits, comfort and aesthetic qualities in an office chair.     

Specific flexion-related low back pain and sitting: comparison of seated discomfort on two different chairs

No study has examined the effectiveness of prescribing seating modifications according to the individual clinical presentation of people with low back pain (LBP). A dynamic, forward-inclined chair (‘Back App’) can reduce seated paraspinal muscle activation among pain-free participants. This study examined 21 participants whose LBP was specifically aggravated by prolonged sitting and was eased by standing. Low back discomfort (LBD) and overall body discomfort (OBD) were assessed every 15 min while participants sat for 1 h on both the dynamic, forward-inclined chair and a standard office chair. LBD increased significantly more (p = 0.005) on the standard office chair, with no significant difference (p = 0.178) in OBD between the chairs. The results demonstrate that, in a specific flexion-related subgroup of people with LBP, increased LBD during sitting can be minimised through modifying chair design. Mechanisms that minimise seated discomfort may be of relevance in LBP management, as part of a biopsychosocial management plan.

Practitioner summary: This study examined low back discomfort (LBD) during a typing task among people with low back pain (LBP). Sitting on a dynamic, forward-inclined chair resulted in less seated LBD than sitting on a standard office chair. Further research is required to examine the long-term effectiveness of ergonomics interventions in LBP.     

Evaluation of a prototype multi-posture office chair

Office chairs have often been designed to promote a single 'correct' rather rigid and upright posture, yet it is acknowledged that allowing changes in posture is good ergonomics practice. The present study investigated office worker's preferences for a standard shaped typist's chair (ST) and a prototype multi-posture (PMP) office chair designed to allow its users a variety of sitting positions. Forty-two (22 male and 20 female) telesales personnel (12), clerical staff (12) and researchers (18) used ST or PMP in their workplace for the first week of a 2-week study (with an even number in each work area). The PMP chair was introduced to participants with a brief lecture on how to use it and with an information booklet. Following this, each participant completed a chair comfort questionnaire. In the second week, participants swapped chairs and again completed the chair comfort questionnaire. At the end of the second week participants were also asked to complete a separate questionnaire about the usability of the information booklet that accompanied the PMP chair. Statistically significant differences in subject's rating of the two chairs were observed in 7 out of 19 questions. On a 100 mm scale, the ST chair was rated as having a greater mean overall acceptability, desirability and suitability for body build than the PMP chair. Participants also claimed to achieve better posture in the ST chair, that they tipped forward less and were more satisfied with its width. Although the participants generally preferred the ST chair, the PMP chair received more favourable ratings among the researchers who were quite mobile in their work, and in whom there was a trend for less neck, shoulder and upper back discomfort. More participants reported an overall preference for the PMP chair. The findings suggest that a more aesthetically acceptable PMP chair should be developed, peoples' reasons for preferring a more traditionally designed chair should be explored, and that the effect of postural stability education on personal preconceptions should be examined to obtain an optimal combination of healthy sitting habits, comfort and aesthetic qualities in an office chair.     

Ontology driven interactive healthcare with wearable sensors

Ubiquitous healthcare is the service that offers health-related information and contents to users without any limitations of time and space. Especially, to offer customized services to users, the technology of acquiring context information of users in real time is the most important consideration. In this paper, we researched wearable sensors. We proposed the ontology driven interactive healthcare with wearable sensors (OdIH_WS) to achieve customized healthcare service. For this purpose, wearable-sensor-based smart-wear and methods of data acquisition and processing are being developed. The proposed system has potential value in healthcare. A smart wear using wearable sensors is fabricated as a way of non-tight and comfortable style fitting for the curves of the human body based on clothes to wear in daily life. The design sample of the smart wear uses basic stretch materials and is designed to sustain its wearable property. To offer related information, it establishes an environment-information-based healthcare ontology model needed for inference, and it is composed of inside-outside context information models depending on the users’ context. The modeling of the proposed system involved combinations of information streams, focusing on service context information. With the proposed service inference rules, customized information and contents could be drawn by the inference engine. In the established OdIH_WS, real-time health information monitoring was achieved. The results of system performance and users’ satisfaction evaluations confirmed that the proposed system is superior to other existing systems.     

The Influence of Various Seat Design Parameters: A Computational Analysis

Nowadays, low back pain becomes a common healthcare problem. Poor or unsuitable seat design is related to the discomfort and other healthcare problems of users. The aim of this study is to investigate the influence of seat design variables on the compressive loadings of lumbar joints. A basis that includes a musculoskeletal human body model and a chair model has been developed using LifeMOD Biomechanics Modeller. Inverse and forward dynamic simulations have been performed for various seat design parameters. The results show that the inclination of backrest and seat pan may or may not decrease the compressive spinal joint forces, depending on other conditions. The medium‐level height and depth of seat pan and the medium‐level and high‐level height of backrest are found to cause the minimum compressive loads on lumbar joints. This work contributes to a better understanding of sitting biomechanics and provides some useful guidelines for seat design.     

Active sitting with backrest support: Is it feasible?

Abstract

Ergonomics science recommends office chairs that promote active sitting to reduce sitting related complaints. Since current office chairs do not fulfill this recommendation, a new chair was developed by inverting an existing dynamic chair principle. This study compares active sitting on the inverted chair during a simulated computer-based office task to two existing dynamic office chairs (n?=?8). Upper body stability was analysed using Friedman ANOVA (p?=?.01). In addition, participants completed a questionnaire to rate their comfort and activity after half a working day.

The inverted chair allowed the participants to perform a substantial range of lateral spine flexion (11.5°) with the most stable upper body posture (≤11?mm, ≤2°, p?≤?.01). The results of this study suggest that the inverted chair supports active sitting with backrest support during computer-based office work. However, according to comfort and activity ratings, results should be verified in a future field study with 24 participants.

Practitioner Summary: This experimental laboratory study analyses the feasibility of active sitting with a backrest support during common office work on a new type of dynamic office chair. The results demonstrate that active sitting with a backrest support is feasible on the new but limited on existing chairs.     

Is active sitting as active as we think?

The aim of this study was to compare the biomechanical characteristics of sitting on a stool without a backrest (so as to encourage active sitting), sitting on a conventional office chair and standing in healthy participants. Thirteen healthy participants performed a keyboard-writing task during four (stable and unstable) sitting conditions and standing. Body segment positions and posture, postural sway and muscle activity of neck and trunk muscles were assessed with a motion capture system, a force plate and surface electromyography. The results showed that body segment positions, postural sway and trunk muscle activity were relatively similar for the stools without backrests compared with standing. All sitting conditions showed lower vertical upper body alignment, less anterior pelvic tilt and larger hip angles, compared with standing (p = 0.000). Unexpectedly, the muscle activity levels and total postural sway, sway velocity and sway in M/L and A/P directions were lower (p = 0.000) for the conditions that encouraged active sitting and standing, compared with the conventional office chair conditions.

Practitioner Summary: Thirteen healthy participants performed a keyboard-writing task during different sitting conditions and standing and were analysed regarding posture, postural sway and trunk muscle activity. Surprisingly, less postural sway and less muscle activity were observed during the conditions that encourage active sitting, compared with sitting on a conventional office chair.     

Prediction of elderly seating comfort from physical condition, chair type and gender

Many persons over 60 years of age have unique problems sitting on chairs. These problems which are caused by decreased mobility, strength or disease suggest that the chairs should be selected carefully with some scientific basis that incorporates the varying demands of the elderly community. Identification of the proper chair for a particular individual, especially if it has to be low cost and nonmotorized, is a difficult job for institutions, elderly themselves, their families and the furniture industry. Keeping in view these problems a prediction model is developed using established statistical methods to predict comfort of sitting of a particular individual sitting in a particular chair. The study is based on experimental data collected on 18 male and female subjects over the age of 64. The equation uses chair type, body fat %, i.e. above average fat etc., body size, i.e. lean etc., and gender as inputs. The equation was tested on new female and male elderly subjects sitting on two new chairs. The model holds out excellent on the validation despite a low coefficient of determination value obtained for the equation. The paper not only presents a comfort prediction model but also shows a new direction for elderly seating research by employing statistical methods and elderly variables which do not appear in the published literature on elderly seating in the manner presented in this paper. This model will have wide applications especially for practioners (e.g., human factors engineers, occupational therapists, product developers) who need such information in a hurry. This approach also has heuristic value for the researcher in providing guidelines for the testing of other critical variables that may impact on the use of a chair or of other pieces of equipment.     

Lumbar posture and trunk muscle activation during a typing task when sitting on a novel dynamic ergonomic chair

Low back pain (LBP) is a common musculoskeletal disorder and prolonged sitting often aggravates LBP. A novel dynamic ergonomic chair (‘Back App’), which facilitates less hip flexion while sitting on an unstable base has been developed. This study compared lumbar posture and trunk muscle activation on this novel chair with a standard backless office chair. Twelve painfree participants completed a typing task on both chairs. Lumbar posture and trunk muscle activation were collected simultaneously and were analysed using paired t-tests. Sitting on the novel dynamic chair significantly (p < 0.05) reduced both lumbar flexion and the activation of one back muscle (Iliocostalis Lumborum pars Thoracis). The discomfort experienced was mild and was similar (p > 0.05) between chairs. Maintaining lordosis with less muscle activation during prolonged sitting could reduce the fatigue associated with upright sitting postures. Studies with longer sitting durations, and in people with LBP, are required.

Practitioner Summary: Sitting on a novel dynamic chair resulted in less lumbar flexion and less back muscle activation than sitting on a standard backless office chair during a typing task among pain-free participants. Facilitating lordotic sitting with less muscle activation may reduce the fatigue and discomfort often associated with lordotic sitting postures.     

Low-power,noninvasive measurement system for wearable ballistocardiography in sitting and standing positions

Ballistocardiography (BCG), the noninvasive measurement of the reaction forces of the body to the cardiac ejection of blood, is one of few methods available for unobtrusively assessing the mechanical aspects of cardiovascular health outside clinical settings. In this study, two sizes of piezoelectric film sensors were installed into the seat cushion of a chair and the foot insole, respectively, to acquire local BCG signals in sitting and standing positions. The design and engineering implementation of the signal processing circuit and data transmission system are discussed below. Although wearable BCG measurement devices have been extensively researched to date, to the authors’ knowledge, they have never been tested in regards to power consumption and electrostatic discharge (ESD) immunity. In this work, comprehensive experiments were conducted to show the low power consumption and high reliability of the proposed system. The shapes and the amplitudes of measured signals were examined in detail. The results suggest that the proposed system can feasibly and reliably be used to continuously record and evaluate cardiovascular changes occurring throughout an individual’s daily life.     

Integrated location aware medical care services

The advent of Mobile technologies has defined ways for providing better flexibility in communication, collaboration and information sharing through wireless medium using portable mobile devices. Technologies allow users to have anytime, anywhere access to information and applications. Specifically, location-aware mobile service has become the most essential component in dealing with mobile based applications. Mobile health care is one such promising area where mobile technologies are highly useful to provide services to the affected people. Worldwide the investment towards mobile health care applications is tremendously increasing. The significance of SMS, sensors, agent’s technologies is widely seen in most of the health care projects. This paper focuses on a system called LAMECS (Location Aware MEdical Care Services) which helps the needy people at the right time. The major focus of LAMECS is to provide timely facilities to people in the mobile based networked environment. Especially, the key objectives are to reduce the time taken to inform the service providers about the situation and to initiate the health care services at an early stage.     

Forget about ergonomics in chair design? Focus on aesthetics and comfort!

Chair users have difficulties distinguishing between chairs of different ergonomics quality. Many ergonomics features that are supposed to relieve discomfort in sitting are indistinguishable because they cannot be perceived. This is due to poor proprioceptive feedback from ligaments, joints and the spine. The joints are relatively insensitive to small changes in angle, and the spine cannot sense differences in pressure due to different body postures. Aesthetics features on the other hand, and features related to comfort and relaxation, are easier to perceive and differentiate. A study of ergonomics chairs verified that users could distinguish between parameters that relate to aesthetics and comfort, but had difficulty in distinguishing between ergonomics features. In the end aesthetics may be more important than ergonomics--at least to the customer who will be guided more by aesthetics than longer-term ergonomic factors.     

Forget about ergonomics in chair design? Focus on aesthetics and comfort!

Chair users have difficulties distinguishing between chairs of different ergonomics quality. Many ergonomics features that are supposed to relieve discomfort in sitting are indistinguishable because they cannot be perceived. This is due to poor proprioceptive feedback from ligaments, joints and the spine. The joints are relatively insensitive to small changes in angle, and the spine cannot sense differences in pressure due to different body postures. Aesthetics features on the other hand, and features related to comfort and relaxation, are easier to perceive and differentiate. A study of ergonomics chairs verified that users could distinguish between parameters that relate to aesthetics and comfort, but had difficulty in distinguishing between ergonomics features. In the end aesthetics may be more important than ergonomics—at least to the customer who will be guided more by aesthetics than longer-term ergonomic factors.     

A content search system considering the activity and context of a mobile user

People routinely carry mobile devices in their daily lives and obtain a variety of information from the Internet in many different situations. In searching for information (content) with a mobile device, a user’s activity (e.g., moving or stationary) and context (e.g., commuting in the morning or going downtown in the evening) often change, and such changes can affect the user’s degree of concentration on his or her mobile device’s display and information needs. Therefore, a search system should provide the user with an amount of information suitable for the current activity and a type of information suitable for the current context. In this study, we present the design and implementation of a content search system that considers a mobile user’s activity and context, with the goal of reducing the user’s operation load for content search. The proposed system switches between two kinds of content search systems according to the user’s activity: the location-based content search system is activated when the user is stationary (e.g., standing and sitting), while a menu-based content search system is activated when the user is moving (e.g., walking). Both systems present information according to user context. The location-based system presents detailed information via menus and a map according to location-based categories. The menu-based system presents only a few options to enable users to get content easily. Through user experiments, we confirmed that participants could get desired information more easily with this system than with a commercial search system.     

Application of Zen sitting principles to microscopic surgery seating

This paper describes the application of an alternative seating concept for surgeons that reflects the research of Zen sitting postures, which require Zazen meditators to maintain fixed postures for long durations. The aim of this alternative approach is to provide sitters with a seat pan with sacral support(1) that provides a more even distribution of seat pressures, induces forward pelvic rotation and improves lumbar, buttock and thigh support. This approach was applied to the development of a chair for microscopic surgery. The experimental chair is a seat pan that closely matches the three-dimensional contours of the user's buttocks. Seat comfort was evaluated by comparing both changes in pelvic tilt and seat pressure distributions using Regionally-Differentiated Pressure Maps (RDPM) with subjective ratings of surgeons while operating in prototype and conventional chairs. Findings include that the sacral support of the prototype chair prevents backward pelvic rotation, as seen in zazen (Zen sitting postures). Preliminary data suggests that the prototype provided greater sitting comfort and support for constrained operating postures than did the conventional chair. These findings support the selective application of concave-shaped seat pans that conform to users' buttocks and reflect Zen sitting principles.     

基于电场传感器的人体坐姿监测

研究表明经常处于同一姿势或者久坐都会对人体的健康造成危害,因此进行相应的坐姿监测并适时给出运动提醒是有必要的.将单只电场传感器安装在办公座椅靠背上,通过测量人体与传感器之间的相对运动,实现人体坐姿监测.人体背部与电场传感器之间的距离发生变化时,两者之间的耦合电容相应发生改变,导致电场传感器输出的电压信号幅值与形状发生变...     

Stability ball versus office chair: comparison of muscle activation and lumbar spine posture during prolonged sitting

OBJECTIVE: The objective of the study was to evaluate the differences between sitting on a stability ball and in an office chair in terms of trunk muscle activation and lumbar spine posture. BACKGROUND: Stability balls have become increasingly popular as an alternative to office chairs to help reduce the prevalence of low back pain; however, little research has been conducted on their use as office chairs. METHODS: The 14 participants (7 men, 7 women) were required to sit on both a stability ball and an office chair for 1 hour each while performing various computer workstation tasks throughout the sitting periods. The activation of eight muscles and lumbar spine posture were measured and analyzed. RESULTS: Increased muscle activation in thoracic erector spinae (p = .0352), decreased pelvic tilt (p = .0114), and increased perceived discomfort (p < .0001) while sitting on the stability ball were observed. CONCLUSIONS: The small changes in biological responses when sitting on a stability ball as compared with an office chair, combined with the increased reported discomfort while on the ball, suggests its use for prolonged sitting may not be advantageous. APPLICATION: Prolonged sitting on a stability ball does not greatly alter the manner in which an individual sits, yet it appears to increase the level of discomfort. Therefore, it is important to fully explore a new chair design and consult scientific research before implementing its use.     

多点传感阵列的体压分布测量系统设计

坐姿不良与许多疾病密切相关,而坐姿体压分布不平衡和一些腰椎疾病的发生有着相当大的联系。应用新型导电橡胶为传感材料,利用其力—电阻特性,研制64点阵式压电传感器型坐姿体压分布测量系统。应用本系统对1例正常人,3例患腰椎疾病者进行体压分布测量。实验结果表明:患腰椎疾病者的体压分布不平衡。证明系统的设计方案合理可行,能实现人体与座椅之间压力分布的动态、实时测量。