The influence of passive extensibility of the posterior oblique sling’s upper portion on contralateral knee extension

Abstract

IntroductionThe posterior oblique sling (POS) serves to improve stability by transferring the force and load during an active movement in muscle contraction. The purpose of this study was to investigate the influence of pelvic positions on the knee extension range of motion (KE ROM) and the influence of trunk positions on the mobility of the lower extremity.MethodsSixteen subjects (age 21.0 ± 1.9 years, height 165.3 ± 7.6 cm, weight 59.56 ± 7.9 kg) participated in this study. The therapist measured the active KE ROM of the dominant leg at three different pelvic positions (neutral position, maximal anterior, and posterior pelvic tilt) and at two different trunk positions (trunk flexion and trunk rotation) using a Bluetooth embed inertial measurement unit sensor. A 10-minute rest was taken between positions. During trunk flexion and trunk rotation, the pelvis was maintained in a neutral position to prevent the change in length of the hamstring muscles. Statistical significance was set at <i>p</i> < 0.05.ResultsIn comparison to the neutral position, the anterior and posterior pelvic tilt significantly decreased (<i>p</i> < 0.001) and increased the KE ROM (<i>p</i> < 0.001). In addition, the trunk rotation significantly decreased the KE ROM (<i>p</i> = 0.002). However, the trunk flexion did not significantly change the KE ROM.ConclusionsThe findings in this study indicate that the changes in the length of the POS significantly influenced the functional mobility in the lower extremity. In clinical practice, the flexibility of POS must be considered during reciprocal movements involving the upper body and contralateral lower extremities.