Rethinking Zone Two: A Modern Look at Aerobic Training

Endurance riders have spent years treating Zone 2 as a single, steady effort. You pick a comfortable pace, stay controlled, and trust that you're building aerobic fitness. But training science is evolving, and it is becoming clear that Zone 2 is not one thing; it lives across a range of intensities, and each part of that range creates a different adaptation. When we see these differences, our endurance training takes on new purpose.

At the lower end of the zone, the body works in a highly efficient metabolic state where mitochondrial growth, capillary expansion, and long-term fat oxidation are developed. These sessions build the structure that supports every harder effort we complete later in the season.

As intensity moves upward within the zone, the signal changes. The body relies slightly more on carbohydrate, heart rate rises a bit, and the aerobic system must sustain performance under greater strain. This work, which we call aerobic power, provides a stronger and more complex stimulus without crossing into threshold.

This two-part view of Zone 2 is built into BaseCamp training. Our system has long separated the zone into distinct targets that help athletes understand exactly what stimulus they are delivering:

• Aerobic Endurance: 50 to 65% of FTP; steady, lower intensity work that reinforces core aerobic efficiency

• Aerobic Power: 56 to 75% of FTP; higher workload endurance that strengthens the aerobic engine and prepares the body for future demands

There is natural overlap, because physiology does not follow rigid boundaries, but these ranges help guide intention.

Adding the Role of Time

Duration plays an important role in shaping the aerobic response. The guidelines below are generalized, not absolute, but they provide practical direction.

• Aerobic Endurance tends to be most effective when rides reach ninety minutes or more in duration. These lower intensities rely on accumulated time to drive deeper structural change.

• If you have less than ninety minutes available, shift the focus toward Aerobic Power to create a stronger return for the time invested. The slightly higher workload produces a meaningful aerobic signal in a shorter window.

There are plenty of reasons we might choose not to follow the guidelines above; we often blend both during a single session, use endurance for recovery days, or lean into aerobic power when preparing for more demanding training. The goal is to make purposeful choices, not follow rigid rules.

How This Applies Through the Base Season

In a well-designed base progression, the blend of aerobic endurance and aerobic power shifts over time.

• Early Base: Emphasize aerobic endurance to build efficiency, rhythm, and durability.

• Late Base: Increase the proportion of aerobic power. The foundation is in place, and the body is ready for a stronger signal that prepares it for threshold, tempo, and event-specific work.

This modern approach transforms Zone 2 from a familiar endurance label into a flexible, targeted training tool. When we match intensity and time with intent, every ride becomes a step toward meaningful aerobic development.

Want to learn how our coaches apply these concepts to build stronger, more durable athletes? Schedule a free coaching consult here!

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At BaseCamp, we believe that every cyclist has the potential to achieve greatness, no matter where they start. Our mission is to create a community-driven training environment where cyclists and triathletes of all levels can train together, support each other, and grow stronger, faster, and more confident in their abilities. Our cycling training programs are expert driven and tailored to your needs. Whether you're a seasoned pro or just getting started, BaseCamp is where you belong.