Myocardial stiffness refers to the resistance of the heart muscle to stretch when it fills with blood during diastole. This parameter is important in determining the ability of the heart to efficiently pump blood throughout the body and can be affected by various conditions such as heart failure, hypertension, and myocardial infarction. Research in this area aims to understand the mechanisms underlying changes in myocardial stiffness and to develop strategies to modulate it in order to improve heart function and overall cardiovascular health. Techniques such as echocardiography, magnetic resonance imaging, and tissue Doppler imaging are commonly used to assess myocardial stiffness in both experimental and clinical settings.