ABSTRACT
In this chapter (and the next two) we will focus on the quantitative analysis of sports movements. This chapter concentrates on what is often called by biomechanists ‘motion analysis’ (perhaps, more correctly, ‘image-based motion analysis’, but this is rather cumbersome). Implicit in the term ‘motion analysis’, as used in biomechanics, is that it involves quantitative analysis, and I will use ‘motion analysis’ in this way in this chapter; however, when it helps to add clarity, I will also use the term ‘quantitative motion analysis’, although the two are essentially synonymous. Motion analysis basically involves motion capture, or motion tracking, followed by analysis of the tracked motion. In this chapter, we will mostly explore the use of video analysis – videography – in the study of sports movements, including the equipment and methods used, experimental procedures and data processing (you, the reader, should also note that the term ‘videography’ is used outside of biomechanics to mean just the process of motion capture, with no reference to later analysis of the tracked motion, so be wary). Videography is by far the most likely method of motion analysis that an undergraduate student will come across. I will also provide an introduction to another method of motion analysis, using automatic marker-tracking systems. The increasing computer control of our main data collection equipment in sports biomechanics, along with much more accessible and user-friendly software, has lessened our need for repetitive and tedious mathematical calculations. Basic mathematical skills can, however, enable us to assess more critically factors that affect the accuracy of our experimental data. Such skills can also improve our understanding of sports performance; two cases in which this is very clear are introduced towards the end of this chapter – the first is projectile motion, and the second examines how rotation of a body generates linear velocities and accelerations. Symbolic representations are used in this chapter (some people, mistakenly, call this mathematics), but mathematical derivations are avoided.
