A trunk supporting exoskeleton configured to be worn by a person to reduce the muscle forces in said person's back during forward lumbar flexion, said trunk supporting exoskeleton comprising: a supporting trunk configured to be coupled to said person's trunk ; first and second thigh links configured to move together with said person's thighs in a manner resulting in flexion and extension of respective first and second thigh links relative to said supporting trunk ; and first and second torque generators located on both left and right halves of said person substantially close to said person's hip, coupling said supporting trunk to said first and second thigh links respectively and configured to generate torque between said first and second thigh links and said supporting trunk, wherein: when a predetermined portion of said supporting trunk is arranged to pass beyond a predetermined angle from vertical , at least one of said first or second torque generators is arranged to impose a resisting torque between said supporting trunk and at least one of the first and second thigh links, to cause said supporting trunk to impose a force against said person's trunk and at least one of said first and second thigh links to impose a force onto said person's thigh and, when said predetermined portion of said supporting trunk does not pass beyond said predetermined angle from vertical , said first and second torque generators, during the entire range of motion of said first and second thigh links, are arranged to impose no resisting torques between said supporting trunk and said respective first and second thigh links. a supporting trunk configured to be coupled to said person's trunk ; first and second thigh links configured to move together with said person's thighs in a manner resulting in flexion and extension of respective first and second thigh links relative to said supporting trunk ; and first and second torque generators located on both left and right halves of said person substantially close to said person's hip, coupling said supporting trunk to said first and second thigh links respectively and configured to generate torque between said first and second thigh links and said supporting trunk, wherein: when a predetermined portion of said supporting trunk is arranged to pass beyond a predetermined angle from vertical , at least one of said first or second torque generators is arranged to impose a resisting torque between said supporting trunk and at least one of the first and second thigh links, to cause said supporting trunk to impose a force against said person's trunk and at least one of said first and second thigh links to impose a force onto said person's thigh and, when said predetermined portion of said supporting trunk does not pass beyond said predetermined angle from vertical , said first and second torque generators, during the entire range of motion of said first and second thigh links, are arranged to impose no resisting torques between said supporting trunk and said respective first and second thigh links. when a predetermined portion of said supporting trunk is arranged to pass beyond a predetermined angle from vertical , at least one of said first or second torque generators is arranged to impose a resisting torque between said supporting trunk and at least one of the first and second thigh links, to cause said supporting trunk to impose a force against said person's trunk and at least one of said first and second thigh links to impose a force onto said person's thigh and, when said predetermined portion of said supporting trunk does not pass beyond said predetermined angle from vertical , said first and second torque generators, during the entire range of motion of said first and second thigh links, are arranged to impose no resisting torques between said supporting trunk and said respective first and second thigh links. <EOS>