Running Tolerance
Running Tolerance tracks how much weekly training stress your body has recently adapted to carry. This page covers the Impact Load model behind it, how Tolerance is derived, and what the chart is telling you.
The chart shows your past 12 weeks of actual training alongside any projected plan volume. It appears on the Basecamp dashboard and inside a Training Plan.
Actual distance and hours
Raw weekly totals from your synced activities — what your watch recorded, in distance and in time on feet. The model's reference figures below are metric; the chart displays them in your profile units.
Impact Load
Impact Load converts raw distance into equivalent stress distance by weighting each run by the musculoskeletal strain it imposed. A fast hilly tempo run costs far more than a flat easy jog of the same distance.
Impact Load = Distance × Intensity Factor × Speed Factor × Terrain Factor
Each factor captures a different dimension of that strain.
Intensity factor
Derived from time in each heart-rate zone during the activity.
| Zone | Multiplier | Why |
|---|---|---|
| Z1–Z2, easy and aerobic | 1.0× | Baseline musculoskeletal load |
| Z3, tempo | 1.5× | Higher ground reaction forces, more recruitment |
| Z4, high intensity | 2.0–2.5× | Threshold through to highest-intensity work |
Where imported data carries a fifth device zone, Basecamp treats it as the top of Johnston Z4 in user-facing analysis while keeping the 2.5× weighting for Impact Load.
A run that is 60% Z2, 30% Z3, and 10% Z4:
Intensity Factor = 0.6 × 1.0 + 0.3 × 1.5 + 0.1 × 2.0 = 1.25×
Speed factor
Faster running raises ground reaction force per stride; research puts those forces at 2.0–3.0× body weight depending on speed. Basecamp normalizes against a 6:00/km (9:39/mi) baseline.
| Pace | Factor | Context |
|---|---|---|
| 7:30/km, recovery | 0.85× | Less force per stride |
| 6:00/km, easy aerobic | 1.0× | Baseline |
| 5:00/km, tempo | 1.2× | 20% more impact |
| 4:00/km, threshold or race | 1.3× | 30% more impact |
Terrain factor
Hills raise cumulative musculoskeletal load. Downhill sections load the quads, IT band, and joints eccentrically; uphill sections have lower per-stride impact but higher metabolic cost and longer ground contact.
| Terrain | Elevation per km | Factor |
|---|---|---|
| Flat road | 0 m | 1.0× |
| Rolling hills | 20 m | 1.05× |
| Hilly trail | 50 m | 1.12× |
| Mountain trail | 80 m or more | 1.2× |
Worked example
A 10 km tempo run at 5:00/km with 30 m/km of climbing, 70% in Z3 and 30% in Z4:
- Intensity:
0.7 × 1.5 + 0.3 × 2.0 = 1.65 - Speed:
6.0 / 5.0 = 1.2 - Terrain:
1.0 + 30/400 = 1.075 - Impact Load =
10 × 1.65 × 1.2 × 1.075≈ 21 km equivalent
That 10 km tempo costs about what 21 km of easy flat running would.
Tolerance
Tolerance is a rolling estimate of the weekly Impact Load your recent training has prepared you to absorb. It is a 6-week exponentially weighted moving average of weekly Impact Load.
- Rises gradually as you consistently complete higher loads
- Drops slowly through rest or taper, floored at 60% of your highest completed week
- Excludes the current week, so an incomplete week does not drag it down
- Updates weekly, drawn as stepped segments
Reading the tolerance line
- Bars below the line — load is under your recent adapted baseline
- Bars near the line — load is at your recent baseline
- Bars above the line — load is above your recent baseline, which is worth extra recovery or a look at how the progression is stacking up
- A rising line — your adapted workload is increasing
The load ratio
The chart reports a ratio in the shape of an acute-to-chronic workload ratio (ACWR):
Load ratio = This week's Impact Load ÷ Tolerance
| Ratio | Reading |
|---|---|
| Below 0.8 | Below your recent baseline — recovery, taper, or reduced training |
| 0.8–1.3 | Within your recent adapted range |
| 1.3–1.5 | Above your recent range — check fatigue and what is coming |
| Above 1.5 | A large spike relative to recent training |
Research does not support reading a single workload ratio as an individual injury prediction, and Minou does not present it as one. It is a progression signal. The Low, Moderate, or High load-risk label compares a plan's peak week against your current tolerance; read it alongside soreness, sleep, illness, terrain, and training history.
How a training plan uses tolerance
Generating a Training Plan puts tolerance to work in 4 places:
- Starting volume — week 1 begins at or near your current tolerance rather than an arbitrary number.
- Progression cap — weekly increases are limited so projected Impact Load does not jump abruptly above recent tolerance.
- Deload scheduling — the 3:1 build-to-deload pattern gives adapted load time to respond.
- Load-risk scoring — the plan's peak week is compared against your recent tolerance.
The purple projected bars let you check that the plan's progression is gradual rather than a cliff.
Reading the chart
| Element | What it shows |
|---|---|
| Blue bars | Your actual weekly distance or hours |
| Orange dashed line | Impact Load — what those runs cost your body |
| Green stepped line | Tolerance — your adapted capacity |
| Purple bars | The plan's projected weekly volume, in future weeks |
Distance / Hours in the top-right corner switches the view. The hours view applies the same intensity, speed, and terrain multipliers to time instead of distance.
Data sources
| Metric | Source | Fallback |
|---|---|---|
| Distance | Strava sync | — |
| Duration | Strava sync | — |
| HR zones | Strava activity streams | Intensity factor of 1.2× |
| Pace | Strava average pace | Speed factor of 1.0× |
| Elevation | Strava elevation gain | Terrain factor of 1.0× |
An activity with no heart-rate data — no chest strap, or wrist gaps — falls back to distance × 1.2, a moderate assumption in place of a measurement.
Limits
- Body weight is not a factor. Heavier runners take higher ground reaction forces per stride, and the model does not currently account for that.
- No cadence or ground contact time. These would sharpen the per-stride force estimate but need Garmin Health API data Basecamp does not have.
- No surface differentiation. Trail and road load the body differently; the model treats them the same.
- Downhill is not separated. Total elevation gain is used, so eccentric downhill load and metabolic uphill load are not distinguished.