Breaking your limits: how to train and improve VT2 for high intensity

In our constant pursuit of unraveling the secrets of endurance performance, we’ve already explored the First Ventilatory Threshold (VT1) as the foundation of our endurance. Today, we’ll raise the intensity to understand the next physiological milestone: the Second ventilatory threshold (VT2).

What is the Second Ventilatory Threshold?

The Second Ventilatory Threshold, commonly known as VT2 or also called the Respiratory compensation point (RCP), marks an even higher exercise intensity than VT1. At this point, the carbon dioxide production by the muscles, due to the exponential increase in lactate production and its subsequent buffering, exceeds the body’s ability to efficiently eliminate it solely with increased ventilation. This causes significant metabolic acidosis and a new, sharp increase in ventilation.

Physiologically, VT2 represents the highest intensity at which a near-steady-state of lactate can be maintained. Above this threshold, the accumulation of lactate in the blood is unsustainable and progressive, leading quickly to fatigue and the inability to maintain the effort for long. It is, in essence, our “upper limit” for sustained high-intensity performance.

Relevance of VT2 in endurance competitions

While VT1 defines the aerobic base and long-term efficiency, VT2 is crucial for performance in those competitions where it is necessary to maintain a high intensity or perform explosive and repeated efforts.

  • 5K and 10K Races (Running): In these distances, athletes often operate around their VT2. Improving this threshold means being able to sustain a faster pace throughout the race before lactate accumulation forces a slowdown.
  • Cycling time trials (ITT) and key segments: For cyclists, VT2 is a fundamental predictor of the power they can maintain in solo time trial efforts or in decisive attacks. The ability to hold high power in this zone is what allows them to make a difference.
  • Olympic or sprint distance triathlon: In these shorter and faster disciplines, the ability to operate at a high percentage of VT2 is critical. The transition and maintenance of a strong pace across all three disciplines depend on a high tolerance for acidosis and efficient management of this threshold.
  • Team sports with intermittent high-intensity efforts: While our primary focus is on endurance sports, it is important to note that the ability to operate near or above VT2, with rapid recovery, is vital in disciplines that require bursts of high intensity followed by periods of lower intensity.

How to improve the second ventilatory threshold?

Improving VT2 involves raising your body’s capacity to tolerate and buffer lactate, as well as enhancing the efficiency of the cardiovascular and respiratory systems at high intensities.

  1. High-intensity interval training (HIIT): Workouts involving short periods of maximal or submaximal effort, followed by recovery periods, are highly effective at raising VT2. These stimulate metabolic adaptations that improve the muscles’ ability to use lactate as fuel and buffer acidosis.
  2. Threshold zone training (Tempo/Sweet Spot): Performing sustained efforts just below or at VT2 for 20-40 minutes (depending on the athlete) is also key. This type of training improves the ability to maintain fast paces consistently and is fundamental for “teaching” the body to tolerate higher lactate levels.
  3. Specific strength training: Strength applied to movement (strength-endurance) can improve the economy of effort at high intensities, reducing oxygen demand and, therefore, stress on the system at a given speed or power.
  4. Accurate monitoring: Precisely identifying VT2 is a challenge in the field, but advanced sports technology tools like CHASKi, which directly measure ventilation, offer an invaluable advantage. By knowing your exact VT2, you can calibrate your intensity workouts optimally, avoiding overtraining or underestimating your potential.

Understanding and training your VT2 will allow you to break through speed and endurance barriers, transforming your ability to compete at the highest levels of intensity. Just as VT1 is the foundation, VT2 is the ceiling you can raise with smart training and precise monitoring.


Sources:

[1] Wasserman, K., & McIlroy, M. B. (1964). Detecting the threshold of anaerobic metabolism in cardiac patients during exercise. American Journal of Cardiology, 14(6), 844-852. 

[2] Beaver, W. L., Wasserman, K., & Whipp, B. J. (1986). A new method for detecting anaerobic threshold by gas exchange. Journal of Applied Physiology, 60(6), 2020-2027. 

[3] Faude, O., Kindermann, W., & Meyer, T. (2009). Lactate threshold concepts: how valid are they? Sports Medicine, 39(8), 669-690. 

[4] Laursen, P. B., & Jenkins, D. G. (2002). The scientific basis for high-intensity interval training: optimising training programmes and maximising performance in highly trained endurance athletes. Sports Medicine, 32(1), 53-73. 

[5] Rønnestad, B. R., & Mujika, I. (2014). Optimizing strength training for running and cycling endurance performance: A review. Scandinavian Journal of Medicine & Science in Sports, 24(4), 603-612.