<p>A seating structure includes a support structure, a seat supported by the support structure and a backrest pivotally connected to the support structure. The seat includes a front and rear. The backrest is positioned adjacent the rear of the seat. The backrest includes a frame having a pair of bow-shaped side members. Each of the side members has a lower section and an upper section. The upper sections extend from the lower sections so as to form a pair of first bowed sections at substantially a lumbar region of the backrest. A flexible membrane is attached to and extends between the side members. The flexible membrane has a second bowed section corresponding to the first bowed sections of the side members. A method of using the seating structure is also provided. <IMAGE></p>