Introduction to Sports Biomechanics: Analysing Human Movement ...

SUMMARY
CAUSES OF MOVEMENT – FORCES AND TORQUES
sensitive to error than for force plates. Pressure insole software usually provides for many
displays of the pressure–time information. The software also allows the user to define
areas of the foot of special interest (up to eight normally) and then to study those areas
individually as well as the foot as a whole. The information available includes the
following:
Three-dimensional ‘colour’-coded wire frame displays of the summary maximum
pressure distributions at each sensor (the maximum pressure picture) and the pressure
distribution at each sample time (a monochrome version of which is shown in
Figures 5.28(a) and (b)), displayed as if viewing the right foot from below or the left
from above; these can usually be animated so that the system user can see how the
pressure patterns evolve over time. These are fascinating patterns of movement that,
to date, have been little used by qualitative analysts.
Force (sum of all sensor readings), maximum pressure and contact area as functions
of time for the whole foot and any specified region of the foot.
Bar charts of the peak pressure, force, contact area and the pressure–time integral for
all regions of the foot.
The centre of pressure path, or gait line (Figure 5.28(c)).
In this chapter we considered linear ‘kinetics’, which is important for an understanding
of human movement in sport and exercise. This included the definition of force,
the identification of the various external forces acting in sport and how they combine,
and the laws of linear kinetics and related concepts, such as linear momentum.
We addressed how friction and traction influence movements in sport and exercise,
including reducing and increasing friction and traction. Fluid dynamic forces were also
considered; the importance of lift and drag forces on both the performer and on objects
for which the fluid dynamics can impact on a player’s movements were outlined. We
emphasised both qualitative and quantitative aspects of force–time graphs. The
segmentation method for calculating the position of the whole body centre of mass of
the sports performer was explained. The vitally important topic of rotational kinetics
was covered, including the laws of rotational kinetics and related concepts such as
angular momentum and the ways in which rotation is acquired and controlled in
sports motions. The use of force plates in sports biomechanics was covered, including
the equipment and methods used, and the processing of force plate data. We also
considered the important measurement characteristics required for a force plate in
sports biomechanics. The procedures for calibrating a force plate were outlined, along
with those used to record forces in practice. The different ways in which force plate data
can be processed to obtain other movement variables were covered. The value of contact
pressure measurements in the study of sports movements was covered. Some examples
were provided of the ways in which pressure transducer data can be presented to aid
analysis of sports movements.
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