GPS ski analysis explained for coaches

GPS athlete data is becoming a greater part of alpine ski racing analysis at every level. It is often described as accurate, objective, and powerful. Those descriptions are incomplete without understanding what GPS actually measures, where it is reliable, and how it should be interpreted alongside video.

This article explains GPS ski analysis in practical coaching terms. If you are looking for a broader overview of how video and GPS data work together in performance review, start with how to analyze alpine ski racing performance with video and GPS data.

What GPS measures in alpine ski racing

In ski racing, GPS primarily measures speed. In addition to speed, line and additional metrics are derived.

• Location on the hill. Each data point corresponds to a geographic coordinate, allowing the athlete’s path to be mapped onto the slope.
• Speed. Speed is calculated using the change in signal strength from the satellites, resulting a very accurate measurement.  
• Time progression. Because each positional sample is time-stamped, elapsed time at any location can be determined.
• Derived metrics. Acceleration and other measures are calculated from changes in speed and direction.

GPS does not directly measure pressure on the ski, edge angle, or body position. Those remain visible through video and coaching observation.

Understanding accuracy in context

GPS accuracy is often discussed as a single number. In practice, accuracy depends on context.

• Speed is the most accurate measurement. GPS in alpine skiing is a speed measurement tool.
  
• Use GPS to see where the athlete lost or gained speed. This plays to GPS's strength of accurate speed related to location on the course.
• Relative comparison is stronger than absolute location. When comparing two runs on the same hill, relative differences are typically more meaningful than the exact location.

For coaches, the key is learning how to GPS to test theories and make their workflows faster.

What GPS does well in slalom, GS and downhill

Each discipline places different demands on analysis.

• Slalom. GPS highlights rhythm changes, entry timing, and where acceleration builds or fades through combinations such as hairpins and flushes.
• Giant slalom. It reveals how force applied above the gate affects speed carry through the fall-line and into the next turn.
• Super-G and downhill. It helps quantify how terrain features, glide sections, and tactical adjustments influence overall time progression.

In all disciplines, GPS is strongest when used to identify sections of interest. Video is then used to explain what happened in those sections.

Virtual splits and sectional analysis

Because GPS links position and time, you can define sections anywhere on the hill. These are often referred to as virtual splits.

• Flexible placement. Sections can be placed at terrain transitions, key tactical gates, or before and after combinations.
• Consistent comparison. Once defined, those sections can be reused across multiple athletes and sessions.
• Immediate prioritization. If one section shows the largest time difference, review can begin there instead of watching the entire run first.

For a deeper walkthrough of side-by-side comparison and reference types, see how to compare ski runs using video and GPS data.

Limitations coaches should understand

GPS athlete data is powerful, but it is not complete on its own.

• It does not explain intent. A drop in speed may reflect a tactical adjustment, a terrain response, or a mistake. Video clarifies which one occurred.
• It does not replace inspection or feel. Athletes still rely on visualizing, terrain awareness, and timing built through repetition.
• It should not be interpreted in isolation. Single metrics can mislead if viewed without context from line choice and execution.

This is why Protern positions GPS as part of a broader category: video and GPS performance analysis for alpine ski racing. The data identifies where to look. The video shows why.

You can see how this fits into the overall training day on the How Protern Works page, and how video and data are connected on the Data-linked video analysis capability page.