Training Zones

Training zones are ranges of effort - defined by heart rate, power, or pace - that target specific physiological adaptations. The zones above follow standard models popularised by Jack Daniels (running) and Andrew Coggan (cycling).

Heart rate zones: The % Max HR method is simple but imprecise. Max HR varies by sport (cycling max HR is typically 3–5 bpm lower than running) and drifts upward during long efforts. The LTHR method is more stable - your threshold HR is the average HR you can hold for a 30-minute time trial.

Pace zones: For runners, pace zones (Jack Daniels VDOT) map threshold pace to E/M/T/I/R bands. Unlike heart rate, pace doesn't drift, but it doesn't account for terrain, heat, or altitude.

Power zones: FTP-based power zones are the gold standard for cycling. Power doesn't drift and isn't affected by heat, caffeine, or nerves. The Coggan 7-zone model (Z1–Z7) maps physiological demands to wattage targets.

The most common mistake: Training in Z3 ("grey zone") for all sessions. It feels productively hard but sits between the two adaptations you need: Z2 (aerobic base) and Z4+ (threshold/speed). Most endurance training should follow an 80/20 easy/hard split. Read our polarised training explainer for more.

Baseline tracks your actual time-in-zone from your device data and shows whether your training distribution matches your goals.