Similar to a washing machine or car engine, all the parts of the body have to work in unison according to certain mechanical principles in order to produce movement. Biomechanics is the science of taking these mechanical principles and applying them to the body. The biomechanics of throwing, for example, examines the interaction of specific parts of the body that then translates into the ability of throwing an object.
To throw an object, a modified system of pulleys and levers is utilized through the shoulder and arms which allows the arm to rotate at the shoulder and use momentum to propel the object forward. However, to throw effectively and with precision, a coordinated sequence of specific movements of the rest of the body is necessary.
The legs and the torso are important aspects in the biomechanics of throwing, especially if an individual is training to increase the effectiveness of propelling an object. For example, taking a step forward on the leg of the side of the throwing arm can produce a stronger throw. Rotation of the hips and torso to “level off” the hips as the object is released can also aid in increasing the force in which the object is thrown. Positioning of the arm in back of the head to start, and moving slightly behind the hip and torso rotation past the head with the elbow in line with the head, gives an individual maximal speed and force as the object is released.
Several other factors affect the biomechanics of throwing, including the structure of the joints. If the hand, wrist, elbow or shoulder is disabled, the ability to throw is diminished. Additionally, if problems exist in the legs or trunk, an individual may be able to go through the arm motions of throwing, but will be unable to provide much power or accuracy behind it. The effects of gravity and outside forces, such as the weight of the object being thrown, are other components to studying the biomechanics of throwing. A heavy object might also make it hard to get the arm into the proper position, which can decrease the precision and power of the throw.
