INTRODUCTION: Cross-country (XC) skiers employ a variable pacing pattern with higher metabolic rates and power production during uphill than flat and downhill sections. To improve performance, refining XC skiers` micro-pacing strategy through adjustments of speed in specific parts of flat and downhill terrain sections can be beneficial. Therefore, the aim of this study was to investigate performance-effects of video- and sensor-based feedback by implementing a terrain-specific micro-pacing strategy in XC skiing. METHODS: Following a simulated 10-km skating time-trial (Race1) on snow, 26 national-level male XC skiers were randomly allocated into either an intervention (INT, n=14) or control group (CON, n=12), before repeating the race (Race2) two days later. Between races, INT received video- and sensor-based feedback through a theoretical lecture and a practical training session aiming to implement a terrain-specific micro pacing strategy focusing on active power production over designated hilltops to save time in the subsequent downhill. CON only received their overall results and performed a training session with matched training load. During the races the skiers were equipped with wearable sensors (GNSS, IMUs, heart rate), and prior to the field test, performance and physiological measures were collected in the laboratory. RESULTS: From Race1 to Race2, INT increased the total variation of chest acceleration on all hilltops (p<.001) and reduced the time spent in a specifically targeted downhill segment (mean group difference: -0.55 s, CI95[-0.9,-0.19 s], p=.003), as well as the overall time spent in downhill (-14.4 [-21.4,-7.4] s, p<.001) and flat terrain (-6.5 [-11.0,-1,9] s; p=.006) compared to CON. The increased speed in the specifically targeted downhill segment did not correlate with the skiers` laboratory measures or a 20-m on-snow speed test, implying that the increase in performance occurred independent of the skiers` physical capacities. However, there were an association between the skier`s speed on the hilltop in Race1 with improved speed on the hilltop from Race1 to Race2 (R=-0.57, p=.036) and reduced time in the following downhill segment (R=-0.68, p=.007). This means that the skiers with lower speed on the hilltop in Race1 improved more than the skiers with higher speed. There was also an association between race-time in Race1 and improvement in race-time, so that skiers with longer race-time in Race1 improved more than the faster skiers (R=0.86, p= <.001). No between-group differences were found for overall time spent in uphill terrain (-9.3 [-31.2,13.2] s, p=0.426) or total race-time (-32.2 [-100.2,35.9] s, p=.339). CONCLUSION: Targeted training combined with video- and sensor-based feedback led to successful implementation of a terrain-specific micro-pacing strategy in XC skiing, which induced reduced time spent in downhill and flat terrain for INT compared to CON. However, no change in overall performance were observed between the two groups of XC skiers.
© Copyright 2022 27th Annual Congress of the European College of Sport Science (ECSS), Sevilla, 30. Aug - 2. Sep 2022. Veröffentlicht von Faculty of Sport Science - Universidad Pablo de Olavide. Alle Rechte vorbehalten.