INTRODUCTION: In the last decade, SKIMO skiers improved their technical and physiological performances in all kinds of races. Due to the complex multiparametric environment conditions and the relatively recent development of the discipline, there is a lack of specific studies, especially under race conditions [4]. On the other hand, technique and physiological analysis comparing normal race and treadmill conditions have been undertaken [1-5]. The purpose of this study is to investigate the kinematics and the energy patterns of elite SKIMO skiers during high-level competitions such as Sprint World Cup races. METHODS: Data collection was performed in 2016, 2017 and 2022 during 3 World Cup sprint qualifications. For each race, a minimum of 5-10 top male and female skiers were analyzed by standard 3D kinematic analysis (CCD-Camera 50Hz) on an uphill section (21°) where the athletes performed Diagonal Stride (DS). Mechanical energy fluctuation was calculated using the same approach presented early where R+ and R(t)cyc indicate the energy recovery indices for only the positive variations or the absolute values of positive and negative energy fluctuations respectively. R(t)cyc is computed by the sum of poling (R(t)pol) and swing phases (R(t)swi) [5]. RESULTS/DISCUSSION: Mean value averaged on 4 movement cycles were calculated. For males, CoG velocity was similar but poling time differs with higher values in the 2016 race. The vertical CoG displacement was higher in 2022 (Tab. 1). The R+ values were consistent (16,12 % vs 15,54%) in both races but differences are noted for R(t)cyc (15,61 % vs 21,14%) and this is mostly accounted for by the amount of the poling phase (R(t)pol Tab.1). Females show lower CoG velocity and higher R+ and Rcyc values (39,37% and 30,71%) respectively. Some linear and nonlinear relationships were found between the R(t) indices and kinematic parameters. CONCLUSION: Significant changes in the time structure occur during the years and this is due mostly to a reduction of the poling time decreasing from 61% to 53% of the entire cycle time (CT). Comparing these results with those obtained for CCS specialists in a WC-race 2009 (8° inclination), CCS show significant differences for the CoG kinematics with higher values of avg_Vel, CL, CT and DispY (45%, 55%, 18% and 52% respectively) as well as for R+, R(t)cycl, R(t)pol and R(t)swi (51%, 44%, 24% and 53% respectively). Relationships between CL, CT and the energy recovery indices are presented.
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