There are many ways to go about discovering the properties of the human body and how it moves. Cameras can be used to record movement. They can then be played back in slow motion to observe the paths of key points to make a dynamic model of a moving part. Cameras can also be used to determine the displacement of a part when a force is acted on it. Videos or photographs can be fed into a computer for further analysis.
Other methods can also be used to determine properties. Stress is equal to the force applied divided by the area over which it is applied. Also, strain is equal to the stress divided by the E value. It is possible to study the stiffness, the viscoelasticity, the viscosity, the strain and the stress by using strain gages and by studying deformation in the parts of interest. Click here to see stress and strain and how strain gages work.
Forces can be applied to various sections of the body in a variety of directions and can either be constant or can be in varying amounts. The varying properties of the body are then measured through deformation, stress and strain and these properties can be used to evaluate the other properties of the body like viscosity, stiffness, etc.