Background and Aim: Muscle fascicle length and pennation angle can be non-invasively studied by applying methods like ultrasonography. The aim of this study was to introduce fascicle length and fascicle angle for the estimation of the strength of skeletal muscle by using ultrasonography.

Materials and Methods: The data of this study have been driven from pubmed and authoritative references available on the internet and in libraries. In all fifteen full text articles and 30 abstracts have been collected and reviewed. Keywords such as: muscle, fascicle, pennation angle, force and ultrasonography were searched to fulfill the purpose of this study.

Results : Detailed information about the angles of pennation and fascicles length are important to predict muscle force. It has been suggested that changes in muscle pennation angles are positively correlated to the length of fascicle in a muscle contraction. While muscle thickness may in some case be remained constant in this relation.

Conclusion: Real-time ultrasonography is a noninvasive procedure to monitor the architecture of the living muscle at rest and during static and dynamic sets. It is a valuable measurement tool to estimate muscle force by measuring the muscle architecture parameters such as angle of pennation and fascicle length.

Keywords : Muscle, Fascicle, Pennation angle, Force, Ultrasonography