Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
Method
The empirical study was carried out on three test days. A test group and
a control group with 23 and 24 age-group swimmers, respectively, were
involved in the study. Between the first and second test day the test
group performed specific workouts for six weeks. On the test days the
program ‘Split’ (SCHACK et al., 2000) was used to evaluate the representational
structure and the swimmers also performed a swimming
test of 2 x 25 meters crawl stroke at full speed. The control group only
performed the swimming test. To evaluate the long-term educational
effects of the cognition-based training, the swimmers of both groups
trained for another 12 weeks. The study was concluded by a final swimming
test for both groups and the test group also used ‘Split’ again.
During the sprints on the test days a) the time over a 10m distance
– from 10 to 20 m – and b) the stroke rate were measured and finally
the stroke length and the stroke index were calculated (the data of the
two trials were averaged). “Split” was used to sort out “basic action concepts”,
called nodes, representing arm/hand actions during crawl stroke.
The nodes were established by the coach in close relation to how he/
she normally describes stroking, however in a more structured manner.
After sorting out all nodes according to the criteria, if they belong
to the anchor node or not, as result one gets an impression of the mental
representation, which the swimmer has of its motion sequence (in
this example of the crawl arm stroke). By means of this computer programme,
the so-called split technique is used in order to achieve the
data of proximity.
“The SDA-M consists of four steps: First, a special split procedure involving
a multiple sorting task delivers a distance scaling between the BACs
of a suitably predetermined set. Second, a hierarchical cluster analysis is used
to transform the set of BACs into a hierarchical structure. Third, a factor
analysis reveals the dimensions in this structured set of BACs, and fourth,
the cluster solutions are tested for non-variance within- and between-groups
(for psychometric details, see Schack, 2001, 2002” (BLÄSING et al. 2009).
The mental representation is described by a so-called dendrogram and
clusters (groups of individual nodes). Analyzing the dendrograms and
the clusters special training-programs were created (theoretical and
practical), which were performed during the six week training period.
The individual stroking instructions were inferred from the results of the
SDA-M tests. The communication between coach and athlete was based
on defined notes. During the workouts established drills were used in
another context, dealing with one or more BAC and their connection
to each other. First the coach explained to the athlete (a) the results of
split and in most of the cases (b) again all the nodes and their impact
in the stroking action, especially the ‘problem-nodes’ of the athlete. This
was the basis of the workouts covering each node with drills and then
later on groups of nodes and especially the ‘problem’ nodes. So in each
workout (after one or more drills) by using the nodes, the connection of
one node to the neighbor-nodes or a group of nodes to each other was
discussed. During stroking the swimmer had to concentrate on what
he was doing and on his feelings (e.g. stroking, propulsion) telling this
later to his coach.
As an example, the BACs of one of the training groups are shown here:
Fingers enter water (1), Shrugging shoulders (2), Rolling to side of action
(3), Downwards (4), Pronation (5), Elbow extension (6), Rolling
back (7), Slicing hand (8), Breathing (9), Hand forward (10).
results
The following figures show the representational structure of one swimmer
at test 1, 2 and 3.
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Fig. 2 Dendrogram of one swimmer (test 1) without any cluster and
without a real regularity of the nodes. The distances between the nodes
are quite large, therefore do not cluster.
Fig. 3 Dendrogram of the same swimmer after the six week training
period (test 2) with three clusters (all nodes are integrated in clusters
and are in biomechanical regularity)
Fig. 4 Dendrogram of the same swimmer after 18 weeks (six weeks specific
training and 12 weeks ‘normal’ training (data 3). The dendrogram
shows four clusters, regularity of nodes, but also partly increased distances
between nodes.
At test 1 the structure is not really sorted, the distances between the BACs
are quite large (it does not have any clusters). After the training period