How To Calculate FTP

How to Calculate and Use FTP in Triathlon Training

Functional Threshold Power (FTP) is one of the most important metrics for endurance athletes, particularly triathletes training for Ironman or 70.3 races. FTP represents the highest power output a rider can sustain for 40-60 minutes, serving as the cornerstone for structuring effective bike workouts.

In this post, we’ll explore how to calculate FTP using indoor and outdoor methods, how to use this critical data in your training, and actionable tips to improve your FTP over time. Let’s dive in.

How to Calculate Your FTP

Indoor FTP Testing Methods

The 20-Minute FTP Test
- Warm up for 10-15 minutes.
- Perform a 5-minute all-out effort to prime your legs.
- Recover for 10 minutes.
- Ride as hard as you can sustain for 20 minutes.
- Calculate FTP: Take your average power from the 20-minute effort and multiply it by 0.95.
The Ramp Test
- Begin at a low wattage, increasing power every minute by a set increment (e.g., 20 watts).
- Continue until you can no longer maintain the required power.
- FTP Estimate: Multiply your highest one-minute power by 0.75.
Longer Time Trials (40-60 Minutes)
- Ride at the highest steady power you can sustain for 45 min to 1 hour.
- Your average power during this effort is your FTP.
- This method is highly accurate but mentally and physically demanding.

Outdoor FTP Testing Methods

While similar to indoor tests, outdoor testing factors in real-world variables like terrain and wind:

Use a power meter to track your output.
Find a steady, uninterrupted stretch of road for consistent effort.
Apply the same calculations as indoor tests.

Tools for FTP Testing

Smart Trainers: Devices like Wahoo KICKR provide precise power readings.
Power Meters: Pedal-based or crank-based systems like Garmin Vector or Stages Cycling are reliable.
Apps: Platforms like Zwift, TrainingPeaks, and TrainerRoad guide you through testing protocols and help you analyze results.

Using FTP in Your Training

FTP acts as the baseline for setting training zones, which are critical for structured workouts:

Training Zones (Example Based on FTP):
- Zone 1: Recovery (0-55% of FTP)
- Zone 2: Endurance (56-75%)
- Zone 3: Tempo (76-90%)
- Zone 4: Threshold (91-105%)
- Zone 5: VO2 Max (106-120%)
- Zone 6: Anaerobic Capacity (>120%)
Pacing for Ironman and 70.3 Bike Legs
- Aim to ride at 65-75% of FTP for Ironman.
- Ride at 75-85% of FTP for 70.3 distance.
- Proper pacing conserves energy for the run while maximizing your bike performance.
Structured Workouts
- Incorporate threshold intervals: e.g., 3x12 minutes at 95-100% FTP with 5-minute recoveries.
- Include VO2 max sessions: e.g., 6x3 minutes at 110-120% FTP with 2 to 3-minute recoveries.

Improving Your FTP Over Time

Progressive Overload
Gradually increase the intensity and duration of workouts to push your limits.
High-Intensity Interval Training (HIIT)
Include short, intense efforts at 110-130% of FTP regularly to boost power.
Aerobic Base Training
Spend lots of time in Zone 2 to build endurance and improve overall efficiency.
Strength Training
Incorporate gym sessions to develop leg strength, which translates to better power output. Things like barbell squats, box jumps, lunges, and more are beneficial. Check out my YouTube channel for great bike strength workouts.
Consistency and Recovery
Work with a coach and stick to a structured plan. Recover well after hard sessions and incorporate yoga or other mobility training into your routine.

Have you thought about hiring a coach for your next iron distance event? Are you ready to crush your next triathlon? Don’t leave your performance to guesswork or generic plans. Click the purple button below to fill out a short form and schedule a call with me. Let’s develop a personalized training strategy to help you achieve your goals and smash your race times!

Mary Timoney

Ironman U Certified Coach

USA Triathlon Coach

ACSM Trainer