Respiratory analysis: the most reliable method to determine your training zones

🎯 Why talk about respiratory analysis?

Defining your training zones correctly is essential for progress, avoiding overtraining, and optimizing your workload. But most athletes still use:

• formulas based on maximum heart rate (often inaccurate),

• FTP percentages ,

• or field tests that measure performance… but not physiology.

Respiratory analysis, on the other hand, directly measures how your body produces its energy . It is the most reliable method for identifying your true physiological zones .

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1. Why is breathing such a powerful indicator?

Your breathing changes depending on the fuel used by your muscles. It reflects in real time:

• the proportion of lipids to carbohydrates used,

• the production of CO₂ ,

• the onset of muscle acidosis ,

• the transitions between energy sectors .

By observing these changes, we can precisely determine the two key physiological thresholds:

• Ventilatory threshold 1 (VT1) : lipid aerobic → carbohydrate aerobic transition

• Ventilatory threshold 2 (VT2) : marked onset of acidosis → intensity difficult to maintain

These thresholds define your true training zones .

2. Why is heart rate not enough?

Heart rate is useful… but it has major limitations:

• cardiac drift during exertion

• emotions and stress

• caffeine, hydration, fatigue

• heat and environment

• very significant individual variability

It does not indicate whether you are in the correct energy sector.

Two athletes with the same heart rate can be in completely different physiological zones.

3. Why are the FTP, Coggan, Vameval or Cooper tests incomplete?

These tests primarily measure:

• performance (power, speed, distance)

• tolerance for exertion ,

• the ability to maintain a rhythm .

But they do not measure physiology or energy systems. Two athletes with the same FTP can have very different VT1 and VT2 values.

➡️ Result: the FTP-based zones are sometimes too high , sometimes too low .

4. How respiratory analysis accurately defines your zones

By measuring respiration, we can detect the two major metabolic transitions:

🔹 VT1: onset of disproportionate increase in ventilatory rate

Indicates the point at which you predominantly leave the lipid pathway.

🔹 VT2: more pronounced respiratory failure (acidosis)

Indicates the area where the effort becomes difficult to sustain for a long time.

These two points allow for the construction of truly individualized zones:

• Zone 1 : Lipid aerobic endurance

• Zone 2 : active endurance / tempo

• Zone 3 : threshold

• Zone 4 : High Intensity

• Zone 5 : VO₂ max

👉 These are the only markers based directly on your metabolism .

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5. Why is this method necessary today?

For a long time, respiratory analysis was reserved for laboratories (masks, bulky analyzers, specialized personnel). Today, field solutions make it possible to obtain this data in real conditions , directly on a bike or during a race.

This is a revolution for:

• endurance athletes,

• the coaches,

• the clubs,

• the physical trainers,

• training centers.

We are finally moving from an estimate… to an objective and individualized measurement .

6. How ZoneX makes this measure accessible

ZoneX, developed by PAIRFS, was designed to offer a truly simple and reliable respiratory analysis, usable by everyone:

• CO₂ measurement, ventilation and gas exchange

• automatic detection of VT1 and VT2

• no calibration

• usable indoors or outdoors

• results in minutes

• automatically generated training zones

You can finally base your training on your true physiological thresholds — not on formulas or approximations.

In summary

Respiratory analysis is the most accurate method for:

• define your training zones

• understand your metabolism

• optimize your sessions

• track your progress

• avoid pacing errors

👉 This is the most scientific, most individualized approach… and now the most accessible thanks to ZoneX.

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