Beyond FTP: Understanding the Metrics That Really Drive Cycling Performance

For nearly two decades, cyclists have lived and trained by one number: FTP — Functional Threshold Power. It’s simple, familiar, and easy to compare. Raise it, and you’re fitter. But as power meters, software, and physiology models have evolved, so has our understanding of what performance really means. FTP still matters, but it no longer tells the full story.

Modern analytics such as WKO5, TrainingPeaks, and AI Endurance can now reveal how each rider actually produces, sustains, and recovers power. These insights go beyond one figure to describe the shape of performance, how long you can hold it, how you fatigue, and which energy systems dominate your effort.

Here’s what those newer metrics mean, and how you can use them to train more effectively.

FTP: Still Useful, But Incomplete

FTP was designed as a practical estimate of the maximal lactate steady state (MLSS) — the highest intensity a rider can sustain while lactate production and clearance remain in balance. Although not a perfect match, it correlates closely with endurance performance and became a useful benchmark precisely because it could be measured without laboratory testing.

But two riders with the same FTP can perform very differently once fatigue sets in. One may crumble after 25 minutes; another may hold steady for an hour. That difference is durability — and it’s why today’s performance modelling digs deeper than a single threshold.

The New Language of Performance

Figure 1. The Performance Pyramid. Each layer contributes to overall performance, with VO₂max setting the ceiling and LT1 forming the foundation for endurance durability.

LT1 — The Aerobic Foundation

LT1 — often called the aerobic threshold and marks the first sustained rise in blood lactate above resting levels, typically around 65–80 % of FTP in trained riders. Below this point, energy production is predominantly aerobic, and the small amount of lactate produced is easily cleared. Training near LT1 improves mitochondrial efficiency and long-duration fatigue resistance and the ability to sustain work for hours without heart rate or power drift. It’s where most endurance adaptations are built.

mFTP — Modelled Functional Threshold Power

Instead of a fixed 20-minute test, mFTP is calculated from your power–duration curve. Every maximal effort, whether 30 seconds or 2 hours, contributes to the model. When you update your curve with new data, mFTP shifts dynamically reflecting your current physiology, not a snapshot from weeks ago.

TTE — Time to Exhaustion

TTE shows how long you can hold mFTP before power declines. A rider with a 280 W FTP but a 60-minute TTE will outperform someone with 300 W FTP and a 25-minute TTE in long events. Extending TTE is one of the most reliable ways to improve real-world endurance and fatigue resistance.

FRC — Functional Reserve Capacity

FRC represents your anaerobic work capacity, measured in kilojoules (kJ). It quantifies the finite amount of work you can perform above threshold before exhaustion, the “battery” you draw from during surges, climbs, or sprints. Once this reserve is depleted, power output must drop back to or below threshold until it’s recharged aerobically. A higher FRC allows you to attack, respond, or repeat hard efforts more effectively.

VO₂max — The Ceiling

VO₂max defines your aerobic capacity — the maximum rate at which your body can consume and utilise oxygen during exercise.

It sets the upper limit for aerobic energy production, and most endurance metrics, like FTP and TTE  are expressed as a percentage of this value.

Improving VO₂max effectively raises the physiological ceiling for performance, allowing greater sustainable power when supported by efficient threshold and durability training.

How Coaches Use These Together

The power of these metrics isn’t in isolation, it’s in their relationships.

• High FTP + Short TTE → Fragile threshold (great power, poor durability).

• Moderate FTP + Long TTE → Diesel engine (efficient, fatigue-resistant, ideal for long events).

• Large FRC + Lower VO₂max → Sprinter profile (needs more aerobic support).

By understanding these interactions, coaches can prescribe training that targets specific physiological needs rather than generic zones. For instance, a time-trial rider with a solid FTP but short TTE might spend several weeks doing long tempo or sweet-spot intervals to extend sustainable duration before chasing higher intensity. A gravel racer, by contrast, may focus on torque endurance and sub-threshold climbing to increase fatigue resistance.

Beyond Numbers — Training Application

Figure 2. Power–Duration Curve with Key Metrics.

The power–duration relationship visualises where metrics such as VO₂max, FRC,mFTP, and LT1 occur across intensity and time.

With these tools, training shifts from chasing arbitrary power goals to developing the right physiological traits for your event:

• LT1 work and below improves aerobic efficiency and durability.

• Threshold (mFTP) intervals enhance lactate clearance and steady-state performance.

• FRC sessions sharpen punch and repeatability.

• VO₂max blocks raise the performance ceiling but demand recovery precision.

Using a power-duration model allows you to see which parts of your curve are under-developed and design sessions to fill those gaps. Each new maximal effort refines the model, giving instant feedback on adaptation and afar more responsive system than traditional testing cycles.

Practical Takeaways for Riders

1. Don’t judge progress by FTP alone — track how long you can hold it.

2. Spend more time around LT1; it’s the most productive training zone for building endurance with low fatigue.

3. Re-evaluate your model monthly and new efforts keep it accurate.

4. Use intensity sparingly; consistency at the right load beats heroic sessions.

5. Let data guide your training, but always interpret it through context and feel.

Closing Thought

FTP will always be part of cycling’s vocabulary, but real progress lies in understanding the layers beneath it. When you know your LT1, mFTP, TTE, and FRC, training becomes less about chasing a single number and more about shaping the entire performance curve.

Written by Simon Beldon, Matt Bottrill Performance Coaching.

www.mattbottrillperformancecoaching.com