Investigation Of Muscle-Tendon Unit By Ultrasound After Static And Dynamic Stretching

Muscle stretching is a very common practice applied in warm-up process in order to enhance performance in sports and to prevent or decrease the risk of sports injury. Muscle stretching is also used for therapeutic purposes in many clinical conditions.

It is generally performed in either static or dynamic manner. Muscle is brought to its lengthened position and is held at that point for a certain period of time in static stretching (SS). In dynamic stretching (DS), however, active movements of muscle take the joint through the range of motion and creates a stretch, but the muscle is not held in the end position.

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.