INTRODUCTION: A free skiing race challenges the athletes to master a wide range of speeds and slopes and to adapt their technique accordingly. Indeed, skiers possess different skiing techniques and continuously change among them during a race. The skating technique has five predominant subtechniques, known as gears (G1-5) as suggested by Nilsson et al. 2004 (G2, G3 and G4 replace the old names V1-V2 and V2alternate). In the '90s several studies have been conducted in attempt to describe the most relevant aspects of XCS freestyle, but the kinematic information is generally limited in the velocity range. More recently Kvamme (2005), Smith (2007), Lindinger (2010), Stöggl (2010), Andersson (2010) compared biomechanical characteristics of the main skating techniques. In this work we collected and analyzed the 3D kinematics of the G2 gear in freestyle XCS performed by elite skiers engaged in recent a World Championships race. G2 is an asymmetrical uphill technique involving one poling action over every second leg stroke. METHODS: The data collection was performed in 2013 during World Championships-XCS individual 15 km FT races. Dedicated software for video analysis (DLT method) was used (Baroni 1998). A total of 11 male skiers (ranking 1-21) were analyzed when performing G2 on an uphill section race (approximately 10° / 17%). RESULTS: Figure 1 shows an example of stick diagram model and the typical pattern of the principal kinematic parameters for the skiers performing G2. Specific kinematics parameters were calculated for each athlete (tab. 1) and were reported as the mean value averaged on 2-3 movement cycles. Angles-vs-angles plots were used to investigate individual coordination patterns. Fig. 1 / Tab. 1: Parameters in Freestyle XCS during World Championships race 2013 DISCUSSION & CONCLUSION: In G2 gear, performed on uphill, we found a positive correlation between mean velocity and Cycle Length (r=0.62) and Push Time (r=0.69). These results present the same trend of previous studies conducted on diagonal stride on uphill in classical technique (Lindinger 2007, Canclini, Smith). Conversely in G2 there is no correlation between mean velocity and CT, as found in G3 and G4. The kinematics patterns of shoulders, elbows and poles angles were found to be quite similar to literature data. Moreover, the skiers adopted different strategy to perform the poling with respect to the trunk, shoulder and elbow angular variations. We focused our analysis on arms and legs asymmetrical movement. --- 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. Veröffentlicht von University of Jyväskylä; University of Salzburg. Alle Rechte vorbehalten. / Übersetzt mit https://www.DeepL.com/Translator