Why vertical ascent rate matters
Skimo races are won on the ascents, so vertical ascent rate (VAM, meters climbed per hour) is the central performance metric, as power is for cyclists. The calculator reports your test rate and an easy guide rate, in meters or feet per hour.
Pacing climbs by VAM and heart rate
Long climbs sit at 70–95% of test VAM: 70% for all-day touring, 95% for race-climb threshold. At 1,200 m/h that is 840–1,140 m/h. Pair it with the five heart-rate zones: Zone 2 for base, Zone 4 for threshold, Zone 5 for steep punches. Vertical rate paces the race. Heart rate manages daily intensity.
Reading the numbers
Test VAM depends on gradient and snow. A consistent, moderately steep skin track is most repeatable. Breakable crust or low-angle terrain lowers it. Re-test on the same climb in similar conditions.
The vertical time trial (skimo field test)
Do it rested, on a consistent climb. It is a maximal effort, so stop if you feel unwell.
- 1
Pick a consistent climb
A steady, moderately steep skin track with a known gain of 500–700 m and no flat sections.
- 2
Warm up
Climb easy for 10–15 minutes with a couple of short pickups.
- 3
Climb hard for the fixed vertical
Climb the full vertical at a hard, even time-trial effort.
- 4
Record vertical and time
Enter meters climbed and elapsed time to get your test VAM and zones.
Worked example
A skier climbs 600 m of vertical in 30:00 during the time trial:
| Vertical climbed | 600 m |
| Test duration | 30:00 |
| Test VAM (600 m ÷ 0.5 h) | 1,200 m/h |
| Easy climb rate (~70%) | 840 m/h |
| Threshold climb rate (~95%) | 1,140 m/h |
The units toggle shows the same rates in feet per hour.
Frequently asked questions
What is VAM in ski-mountaineering?
VAM (velocità ascensionale media) is vertical ascent rate in meters climbed per hour. Climbing 600 m in 30 minutes equals 1,200 m/h. Skimo races are decided on the climbs, so VAM is the key anchor alongside heart rate.
How do I run a vertical time trial?
Pick a consistent, moderately steep climb with a known gain of 500–700 m. Warm up 10–15 minutes, climb it at an even time-trial effort, and record meters and time. Vertical divided by hours is your test VAM.
How fast should I climb on long efforts?
Pace sustained climbs at 70–95% of test VAM: 70% for all-day touring, 95% for race-climb threshold. At a 1,200 m/h test rate that is 840–1,140 m/h.
Should I pace climbs by heart rate or vertical rate?
Pace race climbs by vertical rate, because heart rate lags and drifts over long climbs. Use the heart-rate zones for everyday training: Zone 2 for base, Zone 4 for threshold.
Why does my test VAM change between climbs?
Test VAM changes with gradient and snow. A consistent, moderately steep skin track is most repeatable. Breakable crust or low-angle terrain lowers it. Re-test on the same climb in similar conditions.
Sources
- Ferrari, VAM (velocità ascensionale media). Vertical ascent rate in meters per hour as a climbing-performance metric.
- Seiler & Tønnessen (2009). “Intervals, thresholds, and long slow distance: the role of intensity and duration in endurance training.” Sportscience 13:32–53.