A body support structure includes a frame and a membrane attached to the frame. The membrane includes elastomeric filaments. The membrane includes different regions with different stiffness. The membrane may form a part of a seat or a backrest.

A seating arrangement includes a back arrangement moveable between upright and reclined positions, a linkage arrangement including a first link member comprising a portion of a seat arrangement, a second link member supported on a base, flexibly resilient front link members extending between forward portions of the first and second link members and being integral with the second link member, and a rigid rear link member extending between rearward portions of the first and second link members including a separate piece from the first or second link members, wherein the rearward portion of the first link member extends laterally in a first plane when the back arrangement is upright, and laterally in a second plane when the back arrangement is reclined, where the second plane is angled with respect to the first plane, and is positioned farther away from the base when the back arrangement is reclined than when upright.

A chair for providing seating support to a user and for providing ways for the user to perform exercises. The chair includes a back support that is flexible such that when a force is applied to it by the user's body, the back support bends. The back support may be configured to adapt to the curvature of the user's spine when the user is seated in the chair. The back support may further be configured such that the user can rotate the back support by rotating the user's upper body.

A chair includes a seat surface and a laterally pivotable backrest. The backrest is secured to two joints, which have mutually parallel axes of rotation.

A rotatable chair back includes a lower section attachable to a chair seat, a flexible Y-shaped upper section for supporting a chair back frame, and two rigid supports extending substantially vertically into and between the upper section and the lower section. In use, the substantially vertical supports each serve as an axis of rotation about which the upper section may rotate relative to the lower section.

A seating assembly includes a seat and an upright coupled with the seat. A pliable backrest is coupled with the upright and includes a support face and a coupling face. The pliable backrest includes a pliable material extending between the support and coupling faces. The support face is a first exterior face of the pliable back rest and the coupling face is a second exterior face of the pliable back rest. The coupling face is spaced away from the upright with a deformation gap. Another seating assembly includes a joint assembly along the upright member. The joint assembly includes a pivot configured to promote rotation of a first upright portion of the upright relative to a second upright portion. The joint assembly includes opposed stop interfaces configured to control rotation of the first upright portion relative to the second upright portion.

A body support assembly includes a seat assembly and backrest assembly supported by a tilt control assembly. Methods of using and assembling the body support assembly are provided.

A twistable chair backrest frame is disclosed herein. It has a hollow section and two opposite elastic supporting ribs at a right side and a left side of the hollow section.

A reconfigurable apparatus for seating a user and having: a frame; a seat movable relative to the frame between: a) a first position in which the seat resides with no user sitting on the seat; and b) a loaded position; a back rest with a changeable angular orientation relative to the frame; and an adjusting assembly having a plurality of gears that move relative to each other as an incident of the seat moving from the first position into the loaded position to thereby cause an increase in resistance to changing of the angular orientation of the back rest.

A chair back that includes a back support, an upright frame, and at least one flex wing. The back support is substantially flexible and has a first side portion and a second side portion. The upright frame is substantially rigid and has a first frame side and a second frame side. The flex wing is located between the first frame side and the first side portion, where the flex wing includes a front portion coupled to the first side portion, a back portion coupled to the first frame side, and a web portion interconnecting the front portion and the back portion. The flex wing flexes during engagement by a user.