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Breathing training: 5 simple exercises to improve your VT2 and your tolerance to acidosis

Ventilatory threshold 2 (VT2) is a key marker for athletes: it's the point at which ventilation spikes, acidosis sets in, and exertion suddenly becomes very taxing. Improving VT2 means:

  • increase your ability to sustain high intensity,

  • better tolerate lactate,

  • to be more powerful on restarts, bumps or accelerations,

  • delay the explosion in competition.


For this, intervals are not the only option. 👉 Respiratory muscle training plays a major role — and it is often neglected.


In this article, discover 5 simple exercises , accessible to all, and scientifically validated to strengthen your ventilation and improve your tolerance to acidosis.


1. Why does working on breathing improve VT2?


During efforts close to VT2:

  • CO₂ levels rise sharply.

  • Breathing must accelerate sharply to compensate.

  • The inspiratory muscles become fatigued.

  • The ventilation becomes ineffective.

  • acidosis sets in earlier.


By strengthening your respiratory muscles (diaphragm, intercostals, abdominals), you will:

  • ventilate more efficiently,

  • maintain a stable exhalation,

  • eliminate CO₂ more effectively.

  • delay acidification,

  • stabilize your VT2 threshold.


👉 It's not just about "breathing better": it's about improving your exercise physiology .



2. Exercise 1: Diaphragmatic breathing under constraint (2–4 min)


Objective: to strengthen the diaphragm + improve inhalation/exhalation coordination.

How to do it:

  1. Breathe deeply, expanding your belly.

  2. Exhale slowly, for longer than the inhalation.

  3. Add a light resistance (straw, very light FEO2 mask, or simply pursing the lips).


Why this is useful:

👉 increases the endurance of the inspiratory muscles.

👉 stabilizes ventilation during efforts close to VT2.


3. Exercise 2: Long exhalations (2 x 3 to 2 x 5 min)


Objective: to improve CO₂ elimination and ventilatory tolerance.

How to do it:

  1. Inhale for 2 seconds.

  2. Exhale in 6 to 8 seconds.

  3. Maintain a steady pace.

Utility :

👉 improves ventilatory buffering capacity

👉 helps resist the urge to vent too early

👉 increases tolerance to acidosis


4. Exercise 3: Controlled “Breath Holds” (short apneas)


⚠ Only to be done while resting or seated.

Objective: to increase CO₂ tolerance, key to threshold performance.

How to do it:

  1. Breathe in normally.

  2. Exhale normally.

  3. Hold your breath after exhaling , as comfortably as possible (10–20 sec).

  4. Take a deep breath.

  5. Repeat 5–8 times.


Physiological effect:

👉 Increases CO₂ tolerance

👉 Delays the respiratory reflex during high intensities

👉 improves breath quality at the threshold


5. Exercise 4: Controlled rapid breathing (30” effort / 30” calm)


Objective: to simulate the ventilatory demands of a passage above VT2.

How to do it:

  1. Breathe rapidly (20–30 cycles/min).

  2. Remain as stable as possible.

  3. Alternate with 30 seconds of slow breathing.

  4. Do 6 to 10 repetitions.


Benefits:

👉 strengthens the respiratory muscles

👉 improves the ability to control ventilation at high intensity

👉 prepares you to better manage respiratory explosions


6. Exercise 5: Breathing exercises integrated into training


Objective: to connect breathing & actual intensity.

On a bike / running:

Doing intervals:

  • 3 minutes just below VT2 (controlled breathing)

  • 1 minute above VT2 (high but controlled breathing)


Repeat 4 to 8 times depending on the level.

Why it's powerful:

👉 Your body learns to manage CO₂ in real-world conditions

👉 better ventilatory stability near the threshold

👉 direct performance improvement


7. How ZoneX amplifies the benefits of this workout


With ZoneX you can:

  • to accurately measure VT1 and VT2,

  • View your ventilation in real time,

  • to monitor the progress of the respiratory muscles,

  • analyze your CO₂ tolerance

  • correct ventilatory drift at high intensity.


👉 By combining ZoneX + breathing exercises, you get a rapid and measurable improvement in your threshold performance.



Conclusion


Breathing training is one of the most effective (and most underestimated) methods to improve your VT2 threshold and tolerance to acidosis.

With just a few minutes a day, you can:

  • ventilate more efficiently,

  • to ward off fatigue,

  • better manage high intensities,

  • increase your performance in cycling, running, trail running or triathlon.


👉 Breath is a muscle.

👉 By working on it, you become stronger.

👉 With ZoneX, you measure your progress scientifically.



More information:

  • Changes in the Second Ventilatory Threshold Following Training — Martini et al. (2022): “The second ventilatory threshold (VT2) is an important indicator of exercise intensity tolerance. » PMC

  • Influence of Inspiratory Muscle Training on Ventilatory Efficiency — Salazar-Martínez et al. (2017): Study on the influence of inspiratory muscle training on ventilation in normoxia and hypoxia. PMC

  • The relationship between lactate and ventilatory thresholds — Cerezuela-Espejo et al. (2018): “Recent findings support the idea that a training model based on ventilatory thresholds (VT1 & VT2) could be very effective…” Frontiers

  • The midpoint between ventilatory thresholds approaches maximal lactate steady state — Peinado et al. (2016): demonstrates the link between ventilatory thresholds and the lactate steady state (MLSS). Semantic Scholar

  • Determining the ventilatory inter‑threshold area in athletes — Capellá et al. (2018): “Acidosis begins when VT1 is overwhelmed… compensatory hyperventilation…” apunts.org

 
 
 

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