Introduction to Sports Biomechanics: Analysing Human Movement ...

Scalar variables are shown in italicised type, except for Greek symbols which are not italicised, as
above. Vector quantities are shown in bold type, sometimes italicised, as above. Linear vectors
can be represented graphically by a straight line arrow in the direction of the vector, with the
length of the line being proportional to the magnitude of the vector. Angular vectors can also be
represented graphically; in this case the direction of the arrow is found from the right-hand rule,
shown diagrammatically in Figure 4.11. With the right hand orientated as in Figure 4.11, the
curled fingers follow the direction of rotation and the thumb points in the direction of the angular
motion vector. So, for example, the direction of the angular motion vectors (angular displacement,
velocity and acceleration) for flexion–extension of the knee joint, a movement in the
sagittal plane, lies along the flexion–extension axis, the transverse axis perpendicular to the
sagittal plane. In the case shown here, the angular motion vector and the axis of rotation
coincide. This is often, but not always, the case. See Appendix 4.2 for further information about
vectors.
Figure 4.11 The right-hand rule.
QUANTITATIVE ANALYSIS OF MOVEMENT
projectile motion are negligible. This is a reasonable first assumption for some, but
certainly not all, projectile motions in sport; aerodynamic forces will be covered in
Chapter 5. Although I introduce algebraic symbols and equations in what follows, for
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