INTRODUCTION: The various skating techniques in skiing are sometimes described as similar to gearing systems in cycling where terrain influences the choice of gear. Skating uphill, many skiers use V2 technique on low angled slopes and V1 on steeper hills. Treadmill testing of skating has compared V1 and V2 techniques for various physiological charact-eristics (Kvamme et al., 2005) but measurements on snow are more difficult. Limited energy analysis of classical skiing is available (Pellegrini et al. 2013) but none has been reported for skating. In this paper, world cup racers were analyzed using 3D video techniques on a long climb where both V1 and V2 techniques were used by some skiers. METHODS: Position data in 3D were collected during the men's 15 km (3 x 5 km laps) world cup race at Beitostølen, Norway. Five cameras were used videotaping the athletes in the lower portion of a long uphill where inclination was about 6.5°. The DLT method was implemented in MatLab to determine full-body 3D position-time data. Digitizing of landmarks was completed at 25 Hz. From the 3D data, center of mass position (CM), potential energy (PE), kinetic energy (KE), total energy (TE) and power were determined. Four skiers used V2 technique on the first lap and V1 technique on the third lap of the race providing opportunity to compare the techniques under similar race conditions. RESULTS & DISCUSSION: Skating speeds were slightly slower using V1 in the third lap: 4.1 ± 0.1 m/s with V2 vs 3.8 ± 0.1 m/s with V1. This difference affected overall magnitude of KE observed (Figure 1) but not the pattern of energy fluctuations. Large changes of KE were seen during each V2 cycle (175 ± 62 J) compared to V1 (105 ± 19 J). Likewise, PE changes during a cycle of V2 involved large elevations of CM with each skating stroke (Figure 2). Average work rate against gravity (power) was 323 ± 7 vs 305 ± 15 watts, V2 vs V1. Two large power peaks were observed for V2 with each skating stroke: 902 ± 112 vs 669 ± 65 watts for V1. Not illustrated is TE where for V2 skating two distinctive plateaus were observed which suggest a pendulum like exchange of KE and PE. CONCLUSION: Mechanical energy patterns for V1 and V2 skating exhibited distinctive features: V1 skating involved smaller fluctuations of both KE and PE. The larger energy changes for V2 were associated with two power bursts per cycle which demanded nearly 1000 watt peak outputs. --- 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. Published by University of Jyväskylä; University of Salzburg. All rights reserved.