Local shape and scale of the chair has a great influence for using. For example, it determines the height of the backrest and armrest. Consider the characteristics of human anatomy, the hip muscles is huge and solid, it’s one of the parts of the body which is most able to withstand voltage. So the right seats design should be that let the upper body weight to fall on the hip bones.
(A) The seat surface is too high result in the legs vacant, not only the pressure on the leg muscles, but also the upper legs, lower legs and back muscles are all showed tension, sooner the leg will feel tired.
(B) The seat surface is too low lead to the abdominal muscles crush, and then you will feel the pain and the discomfort.
(C) The width of the surface, if the width of the surface is too narrow, you will feel not appropriate to use and stiff. But if the width is too wide, the arms must be out done. These two ways are all easy to feel tired.
(D) The length of the dynamic range for the backrest is large, and also you can not be provided with a backrest.