To conduct various Tasks and to get relief from that chore we take certain body positions or postures. The posture could be sustained one or intermediate one to achieve a new posture. We often need help of a device, to achieve, maintain or terminate the posture. The devices or amenities for postures, make an activity, transition to or from it, or an interim relief, feasible, and efficient.
The capacity of body, to take-on a posture, sustain it, and leave it, depends on many factors such as: Physiological structure, deformities, age related in-capacities, motor (movement-flexibility) potential and response time, etc. Body posture devices and amenities are primarily designed to make available maximum energy for the activity in appropriate form -direction and level. The efficiency of task operation is a direct function of the body posture achieved.
Gravity is the major force against which the body must achieve a particular position. Hypothetically one may not need many of the body support systems, if the gravity were to be eliminated. In reality, however, one may still need support systems because the body has been genetically and physically conditioned with the presence of gravity. This is the reason why space astronauts sleep in standing position in no gravity zones and their module is rotated (spun) continually at slow speed.
Supports help to maintain the body postures, and also facilitate some of the biological functions. The support and comfort have become synonymous concepts. Just as comfort is a situation-specific requirement, so are the support system.
Support systems are very personalized. Every individual presents a unique combination of stature and body mass. It is difficult to draw a standard support system. Support systems are designed on percentile basis, trying to satisfy the largest section of people for a variegated set of tasks. It may not work effectively across cultures.
Support systems ideal for posture initiation may not be efficient for continuing the posture, or for terminating (or transiting to another one) it. Posture support systems need to have micro variation facilities, to relieve tedium, to reset the pressure on body limbs (including blood and fluid vessels), and to allow sensorial and physical reach in various directions. A technically perfect support system may not be ever comfortable. Due to personal and in-explicit reasons some support systems are preferred to others or totally avoided.
A support system must also function well when employed with the utility for the task. A chair is a seating device, but a writing chair or a counter chair also relates to the specific work surfaces. A hospital bed is a sleeping device but it is also a treatment device.
Posture devices are designed by checking out following points.
■ Do you need any one’s help to take or leave a particular posture?
■ Do you really need any device to take on, maintain or change over to another posture?
■ Which limb of the body is supported by such a device?
■ How long is it supported?
■ Is the device a substantial support system for the body, or partial system for a limb?
■Is the device also a functional tool, gadget, machine, plant or equipment?
■ Is the device also a tool, gadget, machine, or equipment for a particular type of sensual perception or communication?
■ Is the posture, device dependent?
■ Is the device, posture dependent?
■ Are the devices and postures dependent on something else?
■ Is the posture static (substantial period between start and end of a posture)?
■ Is the posture variable (a phase in a series of postures movement spectrum)?
■ Is the posture device assistive or resistive?