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 5-zone 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 due to cardiac creep. The LTHR (lactate threshold heart rate) method is more stable — your threshold HR is the average heart rate you can hold for a 30-minute time trial or the last 20 minutes of a 5K race.

Pace zones: For runners, pace zones don't account for terrain, heat, or altitude. A 4:30/km pace feels very different on a flat road vs. a 6% grade. VDOT tables (Jack Daniels) are the gold standard — they map race performances to equivalent training paces. If you've raced recently, use that result to set your zones; the predictor below is a rough starting point.

Power zones: FTP-based power zones assume you're on a bike trainer or flat road with no wind. Outdoors, power is power — which is why cyclists trust it — but pacing decisions still need to account for course profile.

The most common mistake: Training in Z3 ("grey zone" / tempo) for all your sessions. It feels productively hard but sits right between the two adaptations you actually need: Z2 (aerobic base) and Z4 (threshold). Most endurance training should split 80/20 between easy (Z1–Z2) and hard (Z4+). Zone 3 is the trap.

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