Training Load Calculator
Your acute-to-chronic workload ratio — the single best-known predictor of soft-tissue injury — from this week’s load against the last month’s.
Session load is duration times perceived exertion.
How the training load calculator works
Session load is duration times perceived exertion. The acute load is this week; the chronic load is the rolling four-week average. Their ratio is the number sports science watches.
Below 0.8 you are detraining; between 0.8 and 1.3 is the "sweet spot"; above 1.5 injury risk rises sharply. The finding that matters is that the risk comes from the *change*, not the absolute load — a high chronic load is protective, and it is the spike that hurts you.
Formula: load = duration × RPE; ACWR = acute / chronic
Worked examples
| Inputs | Acute:chronic ratio | Note |
|---|---|---|
| A steady week | 1.1 | 1.13 — the sweet spot |
| A big spike | 1.677 | well into the danger zone |
| A recovery week | 0.612 | under-loaded |
FAQFrequently asked questions
What is the acute:chronic workload ratio?
This week's training load divided by the rolling four-week average. It is the best-established predictor of soft-tissue injury.
What ratio is safe?
Between 0.8 and 1.3 is the usual sweet spot. Above 1.5 injury risk rises steeply in the following one to two weeks.
What is a load unit?
Session duration in minutes times rated perceived exertion out of ten. It is arbitrary but consistent, which is all it needs to be.
Is a high training load bad?
No — a high chronic load is protective. It is the spike relative to what you are used to that causes injuries.
Does this apply to strength training?
The principle does, though the evidence base is strongest in team and endurance sport. Use it as a guide, not a rule.
Where these figures come from
- Riegel PS, "Athletic records and human endurance", American Scientist 1981 — T2 = T1 × (D2 ÷ D1)^1.06
- Cooper KH, "A means of assessing maximal oxygen intake", JAMA 1968 — the 12-minute run test
- Ainsworth BE et al., Compendium of Physical Activities (2024 update) — MET values by activity
- OpenPowerlifting — DOTS coefficients (Tim Konertz, 2019) — the DOTS polynomial used for scoring
- Naismith's rule (1892) as used by UK and Australian walking bodies — 1 hour per 5 km plus 1 hour per 600 m of ascent
- Australian Institute of Sport — national sports-science body
Last checked: September 2026. Formulas are fixed by their published sources; the MET values come from the Compendium of Physical Activities.