Vasaloppet Power Analysis: Ski Performance Data from Skisens Power Grips
On Sunday, March 3rd, 2019, I stood for the ninth time on the Vasaloppet start line in Berga By. For the first time, I raced with the Skisens power grips — a ski power meter measuring real-time force and pole angle — and I was eager to see how both the start and the first major climb would unfold. I was also curious whether the equipment would hold up and whether the data would reveal how well I could maintain power toward the end of the race.
Starting in Wave 3: Challenging Vasaloppet Conditions and First Use of Power Measurement
I started in wave 3, and in addition to using the Skisens grips for the first time, it was also my first race on waxless skis. To make the challenge even greater, the conditions were, as many participants likely remember, the worst since 2011 — perhaps even longer. After finishing, I spoke to a veteran who said the last time conditions were this difficult was possibly 1989.
Despite this, I chose to double-pole the entire race, primarily because I wanted clean power data from the grips without having to estimate leg contribution afterward.
About one minute before the start, I activated a custom training app on my Polar M600, receiving data from the Skisens grips, along with a Polar M400 tracking heart rate. For comfort reasons, I used only one heart-rate strap.
Vasaloppet Power Data: Start Section and First Climb
Below is the power data uploaded to Today’s Plan together with heart-rate data from Polar Flow for the first 25 minutes of my 2019 Vasaloppet. This section includes the start straight and the iconic first climb — a critical segment for pacing and performance analysis in long-distance cross-country skiing.
When the start went off, speeds quickly reached 20–25 km/h. The power curve shows roughly 200 watts, with larger variation at the small rise mid-start, where I periodically had to ease off to avoid skiing into those ahead.
At the road crossing, the field stopped, resulting in sharp drops in speed and power. Once the climb began, the skiing became very stop-and-go.
Power vs Heart Rate: Why Skiers Should Rely on Power for Intensity Control
The power curve in the climb follows speed closely, which is expected on a hill with steady gradient. Heart rate, however, responds more slowly and with lower amplitude than expected. At the road crossing, the five-minute average power was below 100 watts, yet my heart rate never dropped below 145 bpm — despite usually sitting around 110–120 bpm at this intensity during training.
This highlights a key limitation of heart rate–based intensity control, especially in demanding conditions such as Vasaloppet’s start climb. Power data, by contrast, responds instantly and is therefore superior for pacing in both aerobic and anaerobic skiing efforts.
Climbing Performance: Required Power for Vasaloppet’s First Hill
Once the congestion cleared, power output stabilized while speed changed with slope. Approaching the top, power dropped as the terrain turned downhill.
Disregarding the slow sections, my average power in the first climb was around 180 watts (≈2.4 W/kg), which is a useful benchmark for recreational skiers starting in the front of wave 3.
Physics-Based Validation of Ski Power Data
To evaluate the reliability of the Skisens power data, we can verify it using the analytical power equation:
(1) 
m: body mass (kg)
g: gravitational acceleration (9.81 m/s2)
p: air density (1.293 kg/m3)
Cd: drag coefficient (assumed 1.4)
A: frontal area (assumed 0.6 m2 for a forward-leaning skier)
: glide friction (assumed 0.035)
: gradient (percent)
v: speed (m/s)
Assuming glide friction ≈0.035, the expected power on the start flat at 22 km/h is around 230 watts — matching the measured data.
With a 10% gradient and speeds of 6–7 km/h, the climb requires roughly 170–200 watts — again matching the Skisens measurements.
Conclusion: What Vasaloppet Skiers Can Learn from Power Data
Our validation shows that Skisens power measurements align well with physics and real-world performance. This makes it possible to draw meaningful insights about pacing, technique, and required power output for the Vasaloppet start climb.
We will return to this topic in future analyses with additional measurement examples.
//Dan
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