# Influence of the Slope and Gate Offset on Movement Variability and Performance in Slalom Skiing
## 2 Materials and Methods
### Procedures
#### 2.2.2 Course Setting  
In order to simulate different competition scenarios, four SL course settings (Figure 2) were designed in accordance with the rules set by the International Ski Federation (FIS) [51]. The slope (12\({}^{\circ}\) and 21\({}^{\circ}\)) and gate offset (4 m and 3.25 m) were varied to replicate the conditions encountered in various competition sections. For ease of reference, each course was assigned a code based on its slope and gate offset: FT (flat-turned), ST (steep-turned), FS (flat-straighter), and SS (steep-straighter). In these codes, the first letter denotes the slope, and the second letter indicates the skier's trajectory based on the gate offset. A detailed gate analysis was performed on ten consecutive gates for each SL course. Gate placements  
Figure 1: Calibration process and axis orientation. In the lower-left corner, the calibration procedure is depicted, with the \(Z\)-axis perpendicular to the surface. The \(X\)-axis (blue) represents the vertical axis, the \(\gamma\)-axis (green) corresponds to the lateral axis, and the \(Z\)-axis (orange) indicates the antero-posterior axis. The photo has been reproduced with permission from [PERSON]/Comité Olimpico Español and has been edited by the authors.  
were measured precisely using tape measures to ensure consistency across all courses. For the flatter slope courses (FT, FS), the analysis focused on gates 6 to 15, excluding gate 16. Similarly, for the steeper slope courses (ST, SS), the analysis was conducted on gates 19 to 28, excluding gate 29. The initial gate consistently required a right turn (involving the left outer leg). This approach allowed for a comprehensive analysis of gate sequences while maintaining consistency in gate numbers across course configurations. Bar magnets (measuring D33 mm \(\times\) 267 mm, ND35, A.C. magnets 98, Barcelona, Spain) were positioned on ten successive gates for each SL course, adhering to the guidelines provided by [PERSON], et al. [50]. Prior to the trial runs, skiers were given a reconnaissance run to familiarize themselves with the SL courses. They were then instructed to perform 3 to 5 runs at maximum speed for each SL course. In total, 77 runs were collected, with 22 runs conducted on the FT course, 24 runs on the ST course, 16 runs on the FS course, and 15 runs on the SS course. Runs were distributed among five skiers: skier 1 (with counts of 4 FT, 4 ST, 0 FS, 0 SS), skier 2 (n = 4, 5, 4, 4), skier 3 (n = 5, 5, 4, 4), skier 4 (n = 4, 5, 4, 4), and skier 5 (n = 5, 5, 4, 3). Notably, skier 1 faced difficulty completing descents on the FS and SS courses due to lower back pain. To synchronize the accelerometry data with the video recordings of each run for visual validation, a portable Full HD camera (Panasonic HC-V700) recording at 30 Hz was employed. Throughout the data collection process, the snow surface was maintained in hard-packed and groomed conditions. To ensure standardization, coaches and the experimental team meticulously smoothed the course prior to each run. Air temperatures progressively increased from 1.1 \({}^{\circ}\)C to 1.9 \({}^{\circ}\)C over the course of the experiment. Relative humidity slightly decreased from 71% to 61%. The maximum recorded wind speed was 6.3 km/h, blowing from a south-westerly direction, perpendicular to the course.  
Terrain characteristics, such as the slope, were determined by generating a digital elevation model using high-resolution images obtained through a drone (DJI Mavic Air, SZ DJI Technology Co., Hong Kong, China) and several photogrammetry software (Agisoft Metashape Professional(r) 1.5.2 version, Agisoft LLC., St. Petersburg, Russia, and ArcGIS free software version 10.3, Environmental Systems Research Institute, Inc., Redlands, CA, USA).