A Comparıson of Immedıate Effects of Passıve Stretchıng Exercıses and Manual Therapy Technıques for Reducıng Stıffness on Muscle and Tendon Unıt of Quadrıceps Femorıs Muscle

Abstract

Stretching exercises and manual therapy techniques are commonly used in order to reduce stiffness of muscle and tendon. It is suggested that muscle dynamics consisting of excitation-contraction coupling, electromechanical delay and muscle fiber vibration and force output may be altered using these thechniques. Time delays between onset of electromyographic (EMG), mechanomyography (MMG) and Force (FORCE) have been using to assess the changes in the dynamics of muscle after various techniques. The aim of this study was to investigate acute changes in the electro-mechanical properties of quadriceps femoris muscle and tendon after passive streching and manual therapy techniques. A total of 56 healthy subjects aged between 20-35 years old ( have been divided into 4 groups as passive stretching, manual therapy, passive stretching + manual therapy and control group. Subjects in the interventional groups had only one treatment session and they have been assessed immediately after the session. There was no application for the control group. The delays between EMG and MMG signals and, Force-Output of quadriceps femoris during voluntary isometric contraction at three different knee flexion angles, 15°,30° and 45° were simultaneously measured on a device originally derived for positioning lower extremities and a custom made amplifier for signal detection. Signal records have been taken from Rectus Femoris (RF) and Vastus Medialis (VM) muscle fibers. For RF muscle, time delay between EMG-MMG and MMG-Force increased after stretching at 15° knee flexion, while time delay between EMG-Force (electromechanical delay) increased after manual therapy at 15° and 30° knee flexion. Manual therapy + stretching has lengthened the time delay between all onsets of EMG, MMG and Force output in isometric contraction at 15° knee flexion, while time delay between EMG-MMG and EMG-Force has incresed at 30° and 45° knee flexion. For VM muscle, time delay between EMG-Force increased at 15° and 45° knee flexion after stretching. Manual therapy has increased time delay between EMG-Force only at 15° knee flexion. Manual therapy + stretching has lengthened all time delays between EMG, MMG and Force at 15° knee flexion while time delay between EMG-MMG increased only at 30° knee flexion. Comparison of the all application groups revealed that the application of manual therapy has better effects than stretching or manual therapy + stretching when they were tested at 15° of knee flexion for both RF and VM muscles. Stretching was more efficient to reduce stiffness at muscle fiber level for RF muscle during force generation in 15° of knee flexion, whereas manual therapy had beneficial effects to increase time of overall process starting by EMG signal till the generation of force output at both 15° and 30° of knee flexion. For VM muscle, both stretching and manual therapy were efficient to increase time delay of overall process between EMG and Force at 15° of knee flexion. Combination of manual therapy + stretching has increased time delay of overall process in EMG signals in accordance with force output at 15° of knee flexion. Such increase in time delay between EMG signals and force output began to gradually decrease at 30° and 45° of knee flexion for both RF and VM muscles.