INTRODUCTION: The varying snow conditions in cross-country skiing races lead to significant changes in the resistive forces caused by ski-snow friction. Previous studies have examined how this affects skiers while skating on snow [1,2] and roller skis on a treadmill [3], but somewhat conflicting results have emerged. A common factor in these studies is that skier velocity was restricted. This study aims to investigate how cross-country skiers adjust their technique across varying resistive forces, on both traditional and roller skis, using perceived exertion and heart rate as a controlled factor to simulate a race-like situation. METHODS: The study involved 5 to 8 national-level cross-country skiers who participated in three tests conducted under different conditions: cold, hard-packed snow (-16ºC), warm, soft snow (3ºC), and on a roller-ski track (10ºC). Each athlete alternated between fast and slow skis, performing three intervals with each pair, while maintaining a self-selected skiing intensity corresponding to their threshold pace. Motion data were collected using advanced inertial measurement units (IMU) and GPS sensors (ASI, Switzerland) along a predefined flat track segment of 140 meters (approximately 10 cycles per segment). Cycle duration, cycle length, and velocity were calculated using Archinisis software (Archinisis, Düdingen, Switzerland). Data were analysed using paired t-tests to determine significant differences in technique adaptations between the fast and slow skis. RESULTS/DISCUSSION: The G3 segment data presented in Table 1 showed no significant change in cycle duration between fast and slow skis. However, longer cycle lengths and higher speeds were observed with faster skis. This suggests that athletes adapt by increasing cycle length rather than altering skiing frequency. These results somewhat contradict the findings of Ohtonen et al. [1], where skiing frequency increased with higher friction at constant speed, indicating that increased intensity leads to higher frequency. Moreover, when comparing roller skiing with snow skiing, similar cycle data were recorded, despite nearly double the friction coefficients. This difference points to varying friction mechanics between gliding and skating phases on snow and asphalt. CONCLUSION: The study concludes that cross-country skiers primarily adjust their G3 skating technique by increasing cycle length while maintaining a constant skiing frequency when using faster skis and sustaining a constant intensity. The findings also highlight the need for further research into the friction dynamics of roller skiing. This knowledge may help optimize skiing techniques for various environmental conditions, contributing to enhanced race performance.
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