Training in Zone 2: how to do it, what are the benefits and for what type of practice?

PAIRFS
2 days ago
3 min read

Zone 2 has become an essential term in endurance training. Cyclists, runners, triathletes, coaches, and scientists alike are all talking about this "moderate endurance" work, which forms the basis of sustainable performance.

But what exactly is Zone 2? How can you be sure you're training there correctly? What physiological benefits can you really expect from it? And for which activities is it most useful?

We take stock, with an approach centered on physiology — and on ventilatory thresholds.

1. What exactly is Zone 2?

Zone 2 corresponds to an intensity around your first ventilatory threshold (VT1) :

Deeper but still controlled breathing
sustained intensity, but without significant ventilatory drift
Conversation possible in short sentences
Stable, non-lactic effort

👉 This is the heart of aerobic work , just before the metabolism switches towards an increased reliance on carbohydrates.

2. The physiological benefits of training in Zone 2

Zone 2 produces profound adaptations that are documented in the scientific literature.

✔ Mitochondrial development

Mitochondria become more numerous and more efficient → improved aerobic capacity.

✔ Improved fat burning

The body learns to use more lipids as fuel → saving glycogen, better endurance.

✔ Respiratory stabilization

We enhance the respiratory system's ability to manage CO₂ without excessive drift.

✔ Improved oxidative circulation

Increased capillarization → better muscle oxygenation.

✔ Reduction of physiological stress

Zone 2 builds the base without excessive fatigue → better recovery.

This is why Zone 2 is used extensively in endurance sports…and sometimes constitutes 60 to 80% of a high-performance athlete’s weekly training.

3. How can you tell if you are really in Zone 2?

Many athletes think they are training in Zone 2… when they are already in Zone 3.

To be sure:

✔ The most reliable reference point → your ventilatory thresholds VT1 / VT2

Zone 2 corresponds to an intensity around VT1 :

under VT1: Z1 (basic endurance)
around / slightly above VT1: Zone 2
above VT1: Zone 3 (tempo)

With ZoneX, the reference point is simple:

👉 you remain in the ventilatory stability zone , without switching towards CO₂ compensation.

✔ Practical tips if you don't yet have ZoneX

You can speak, but not sing.
regular breathing, without panting
Heart rate remains stable over 20–40 minutes
RPE around 2–3/10

Learn more about ZoneX

4. How to train in Zone 2 in practice?

📌 Duration

30 to 90 minutes for beginners

1.5 to 3 hours (or more) for experienced athletes

📌 Frequency

2 to 4 sessions per week depending on the discipline.

📌 Types of sessions

1. Continuous exit in Z2

The classic → cycling, running, rowing, swimming.

2. Long exit (LSD – Long Slow Distance)

Duration greater than 2 hours in cycling / trail running to strengthen deep endurance.

3. Z2 progressive

Finish the last 20 minutes slightly below VT2 to improve the transition.

4. Z2 technical

Useful in swimming or running → also work on movement economy.

5. Common mistakes in Zone 2

❌ Going too fast

Many athletes slip into Zone 3 → too tiring for the benefit.

❌ Wanting to “feel the difficulty”

Zone 2 is not supposed to be difficult.

❌ Relying solely on heart rate

FC = drift, heat, stress → not reliable.

❌ Doing too much Zone 2 without intensity

Zone 2 builds the base, but VT2 / Zone 4 develop the performance.

❌ Do not recalculate the zones regularly

The thresholds change every 4 to 8 weeks.

With ZoneX, thresholds are measured automatically → zones are always accurate.

6. For which sports is Zone 2 most useful?

✔ Cycling

Essential for long rides and uphill performance.

✔ Running

Develops running economy and ventilatory resistance.

✔ Triathlon

Foundation of cycling and running, useful for transitions.

✔ Trail

Key to managing long climbs without metabolic overheating.

✔ Team sports

Essential aerobic base for repeating sprints.

7. ZoneX: the best way to know if you are really in Zone 2

ZoneX measures your respiratory transitions in real-world conditions:

automatically detects VT1
tells you if you are still in the right area
adapts to your fatigue, heat, hydration
Avoid the mistake of “I thought I was in Zone 2 but I was already too high”

Training Zone 2 is good.

Training the real Zone 2 is better.