Should I Train by FTP or Heart Rate?

Use power as your primary target — it's instantaneous, repeatable, and immune to caffeine, heat, or stress. Use heart rate as your second-opinion check — it tells you whether your body is actually expressing the power you're producing. The right answer for serious amateurs is almost always 'both, layered'.

FTP or Heart Rate Training? Which to Use

The honest answer is that this isn't a binary. Power and heart rate measure different things, and pretending one replaces the other is one of the costliest mistakes amateur cyclists make. Power is mechanical output. Heart rate is the cost of producing that output. They're complementary inputs, not competing ones.

Power should be your primary target on hard days. It responds instantly, doesn't drift with caffeine or temperature, and is repeatable across rides. When you're prescribed 4×8 minutes at 105% FTP, the power number is what you hit. Heart rate would arrive 60-90 seconds late and would be elevated by heat, dehydration, or under-recovery — exactly the variables you're trying to ignore for a structured interval session.

Heart rate earns its keep on long endurance rides and as a fatigue/recovery signal. On a 4-hour zone 2 ride, your heart rate at the same power tells you whether you're well-rested or quietly cooked. A drift of 10+ bpm at constant power 90 minutes in (cardiac drift) is normal; a drift of 20+ bpm screams under-recovery, dehydration, or under-fuelling. The Roadman Comparison page on heart rate vs power has the full breakdown of when each metric leads.

Practically, the elite amateurs Anthony has interviewed all use the same hierarchy. Hard sessions: power leads, HR is the witness. Endurance/recovery sessions: HR leads (so you don't accidentally ride too hard), power is the witness. Race day: power for pacing, HR for spotting trouble before it becomes a bonk. That's the pattern Joe Friel and the Roadman coaching team apply, and it's the one most coached amateurs end up using whether they realise it or not.

WHERE THIS COMES FROM

Joe Friel — The Power Meter Handbook

Friel's foundational text codified the 'power leads, heart rate witnesses' hierarchy that coached cyclists still use today.

Andy Coggan — Training and Racing with a Power Meter

Coggan's framework for layering power zones with heart rate response remains the industry standard for serious amateurs.

Roadman — Heart Rate vs Power Comparison

Side-by-side breakdown of when each metric tells the truth and when each one misleads, with concrete session examples.

COMMON FOLLOW-UPS

If I have to pick one, which is better — power or heart rate?

Power, by a clear margin, for structured training. It's repeatable, instantaneous, and unaffected by stress, heat, or sleep. But if budget rules out a power meter, structured heart rate training with proper zone calibration still works — it's how generations of cyclists got fast.

Why does my heart rate feel high at low power some days?

Cardiac drift, heat, hydration, sleep, and stress all elevate HR for the same power output. An honest answer is: if HR is more than 10-15 bpm above its normal value at a given power for two days in a row, treat it as a recovery signal, not a fitness signal.

Should I race by power or heart rate?

Pace by power, monitor by heart rate. Power gives you a fixed target you can hit and hold. Heart rate is your early-warning system for going too deep, dehydrating, or running into heat trouble. Use both — but commit to your power numbers first.