What is ACWR?
The acute:chronic workload ratio, comparing this week's training load with a rolling four-week average. It flags whether you have ramped up too fast.
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Training Load Impact Calculator
The acute:chronic workload ratio (ACWR) flags whether a recent spike in training load pushes an athlete into a higher injury-risk zone. A widely used sports-science guide.
ACWR = acute (this week) load / chronic (4-week average) load
Frequently asked questions
Why does a sudden spike raise injury risk?
Because the body adapts gradually. Loading far above what it is used to (a high ratio) is linked in research to higher injury rates, while steady progression is safer.
What is the sweet spot?
Studies often cite a ratio around 0.8 to 1.3 as lower risk. Below that may mean detraining; well above it is the danger zone the calculator warns about.
Is ACWR settled science?
It is widely used but also debated, with critics noting it depends heavily on how load is measured. Treat it as a useful guide, not gospel.
How do I measure 'load'?
Commonly as session duration times perceived effort, or via distance and intensity from a tracker. Use the same method for both figures so the ratio is meaningful.