Ground reaction force patterns represent the level of training.
BACKGROUND
Hopping dependent on speed causes different characteristics of ground reaction force pattern. Strongly set training-specific stimuli equally induce a corresponding characteristic of the force shape that is widely independent of hopping frequency. Thus it could be shown that 'jumpers' still generate a single modal force pattern with slow frequencies. Concerning other athletes, it only exists around the preferential frequency of motion. On this account we raised the question whether different types of sports are differentiated by the ground reaction force pattern and whether conclusions on the level of training could be made.


METHODS
Twenty-one athletes took part in the study. They had to perform speed depending hopping series. Since only the shape of force course was of interest, a normalisation was conducted. Additionally, this force shape was compared with a so-called 'standard-course'. The degree of variance was formed by the sum of residuals.


RESULTS
The ground reaction force differs from the standard course significantly with the reduction of the frequency of motion. The analysis of the test persons resulted in five different highly-significant clusters which are directly related to the contents of training (strength, endurance, etc.). With increasing performance level, the sum of residuals decreases most significantly. With the underlying method athletes from different types of sport can be classified. Furthermore, the item obtained by the analysis allows statements about the particular level of performance.


CONCLUSIONS
On the basis of the presented results this procedure can be seen as a simple possibility for performance diagnostics.
Department of Motion Science Institute of Sport Science FSU, Jena, Germany - thomas.ertelt@uni-jena.de.
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D056352:Athletes; D001696:Biomechanical Phenomena; D006801:Humans; D035002:Lower Extremity / Q000502:physiology; D015233:Models, Statistical; D009068:Movement / Q000502:physiology*; D064797:Physical Conditioning, Human / Q000502:physiology*