Introduction to Sports Biomechanics: Analysing Human Movement ...

IDENTIFYING CRITICAL FEATURES OF A MOVEMENT
Much of our work as movement analysts involves the study and evaluation of how
sports skills are performed. To analyse the observed movement ‘technique’, we need
to identify ‘critical features’ of the movement. These features should be crucial to
improving performance of a certain skill or reducing the injury risk in performing that
skill – sometimes both. For a qualitative biomechanical analyst, this means being able to
observe those features of the movement; for the quantitative analyst, this requires
measuring those features and often, further mathematical analysis (Chapters 4 to 6).
Identification of these critical features is probably the most important task facing a
qualitative or quantitative analyst, and we will look at several approaches to this task in
this section. None is foolproof but all are infinitely better at identifying these crucial
elements of a skill than an unstructured approach. Sometimes it can be helpful to define
a ‘scale of correctness’ for critical features, for example poor = 1 to perfect = 5, or a
‘range of correctness’, such as ‘wrist above elbow but below shoulder’.
The ‘ideal performance’ or ‘elite athlete template’ approach
This involves devising a set of critical features identified from an ‘ideal’ (sometimes
called a ‘model’) performance, often that of an elite performer, hence the alternative
name. This approach has nothing to recommend it except, for a lazy analyst, its
minimal need for creative thought. It assumes that the ideal or elite performance is
applicable to the person or persons for whom the analyst is performing his or her
analysis. There is now wide agreement among movement analysts that there is no
universal ‘optimal performance model’ for any sports movement pattern. Each
performer brings a unique set of organismic constraints to a movement task; these
determine which movements, out of the many possible solutions for the task under
those constraints, are best for him or her.
Movement principles approach
QUALITATIVE ANALYSIS OF SPORTS MOVEMENTS
As we saw in a previous section, different authors propose different principles underlying
coordinated movements in sport. This does not provide a convincing backdrop
for identifying critical features of any movement by reading down a list of such
principles. Categorising principles as general, partially general, or specific (as in
Box 2.3), while it does conform to the constraints-led approach (see below), does not,
in my recent experience, necessarily provide the answer either.
Nevertheless, the ‘list of principles’ approach is commonly used and often works well
when analysing low-skill individuals. However, it is very susceptible to blind alleys
as relationships between critical features are not apparent, in stark contrast to the
deterministic modelling approach. I would caution against a mechanistic application of
the movement principles approach. I would advise instead awareness of the important
movement principles that need to be used in devising a deterministic model of a given
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