FTP: Calculating Functional Threshold Power for Cycling Training

How Do I Calculate My FTP?

Calculating your Functional Threshold Power (FTP) involves performing a specific, maximal effort cycling test, most commonly a 20-minute sustained effort or an incremental ramp test, and then applying a specific calculation to the power data gathered during that test.

What is FTP?

Functional Threshold Power (FTP) is a critical metric in cycling and endurance sports, representing the highest average power output you can sustain for approximately one hour. While the precise physiological definition relates to the maximal lactate steady state, for practical purposes, it's your best effort over an extended period. It serves as a cornerstone for setting accurate training zones, tracking fitness progression, and pacing during events.

Why Calculate FTP?

Determining your FTP offers several significant advantages for athletes of all levels:

• Personalized Training Zones: FTP is used to establish personalized power-based training zones (e.g., Active Recovery, Endurance, Tempo, Threshold, VO2 Max, Anaerobic Capacity). These zones ensure your training efforts are precisely targeted to elicit specific physiological adaptations.
• Performance Tracking: Regular FTP testing allows you to objectively track your fitness improvements over time. An increase in FTP indicates enhanced endurance and power output.
• Effective Pacing: Knowing your FTP helps you pace yourself optimally during races, time trials, or long training rides, preventing you from going out too hard and blowing up, or not pushing hard enough.
• Workout Prescription: Coaching platforms and training plans often prescribe workouts based on percentages of your FTP, ensuring appropriate intensity and volume.

Prerequisites for FTP Testing

Before attempting an FTP test, ensure you have the necessary equipment and are adequately prepared:

• Power Meter or Smart Trainer: A device capable of accurately measuring and recording your power output in watts is essential. This can be a crank-based, pedal-based, hub-based, or wheel-based power meter, or a smart indoor trainer.
• Cycling Computer/App: A device or application (e.g., Garmin, Wahoo, Zwift, TrainerRoad) to record your data and guide you through the test protocol.
• Adequate Fitness: You should have a foundational level of cycling fitness and be accustomed to sustained efforts.
• Good Health: Ensure you are well-rested, properly fueled, and hydrated. Do not attempt an FTP test if you are feeling unwell or fatigued.
• Controlled Environment: A consistent environment (indoors on a trainer is often preferred for consistency) minimizes external variables like traffic, wind, or terrain changes.

Common FTP Test Protocols

There are several methods to calculate your FTP, each with its own advantages and considerations. The two most common and reliable are the 20-minute FTP test and the Ramp Test.

20-Minute FTP Test

This is arguably the most widely recognized and frequently used protocol. It relies on the strong correlation between a maximal 20-minute effort and your actual 60-minute FTP.

• Protocol:

  • Warm-up (20-30 minutes): A thorough warm-up is crucial. A typical warm-up might include:
    • 10-15 minutes easy spinning (Zone 1-2).
    • 3 x 1-minute efforts at high cadence (100+ RPM) with 1 minute easy spinning recovery.
    • 5 minutes easy spinning.
    • 3 x 30-second efforts at maximal power (all-out sprint) with 30 seconds easy spinning recovery. This helps to open up the legs and clear the system.
    • 5 minutes easy spinning.
  • Main Effort (20 minutes): After the warm-up, begin a maximal, sustained 20-minute effort. The key here is pacing. You need to ride as hard as you possibly can for the entire 20 minutes without fading significantly in the last few minutes. It should feel like a very hard time trial.
  • Cool-down (10-15 minutes): Easy spinning to aid recovery.

• Calculation:

  • Take your average power output for the 20-minute main effort.
  • Multiply this average power by 0.95 (95%).
  • Example: If your average power for the 20-minute effort was 250 watts, your FTP would be 250 watts * 0.95 = 237.5 watts.

Ramp Test

The Ramp Test, popularized by platforms like Zwift and TrainerRoad, is an increasingly popular alternative due to its shorter duration and less demanding mental component compared to the 20-minute test.

• Protocol:

  • Warm-up: Typically a short, easy warm-up.
  • Incremental Steps: After the warm-up, the power target increases incrementally (e.g., 20-25 watts every minute) until you can no longer maintain the target power. The test ends when you fail to hold the required power for a specified duration (e.g., 5-10 seconds).
  • Cool-down: Easy spinning.

• Calculation:

  • Many platforms automatically calculate your FTP based on the Ramp Test. Generally, the calculation involves taking a percentage of your best 1-minute power output achieved during the test, often 75% of your peak 1-minute power.
  • Example: If your peak 1-minute power during the ramp test was 300 watts, your FTP might be calculated as 300 watts * 0.75 = 225 watts.
  • Note that the exact percentage can vary slightly between platforms due to proprietary algorithms.

Other Considerations for Testing

• Consistency: Always try to perform your FTP tests under similar conditions (same time of day, same equipment, same environment – indoors is ideal for this) to ensure reliable comparisons over time.
• Recovery: Ensure you are well-rested before the test (e.g., a rest day or very easy day prior).
• Fueling: Be properly fueled and hydrated. Avoid heavy meals close to the test, but ensure you have adequate energy stores.

Interpreting Your FTP Score

Once you have your FTP number, you can use it to establish your personalized training zones. While specific zone percentages can vary slightly between coaches and methodologies (e.g., Coggan's Power Zones), here's a general guideline:

• Zone 1: Active Recovery (<55% FTP)
• Zone 2: Endurance (56-75% FTP)
• Zone 3: Tempo (76-90% FTP)
• Zone 4: Threshold (91-105% FTP) - This is your FTP zone itself.
• Zone 5: VO2 Max (106-120% FTP)
• Zone 6: Anaerobic Capacity (>120% FTP)

These zones provide the framework for structured training, allowing you to target specific physiological systems and improve different aspects of your cycling fitness.

Improving Your FTP

Improving your FTP requires consistent, structured training that progressively challenges your aerobic system. Key training components include:

• Threshold Intervals: Sustained efforts at or just below your FTP (e.g., 2x20 minutes at 90-95% FTP).
• Sweet Spot Training: Slightly below threshold, these efforts are sustainable for longer durations and build aerobic fitness (e.g., 2x30 minutes at 88-92% FTP).
• VO2 Max Intervals: Shorter, harder efforts above FTP to improve your maximal oxygen uptake (e.g., 5x3 minutes at 106-120% FTP).
• Long Endurance Rides: Building your aerobic base with longer rides at a steady, conversational pace.
• Consistency and Recovery: Regular training combined with adequate rest and proper nutrition is paramount for adaptation and improvement.

When to Retest Your FTP

Retesting your FTP regularly is crucial for monitoring progress and ensuring your training zones remain accurate. A good general guideline is to retest every 4-8 weeks, or after completing a significant training block. If you've had a long break from training or are returning from injury, it's wise to retest to establish a new baseline.

Important Considerations and Safety

• Listen to Your Body: FTP tests are demanding. If you feel any sharp pain, dizziness, or unusual discomfort, stop immediately.
• Consult a Professional: If you have underlying health conditions or concerns, consult with a medical professional before undertaking intense exercise tests.
• Pacing is Key: Especially for the 20-minute test, proper pacing is critical for an accurate result. Avoid starting too fast and fading, or starting too slow and leaving power on the table.
• It's a Benchmark: Remember that FTP is a training tool, not a measure of your worth as an athlete. Use it to guide your training, not to define your enjoyment of the sport.