Changes in Activity of Erector Spinae and Gluteus Medius Muscles With the Presence of Simulated Lower Limb Dysmetria

Background: Length leg discrepancy (LLD), regardless of its origin, is a very common pathology that can contribute to low back pain. Various authors point out its relationship with the lack of activation of both the gluteus medius (GM) and the ipsilateral erector spinae (ES). The purpose of this study was to identify the activation of Es and GM with different simulated LLD, correlating said activation with the LBP. In turn, to evaluate whether ES and GM activity has an effect on jumping ability as assessed through CMJ. (2) Method: a sample of healthy subjects was selected to whom an artificial LLD was incorporated through a 0.5, 1 and 1.5 cm insole, measuring with EMGs in these 3 moments while walking and performing a counter movement jump (CMJ). The measurement was carried out in random order, in terms of insole height, using a Latin Square. Muscle activation patterns were recorded for 30 seconds at each of the insole heights while walking at 5.7 km/h and compared with the maximum voluntary contraction (MVC), both on the ipsilateral and contra-lateral sides. These muscles were then measured under the same circumstances during the development of the CMJ. (3)