Endurance & Cardio Coaching
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How endurance coaching works
FitSum builds an aerobic base progressively, prioritising training volume before intensity. The coaching engine tracks your cardio sessions over time and prescribes the next session based on where you are in your development — not a static plan.
Endurance coaching applies to GPS-tracked cardio exercises (runs, rides, walks, and similar activities tracked with the Distance & Pace tracking type). Other exercise types (e.g. rowing by distance, continuous stationary cycling) also contribute to your overall aerobic load.
What the app considers:
- Your recent session volume and frequency
- The intensity of each session (measured in training load points — see 5.2)
- Your aerobic base status and how consistently you've been training
- Your heart rate zones (if HR data is available)
- Any declared race goal or endurance goal preference
Training load points
Training load points are how FitSum measures how much cardiovascular stress a session creates. A longer, harder session earns more points than a shorter, easier one. Higher-intensity sessions earn more points per minute.
This is a standard concept in endurance science — the app just presents it in plain numbers rather than using technical terminology. The actual value isn't important; what matters is the trend over time.
The coaching engine tracks two timeframes — recent load (the last week or so) and your longer-term load (the past four weeks). When recent load spikes significantly above your longer-term average, the engine scales back the next session's prescription to reduce injury risk.
What counts as a successful session
Unlike strength training, there's no single rep target to hit. Endurance sessions are evaluated on two things:
- Volume compliance — how much of the prescribed duration (or distance) you completed
- Effort — your RPE or heart rate zone for the session
A session is considered on-track when you complete close to the prescribed duration at the right effort level. Based on that:
- On track → prescribed volume increases next cycle
- Partial completion or slightly off → volume holds until you're consistently hitting sessions
- Significantly under target → volume is reduced to a level you can sustain
The engine is deliberate about not increasing load until you're completing what's already prescribed. If you're consistently finishing sessions comfortably, volume will increase automatically — there's nothing to set or unlock.
Heart rate zones
FitSum uses five HR zones to describe workout intensity. Your zone boundaries are calculated from your personal maximum heart rate and resting heart rate (entered in Heart Rate Monitor or inferred from your profile).
| Zone | Description |
|---|---|
| Zone 1 | Very easy — warm-up, cool-down, recovery |
| Zone 2 | Easy — aerobic base building, conversational pace |
| Zone 3 | Moderate — threshold border, comfortably hard |
| Zone 4 | Hard — threshold effort, cannot sustain long |
| Zone 5 | Maximum — sprint intervals, very short efforts |
Most prescribed endurance sessions target Zone 2–3 unless your programme specifically calls for intervals. This is intentional — research consistently shows that most of your running volume should be easy.
HR zone data appears in workout detail, the post-workout summary, and the Progress → Charts tab.
Cardio preferences and goal
Your endurance coaching is personalised by the preferences you set in Training Settings → Cardio (open Training Settings from the Workout tab).
Endurance goal:
- General — Balanced approach, no event target
- Build — Prioritises easy volume
- Speed — Includes structured intensity work
- Maintain — Keep your current level steady
- Race (see 5.7) — Tailored to an upcoming event
Primary cardio type: What you primarily do — running, cycling, walking, mixed, etc. This affects exercise selection in recommendations.
Secondary cardio types: Other activities you do. These earn cross-training credit toward your endurance targets (at a slight discount to primary-type training).
Endurance days per week: How many cardio sessions you plan to do each week. The engine divides volume across this number.
Long session day: Which day your longer, lower-intensity session falls on. Set to Auto to let the engine decide.
Cross-training credit
Non-running cardio (cycling, swimming, walking, hiking) counts toward your endurance targets, but at a slight discount compared to your primary cardio type. This reflects the fact that fitness transfers partially between modalities — doing plenty of cycling will improve your running, but not as directly as running itself.
The app applies this automatically. You don't need to configure anything — just log the activity.
Race goals
If you're training for a specific event, set a race goal in Training Settings → Race Goal (open Training Settings from the Workout tab).
Supported event types include running (5K, 10K, half marathon, marathon), cycling (50 km, 100 km, century), and walking events (10K, half marathon, marathon walk). The options shown depend on your primary cardio type.
When a race goal is active:
- Your endurance prescription phases toward peak training in the weeks before the event
- A countdown appears on the race goal card
- Training intensity recommendations adapt to your timeline
You can update or remove the race goal at any time.
Return-to-training after a break
If you stop cardio training for more than a week, the engine adjusts your re-entry point so you're not returning to where you left off at full volume.
Build cycle position:
- Under 8 days: no change — your build cycle advances normally
- 8–20 days: the build cycle is frozen at your pre-absence position; the gap counts as rest, not training
- 21+ days: the build cycle resets to week 1 — you come back at a lower volume and rebuild from there
Aerobic base status: If you're away for 28 days or more without a session, your aerobic base status is demoted one tier. For example, if you had a developed base, you'd return at the building-base level. This affects how much volume is prescribed, not just the build cycle position. Consistent training over several weeks will return you to your previous level automatically.
There are no cards or prompts to acknowledge — the adjustments happen in the background the next time you start a cardio session.
Endurance coaching cards
Coaching cards for endurance appear on the Workout screen home alongside strength cards.
| Card | Trigger |
|---|---|
| High aerobic load | Recent training significantly elevated |
| Easy week | Cardio deload period |
| Aerobic base building | Early phase of base development |
| Fitness progressing | Consistent performance improvement |
Cardio deloads work the same way as strength deloads: a temporary reduction in volume after a sustained block of training. A coaching card confirms when one is active.
Improving coaching accuracy
The more HR data the app has, the more precisely it can calibrate your zones and gauge real effort.
- Wear a heart rate monitor during GPS sessions — the app uses real-time HR to confirm whether your easy runs are actually easy
- Connect Apple Health or Health Connect so that HR data recorded by your watch or phone is available even without a Bluetooth monitor
- Keep resting heart rate and max HR current in Profile → Heart Rate Monitor — these values define your zone boundaries
If HR data is unavailable, the engine falls back to pace and perceived effort (RPE) to estimate training intensity.