Abstract: A chair that includes a frame and a seat disposed there above, and an upwardly protruding back support that is located in an area behind the seat. A front part of the back support has a lumbar support device that is disposed a certain level above the seat to support the lumbar spine and/or pelvis rim of the user. The seat is movable relative to the frame between the forward starting position, on the one hand, in which the seat is remote from the back support and is the normal position when the seat is not used by a sitting person and a rear end position, on the other hand, has a lumbar support in which the seat has moved closer to the back support. More particularly, it is closer for the purpose of bringing the pelvis of the person sitting on the seat to partially shift in against or below the lumbar support device.

Abstract: A chair that includes a frame, a seat, and a back support that has a lumbar support device to support the back bone of the user. The seat includes a soft cushion and a support panel that includes a front and rear disc part of which the latter protrudes as a free end from the first and is not in contact with the back support. The cushion has a rear seating area that is recessed relative to a forward seating area so that a transition area is formed that provides a knob against which the user's sitting bones may bear against with a view to prevent forward gliding of the user's thigh bones along the seat. The rear disc part is also lowerable from an upper starting position to enable a variation of the height level.