Why vertical ascent rate matters
In ski-mountaineering the race is won and lost on the ascents, so vertical ascent rate, VAM, metres of vertical climbed per hour, is the central performance metric. It cuts through terrain and distance to a single number you can pace and improve, just as power does for cyclists.
VAM is simply vertical metres divided by hours: 600 m climbed in 30 minutes is 1,200 m/h. The calculator reports your test rate and an easy guide rate, and the units toggle switches the display between metres per hour and feet per hour.
Pacing climbs by VAM and heart rate
Use your test VAM to pace efforts: long, sustained climbs are typically held near 70–95% of test VAM, with the easy end (~70%) for all-day touring and the upper end for race-climb threshold. At a 1,200 m/h test rate that is roughly 840 m/h easy up to about 1,140 m/h at threshold.
Pair vertical rate with the five heart-rate zones for everyday training: Zone 2 for the long aerobic climbing base, Zone 4 for race-climb threshold, Zone 5 for steep punches and the final climb. Vertical rate paces the race; heart rate manages day-to-day intensity. The two together beat either alone.
Reading the numbers
Test VAM is sensitive to gradient and snow: a consistent, moderately steep skin track gives the most repeatable figure, while breakable crust or very low-angle terrain depresses it. Re-test on the same climb in similar conditions to track real fitness change rather than terrain noise.
Because heart rate lags effort and drifts on long climbs, treat the vertical rate as the pacing anchor on race climbs and use heart rate to confirm you are in the intended zone over the steady middle of an effort.
The vertical time trial (skimo field test)
A vertical time trial gives you a personal test VAM to pace climbs and intervals. Do it rested, on a consistent climb, after a thorough warm-up. It is a maximal sustained effort, stop if you feel unwell.
- 1
Pick a consistent climb
Choose a steady, moderately steep skin track with a known vertical gain, ideally 500–700 m without flat interruptions.
- 2
Warm up
Climb easy for 10–15 minutes with a couple of short pickups to open the legs and lungs.
- 3
Climb hard for the fixed vertical
Climb at a hard but sustainable, evenly-paced effort over the full known vertical, pace it like a time trial, not a sprint start.
- 4
Record vertical and time
Note the metres climbed and the elapsed time. Enter both here to get your test VAM and heart-rate 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 |
Switch the units toggle to read the same rates in feet per hour for US trail maps.
Frequently asked questions
What is VAM in ski-mountaineering?
VAM (velocità ascensionale media) is your vertical ascent rate, metres climbed per hour. It divides vertical gain by time in hours, so climbing 600 m in 30 minutes equals 1,200 m/h. In skimo, where races are decided on the climbs, VAM is the key performance anchor alongside heart rate.
How do I run a vertical time trial?
Pick a consistent, moderately steep climb with a known vertical gain of about 500–700 m. After a 10–15 minute warm-up, climb the full vertical hard at an even, time-trial effort, then record the metres climbed and elapsed time. Dividing vertical by hours gives your test VAM.
How fast should I climb on long efforts?
Pace sustained climbs near 70–95% of your test VAM. The easy end (~70%) suits all-day touring and aerobic base work; the upper end (~95%) is race-climb threshold. At a 1,200 m/h test rate that is roughly 840 m/h easy up to about 1,140 m/h at threshold.
Should I pace climbs by heart rate or vertical rate?
Use vertical rate as the pacing anchor on race climbs, because heart rate lags effort and drifts over long efforts. Use the five heart-rate zones to manage everyday training intensity, Zone 2 for base, Zone 4 for threshold. Combining both beats relying on either signal alone.
Why does my test VAM change between climbs?
VAM is sensitive to gradient and snow. A consistent, moderately steep skin track yields the most repeatable figure, while breakable crust or very low-angle terrain lowers it. Re-test on the same climb in similar conditions to measure real fitness change rather than terrain noise.
Sources
- Ferrari, VAM (velocità ascensionale media). Vertical ascent rate in metres 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.