Office chairs are becoming a modern status symbol in the workplace. Many individuals are seated on office chairs for most of the working day. As a result of using poorly designed chairs injury and discomfort are frequently experienced, most particularly lower back pain. Correct design of chairs is imperative, and must be user-centered. The aim of this investigation has been to gather anthropometric dimensions characteristic of the South African population, as this information has not been widely assimilated to date. Once collated, this information could be used in the design of an ergonomically correct office chair, suitable for the unique characteristics of the South African working population. Anthropometric dimensions were collected from 683 South Africans (comprising 448 South African females and 235 South African males) from pre-selected companies in major centres in South Africa (Johannesburg, Pietermaritzburg, Durban, East London, Grahamstown, Port Elizabeth and Cape Town). Measurements included participants’ personal information (age, sex, home language and ethnic group), basic anthropometric measures (stature, shoulder height, mass, and waist and hip circumference) as well as specific measures of fit of the individual to the specially designed, adjustable chair. Of the 448 females, 317 were Black females, 77 were White females, 35 were Coloured females and 19 were Indian/Asian females. Of the 235 males, 112 were Black males, 79 were White males, 26 were Coloured males and 18 were Indian/Asian males. Office chair dimensions for each ethnic group were represented and differences were noted. A comparison between a current office chair’s dimensions and the South African sample office chair’s dimensions indicated modifications that would need to be constructed to suit the South African sample. The conventional office chair is still the most widely accepted office chair due to its stability and support structures that maintain the correct sitting posture of the user. An ergonomic office chair needs to incorporate anthropometric dimensions worldwide.

Seating is an integral part of work environment. When people are at work, they often sit in chairs for long periods of time without changing postures. This results in reduced blood circulation in the body, especially in the buttock-thigh area causing muscle fatigue, pain and discomfort. Ergonomically designed task chairs adopt a passive approach to guiding people into better postures by providing adjustability inside the chair. However most people do not adjust their chairs because they fail to sense the need for changing posture. They are left to sensing the need to change posture through guesswork or extreme discomfort. This thesis proposes a new system to address this problem by sensing static posture in a seated person with the use of electronic sensors embedded in the seat, and by providing interactive feedback to static posture via sound, light and tactile channels. The new technology is an sensing-feedback mechanism embedded in a chair, that allows people to receive postural information and make body adjustments periodically to avoid pain and discomfort caused by prolonged seating.The feedback mechanism was tested with four subjects to determine its efficacy in generating posture change through pressure relief and user feedback was gathered in order to design the final prototype.