# Performance-Determining Variables of a Simulated Skimo
## 2 Methods
### Day 4  
#### 2.7.1 Simulated Sprint Competition  
The sprint competition was simulated on a racecourse that adhered to the ISMF sprint rules (see Figure 2) [3]. The race consisted of four technical sections (Section 1 on skis, S1S; Section 2 on foot, S2F; Section 3 on skis, S3S; Section 4 downhill, S4D) and three transitions (T1-2-3), with specified distances and climbs for each section.  
Figure 2: Three-dimensional profile of the racecourse. In accordance with ISMF sprint rules [3], the simulated sprint event took place on a 645 m course, which included both uphill (338 m) and downhill (307 m) sections, resulting in a total climb of 67 m. The average slopes for uphill and downhill were 21.1% and 23.2%, respectively. The blue line marks uphill skiing sections; the green line marks the uphill running section; the red line marks the downhill section; black squares with red outlines mark transition areas between sections; Start marks the race start; Finish marks the race finish.  
The weather during the competition remained stable, characterized by partly cloudy and foggy conditions. The mean (range) values for ambient air temperature, relative humidity, and snow temperature were \(-\)3.1 \({}^{\circ}\)C (\(-\)2.75 to \(-\)3.5 \({}^{\circ}\)C), 84% (83-85%), and \(-\)4 \({}^{\circ}\)C, respectively. No wind was observed on the course, and the snow comprised older layers with new snow from previous days.  
The skiers were equipped with a combined GNSS, inertial measurement unit (IMU), and barometric pressure sensor (Naos, Archinisis GmbH, Duldingen, Switzerland), which was replaced between different finals. The methodology used has been previously described [32]. To enhance GPS accuracy, all sensors were activated at least 45 min before testing. Archinisis software (0.1.3 ANAVS) improved precision by computing an average reference course with a defined course and elevation profile using data from 10 segments. The sensor automatically detected movement cycles and their corresponding sub-techniques, utilizing trunk inclination peaks as cycle indicators. It applied a Gaussian mixture model to classify these cycles into sub-techniques, considering metrics like cycle distance, lateral excursion, and trunk inclination consistency within each cycle [33].  
Participants wore electrode belts to monitor heart rate (Polar H10, Polar, Kempele, Finland), and used their own ski equipment, including poles, boots, skis, and skins during the simulated competition. Athletes had an hour for individual warm-up routines. Subsequently, they participated in an individual time trial to determine quarterfinal heats based on their TT rank. The two fastest skiers (rank 1-2) from each quarterfinal advanced to the semifinal heats, while the four slowest skiers (two withdrew after TT) competed in the Lucky Loser Final (LLF). The two fastest skiers from each SF advanced to the big final, whereas the two slowest skiers from each SF competed in the small final. Recovery times between TT, QF, SF, and F were set to 45-60 min, 30 min, and 30 min, respectively, to avoid potential impacts on subsequent performance. Rate of perceived exertion (RPE) was assessed utilizing the 6-20 Borg scale [34].