european college of sport science

PP-TT17 Training and Testing 17
INDUCED INCREASE OF SYSTEM IMMANENT VARIABILITY THROUGH AN ELASTIC CORD TECHNIQUE TRAINING DEVICE
AND A PRACTICAL APPLICATION
HAUDUM, A., BIRKLBAUER, J., KRÖLL, J., SCHWAB, R., MÜLLER, E.
CHRISTIAN DOPPLER LABORATORY ‘BIOMECHANICS IN SKIING’, UNIVERSITY OF SALZBURG
In motor learning a leading aspect has been on the contentious issue whether movement variability is dominantly attributable to measurement
error (Van Emmerik & Van Wegen 2002) or whether it is a system inherent necessity to flexibly adapt to changing environment.
Ever since Kelso’s coordination dynamics theory (1995) and Schöllhorn’s practical application of various forms of variable practice (2000)
movement variability is seen as an inevitable and intrinsic feature for motor learning. According to Bernstein (1967) movement outcome is
the result of an equivocal relationship between forces generated by muscle contraction and so called reactive phenomena (gravitation,
inertia, forces stored in muscle-tendon unit). Hence, if variability of non-muscular genesis is a determinant in movement outcome
changes in reactive phenomena should be increased to develop an interpolation ability to adequately adapt to new situations, i.e. stability
at one point that relies on the freedom of others to vary. This demand could be put into practice with elastic cords fastened between
joints acting as constraints to increase the degrees of freedom and consequently skill related movement variability within the optimal
range.
In two experiments we investigated the effect of elastic cords in a complex closed skill under laboratory conditions and in an open sport
skill under training conditions. In the latter one variability was further increased by purely altering cord applications.
In the first experiment variability in muscle activity during treadmill running increased with the elastic cords between 39 and 119 % (2
(running condition) X 7 (block) ANOVA: eta2=.55-.70; p