Heart rate fluctuates with heat, caffeine, fatigue, and stress. Perceived effort is subjective. Power — measured in watts — is none of those things. A power meter gives you an objective, real-time measurement of exactly how hard you are working, making it the single most valuable training tool available to cyclists.
But a power meter is only useful if you know your zones. Training by watts without defined zones is like driving with a speedometer but no speed limits — you have data but no framework. This guide walks you through testing your Functional Threshold Power (FTP), calculating all 7 zones, and building a structured training week.
Testing Your FTP
Functional Threshold Power is the highest average power you can sustain for approximately 60 minutes. The standard field test protocol uses a 20-minute effort:
- Warm up for 20 minutes with progressive intensity
- Ride 5 minutes at maximum effort (clears anaerobic capacity)
- Recover for 5 minutes at easy spin
- Ride 20 minutes at the highest sustainable effort — aim for an even or slightly negative split
- Multiply your 20-minute average power by 0.95 to estimate FTP
For example, if you average 280 watts for 20 minutes, your estimated FTP is 266 watts. Retest every 6-8 weeks as fitness changes.
The 7 Power Zones
Andrew Coggan's widely adopted model defines seven zones based on percentage of FTP:
- Zone 1 — Active Recovery: less than 55% FTP. Easy spinning for recovery days.
- Zone 2 — Endurance: 56-75% FTP. The foundation zone — long rides, fat oxidation, aerobic base building.
- Zone 3 — Tempo: 76-90% FTP. "No man's land" — too hard to recover from quickly, too easy to drive adaptation. Use sparingly.
- Zone 4 — Threshold: 91-105% FTP. Sustained hard efforts, 8-30 minute intervals. Drives FTP improvement.
- Zone 5 — VO2max: 106-120% FTP. Short, intense intervals of 3-8 minutes. Expands aerobic ceiling.
- Zone 6 — Anaerobic Capacity: 121-150% FTP. Explosive 30-second to 3-minute efforts.
- Zone 7 — Neuromuscular Power: greater than 150% FTP. Maximal sprints under 30 seconds.
The Zone 3 Trap
The most common training mistake in cycling is spending excessive time in Zone 3. It feels productive — hard enough to hurt, fast enough to feel like training. But research by Seiler (2010) shows that a polarised approach — roughly 80% of volume in Zones 1-2 and 20% in Zones 4-5 — produces superior endurance adaptations compared to a threshold-heavy distribution.
Zone 3 generates moderate fatigue without the powerful stimulus of higher zones. Athletes who default to Zone 3 often plateau within 6-12 months. Discipline yourself: go easy on easy days, go hard on hard days.
Sample Training Week
For a cyclist training 8-10 hours per week with an FTP of 250 watts:
- Monday: Rest or 45-minute Zone 1 spin
- Tuesday: 90 minutes with 3 x 10 minutes at Zone 4 (228-263W)
- Wednesday: 60-minute Zone 2 endurance (140-188W)
- Thursday: 75 minutes with 5 x 4 minutes at Zone 5 (265-300W)
- Friday: Rest
- Saturday: 3-hour Zone 2 endurance ride
- Sunday: 2-hour Zone 2 with 2 x 20 minutes at Zone 4
Common Mistakes to Avoid
Beyond the Zone 3 trap, watch for these errors: testing FTP indoors and applying results outdoors (outdoor power is typically 5-10% higher due to cooling and motivation), ignoring power-to-weight ratio (watts per kilogram matters more than raw watts for climbing), and chasing FTP at the expense of Zone 2 base. A strong aerobic base built through 12-16 weeks of high-volume Zone 2 work is the foundation for all higher-intensity gains.
Proper fueling is equally important — Zone 4 and 5 intervals burn through glycogen at 3-4g per minute. Arriving under-fueled guarantees poor interval quality. For a detailed nutrition plan matched to your power targets and session duration, use the Race Day Nutrition Planner to calculate exact carbohydrate needs per session.