Seating Ergonomics

Ergonomics is the applied science of equipment design for the workplace, intended to maximize productivity by reducing operator fatigue and discomfort. passive comfort This type of comfort refers to aspects that are not related to adjustable systems or mechanisms on the chair. The most significant of these are: 1  CONTOURS OF THE SEAT AND BACKREST These contribute to a better body weight distribution. 2  WATERFALL EDGE ON SEAT The curved edge of the seat front helps to eliminate pressure points behind the knee. 3  THE ARMRESTS Armrests play an important role in the minimisation of shoulder and neck strain. Some armrests are height/width adjustable. active comfort SEAT HEIGHT ADJUSTMENT Enables the user to adjust the chair height in order that their feet are placed firmly on the floor If the seat is too high – the user is forced to lean forwad and therefore forfeits the back suppport If the seat is too low – weight shifts to the buttocks, which results in excess pressure on the underside of the thighs Knees should be bent at right angles to the thighs BACKREST ANGLE ADJUSTMENT This enables the backrest to support various angles of recline It ensures the back stays in permanent contact with the users back – the seat position does not change By supporting your back properly, with an even distribution of body weight this results in less pressure on the lower back The angle of the backrest should range from 85°–120° (slightly beyond upright) SWIVEL AND TILT This allows the chair to tilt backwards A reclined chair transfers upper body weight to the backrest of the chair FORWARD/KNEE TILT This allows the chair to tilt backward from the front-end of the seat The user’s feet remain fi rmly on the ground, thus improving stability and posture SYNCHRONISED MOVEMENT This mechanism enables a relationship between the backrest and seat, whereby for every 3 degrees of tilt  enforced onto the backrest, the seat automatically tilts  by 1 degree, ie the chair moves with your body It permits the user to select a fi xed angle sitting position or a free-fl oating, recline This mechanism allows for a negative tilt on the seat; thighs  slope downward thus widening the angle between the  trunk and thighs, reducing pressure on the spinal discs The tension adjustment facilitates the effortless “to and fro” movement of the seat proportional to your body weight HEIGHT ADJUSTABLE ARMS This feature provides support to the forearms, and/or elbows to avoid “raising the shoulders”. This occurs when the armrests are too high “Slouching” or leaning to either side of the chair is an indication that the armrests are too low LUMBAR SUPPORT A backrest that is height adjustable allows the backrest to be raised or lowered This feature allows the user of that chair to decide “where” and how the lumbar curve should support their back, therefore suiting people of different sizes SLIDING SEAT/SEAT DEPTH This involves the “forward/backward” movement of the seat, facilitating various depth options of the seat depending on the stature of the user A person of larger stature will improve their posture by sliding the seat forward to create a deeper seat. Likewise, a smaller person will accomplish this comfort by sliding the seat backwards The seat should be deep enought to support the upper legs, up to just behind the knees