In vivo assessment of muscle mechanical properties using a low-cost surface wave method

Knowledge of muscle mechanical properties is important in clinical practice and biomechanical research. In usual clinical practice the muscle´s Young modulus (Y) is qualitatively inferred through manual palpation and others valuation techniques of joint range. Although these methods are sensitive, they have predictable variations between different examiners, which reveals the need for methods capable of providing reliable quantitative values of muscular elasticity. Previous studies have shown that transient elastography (TE) is a useful method for assess locally and in vivo the Young modulus of muscle. In these works, experiments using TE were carried out on biceps brachii of healthy volunteers, testing the muscular elasticity changes under three load conditions: 0, 1 and 2 Kg. However, due to its high cost, this method is currently unavailable in many countries for standard clinical practice. In this work, taking into account the existing background with TE, we propose a low-cost method based on surface wave (SW) propagation for the in vivo assessment of the muscle´s global mechanical properties. To validate the method, we repeated the experiments with TE, and compared the quantitative values and the general behavior exhibited by both methods. The results showed a good agreement between TE and SW methods, explaining the differences mainly by diffraction effects. We think that the in the current context, this method could be used widely in the rehabilitative and sports medicine field, both as a monitoring tool as well as research.