Evidence hub / ACWR

ACWR for CrossFit: train the rate of change, not just the volume

Injury risk isn't mainly about how much you train — it's about how fast the load changes. The acute:chronic workload ratio (ACWR) divides your last 7 days of load by your rolling 28-day average. Ramping that ratio past ~1.5 spikes injury risk; sitting too low (<0.8) means detraining. The safe region is the middle of a U-shaped curve, roughly 0.8–1.3.

0.8–1.3

sweet spot

>1.5

ramping too fast — risk spike

<0.8

detraining

What the research says

Tim Gabbett's work reframed the "more training causes injury" assumption. High chronic workloads, built gradually, are actually protective — well-trained athletes tolerate hard sessions. What predicts injury is the spike: acute load jumping well above what the body has adapted to. The relationship is U-shaped, so undertraining is also a risk because it leaves the athlete underprepared for the demands they eventually face.

Each session's load is quantified — by heart-rate-based TRIMP when HR is logged, or RPE × duration otherwise — then aggregated into acute (7-day) and chronic (28-day) windows. The ratio tells you whether this week is a sensible progression or a gamble.

How Dawg & Rabbit Fitness applies it

The app computes your ACWR continuously from logged sessions and keeps week-to-week progressions inside the safe band, deloading automatically when form (TSB) drops too far or monotony climbs. You see the live ratio, color-coded, with the threshold logic and Gabbett citation attached — so the load math is structural, not narrative.

Source.
Gabbett (2016). The training–injury prevention paradox: should athletes be training smarter and harder? British Journal of Sports Medicine, 50(5), 273–280. doi:10.1136/bjsports-2015-095788

Last updated: 9 June 2026

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