Kinematic differences between uphill roller skiing and on-snow skiing using the V2 skating technique

Purpose Roller skiing is the primary sport-specific training and testing mode during pre-competition periods for cross-country skiers, biathletes, and Nordic combined athletes. The present study aimed to compare the kinematics between uphill roller skiing and on-snow skiing using the V2 sub-technique. Methods In a cross-over design, nine well-trained male skiers performed short trials (< 40 s) at constant inclination (8.0 degrees), speed (3.0 m.s(-1)), and controlled rolling/gliding friction on asphalt (in the fall), on the treadmill (in the fall and winter), and during on-snow skiing (in the winter). Kinematic data were collected using a validated inertial measurement unit system. Results Repeated-measures ANOVAs revealed no differences between treadmill and asphalt roller skiing. Further, including on-snow skiing showed moderate to good reliability (ICC >= 0.63, p <= 0.001) for ground-contact temporal variables. However, on-snow skiing moderately increased hip range of motion around the longitudinal axis (22.2 +/- 7.7 degrees vs. 14.1 +/- 4.7 degrees), lateral hip displacement (44.1 +/- 7.1 cm vs. 37.2 +/- 6.6 cm) and pole push times (422 +/- 41 ms vs. 386 +/- 31 ms), and on-snow skiing was characterized by altered hip rotational patterns compared to roller skiing. Conclusion V2 roller ski skating simulates on-snow ski skating to a large extent, but the mechanical properties of the skis and/or surface hardness systematically alter skiers' hip movements and pole push times. This implies a potential for equipment optimization to increase training specificity during pre-competition periods and highlights a need for future studies to examine the kinematic effects of snow hardness on all sub-techniques.