INTRODUCTION: The "new" freestyle (FT) in XCS was formally introduced in 1985 in specialized races. In the `90s several studies have been conducted in an attempt to describe the most relevant aspects of XCS freestyle, but the kinematic information is generally limited over the full velocity range. More recently Stöggl (2010), Andersson (2010), Lindinger (2011) compared biomechanical characteristics of the main skating techniques identified as gears G1-G5 as proposed by Nilsson (2004). The purpose of this work was to analyze the 3D kinematics and its changes of the main gears (G3 & G4) performed by elite skiers during sprint World Cup races in the last decade and to calculate energy recovery parameters. METHODS: The data collection was performed in 2012 (Dobbiaco) and 2023 (Livigno) during WC XCS individual Sprint Qualification FT races. In the 2012 race a total of 11 male skiers (ranking 122) were analyzed on flat sections where the athletes performed G3 or G4. In the 2023 race, in similar conditions of flat terrain, all the 30 skiers qualified for the heats were analyzed where 16 performed G3 and 14 performed G4. RESULTS/DISCUSSION: Linear kinematic and angular parameters were calculated for each athlete (Table 1) as their mean values averaged over several cycles for each race. For the CoG Velocity we found some significant differences between G3 and G4. The CoG velocity in G4 was lower than in G3 about 4%, in 2012, and 9%, in 2023. The faster skiers have lower cycle time/higher cycle rate, in both strides: G3 (r=0.62) and G4 (r=0.66). The corresponding energy recovery indices are reported in Table1. We found a significant decrease of the R% between the 2012 and 2023 races: R% is lower 36% for G3, and 50% for G4. CONCLUSION: Skiers that adopted the G3 technique were faster than G4-skiers. Moreover we found that the faster skiers, in G3 and G4, have a longer cycle rate. The skiers adopted to a different strategy to perform the poling with respect to the trunk, shoulder and elbow angular variations. In the Double Poling (Canclini 2021) we calculated similar values of R% (32%) only for the 2° slope.
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