Introduction to Sports Biomechanics: Analysing Human Movement ...

jumper’s body closest to the take-off board is behind where the feet land. That leads to
Figure 2.15, which contains our last three critical features. First, from the observation
that the athlete should land with his or her centre of mass behind their feet and low to
increase take-off height, we derive the need to land with ‘hips flexed and knees
extended’ (CF9), which is evident from Figure 2.4. To reduce any loss of landing
distance from touching the sand behind the landing point for the feet, we note simply
‘don’t touch the sand behind the landing point’ (CF10). The final critical feature is less
obvious and emphasises two important points: the need to be aware of the movement
principles relevant to the activity analysed and to have a thorough knowledge of that
activity. The forces acting on the jumper from the take-off board generate ‘angular
momentum’ that tends to rotate the jumper forwards during flight. If uncontrolled, this
would cause an early landing in the pit, which is why tucking or piking during flight are
counterproductive. Instead, the jumper needs either to minimise forward rotation by
adopting an extended ‘hang’ position, as in Figure 2.4 or, for longer jumpers, to transfer
this angular momentum (see Chapter 5) from the trunk to the limbs using a ‘hitch-kick’
technique, leading to our last critical feature ‘use hitch kick or hang’ (CF11).
Well we’ve got there, although it may have seemed a long journey. It is worthwhile,
because we finish up with confidence in our critical features from the rigour of the
deterministic modelling process, which is impossible to achieve from the copying of an
‘ideal’ or ‘model’ performance, very difficult to achieve merely from a list of movement
principles, and not always clear from other approaches. Also, as already noted, the
process highlights blind alleys, helping us to avoid them, and provides a well-structured
approach for identifying critical features.
Summary of the use of deterministic models in qualitative movement analysis
Using diagrammatic deterministic models is, in many cases, the best approach to
identifying critical features of a movement if we can formulate a clear performance
criterion.
It helps to overcome many pitfalls of qualitative analysis, such as a lack of a structured
approach to identifying critical features even within an overall structured
approach, and wandering down blind alleys.
It can suffer from rigid formalism; however, the step from the initial ‘qualitative or
quantitative’ approach to the identification of the critical features to be observed in a
qualitative analysis allows greater freedom, as in the long jump example above.
This greater freedom can be a problem as well, which can only be avoided by
thorough knowledge of the activity being analysed and from an awareness of
relevant movement principles and the constraints on the movement.
Other approaches to identifying critical features
QUALITATIVE ANALYSIS OF SPORTS MOVEMENTS
In Chapter 1, we touched on the constraints-led approach to human movement
analysis. In this relatively new approach, a particular sports movement is studied as a
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