FTP & Power Zones: Training by Numbers

Functional Threshold Power (FTP) is defined as the highest average power output you can sustain for approximately one hour in a quasi-steady state. It corresponds closely to the power at your lactate threshold (LT2 / maximal lactate steady state). Once you know your FTP, you can derive seven distinct training zones, each targeting a specific physiological adaptation. This article explains how to test your FTP, how the seven Coggan power zones work, what each zone trains, and how to use them to structure your cycling or triathlon bike training.

What FTP Represents Physiologically

FTP is not an arbitrary construct. It maps directly to the boundary between sustainable and unsustainable exercise:

• Below FTP: Lactate production and clearance are in balance. You can sustain the effort for 60+ minutes. Heart rate and ventilation are elevated but stable.
• At FTP: You are right at the edge of equilibrium. Lactate is accumulating very slowly. The effort is hard but maintainable for roughly 45-75 minutes depending on fitness, fueling, and conditions.
• Above FTP: Lactate accumulates progressively. The higher above FTP you go, the shorter the duration you can maintain. At 120% of FTP, most athletes last only 5-8 minutes.

This relationship between power and sustainability is what makes FTP such a powerful training anchor. Every zone defined relative to FTP has a distinct metabolic signature and targets a specific adaptation.

The Seven Coggan Power Zones

The system developed by Dr. Andrew Coggan and Hunter Allen in "Training and Racing with a Power Meter" is the most widely used power zone framework. Here are the seven zones:

Zone-by-Zone Breakdown

Zone 1 -- Active Recovery (< 55% FTP). Spin the legs with almost no resistance. This zone exists for recovery rides and warm-up/cool-down. There is no training stimulus here; the purpose is to promote blood flow without adding fatigue.

Zone 2 -- Endurance (56-75% FTP). The bread and butter of endurance training. You build aerobic base, increase mitochondrial density, improve fat oxidation, and develop the cardiovascular plumbing (capillary density, stroke volume) that underpins all other fitness. Most of your weekly volume should be here. A common mistake is riding Zone 2 too hard -- creeping into Zone 3 -- which adds fatigue without the specific benefit of either endurance or threshold work.

Zone 3 -- Tempo (76-90% FTP). A no-man's land for some coaches, a key zone for others. Tempo riding builds muscular endurance and is useful for Ironman-distance athletes who race in or near this zone. However, spending excessive time here can compromise recovery without generating the sharp stimulus of Zones 4-5. Use it purposefully, not by default.

Zone 4 -- Lactate Threshold (91-105% FTP). The money zone for most competitive cyclists and triathletes. Training here improves lactate clearance, shifts the lactate threshold to a higher power output, and directly raises FTP. Classic workouts: 2 x 20 minutes, 3 x 15 minutes, or 4 x 10 minutes at 95-100% FTP with 5-minute recoveries.

Zone 5 -- VO2max (106-120% FTP). Short, intense intervals that drive your maximal oxygen uptake higher. The target is to accumulate time at or near VO2max. Typical sessions: 5 x 4 minutes at 108-115% FTP with 3-4 minutes recovery. These sessions are demanding and require 48+ hours of recovery.

Zone 6 -- Anaerobic Capacity (121-150% FTP). Efforts lasting 30 seconds to 3 minutes that tax the anaerobic energy system. Used for developing the ability to respond to attacks, power over short climbs, and improve repeatability of hard efforts. Example: 8 x 1 minute at 130-140% FTP with 2 minutes recovery.

Zone 7 -- Neuromuscular Power (> 150% FTP). All-out sprints and explosive efforts under 30 seconds. Power here is limited by neuromuscular recruitment, not metabolic capacity. Used for sprint finishes, jump power, and peak force development.

How to Test Your FTP

The 20-Minute Test (Most Common)

This is the widely used 20-minute protocol, whose accuracy Borszcz et al. (2018) examined:

1. Warm up (20 minutes): 10 minutes Zone 2, then 3 x 1 minute at Zone 4-5 with 1 minute recovery, then 5 minutes easy.
2. 5-minute blow-out: Ride 5 minutes as hard as you can sustain. This pre-fatigues the anaerobic system so it does not inflate your 20-minute number. Record the power but discard it from FTP calculation.
3. Easy recovery: 5 minutes of very light spinning.
4. 20-minute effort: Ride the hardest average power you can sustain for exactly 20 minutes. Start conservatively -- slightly below what you think you can hold -- and increase in the second half if possible. Even pacing or slight negative splits are ideal.
5. Cool down: 10 minutes Zone 1.
6. Calculate FTP: Average power for the 20-minute effort x 0.95.

The Ramp Test (Alternative)

Start at a low wattage (100-150W) and increase by 20W every minute until failure. FTP is estimated as 75% of the highest 1-minute power achieved. This test is easier to pace but can overestimate FTP in riders with high anaerobic capacity.

The 8-Minute Test

Two 8-minute all-out efforts separated by 10 minutes of recovery. Average the power of both efforts and multiply by 0.90. Less common but useful for athletes who struggle with pacing a 20-minute effort.

Worked Example: Building a Complete Zone Table

Athlete: Tom, age 42, competitive age-group triathlete. Completes a 20-minute FTP test with an average power of 263 watts.

Step 1: Calculate FTP - FTP = 263 x 0.95 = 250 watts

Step 2: Build the 7-zone table

Step 3: Design a sample training week

Weekly volume: ~9.5 hours. Approximately 75% in Zones 1-2, 10% in Zone 3, 15% in Zones 4-5.

Sweet Spot Training: The Efficient Middle Ground

Sweet spot training targets 88-94% of FTP -- the upper end of Zone 3 and lower end of Zone 4. It sits just below threshold intensity but accumulates significant training stress with less recovery cost than full threshold work.

For Tom at 250W FTP: - Sweet spot range: 220-235 watts - Classic session: 2 x 20 minutes at 228W with 5 minutes recovery - Why it works: high stimulus-to-fatigue ratio; you can do more total work than at full FTP intensity

Sweet spot is particularly valuable for time-crunched athletes who cannot dedicate 12+ hours per week to training. It provides a strong threshold stimulus in a compact time window.

Practical Rules for Power-Based Training

1. Test your FTP properly every 6-8 weeks. Training with an outdated FTP means your zones are wrong. If FTP has increased and your zones are too easy, you lose training stimulus. If FTP has decreased (detraining, illness) and zones are too hard, you accumulate excessive fatigue.

2. Respect Zone 2. The most common mistake in power-based training is riding Zone 2 sessions too hard. If your FTP is 250W, a Zone 2 ride should feel genuinely easy at 140-188W. If you find yourself consistently at 195-210W, you are in tempo territory and compromising recovery.

3. Use 3-second or 5-second smoothed power for pacing intervals. Instantaneous power fluctuates wildly. Smoothed power gives you a readable target. But analyze your workouts using Normalized Power (NP), which accounts for the metabolic cost of power variability.

4. Prioritize Zone 4 for FTP improvement. If your primary goal is raising FTP, accumulate 30-40 minutes of Zone 4 work per session, 2 times per week. Classic protocols: 2 x 20 min, 3 x 15 min, or 4 x 10 min at 95-100% FTP.

5. Do not neglect Zone 2 volume. High-volume Zone 2 riding builds the aerobic infrastructure that makes threshold and VO2max work effective. Athletes who only do intervals without an endurance base plateau quickly and accumulate fatigue.

6. Use power-to-weight for climbing and performance projection. Tom's FTP of 250W at 75 kg gives him 3.33 W/kg. For reference:

1. When in doubt, start the test or interval conservatively. You can always push harder in the second half. Starting too hard leads to a collapse in power and an underestimated FTP or a failed workout.

Evidence Base

Allen & Coggan (2010) authored the definitive guide to power-based cycling training, now in its third edition. Their seven-zone model has become the industry standard, adopted by TrainingPeaks, Zwift, and virtually every cycling coaching platform. The framework was developed through a combination of laboratory testing, field data from thousands of athletes, and physiological principles. The key insight was that anchoring all zones to a single, easily testable reference point (FTP) creates a practical system that self-adjusts as the athlete's fitness changes. Their work also introduced Training Stress Score (TSS), Normalized Power (NP), and Intensity Factor (IF) -- metrics that revolutionized training load quantification.

Borszcz et al. (2018) examined how well FTP estimated from the 20-minute test corresponds to a laboratory threshold in trained cyclists, comparing it against each rider's individually determined anaerobic threshold. They found the two were strongly correlated, so 95% of 20-minute power is a usable proxy -- but with an important caveat: on average, 95% of 20-minute power tended to overestimate the power the riders could actually sustain for a full hour. In other words, the 0.95 factor is a reasonable starting point, not an exact conversion; for many athletes true 60-minute power sits slightly below it. Their practical message is to treat the 20-minute estimate as an approximation to be refined against how efforts actually feel over longer durations, especially for less-trained riders whose higher anaerobic contribution inflates the 20-minute number.

Together, these works established power-based training as the most objective and reproducible method for prescribing cycling intensity. Heart rate remains a useful supplementary metric -- particularly for detecting fatigue, overtraining, and cardiovascular drift on long rides -- but power is the primary training currency for any cyclist or triathlete with access to a power meter.