INTRODUCTION: Over the last decade a new sprint technique has emerged, the diagonal running (DIA-run) technique. This technique differs from diagonal stride (DS) due to the absence of the gliding phase and therefore resembles running. It is regularly used in sprint races for acceleration and high speed diagonal skiing. No previous study has biomechanically compared the DIA-run with the DS or herringbone (HB) techniques on snow. Hence, the aims of the present study were to examine the kinematics and kinetics that differentiate the techniques, as well as performance. METHODS: Thirteen male elite cross-country skiers performed two maximal sprint trials uphill with; 1) the DS and HB and 2) entirely the DIA-run technique. The slope had a steady incline of 7.5° for the first 40 m with an increase to 15° for the last 10 m. It was divided into two measuring sections (S1-2); S1) 20 m of moderate (7.5°) incline and S2) 8 m of steep incline (15°). RESULTS: In S1 the DIA-run was 4.9% faster than the DS technique, and in S2 HB was 6.1% faster than the DIA-run technique (both P < 0.05). The cycle rate (CR) was 1.77 ± 0.12 Hz for DIA-run vs. 1.42 ± 0.21 Hz for DS and the cycle length (CL) was 3.19± 0.28 m for DIA-run vs. 3.78 ± 0.48 m for DS (both P < 0.05). In S2 the CR was similar for HB and DIA-run, -1.60 ± 0.13 Hz. Thus, the higher speed when using HB was due to the longer CL, 2.31 ± 0.22 m vs. 2.17 ± 0.16 m (P < 0.05). In both sections, there were no significant differences between the techniques for peak pole and foot forces. All together, peak pole and foot forces were 25.0 ± 4.9 and 123.4 + 26.3% of body weight respectively. Pole/foot-force impulse ratio in S1 was 14.6 ± 4.0% for DS and 12.4 ± 4.2% for DIA-run. In S2 the ratio was 15.7 ± 5.5% for HB and 18.4 ± 7.7% for DIA-run. A group comparison revealed that for both trials the six fastest skiers had -18% higher relative peak foot force and -14% higher rate of foot force development (both P < 0.05). CONCLUSION: In the current study DIA-run was only beneficial to use on the 7.5° incline, the HB technique was faster on the steep 15° incline. The pole/foot-force ratio revealed large individual differences in how the contribution of forces from the upper vs. the lower body are distributed and remains to be further investigated. The necessity for fast force production highlights the importance of training to improve explosive strength and power to increase maximal skiing speed.
© Copyright 2010 Book of Abstracts. 5th International Congress on Science and Skiing, Dec. 14 - 19, 2010, St. Christoph am Arlberg. Published by University of Salzburg, Interfakultärer Fachbereich Sport- und Bewegungswissenschaft/USI. All rights reserved.