Why Zone 2 is essential for progression

In cycling, we often hear about FTP (Functional Threshold Power), power records, or big thighs. But what distinguishes a cyclist capable of performing over time is not just their ability to ride or climb fast. It’s their aerobic base, built through regular Zone 2 training. Too many riders neglect this essential zone and see their progress stagnate. Here’s why.

By Guillaume Judas – Photos: depositphotos.com

What is Zone 2?

Zone 2 corresponds to a moderate intensity, generally between 75 and 85% of your maximum heart rate or approximately 55-75% of your FTP. At this pace, you can talk without being out of breath, but the effort remains sustained (it’s not about coasting). This is the zone where your aerobic system works efficiently to develop endurance and energy efficiency without accumulating excessive fatigue.

How to tell if you’re not spending enough time in Zone 2?

A rider who neglects time spent in Zone 2 shows revealing weaknesses, far beyond a level that stagnates over months. When the aerobic base is insufficient, several phenomena are observed:

• A less efficient heart: an underdeveloped aerobic system limits the progression of VO₂max (maximum capacity to use oxygen) and reduces the number of mitochondria, the cells’ energy factories (Holloszy, J. O., & Coyle, E. F. (1984). Adaptations of skeletal muscle to endurance exercise and their metabolic consequences. Journal of Applied Physiology.). Result: you fatigue faster.
• More glycogen dependence: with too little Zone 2 training, your body primarily burns glycogen during effort, rather than fat, which can lead to cravings and early fatigue during long rides (Brooks, G. A. (2018). The science and translation of lactate shuttle theory. Cell Metabolism).
• Slower recovery: a fragile base overloads the nervous system, slows recovery, and increases the risk of stagnation or injuries (Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance).
• Less tolerance for heavy training loads : without a solid foundation, long efforts become difficult, and you quickly plateau.
• Rapid breathlessness: poor aerobic capacity accelerates lactate production, making high-intensity efforts very difficult (Billat, V. L. (2001). Interval training for performance: A scientific and empirical practice. Sports Medicine).
• Increased risk of injuries: the fatigue resulting from intense efforts without sufficient prior preparation increases the risk of tendinitis or overtraining (Meeusen, R., et al. (2013). Prevention, diagnosis, and treatment of the overtraining syndrome. Medicine & Science in Sports & Exercise).
• Limited technical progress: without long, low-intensity rides, you lack time to refine your position, pedaling technique, or bike handling.

Why riding in Zone 2 changes everything

Zone 2 is a training intensity on which all sustainable cycling performance relies. Even before the advent of heart rate monitors, power meters, analysis tools, or books offering training plans, cyclists considered their endurance base an indispensable condition for a successful season. They spoke in terms of number of km, or hours in the saddle, but were ultimately not so far from reality. Even today, those who ride only by feel or who accumulate fast-paced rides without a precise plan do no worse than those who do almost exclusively high-intensity indoor trainer sessions.

Zone 2, as defined above, significantly improves your endurance. By strengthening your aerobic system, you can ride longer without exhausting yourself. Raising your endurance level also allows for better utilization of fat as fuel, saving glycogen reserves. Fatigue is thus pushed back, and you retain more energy for decisive efforts at the end of a ride or event. Finally, riding in a controlled manner in Zone 2 allows you to accumulate training volume without excessive overload, which promotes consistent progress over time.

Studies show that endurance athletes like professional cyclists spend about 80% of their training time at low to moderate intensities, such as Zone 2, to maximize their energy efficiency and recovery (Stöggl, T., & Sperlich, B. (2015). The training intensity distribution among well-trained and elite endurance athletes. Frontiers in Physiology).

How to integrate Zone 2 into your training?

To ensure you increase your training time in Zone 2, you must first determine it. Use a heart rate monitor or power meter, and base it on your maximum heart rate (Zone 2 is between 75 and 85% of your max HR) or your FTP (between 55 and 75%). You will find that Zone 2 is not just a leisurely stroll, but that you are a little busy, focused on a steady effort, not difficult but not completely trivial either. If you don’t have a sensor, rely on your feeling: you should be able to talk without being out of breath, but you remain slightly engaged. To optimize time spent in Zone 2, know when to ease off on ascents to stay comfortable, but also pedal energetically on descents to stay in the zone.

Plan two to three rides per week in Zone 2 only, including at least one of three hours or more, depending on your level. The goal is to accumulate time at this intensity.

Riding in Zone 2 should represent about 80% of your weekly volume. But you need to supplement with interval sessions or threshold work to build power, in addition to active recovery sequences, of course.

Finally, be patient. The benefits of this kind of work build up over several weeks. Consistency in training remains the key to progress.

Reorienting training intensities

Thanks to or because of modern training tools and applications, more and more riders have become aware of the need to calibrate sessions so that each outing is productive. But by wanting too much, some forget the essential: without solid foundations, it is impossible to progress sustainably. This is often seen in those who ride a lot on an indoor trainer, only in circuits with other cyclists (like at Longchamp), or who ride alone without the advice of a coach. They think No Pain No Gain, but often end up getting discouraged due to lack of results.

Riding in Zone 2 is not very exciting but it is essential. By building a solid aerobic base, you improve your endurance, delay fatigue, and reduce the risk of injuries. It is the foundation that then allows intense efforts to make all the difference.

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