Elevation is the single most important metric in trail running. It doesn't matter whether it's 30 km or 100 km: the D+ decides how much you'll suffer. And the D− decides how long you'll take to recover.
Elevation gain (D+) and loss (D−): the key difference
- D+ — total metres of climbing accumulated. The main indicator of how hard a route is.
- D− — total metres of descent. The one everyone forgets. It wrecks the quads through eccentric contraction.
Quick guide by difficulty level
| Cumulative D+ | Level |
|---|---|
| Up to 500 m | Easy |
| 500 – 1,500 m | Moderate |
| 1,500 – 3,000 m | Hard |
| Over 3,000 m | Extreme |
D− and the descents: why they matter so much
Descending loads the muscles eccentrically (they contract while lengthening). That does more muscle damage than climbing and it's the main reason your legs turn to wood in the closing kilometres of an ultra.
A real example
| Route | Distance | D+ | D− | Recovery |
|---|---|---|---|---|
| A | 50 km | 2,000 m | 2,000 m | Slow · badly trashed quads |
| B | 50 km | 2,000 m | 500 m | Quick · mild soreness |
Why D− matters more than you think
In a 50 km race with 2,000 m D+ and 2,000 m D−, you'll spend more time going down than going up, because on technical descents your times end up close to your climbing times. But the muscle damage is far greater on the way down.
Specific training
- Eccentric squats: the most specific exercise there is for getting your quads ready to descend.
- Controlled technical descents: practise descending at a progressive pace on terrain similar to your race.
- Progressive loading: add D− to your long runs week by week so the muscle adapts.
Common mistakes
- Assuming that "if I climb slowly, I'll descend fast". Descents on tired legs are almost as slow as the climbs.
- Ignoring the D−. Plenty of runners plan around D+ alone. The D− is the sting in the tail that destroys fresh legs.
- Not training descents. If you only train on the flat or on climbs, come race day your quads won't be ready for eccentric work.
Summary
Elevation = difficulty. The D+ tells you how demanding the race is. The D− tells you how demanding your recovery will be. Understand both before you commit to a race.