Heart Rate Zones
Heart rate zones divide your cardiovascular effort into bands, each producing different training adaptations. Apex Run uses 5 zones.
Setting Your Zones
Zones are calculated as percentages of your maximum heart rate (max HR). Apex Run lets you set max HR two ways:
- Formula estimate — Enter your date of birth; Apex Run uses the standard formula (220 − age) as a starting point.
- Manual entry — If you’ve measured your max HR through a field test or know it from experience, enter it directly in Settings → Heart Rate Zones.
The Five Zones
| Zone | % of Max HR | Name | What it develops |
|---|---|---|---|
| Zone 1 | 50–60% | Recovery | Active recovery, blood flow without stress |
| Zone 2 | 60–70% | Easy / Aerobic Base | Aerobic efficiency, fat metabolism, the foundation of endurance |
| Zone 3 | 70–80% | Tempo | Lactate threshold — the highest pace you can sustain for ~1 hour |
| Zone 4 | 80–90% | Threshold | VO2 Max development, race-specific fitness |
| Zone 5 | 90–100% | Maximum | Neuromuscular power, anaerobic capacity |
Reading Zone Data in Apex Run
- Run Detail — The heart zone section shows what percentage of a run you spent in each zone, as a horizontal bar.
- Insights — The Training Structure card on the Summary tab shows your recent zone distribution across all runs.
Training Structure
Apex Run maps your zone distribution across recent runs to show whether your training follows the 80/20 rule — the pattern consistently found in elite endurance athletes. See the 80/20 Training Structure page for the full breakdown.
The Training Structure card in the Insights tab color-codes your effort distribution:
- 🔵 Easy (Zone 1–2) — Target 75–80% of total training time
- 🟢 Moderate (Zone 3) — Target 10–15%
- 🔴 Hard (Zone 4–5) — Target 5–10%
Pace Zones
Pace zones define training intensity by speed rather than heart rate. Based on Jack Daniels’ running formula, each zone targets a specific physiological adaptation and corresponds to a specific training purpose.
Setting Your Pace Zones
In Settings → Training Pace Zone, enter a recent race result (distance and finish time). Apex Run derives your five training paces from this using standard formulas.
The Five Pace Zones
E — Easy Pace
Used for the majority of your training. Builds aerobic base and promotes recovery between hard sessions. You should be able to hold a conversation at this effort. Most of your weekly mileage — long runs, warm-ups, cool-downs — should be at Easy pace.
M — Marathon Pace
Your goal marathon race pace. Used for marathon-specific tempo runs and race simulation workouts. Bridges Easy and Threshold — specific enough to build race fitness, steady enough to accumulate significant volume.
T — Threshold Pace
Comfortably hard — the fastest pace you can sustain for roughly 60 minutes. Improves your lactate clearance capacity and endurance sustainability. Used in tempo runs (20–40 min continuous) and cruise intervals (shorter reps with brief recoveries).
I — Interval Pace
Approximately your 5K race effort. Targets VO2 Max directly — the ceiling of your aerobic system. Used in track-style intervals (800m–1200m repeats) with adequate recovery between reps. Demanding: limit this work to once a week.
R — Repetition Pace
Faster than interval pace — 1500m to mile race effort or quicker. Improves running economy and neuromuscular coordination (speed skill). Used in short, fast repeats (200m–400m) with full recovery. The goal is quality mechanics, not cardiovascular load.
The Grey Zones: What to Avoid
Between each named zone are gaps — paces that don’t target any specific adaptation efficiently. Training in these gaps is common but ineffective: you accumulate fatigue without getting the full benefit of either adjacent zone.
| Grey Zone | Between | Why to Avoid |
|---|---|---|
| Easy–Marathon | E and M | Tiring without the aerobic base benefit of Easy or the race-specific stimulus of Marathon pace. Slow down to Easy. |
| Marathon–Threshold | M and T | Too slow for lactate threshold training, too fast for marathon-specific benefits. Clarify the session purpose. |
| Threshold–Interval | T and I | High fatigue accumulation with vague benefits — neither reaching VO2 Max nor efficiently clearing lactate. Stick to defined zones. |
| Interval–Repetition | I and R | Lacks the speed for neuromuscular adaptation, but form tends to break down and lactate accumulates. High injury risk. |
The Pace Zone Distribution chart in Run Detail helps you see exactly where your effort landed. If you find yourself consistently in the grey zones, adjust your training plan to hit the intended targets cleanly.
See also: 80/20 Training Structure — how to balance time across zones · Running Glossary — definitions for GAP, EF, ACWR, and other metrics