Introduction to Sports Biomechanics: Analysing Human Movement ...

INTRODUCTION TO SPORTS BIOMECHANICS
linear regression equation with one or more anthropometric variables. Even the latter
may cause under- or over-estimation errors of total body mass as large as 4.6%.
Body segment data have been obtained from living people using gamma-ray scanning
or from imaging techniques, such as computerised tomography and magnetic
resonance imaging. These may eventually supersede the cadaver data that are still too
often used.
Obtaining body segment parameter data from sports performers may require sophisticated
equipment and a great deal of the performer’s time. The immersion technique is
simple, and can be easily demonstrated by any reader with a bucket, a vessel to catch the
overflow from the bucket, and some calibrated measuring jugs or a weighing device (see
Figure 4.10 and Study task 5). It provides accurate measurements of segment volume
and centre of volume, but requires a knowledge of segmental density to calculate
segment mass. Also, as segment density is not uniform throughout the segment, the
centre of mass does not coincide with the centre of volume.
Figure 4.10 Simple measurement of segment volume.
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