The use of free vibration techniques to evaluate the responsiveness of a one-degree-offreedom dynamic system linked to musculo-articular stiffness (MAS) of the plantar flexors has become an accepted procedure in scientific literature. However, the applicability and widespread use of this parameter have been limited thus far for different issues. On the one hand, the measurement of this parameter requires a noninvasive, nonstress laboratory test, which implies the use of appropriate in-lab infrastructure, ad hoc mechanical devices, and specific signal sensing units. On the other hand, it requires an efficient treatment and processing of the signal data obtained from laboratory tests through different signal filtering techniques and mathematical transformations. In the present manuscript, the fundamentals of the free vibration technique, the measurement device, the adjustment procedure, and finally the software based on java platform are presented in order to show the applicability of the MAS as parameter to evaluate the functional response of one subject based on his mechanical response of the lower part of the body once the whole procedure is addressed and controlled to ensure the reproducibility and the reliability of the test.