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The purposes of this study were to monitor the integrated electromyographic activity of the erector spinae (ES) muscles and to measure lumbar curvature (LC) during static and dynamic postures in three chairs--a Balans Multi-Chair (BC), and office chair (OC), and a straight-back chair (SBC)--and during standing. Integrated electromyographic data were recorded in relaxed and erect postures at L2 and L5 in 20 volunteers. Lumbar curvature was measured with a flexible ruler. Analyses of variance for repeated measures (p = .05) and paired t tests were used to compare the IEMG and LC measurements. During relaxed postures, there was more IEMG activity and greater LC in standing than in the OC or the SBC. During erect postures, there was more IEMG activity in standing than in the OC and no difference in LC between chairs. The IEMG activity at L5 was greatest on the left side across chairs. In typing and writing, significant differences in IEMG activity were found between sides, but not between chairs. The LC was greater in the BC than in the SBC in relaxed sitting, typing, and writing. The pattern of IEMG activity is not similar to corresponding LC measurements. Care and prevention of low back injury is a critical focus in physical therapy. The BC could contribute to treatment. Further research is needed to support its use in back care programs.

The task dictates the requirements made of a seat in the industrial setting. This is now generally accepted, but the question remains as to how to evaluate a particular seat. This study has attempted to bring together recognized experimental evaluation techniques to provide an integrated test regime, which has been applied in the development of a new sit-stand seat.

For a tiltable office chair, subjective height preferences may be different to those for conventional fixed-seat chairs, due to altered biomechanics. These preferences, with a tiltable chair and associated table, have been investigated with a total of 108 subjects. To determine the shortest possible way to obtain reliable height measurements, a study (n = 10) was undertaken. It was demonstrated that two days of measurement seem necessary, the first day involving both a too-high and a too-low start position, the second day only a too-high one. Preferences were measured for each of four groups, one (n = 21) accustomed to and another (n = 35) unaccustomed to a tiltable seat; a third (n = 23) was composed of children and the fourth group (n = 19) was making large-scale drawings. When accustomed to the seat, the subjects preferred a greater seat height. The children's seat-height preference was relatively equal to that of adults, whereas their preferred relative table height was greater, most evidently so with decreasing age. The greatest relative seat height was preferred in connection with large-scale drawings. For desk work it is recommended that the seat height should be approximately 3–5 cm above popliteal height, including shoe heels, and the table height 4–6 cm above the actual elbow height.

This paper deals with what the author believes to be the two most critical factors necessary to ensure the design of ergonomically correct task seating. First, the contoured shapes and the overall dimensions of a task seating product can, and must, correspond to the full anthropometric range of the adult male/female use population. Second, user design management function must be a meaningful part of the product development process. It must function as a politically independent management tool to be reconciled with by the traditional product development management functions of marketing, engineering, and manufacturing.

Kipling has said that he who has once been a journalist remains a journalist to the end. He said this in a semi-autobiographical sense. But when a man has reached the point of having it even rumoured that syndicates are formed to buy his manuscripts at the rate of so much a word the mill of daily journalism must go round without him.

The boundaries of maximum possible arm reach for tasks on vertical instrument racks were determined on a stratified sample of twenty subjects, when seated in a standard office chair. The limiting effects of 3-1/2 inch thick service shelves, varying in depth from 10 through 25 inches and in height from 27.9 to 30.1 inches, were measured together with optimum seat height and leg clearance. The 5th, 50th, and 95th percentile reach contours show that shelf depths greater than 10 inches decrease arm reach, the amount being dependent upon shelf height. Service shelf depth, when at the optimum of height of 28 inches, should not be much greater than 20 inches if 95 percent of the operators are to reach a vertical display beneath it.

In this paper, the author introduces a novel method for non-invasive, implicit human-computer interaction based on dynamically evaluated sitting postures. The research question addressed is whether or not the proposed system is able to allow for non-obtrusive screen content adaptation in a reading situation. To this end, the author has integrated force sensor array mats into a traditional office chair, providing sitting postures/gestures of the person seated in real time. In detail, variations in the center of pressure were used for application control, starting more generally with usability assessment of cursor control, breaking them down to simple(r) pan and zoom of screen content. Preliminary studies have indicated that such a system cannot get close to the performance/accuracy of keyboard or mouse, however its general usability, e.g., for handicapped persons or for less dynamic screen content adaptation, has been demonstrated and some future potential has been recognized.

Today’s office chairs are not known to promote active sitting or to activate the lumbar trunk muscles, both of which functions are ergonomically recommended. This study investigated a newly developed dynamic office chair with a moveable seat, specifically designed to promote trunk muscle controlled active sitting. The study aimed to determine the means by which the seat movement was controlled during active sitting. This was accomplished by quantifying trunk and thigh muscular activity and body kinematics. Additionally, the effect of increased spinal motion on muscular activity and body kinematics was analysed. Ten subjects were equipped with reflective body markers and surface electromyography on three lumbar back muscles (multifidus, iliocostalis, longissimus) and two thigh muscles (vastus lateralis and medialis). Subjects performed a reading task during static and active sitting in spontaneous and maximum ranges of motion in a simulated office laboratory setting. The temporal muscle activation pattern, average muscle activity and body segment kinematics were analysed and compared using Friedman and post-hoc Wilcoxon tests (p≤0.05). Active sitting on the new chair significantly affected the lumbar trunk muscles, with characteristic cyclic unloading/loading in response to the seat movement. Neither thigh muscle activity nor lateral body weight shift were substantially affected by active sitting. When participants increased their range of motion, the lumbar back muscles were activated for longer and relaxation times were shorter. The characteristic activity pattern of the lumbar trunk muscles was shown to be the most likely dominant factor in controlling seat movement during active sitting. Consequently, the new chair may have a potential positive impact on back health during prolonged sitting. Further studies are necessary to analyse the frequency and intensity of active sitting during daily office work.

THEORY Comfort Experience Theory on Comfort A Theory on Pressure Distribution and Seat Discomfort Participatory Ergonomics and Comfort CASES ON REDUCING DISCOMFORT IN WORK Discomfort and Productivity in Improved Bricklaying Reducing Discomfort in Work by New Products for Glaziers Reducing Discomfort in the Installation Work Reducing Discomfort in Office Work Productivity and Discomfort in Manual Assembly Operations Productivity and Discomfort in Assembly Work: The Effects of and Ergonomic Work Place Adjustment at Philips DAP CASES ON CHAIR COMFORT Comfort in Furniture at Home Discomfort and Dynamics in Office Chairs Designing Comfortable Passenger Seats Comfort by an Emotion-Aware Office Chair CASES ON HAND TOOL COMFORT Towards a Comfortable Paint Scraper Development of a Handheld Steelfixing Tool Comfort Effects of Participatory Design of Screw Drivers Comfortable Manual Bag Sealing CASES ON VEHICULAR INTERIOR COMFORT Comfortable View in an Earth Moving Machine of 2015 Tram Drivers' Comfort Redesign of Earth Moving Machines: It's Also in the Details Concept of a Future Nissan Car Interior COST/BENEFITS Cost/Benefits of Comfort Products for Professional Use

In this study an anatomically accurate 3D Finite Element (FE) model of the lower limbs was developed from axial cryosection images of the Visible Man (VM). The relative position of the lower limbs of a subject in standing and sitting positions was acquired with a laser scanner. A subset of these data points were used as control points in a novel application of the Host Mesh Fitting (HMF) technique, where the generic model geometry was morphed to subject data in the standing position, and then this subject-specific model was articulated to the seated posture. The gluteus maximus muscle and a portion of the skin mesh of the customised model were selected to provide a framework with which to examine the mechanics of sitting. Passive material properties were taken from the literature and were implemented in two two-parameter Mooney-Rivlin models to assess the response of the anatomical models to applied forces and pressures. The average deformation of the skin mesh was 0.77plusmn1.525 mm which resulted in a maximum von Mises stress of 3.98 kPa. The average deformation of the gluteus maximus mesh was 2.69 plusmn 0.6 mm which produced a maximum von Mises stress of 43 kPa. The results of the von Mises stress distribution support the theory that the highest stress occurs in the region immediately beneath the ischial tuberosities. The results of this research confirm previous conclusions reached using geometrically less complex models and the application of customisation to non linear mechanics provides a novel avenue to quantitatively assess office chair design and to analyse the mechanics of sitting.

This study aims to improve user comfort and satisfaction regarding the thermal environment in the open plan office, which is a current challenge in the workplace addressed by limited research. The main difficulty in an open plan setting is that changing the room temperature in an area affects all occupants seated nearby. This issue in addition to individual differences in perceiving the thermal environment create a great challenge to satisfy all occupants in the workplace. This study investigates the application of an advanced thermal system, a user-controlled thermal chair, which allows individual control over their immediate thermal environment without affecting the thermal environment and comfort of other occupants. The performance of the chair was further analysed through Computational Fluid Dynamics (CFD) simulations providing a detailed analysis of the thermal distribution around a thermal chair with a sitting manikin. The results indicated that user thermal comfort can be enhanced by improving the local thermal comfort of the occupant. A prototype of an office chair equipped with thermal control over the seat and the back was produced and examined in an open plan office in November in Leeds, UK. Forty-five individuals used the chair in their everyday context of work and a survey questionnaire was applied to record their views of the thermal environment before and after using the chair. The results of the field study revealed 20% higher comfort and 35% higher satisfaction level, due to the use of thermal chair. Thermal measurements showed acceptable thermal conditions according to the ASHRAE Standard 55-2013. Over 86% of the occupants set the temperature settings of the seat and the back of the chair between 29 °C and 39°. 82% of the occupants expressed their satisfaction level as “satisfied” or “very satisfied” regarding the performance of the thermal chair. The thermal chair energy consumption was relatively low (0.03 kW) when compared with that of typical personal heaters, which are about 1–1.5 kW. Further research is recommended to improve the design and application of the thermal chair to improve user overall thermal comfort and also further reduce energy consumption.

In the study and investigation of neurologic cases. I am constrained to believe that the knee-jerk or patellar tendon reflex, correctly obtained, is one of the most important tests, if not the most important, in a great variety of cases. It is certainly a test that the general practitioner should more frequently make in the ordinary routine examinations of his practice. Perhaps not everyone is aware that the knee-jerk is often present, but inhibited by the patient, and that any method that will insure a correct response is well worth consideration. I have found it practically impossible for a patient to inhibit the knee-jerk if the method here described is employed. It was in an endeavor to prevent this frequent occurrence that the following plan was evolved. The patient, male or female, should sit in an ordinary straight-backed office chair, relaxing the entire body as far as possible. The feet

Background Several risk factors exist for the development of low back pain, including prolonged sitting and flexed spinal curvature. Several investigators have studied lumbar support devices and spinal curvatures in sitting, however few have investigated a pain population and reported a quantitative measure of comfort. The purpose of the current project was to determine whether a lumbar support pillow, outfitted with a cut-out to accommodate the bulk of posterior pelvic soft tissue volume, is more effective than a standard chair in promoting a neutral spinal posture and improving subjective and objective measures of comfort in healthy individuals and patients with low back pain. Methods Twenty eight male participants with and without a history of low back pain sat in a standard office chair and in a chair with the lumbar support pillow for 30 minutes. Lumbar and thoracolumbar postures were measured through electromagnetic markers. Comfort was determined based on the least squares radius of centre of pressure shifting, measured at the buttock-chair interface as well as reported discomfort through visual analog scales. Chair support effects were assessed through ANOVA methods. The study was approved by the Canadian Memorial Chiropractic College research ethics board. Results There was a main effect of condition on lumbar posture (p = 0.006) and thoracolumbar posture (p = 0.014). In the lumbar region, the support and standard chair differed by 2.88° (95% CI; 1.01-4.75), with the lumbar support being closer to neutral than the standard chair. In the thoracolumbar region, the support and standard chair differed by -2.42° (95% CI; -4.22 to -0.62), with the standard chair being closer to neutral than the support device. The centre of pressure measure was significantly improved with the pillow (p = 0.017), however there were no subjective changes in comfort. Conclusions A lumbar support pillow with a cut-out for the posterior pelvic tissues improved an objective measure of comfort in healthy individuals and patients with low back pain. Lumbar flattening was decreased and thoracolumbar curvature was increased. However, angular changes were small and future work is required to determine clinical relevance over the long term. Trial registration ClinicalTrials.gov, NCT00754585