Tools / 04

Heart rate
zones

Five zones, calculated either off max heart rate or off the reserve between resting and max. Pick the method you trust.

Inputs

Max heart rate (bpm) Resting heart rate (bpm)

Method

Karvonen: percentages are taken of the resting-to-max range. Usually the better fit for trained riders.

No max HR test? Estimate from age

140 bpm

Beats between resting and max

ZoneNameBPMPercentWhat it feels like

Age formulas are a starting point, not your physiology. The highest number you have actually seen in a hard effort is better data.

On day two of an ultra your heart rate drifts up at the same effort, then stops responding at all. Trust power and feel over bpm by then.

Heat, caffeine and dehydration all move these numbers. Treat the zones as a band, not a line.