The bow works with the principles of accumulating a certain energy and transferring it to the arrow. In principle, the outer surface of a material subject to bending tries to elongate and the inner surface tries to compress. In simple wooden bows, the resistance to these forces is limited by the properties of the wood used. In composite bows such as the Ottoman bow, the limited capabilities of wood have found the opportunity to be further developed by using other materials. If the outer surface of the spring cannot be extended enough, the spring breaks because the bond inside the tree will break. This shortcoming is replaced by the use of a much more flexible and durable sinew (tendon) on the outer surface of the spring. In this video, we will see how and where the tendons (sinew) of a calf’s leg (the leg from the knee to the hoof) should be removed and we will have an idea about the working principle of the tendon in the animal leg.