Biomechanics comes from the Greek bios (life) and mechanike (mechanics) — the study of the mechanical principles of living organisms, mainly humans. Within mechanics, biomechanics sits under 'dynamics' (systems with acceleration) rather than 'statics' (systems at rest or constant velocity); dynamics itself splits into kinematics (the geometry of motion — time, displacement, velocity, speed, in a straight or rotary direction) and kinetics (the forces causing or resulting from motion). Sports biomechanics specifically is the quantitative study of athletes and sporting activity — in the textbook's own words, 'the physics of sports' — explaining how and why the human body moves the way it does, often through mathematical modelling, computer simulation and measurement.

Several scholars have defined biomechanics formally: Hatze (1974) frames it as studying the movement of living things using the science of mechanics; another definition calls it the area of study where the knowledge and methods of mechanics are applied to the structure and function of the living human system; and James G. Hay defines it as the science concerned with the internal and external forces acting on a human body and the effects those forces produce. …