Understanding Ski Power Metrics: How Slower Skiers Can Become Faster (2/2)

Understanding the detailed force curves shown in the previous article requires some technical background and is primarily aimed at coaches, elite skiers, and those with the time and drive to dive deeply into skiing biomechanics. For skiers with less time — but who still want to improve — Skisens offers several other ways to analyze skiing technique using key metrics plotted against time or distance.

For capacity analysis, we use power — an effort-neutral metric representing the body’s useful work per unit of time. The figures below show power plotted against time for the cases of increasing speed and increasing incline, corresponding to the force curves in Figures 2 and 3. It should be noted that both tests were performed close to the athlete’s maximal capacity. From the power curve alone, we cannot distinguish the technical differences observed in the force curves — but we can when we study impulse and frequency over time.

Fig. 4. Power during increased speed (left) and increased incline (right). Red curve: measured with Skisens grips. Blue curve: calculated from treadmill friction, speed, and incline.

Technique Insights Without Studying the Full Force Curve

If you want to study technique without diving into the details of the full force curve, Skisens provides simple yet powerful key metrics such as frequency, impulse, and ground-contact time. Figure 5 shows how impulse and frequency changed for a test skier during the maximum-speed test illustrated on the left side of Figure 4.

It is clear that the skier increases frequency as ground-contact time decreases and impulse drops. The horizontal (forward-directed) impulse declines even more than the total impulse — exactly as seen in the force curve in Figure 2. This indicates that the skier has the potential to improve technique for more efficient high-speed skiing.

Fig. 5. Frequency and impulse during increased speed in a maximum-speed test.

Force–Velocity and Power–Velocity: Advanced Tools for Ski Capacity Analysis

For skiers interested in a more statistical approach to understanding how force production changes with speed and over time, Skisens allows you to plot “force-velocity” and “power-velocity” diagrams. These are commonly used to analyze sprinters’ ability to accelerate and show clearly how the ability to generate forward force decreases as speed increases.

A rough approximation is that force decreases linearly with speed. Under this assumption, power scales quadratically with speed and reaches a maximum before dropping toward zero at the speed where the skier can no longer generate forward-directed force. Figure 6 shows two diagrams from a 2.5-hour roller-ski session illustrating this behavior.

Fig. 6. Data collected during a 2.5-hour roller-ski training session.

The upper boundary lines in Figure 6 represent what was achieved during short periods of the workout. These values are relevant for estimating maximum sprint potential. A sprint skier, for example, can generate high force at high speed — something that may not be apparent from a single submaximal training session. By comparing curves across multiple sessions, these diagrams become powerful tools for tracking development while accounting for day-to-day variations and environmental factors.

Power Profile: Understanding Aerobic Capacity Over Time

Over longer time periods, power output is limited by aerobic endurance. A very useful tool for illustrating this is a curve showing average power over time — commonly called a “power profile” in cycling. This provides a clear picture of overall capacity. Figure 7 shows the power profile from the same roller-ski session as in Figure 6.

Fig. 7. Power profile from a 2.5-hour roller-ski session.

Just like the force-velocity and power-velocity diagrams, the power profile must be built up over multiple sessions to give a fair representation of a skier’s capacity. When properly developed, it clearly highlights the characteristics trained in each session. For example:

– Sprint sessions show high values up to 15–20 seconds
– Aerobic intervals show high values between 1 and 20 minutes (or more)

Power profiles are a well-established tool in cycling. Our coaching partner, Guided Heroes, has deep expertise in using them. We are now learning which elements transfer directly to skiing and which need adaptation.

Compared to cycling, power profiles in skiing are flatter — skiers cannot reach as high short-duration power due to technical constraints at high speed. On a bike, gearing allows optimal force application at any speed. In skiing, technique limits power output at high speed. One reasonable hypothesis is that extremely high short-duration power could be achieved when double-poling up a very steep hill. Another is that elite skiers can maintain higher power across different speeds compared to recreational skiers. We will return to this with more data once testing has been carried out under the right conditions.

Looking Ahead: Field Testing, Coaching, and Improving Your Skiing Efficiency

In the coming winter, Skisens — together with our coaching partner Guided Heroes — will offer field-based technique and capacity testing using the key performance metrics discussed above. Skisens identifies your potential and your areas for improvement, and Guided Heroes’ experienced ski coaches help take your technique and performance to the next level.

Together, we help skiers who want to become faster.

– Dan Kuylenstierna