An exoskeleton includes two torque generators, two thigh links, and a supporting trunk rotatably coupled to the thigh links. When a wearer bends forward in the sagittal plane such that the supporting trunk extends beyond a predetermined angle A with respect to vertical, at least one of the torque generators imposes a resisting torque between the supporting trunk and a corresponding thigh link, thus imposing a force onto a wearer's trunk and thighs to aid in supporting the wearer in a bent position. The exoskeleton may include an active or passive means for actuating the generators. When the supporting trunk does not extend beyond the predetermined angle A, the torque generators do not impose resisting torques between the supporting trunk and the thigh links during the entire range of motion of the thigh links, thus enabling a wearer to walk, run and sit without constraint while in an upright position.