Training by heart rate

Heart rate is optional, and choosing it does not take pace away. Pace stays every athlete’s default; heart rate is something you turn on.

One number, five bands

Everything is anchored on your Lactate Threshold Heart Rate — the heart rate you can hold for about an hour. It is threshold, so it sits at the top of Z3, exactly where threshold pace and Critical Power sit. The five Heart Rate Zones are worked out from it: Z1 below 80 percent, Z2 80–90, Z3 90–100, Z4 100–105, Z5 above 105. They line up with your pace and power zones by number.

AgentRunCoach keeps no maximum heart rate and no resting heart rate. Maximum heart rate is rarely measured well, and resting heart rate is a fatigue sign rather than an anchor.

Finding the number

The best evidence is a race of 30 to 60 minutes: its average heart rate is close to threshold. A 30-minute solo time trial works too, using the average of the last 20 minutes, and a watch’s own estimate is accepted as provisional. Your coach can read a race you have already run and propose the number with the race named beside it. The number is yours — it is saved when you agree, and it never changes on its own. Retest after a new race of the right length, or every six to eight weeks when training has clearly moved.

You can also enter it on the Run Fitness screen beside Critical Power.

Turning it on

Once you have Heart Rate Zones, choose Heart rate under Workout targets on your profile. Plans generated from then on carry bpm targets; an active plan keeps its existing targets until it is regenerated. Until you choose it, your threshold number stays on the Run Fitness screen beside Critical Power, where its five bands are shown for reference, and no workout carries a bpm band: heart rate is not a cross-check for an athlete who did not ask for it.

One run by heart rate

You do not have to switch everything. Ask your coach to make one run a heart-rate run — a long run in the heat or at altitude, a hilly trail run, a first run back from a cold, a treadmill session with no pace worth trusting — and that session reads beats per minute while the rest of the week stays by pace. It needs your threshold heart rate, like the full choice does, and follows the same rule: the steady running is by heart rate, the reps are by pace. The reverse works too: if you train by heart rate and want one tempo by pace, say so, and the heart-rate band still shows beside it. If you find yourself asking for this two or three times, that is the signal to choose heart rate under Workout targets instead.

Which runs read beats per minute

• Aerobic work by heart rate. Easy runs, long runs, recovery, steady and marathon-pace work and tempo — everything up to threshold — are prescribed as a bpm band, with the pace alongside.
• Reps by pace. Intervals and repetitions keep pace as the target, with the bpm band alongside for review. Heart rate takes a minute or more to respond to a hard effort and bunches up above threshold, so a bpm target on a short rep is a number your heart cannot reach in time. A workout sent to your watch shows pace on reps and on the jogs between them, and heart rate on everything else. A race’s own steps are by pace too.

What to expect

Heart rate lags at the start of a tempo and drifts upward late in a long run, in heat, after poor sleep or with caffeine. A long run that climbs into Z3 at the same pace is information about the day, not a failed session; your coach can say so and adjust the score. On hills and in wind, heart rate is the better guide, since pace stops meaning much there.