The role of the psoas and iliacus muscles for stability and movement of the lumbar spine, pelvis and hip

Abstract

The activation patterns of the psoas and iliacus muscles were investigated in 7 healthy adult subjects (4 men and 3 women) during a variety of motor tasks in standing, sitting and lying. Myoelectric activity was recorded simultaneously from the 2 muscles using thin wire electrodes inserted under guidance of high‐resolution ultrasound. In general, both muscles were coactivated, albeit to different relative levels, particularly when hip flexor torque was required. Selective activation of the iliacus could, however, be seen to stabilize the pelvis in contralateral hip extension during standing. Psoas was found to be selectively involved in sitting with a straight back and in contralateral loading situations requiring stabilization of the spine in the frontal plane. During training exercises from a supine position, such as sit‐ups, the contribution of the psoas and iliacus muscles could be varied by changing the range of motion as well as the position and support for the legs. Thus, the 2 anatomically different muscles of the iliopsoas complex were shown to have individual and taskspecific activation patterns depending on the particular demands for stability and movement at the lumbar spine, pelvis and hip.

Post-operative guidelines following hip arthroscopy

“…Historically, there has been much discussion over the primary function of the psoas [22,23] as a hip flexor or a lumbar stabilizer. Following hip arthroscopy, patients often present with the psoas muscle inhibited.…”

Efeitos imediatos do alongamento em diferentes posicionamentos

“…É consenso na literatura que o músculo iliopsoas é o fl exor primário da articulação do quadril (8,(30)(31)(32), porém possui outras funções bastante discutidas. Alguns autores consideram-no rotador externo, outros interno; látero-fl exor da coluna para lado ipsilateral ou contralateral, lordosante ou cifosante lombar.…”

“…Este músculo, por meio de sua ação sinergista, promove estabilização deste segmento, sendo responsável pela manutenção da postura (5)(6)(7)(8)(9). Disfunção do movimento pode provocar desequilíbrios musculares, quando os músculos permanecem constantemente encurtados ou alongados um em relação ao outro (2).…”

Development of a new instrument for evaluating leg motions using acceleration sensors (II)

“…The average acceleration in the high-risk group at the lumbar position was significantly lower than that in the low-risk group when classified by fall experience and carelessness. These results are associated with a decline in walking ability since muscle weakness leads to significant postural instability as well as inactivity in daily life [22]. The average acceleration at the lumbar position in the aged group was higher than that in the young group due to trunk instability in the former [23].…”