INTRODUCTION: Classification is a critical aspect of the Paralympic sport since it determines who is and who is not eligible to compete in Paralympic Sport (van de Vliet 2012). Therefore the decisions determining eligibility into Paralympic sport are getting more important. Determining the minimum disability criteria, and furthermore a framework to classify the athletes based on their individual limitations, should be based on empirical evidence as the class allocation based on functional limitations may leave room for interpretations (Vanlandewijck et al. 2011). As it was shown in non disabled skiers in different sitting positions (Rapp et al. 2014), stabilizing the trunk muscles is essential in order to achieve good core stability for an effective pole impact. In disabled sit skiers a coordinated activation of trunk and arm muscles is therefore expected to be a pre requirement for good skiing performance. Neuromuscular activation characteristic are well known in non disabled cross country skiers (Lindinger et al. 2009, Holmberg et al. 2005). In disabled sit skiing, however, research is lacking at present. Therefore research in Paralympic Nordic sit skiing should focus to get more insight into the activation characteristics in the functionality of skiing performance in sit skiers from different levels of impairment. METHOD: In the last 2 years a test battery was established to evaluate neuromuscular activation from non disabled and as well elite disabled sit ski athletes. The test consists of an ergometer test, simulating double poling with maximal velocity and a balance test. In the balance test unforeseen forward and backward movements were elicited in the individual sitting position of each athlete, sitting in his/her own sledge. For non disabled participants an adjustable chair was constructed to simulate the sitting positions commonly used in competition. Pulling forces and ground reaction forces were recorded synchronously with surface EMG from arm and from different trunk, hip and thigh muscles. Kinematic analyses were done by video analyzing. For comparison of the laboratory situation with real skiing performance disabled athletes performed in Vuokatti Ski tunnel trials with maximum velocity and sub maximum velocity in a flat and uphill terrain. RESULTS: In the perturbation test a muscular response to the forward motion of the platform was shown in the abdominal muscle group at about 200 ms after the perturbation which is interpreted as reflex activity. In a functioning neuromuscular system this reflex mediated muscle response is therefore essential to maintain the sitting balance. No such activation was visible in disabled athletes from classes lower LW11. Preliminary results utilizing cluster analysis support that than trunk activation is an important factor in grouping the athletes. Comparing the performance at the ergometer test in the laboratory and the maximum speed in the tunnel it could be shown, that the fastest athletes in ergometer performed also best in the tunnel. DISCUSSION & CONCLUSION: From a methodological point of view neuromuscular recording with surface EMG in disabled athletes is challenging, especially in spinal cord injury persons with a high lesion. The perturbation test and cluster analysis seem to be applicable to be used in the classification process in the future. It needs to be tested if the information related to trunk activity can be obtained by using inertial measurement units (IMU) instead of EMG. Furthermore, measurement of MVC contraction for normalization the neuromuscular activity is a point for further discussion. --- The hosting University of Jyväskylä is planning to publish conference proceedings "Science and Nordic Skiing III". In case you are interested in this publication please contact the editors (Anni Hakkarainen anni.s.j.hakkarainen@jyu.fi) to become registered for the book.
© Copyright 2015 3rd International Congress on Science and Nordic Skiing - ICSNS 2015. 5-8 June 2015, Vuokatti, Finland. Julkaistu Tekijä University of Jyväskylä; University of Salzburg. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator