Acute:Chronic Workload Ratio (ACWR)

ACWR (Acute:Chronic Workload Ratio) is the ratio between your recent training load and the base you built up in the weeks before. The ratio makes it visible at a glance how big a jump in load you’re making.

What is ACWR?

The idea: it isn’t the absolute size of a training week that drives the risk, but the jump relative to what your body is used to. The same eight-hour week is routine for someone who’s trained at that level for months, and a big spike for someone coming from four hours. ACWR expresses exactly that ratio — around 1 you’re training in line with your base, clearly above it you’re making a jump.

In the sports-science literature a moderate zone around and just above 1 is often named as a workable range. It’s important to note that the research is mixed: ACWR is a useful signal for jumps in load, but not an injury predictor and not a medical diagnosis.

How do you calculate ACWR?

The classic form divides the average load of the past week (acute, often 7 days) by the average of the past four weeks (chronic, often 28 days), based on load scores such as TSS or training duration. More modern variants use exponentially weighted averages, which let recent days count heavier and are less sensitive to the exact cut-off point.

The biggest pitfalls: a ratio says nothing without context (after a rest period a "high" ratio is unavoidable and even desirable to build back up), and the chronic base has to consist of enough data to mean anything. So use ACWR alongside — not instead of — recovery, niggles and how you feel.

How Trimetra personalises this

Trimetra uses ACWR as one of several signals for the size of your load jump, always together with your recovery signals, reported niggles and your own earlier response to similar build-ups. When there’s a big jump, the app plans more cautiously with extra quality; the label emphatically does not predict that an injury will occur.

Frequently asked questions

What is a safe ACWR?

The sports-science literature often mentions a moderate zone around and just above 1 as workable territory: you are then training in line with what your body is used to. But the research is mixed — see the ratio as a signal for load jumps, not a hard limit.

Does ACWR predict injuries?

No. ACWR makes visible how big the jump is relative to your built-up base, but it is not an injury predictor and not a medical diagnosis. Use the ratio alongside — not instead of — recovery, complaints and feel.

Why is your ACWR high after a rest period?

Because your chronic base dropped during the rest, every normal training week afterwards is mathematically a "jump". That is unavoidable and even desirable — you have to build back up after all. So always read the ratio in context.