Multi-dimensional coordination in cross-country skiing analyzed using self-organizing maps.
This study sought to ascertain how multi-dimensional coordination patterns changed with five poling speeds for 12 National Standard cross-country skiers during roller skiing on a treadmill. Self-organizing maps (SOMs), a type of artificial neural network, were used to map the multi-dimensional time series data on to a two-dimensional output grid. The trajectories of the best-matching nodes of the output were then used as a collective variable to train a second SOM to produce attractor diagrams and attractor surfaces to study coordination stability. Although four skiers had uni-modal basins of attraction that evolved gradually with changing speed, the other eight had two or three basins of attraction as poling speed changed. Two skiers showed bi-modal basins of attraction at some speeds, an example of degeneracy. What was most clearly evident was that different skiers showed different coordination dynamics for this skill as poling speed changed: inter-skier variability was the rule rather than an exception. The SOM analysis showed that coordination was much more variable in response to changing speeds compared to outcome variables such as poling frequency and cycle length.
Faculty of Sports and Health Science, Technische Universität München, Munich, Germany. Electronic address: peter.lamb@tum.de.
Peter F
PF
Lamb
School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand.
Roger
R
Bartlett
Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria.
Stefan
S
Lindinger
School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand.
Gavin
G
Kennedy
D000054:Acceleration; D000293:Adolescent; D000328:Adult; D054874:Athletic Performance; D001696:Biomechanical Phenomena; D004576:Electromyography; D005080:Exercise Test; D006801:Humans; D008297:Male; D016571:Neural Networks, Computer; D011597:Psychomotor Performance; D012865:Skiing / Q000523:psychology*; D013548:Sweden; D055815:Young Adult
2330; 3720; 4160; Attractors; Coordination dynamics; Cross-country skiing; Double poling; Multi-dimensional coordination; Redundancy; Self-organizing maps