TrailMetrics
Trail metrics, written onto every Strava Trail Run.
Connect once. Every time you log a Trail Run on Strava, we analyze your terrain, km-effort, GAP, VAM, longest climb, fatigue, and training load — and append a clean report to your activity description.
100% Free · No credit card required · Instant setup
The metrics in your Strava report
Strava already gives you distance, total time, and elevation gain. TrailMetrics skips the redundancy and enriches your activity description with the 8 essential mountain performance metrics.
Terrain Category & Vert Density
Classifies route steepness into Rolling Trail, Mountain Trail, Rugged Mountain, Alpine Skyrun, or Extreme Vertical based on vertical meters gained per kilometre (m+/km).
Km-effort & Category
Normalized route workload score: distance (km) + elevation gain (m) / 100. Mountain runs starting at 25 km-effort receive an official category from Cat. XS up to XXL.
GAP (Grade Adjusted Pace)
Average pace normalized for terrain gradient — showing what climbing and descending efforts equate to on flat ground — alongside your best and worst kilometre splits.
VAM (Ascent & Descent Speed)
Vertical speed in metres per hour for climbs (↑VAM) and downhills (↓VAM). The mountaineering standard for uphill climbing power and technical descent speed.
Longest Climb
Identifies your longest continuous uphill segment (>+2% grade), displaying total climb distance and cumulative elevation gained (+m).
Training Load (TRIMP)
Cardiovascular training impulse based on Banister's formula, rating exertion from Easy to Very Hard. Estimated with default values — soon you will be able to configure your personal heart rate zones.
Pacing Fatigue Index
Measures pace fade by comparing grade-adjusted pace between the first and last thirds of runs with ≥ 6 km, detecting steady pacing, positive split fade, or negative splits.
Uphill / Downhill Split
Exact percentage share of moving time spent climbing (>+2% grade) versus descending (<−2% grade), revealing the terrain elevation balance of your route.
How it looks in your Strava feed
Here is an exact simulation of what appears on your activity. Your own notes stay at the top, followed by the neatly formatted TrailMetrics breakdown.
Guadarrama National Park · Oct 4, 2026 at 08:15 AM
Morning Alpine Ridge Loop 🏔️
Distance
16.40 km
Elev Gain
1065 m
Time
1h 58m
Avg Pace
7:14 /km
Strava Activity Description
Original description preserved + TrailMetrics added"Early start before the heat. Amazing views from the high ridge and fast technical descent back through the pines."
⛰️ — TRAILMETRICS — 🟠 Rugged Mountain (65 m+/km) 🗺️ Km-effort: 27.1 km (Cat. XS) ⚡ GAP: 5:29/km (best 5:10 · worst 6:01) 🚀 VAM: ↑847 m/h · ↓1662 m/h 🧗 Longest climb: 4.00 km · +550 m 📊 Load: 294 TRIMP (Hard, est.) · 📉 Fatigue: +2.1% (steady pacing) ⬆️⬇️ Uphill 62% · Downhill 32% 👉 Join the club: strava.com/clubs/trailmetrics 📲 trailmetrics.app
How it works
01
Connect Strava
Authorize read and write access once so we can safely enrich your descriptions when new activities arrive.
02
Log a Trail Run
Upload your run as usual. TrailMetrics triggers automatically when the activity sport type is Trail Run in Strava (or an outdoor run with at least 100 m of climb and 20 m+/km).
03
Enjoy the report
Within seconds, a compact report appears in your Strava description with terrain category, km-effort, GAP, VAM, longest climb, training load, and pacing fatigue.
Designed for Trail & Mountain Runs
Activates on Trail Runs and outdoor runs with at least 100 m of climb and 20 m+/km. Flat road runs and track workouts remain completely untouched so your feed stays clean.
Frequently Asked Questions
Everything you need to know about TrailMetrics, your data, and how it works.
Is TrailMetrics completely free?
Yes! TrailMetrics is 100% free with zero hidden fees. There are no subscriptions and no credit card is ever required. The automated report written to your Strava activity descriptions will always remain free.
Will it overwrite or erase my personal Strava notes?
Never. TrailMetrics only appends its structured report block cleanly at the bottom of your description box. Your custom titles, personal notes, photos, and tagged friends remain completely untouched. If you edit your notes later, our system is idempotent and will never duplicate the report.
Which Strava activities are enriched?
TrailMetrics is built specifically for mountain runners. It activates automatically for activities categorized as Trail Run on Strava, as well as outdoor runs with at least 100 m of climb and a vertical density of ≥20 m+/km. Flat road runs and track workouts are ignored so your feed stays clean.
What happens if I don't run with a heart rate monitor?
All core GPS metrics (terrain category, km-effort, GAP, VAM, longest climb, uphill/downhill balance, and pacing fatigue) calculate perfectly from GPS and elevation data alone. The only metric that requires heart rate is Training Load (TRIMP); if HR data isn't present, that line is simply omitted cleanly from your report.
How is Training Load (TRIMP) estimated?
It uses Banister's cardiovascular impulse model based on duration and heart rate reserve. Currently, it is an estimation calculated with default baseline values (assuming 60 bpm resting HR and your session's peak HR as max HR). It provides a reliable relative gauge of workout strain, and soon you will be able to configure your personal heart rate zones.
Does it enrich past activities I already uploaded?
No. Strava's webhook architecture only triggers on new activities uploaded after you link your account. We never alter your past activity history or retroactively modify historical runs.
Can I edit or delete the report from a specific activity?
Yes, absolutely. The report is written as regular text into your Strava activity description. You can edit, format, or delete any part of it at any time directly in the Strava mobile app or website, exactly like your own personal notes.
How are Km-effort and categories (Cat. XS to XXL) determined?
Kilometer-effort is the international benchmark for mountain route hardness: Distance (km) + Elevation Gain (m) / 100. For outings starting at 25 km-effort, we assign official mountain race sizing categories: XS (≥25), S (≥45), M (≥75), L (≥115), XL (≥155), and XXL (≥210).
Can I join the TrailMetrics Strava club?
Yes! Every activity report includes an invite link, or you can join anytime at strava.com/clubs/trailmetrics to connect with other trail runners, follow group routes, and participate in community leaderboards.
How can I disconnect if I change my mind?
You can revoke access at any time directly from your Strava account. In Strava, go to Settings → My Apps (or 'Connected Apps') and click 'Revoke Access' next to TrailMetrics. Strava immediately notifies us, and we automatically purge your tokens and athlete records.