Acute Load (7 Days)
46.2 km
Total running load over the last 7 days.
ACWR injury monitor
Analyze your weekly training load progress and manage injury risk using evidence-based workload ratio models.
Input Panel
Training Log & Config
Select your tracking metric, pre-fill a preset scenario, and log your daily workloads for the past 4 weeks (28 days).
A gradual, structured base-building progression (~10% weekly steps).
Day 28 represents Today
Week 1
D1
D2
D3
D4
D5
D6
D7
Week 2
D8
D9
D10
D11
D12
D13
D14
Week 3
D15
D16
D17
D18
D19
D20
D21
Week 4
D22
D23
D24
D25
D26
D27
D28
Outputs
Injury Risk Dashboard
Calculated load indices and next-week training recommendations.
Acute-to-Chronic Ratio (Rolling Average)
1.14
The Sweet Spot
Chronic Load (28 Days)
40.4 km
Average weekly volume over the last 4 weeks.
ACWR Progression (Last 14 Days)
Next Week Safe Load Targets
To train safely next week (over the next 7 days combined), aim for these total target km sums:
Under-training Limit
< 32.3 km
Sweet Spot Range
32.3 – 52.6 km
Overreaching Limit
52.6 – 60.6 km
Danger Zone Spike
> 60.6 km
Next step
Refine your plan with a related calculator.
Understanding the Acute-to-Chronic Workload Ratio
Managing training volume is the most critical factor in running longevity and injury prevention. Most running injuries (like shin splints, IT band syndrome, and runner’s knee) do not happen because of a single workout, but rather due to a sudden increase in training load that exceeds the body’s adaptive capacity.
The Acute-to-Chronic Workload Ratio (ACWR) offers a mathematically sound framework to assess whether you are progressing safely, undertraining, or moving into a high-risk zone.
Simple Rolling Average vs. EWMA Models
This calculator provides both the standard Rolling Average (RA) model and the advanced Exponentially Weighted Moving Average (EWMA) model:
Simple Rolling Average (RA) ACWR
ACWR = Sum(Last 7 Days Load) / (Sum(Last 28 Days Load) / 4)
Calculates the ratio of the acute 7-day average daily workload divided by the chronic 28-day average daily workload.
Exponentially Weighted Moving Average (EWMA) ACWR
EWMA_today = Load_today * lambda + EWMA_yesterday * (1 - lambda)
Where lambda = 2 / (N + 1). We apply N = 7 for acute load (lambda = 0.25) and N = 28 for chronic load (lambda = 0.069). Recent workouts have the highest weight, reflecting physiological fitness and fatigue decay.
While the Rolling Average is simpler, the EWMA is widely preferred in sports science because it aligns with physiological recovery curves: your run yesterday has a much larger impact on your fatigue today than a run you completed three weeks ago.
Interpreting the ACWR Zones
| ACWR Ratio | Training Status | Injury Risk | Coaching Action |
|---|---|---|---|
| < 0.80 | Undertraining | Elevated | Increase volume gradually; body is unconditioned for higher load. |
| 0.80 – 1.30 | The Sweet Spot | Lowest Risk | Maintain or slowly progress. Optimal ratio for building fitness safely. |
| 1.31 – 1.50 | Overreaching | Moderate Risk | Hold volume steady. Monitor fatigue, sleep, and muscle soreness closely. |
| > 1.50 | The Danger Zone | High Risk | Reduce training load immediately. Focus on recovery and active stretching. |
Why Session RPE (sRPE) is Superior to Mileage
While monitoring mileage is simple, it misses intensity. A 10-kilometer run performed at threshold pace stresses the skeletal, cardiovascular, and endocrine systems far more than a 10-kilometer run completed at an easy recovery pace.
Session RPE (sRPE) solves this. At the end of every running session, rate your overall exertion on a scale of 1 (extremely easy) to 10 (maximal effort), then multiply that number by the duration of the run in minutes.
sRPE = Workout Duration (minutes) × Rate of Perceived Exertion (1–10)
Using sRPE gives you a unified "Workload Units" score that automatically reflects both training volume and hard pacing efforts.
Scientific References
The training—injury prevention paradox: should athletes be training smarter and harder?
British Journal of Sports Medicine (Gabbett, 2016)
Better way to determine the acute:chronic workload ratio? (Williams et al., 2017)
British Journal of Sports Medicine
How much is too much? (Consensus Statement on training load and injury, Soligard et al., 2016)
British Journal of Sports Medicine
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