 Although recent studies suggest that static stretching has adverse effects on performance, reduces maximal muscle force and is not successful in preventing non-contact injuries, as believed so; and the dynamic type therefore gaining popularity; it is reported that flexibility and range of motion can be improved by stretching as a consequence of the decrement in muscle stiffness. However, the effects of stretching depend on the type, duration and timing of stretching and there is still debate over which prescription provides the best results in terms of flexibility, power, performance or injury protection. And what happens to the viscoelastic properties of a muscle when it is stretched statically or dynamically is still not well documented. Ultrasound seems to be a good option as it offers an objective and a non-invasive way to expose the alteration in muscles and tendons due to stretching. 