Successful diagnosis and treatment of musculoskeletal dysfunction requires an understanding of both basic anatomy and the dynamic relationship of anatomic structures to one another known as functional anatomy. Biomechanics is the study of the physical actions of forces or mechanics applied to a biologic system and the implications this has on anatomic and functional relationships. The forces can be divided into static and dynamic types. Static biomechanics involve a physiologic system in which the forces result in a state of equilibrium with a net of zero change in the system velocity. In this case the body can remain at rest or in motion; however, a constant velocity persists due to the balance of forces. Dynamic forces result in net acceleration of the physiologic system due to the unbalanced application of forces.
Kinetics is the study of motion; this is a general term with implications across many sciences. Human kinetics is the study of motion of the human body with a focus on the forces that produce motion. The structure and stability of each extremity reflect the forces imparted and, ultimately, the functional demands placed on the limb. The functional demands of the upper limb are vastly different than those of the lower limb, and the forces imparted are therefore different. The amount of movement versus amount of stability necessary for function at a joint governs its size, shape, and infrastructure. This difference is clearly seen when the hip joint is compared with the glenohumeral joint. Kinematics is a branch of science that describes the motion of points, objects, or systems without consideration of the cause of this motion, and can also be described as the geometry of motion. This includes consideration of time, displacement, velocity, acceleration, and space factors of a system’s motion.
Two types of motion occur about most joints to varying degrees based on function: translation (linear displacement) and rotation (angular displacement). These two movements occur within the three orthogonal planes: the coronal, sagittal, and transverse. Although complex motion occurs across many planes simultaneously, the motion can be subdivided into the aforementioned planes with the use of image capture and computer-aided motion analysis. When analyzing motion that is occurring in any one plane, the structure that serves as or creates that axis of rotation, perpendicular to the major plane of motion, must be determined. For example, motion in the coronal plane occurs about an axis of rotation that is in the sagittal plane. If one understands the structures that determine the axis of rotation, these can then be examined for pathologic disease processes or function.
Kinesiology requires an understanding of functional anatomy and combines the sciences of kinetics and kinematics as well as biomechanics, anatomy, and physiology in the study of movement. It is through a fundamental understanding of kinesiology and implementation of its principles that one can recognize normal and abnormal function and use this information to optimize ...