In Chapter 4, we covered quantitative motion analysis in sports biomechanics, particularly videography. In the final two chapters of this book, we will explore how sports movements are generated. In this chapter, we will consider the forces that affect the movement of the sports performer. This branch of knowledge is often called ‘kinetics’, and is subdivided into linear and angular (rotational) kinetics; it deals with the action of forces and moments of force in producing or changing motion. We will also look at how we measure the forces and pressures acting on the sports performer.