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Trail running & breathing: how to manage your ventilation uphill, downhill and on technical terrain

In trail running, pace is not a reliable indicator: the same effort can vary from one to three times as much depending on the slope, the ground, the altitude or the technicality. But there is an internal indicator which remains accurate everywhere: breathing .


The way you ventilate reveals in real time:

  • your energy sector,

  • your level of fatigue,

  • your positioning relative to VT1 and VT2,

  • your ability to sustain the effort.


That's why breathing is the most reliable tool for managing a trail run, from short to long.


1. Why pace doesn't work in trail running


Unlike the road:

  • A 10% increase in temperature can double your energy costs.

  • A technical trail can halve the pace without changing the intensity.

  • A rapid descent can increase ventilation without increasing speed.

  • The heart takes time to react (often too late).


👉 Breathing, on the other hand, reacts instantly to metabolic stress.

It is therefore perfect for guiding the effort.


2. How to use breathing while climbing uphill


The climb is the moment when errors in intensity are most costly.

🔹 What your breathing should indicate:

  • steady breathing = below VT1 (endurance effort)

  • accelerated but controlled breathing = between VT1 and VT2 (tempo / sustained)

  • Shortness of breath, difficulty speaking = above VT2 (lactic zone)


🔹 The golden rule for climbing:

Never exceed VT2 at the start of a trail run.

Otherwise :

🔥 early acidosis

🔥 Glycogen burned too fast

🔥 explosion in the second half


Trick :

Use a “breathing pacing” technique:

  • if breathing becomes unstable,

  • ➡️ Slow down before your legs start to burn.


With ZoneX, the sensor detects ventilatory drift in real time → impossible to mistake the zone.



3. How to use breathing on the flat


On flat terrain but on trails, the goal is often to stabilize :

  • regular breathing rate

  • controlled breathing

  • maintenance below or around VT1 depending on the duration of the test


This is your “economic” zone.

👉 Ideally: to feel a fluid breath, without chest tension.

👉 At the slightest sign of rapid breathing, slightly reduce the pace.


4. How to manage breathing while descending


The descent is deceptive: you think you're recovering... but the ventilation often runs out of control.

For what ?

  • muscular impacts → ventilatory stress

  • speed → activation of the nervous system

  • Chest and shoulder tension → shallow breathing


Objective :

🔹 descend quickly… without hyperventilating.


How to do it:

  • relax the upper body

  • breathe deeper, wider

  • use long exhalations to calm the nervous system


👉 Controlled breathing on descent = better recovery + more stable pace afterwards.


5. Technical aspects: breathing as a stabilizer


In technical sections, the problem is not only physical but cognitive : the more complicated the terrain, the faster breathing automatically becomes.


To remain effective:

  • breathe deeply BEFORE entering the section

  • maintain a steady breath despite the instability

  • avoid involuntary breath-holding (very common in trail running)


Short apneas increase instantly:

  • muscle pressure

  • the accumulation of CO₂

  • respiratory fatigue


👉 Continuous ventilation allows for better engine control.


6. How to adapt trail running training with VT1 & VT2


🔹 Below VT1 → basic endurance


Goals :

  • work very long

  • improve the lipid pathway

  • prepare the ultras


Use :

  • Long outings, hiking and running

  • Slow, continuous climb


🔹 Between VT1 and VT2 → active endurance / trail running


Goals :

  • to be efficient uphill

  • stabilize breathing

  • increase speed on rolling terrain


Use :

  • gently sloping blocks

  • tempo on the paths

  • respiratory “up-down” session


🔹 Above VT2 → short and specific intensity


Goals :

  • manage follow-ups

  • passing a technical passage

  • responding to an attack


Use :

  • interval training trail short

  • series on steep slopes

  • power work


👉 Use sparingly to avoid excessive respiratory fatigue.



7. What ZoneX changes for trail runners


With ZoneX, a trail runner can:

  • Knowing your true VT1/VT2, regardless of the terrain

  • monitor your breathing in real time during the climbs

  • avoid respiratory drift from the first hours

  • stabilizing one's breathing over long distances

  • adjust your pacing according to the course profile

  • analyze the moments when breathing becomes rapid and intense (too rapid a rhythm)


This allows for a more consistent, more controlled, less energy-intensive trail run.


Conclusion


In trail running, breathing is your best indicator of intensity.

With VT1 and VT2, you can:

  • better manage your climbs

  • no longer explode too early

  • descend faster while remaining lucid

  • stabilize the effort in the difficult sections

  • improve your overall endurance


👉 Pace doesn't tell the whole story in trail running.

👉 Cardio sometimes lies.

👉 Breathing, however, always tells the truth about your effort.



 
 
 

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