Skisens App Launch: Tracking Power on SkiErg, Treadmill, and Outdoor Skiing

A few weeks ago, Skisens launched its new training app, making it possible to connect and log workouts directly from the SkiErg. In the app, athletes can view power graphs, lap times, and performance metrics in the same way as during outdoor skiing or treadmill sessions. All training data flows into one system, collected in a single place and fully compatible with platforms like Strava. One of the most common questions skiers ask is how to compare watts on the SkiErg versus watts on the treadmill and outdoors.

Technique vs Power: What SkiErg Watts Really Mean

As we’ve highlighted before, “real” skiing places much higher demands on technique in order to direct force forward efficiently. Still, there are strong similarities in how power data can be interpreted. By tracking key metrics on both the SkiErg and the treadmill, skiers become more aware of which technical weaknesses they need to improve to increase speed on snow.

Roller Treadmill vs SkiErg: The Test Setup

To compare the two environments, we conducted two ramp tests with gradually increasing power — first on the treadmill, then on the SkiErg. On the treadmill, the incline was set to 5% with a starting speed of 9 km/h. Speed increased by 1.5 km/h per level. Each level lasted four minutes, with about one minute of rest between intervals. Rest periods were slightly longer on the treadmill to allow for lactate measurements. The treadmill data is shown in Figure 1.

Two days later, the same protocol was repeated on the SkiErg. The resistance was set to 7.5 (drag factor 100), which the athlete felt was similar to the 5% incline on the treadmill. The skier was instructed to match the same watt levels recorded on the treadmill. Figure 2 shows the SkiErg time series.

Heart Rate and Power: Almost Identical Responses

Comparing Figures 1 and 2 reveals that heart rate development is almost identical in both tests. The perceived exertion was also similar. To simplify comparison further, Figure 3 plots average heart rate versus average power per level for the SkiErg and treadmill. The heart rate matches power nearly 1:1 across both environments.

SkiErg vs Treadmill: Why Force Output Behaves Differently

Although heart rate and power correlate well across both platforms, the force profile differs significantly, as shown in Figure 4. On the SkiErg, pull force increases linearly with power, while on the treadmill the force is initially constant and even drops slightly from level one to level two.

The SkiErg’s resistance comes from a fan flywheel, where resistance increases with rotation speed. On the treadmill, resistance is determined by incline and rolling resistance, which remain nearly constant. The force drop from level one to level two results from wheel warming and reduced rolling resistance. As speed increases, technique becomes more limiting, forcing the athlete to generate more pole force.

Understanding Pole Efficiency: A Key Skiing Metric

The share of force directed forward — known as the pole-efficiency index — is defined as η = Fav / Fax, where Fav is the average forward-driving force and Fax is the average axial pole force. Maintaining efficiency under higher loads requires good technique. As efficiency drops, the skier must produce more force to maintain external power.

External Power vs Internal Load

External power (Pext) is the forward-driving power that moves the skier in real skiing. Internal load is the total muscular effort. These are tied together by efficiency:

_Pext = F_av * v = η * F_ax * v

If efficiency drops, axial force must rise — which explains the increasing pole force seen in Figure 4. Pole power correlates strongly with internal load, which is why heart rate tracks pole power more closely than external power.

SkiErg Training vs Real Skiing Performance

The SkiErg is an excellent tool for tracking capacity in watts and for power-based intensity control. The challenge is that the SkiErg does not stimulate ski-specific technique. In fact, frequent SkiErg use can reinforce a technique that works indoors but doesn’t translate to snow.

Skisens provides tools to monitor technique through frequency, contact time, impulse, and force curves — increasing the likelihood that SkiErg improvements also lead to faster skiing outdoors.

Why You Should Test on a Treadmill Regularly

If a large share of your training is SkiErg-based, we recommend a reference treadmill session once per month. This lets you track your pole-efficiency index, monitor key metrics, and convert SkiErg watts into expected outdoor performance. You can improve skiing performance by raising either efficiency or capacity — and Skisens helps you identify where your greatest potential lies.

Don’t forget to download the Skisens app and see how you stack up!

Merry Christmas and Happy New Year!