Efeito da fadiga do core na biomecânica de testes funcionais com salto unipodal em mulheres corredoras recreativas com e sem valgo dinâmico

Abstract

Introduction: In conditions of core muscle fatigue, runners may present altered biomechanics of their sporting gestures, making them more susceptible to injury. Runners with dynamic knee valgus seem to be more susceptible to the changes triggered by fatigue. Unipodal hop tests could simulate the phases of running, allowing the assessment of movement and dynamic postural control. Objective: To compare the effect of core fatigue on the kinetic, kinematic and electromyographic parameters of the lower limbs and trunk during single hop tests (Single-Leg Drop-Landing and Single-Leg Hop for Distance) between runners with and without dynamic knee valgus. Methods: The participants performed the Single-Leg Drop-Landing (valgus group: n=14; non-valgus group: n=13) and Single-Leg Hop for Distance (valgus group: n=17; non-valgus group: n=21) tests in random order before and after core muscle fatigue. The joint angles in the sagittal and frontal planes, the linear displacement of the shoulder and the electromyographic activity of the main muscles of the lower limb were analyzed. The integral of the electromyographic activity was calculated according to the phases of movement for each of the tests. The vertical ground reaction force in the Single-Leg Drop-Landing and performance in the Single-Leg Hop for Distance were also evaluated. Results: In the Single-Leg Drop-Landing, after fatigue, both groups showed greater dynamic knee valgus and greater gluteus medius activity in the third phase of the movement (from peak knee flexion to the end of the movement). The valgus group showed greater angular excursion of the hip in the sagittal plane and greater vertical linear displacement of the shoulder compared to the non-valgus group. In the Single-Leg Hop for Distance, after fatigue, there was a reduction in performance and both groups showed greater hip abduction, knee adduction and trunk displacement towards the supporting lower limb, as well as lower biceps femoris activity during the preparatory phase. The valgus group showed greater activation of the vastus lateralis and semitendinosus muscles in the preparatory phase. Conclusion: Core fatigue alters the kinematics of the proximal and distal joints and the activity of muscles that contribute to stabilizing the knee in the frontal plane. The groups adopted different strategies to deal with the demands of the task, whether during vertical or horizontal hop, regardless of core fatigue.