ACWR calculator (acute:chronic workload)

ACWR (Acute:Chronic Workload Ratio) compares your last 7-day load (acute) to the 28-day weekly average (chronic). Above 1.5, injury risk rises significantly (Gabbett, 2016).

The tool places you in a risk zone (undertraining, sweet spot, caution, danger) and gives the action to take.

The calculation

ACWR = acute load (last 7-day sum) / chronic load (weekly avg over 28 days)

• Arbitrary units (sRPE): session RPE × duration in minutes. Universal.
• Kilometres: for running.
• Tonnage: sets × reps × load, for strength and powerlifting.

The 4 zones

• < 0.8 (undertraining): doing less than average. Risk of detraining.
• 0.8 to 1.3 (sweet spot): optimal zone, adaptation and progression.
• 1.3 to 1.5 (caution): load rising faster than absorption capacity. Watch fatigue, sleep, signals.
• > 1.5 (danger): significantly increased injury risk. Reduce next week.

Coach use

ACWR is widely used in team athletic prep and sports physiotherapy. Indicators: post-injury return (ratio < 1.3), peak season (tolerate 1.3-1.5 for 1-2 weeks then deload), back-to-back competitions.

Limits of ACWR

ACWR was challenged in 2019 (Impellizzeri et al.) on its pure predictive value. It remains a solid trend indicator: a big jump within a few days means risk, whatever the absolute ratio.

In Unbrokn, ACWR is computed automatically from the RPE and duration you enter at the end of each session. You find it in My Evolution, and your coach sees it in their tracking view. The check-in adds sleep, pain and motivation.

FAQ

Which unit for my discipline?

Running: km. Strength: tonnage. Team sports or hybrid: sRPE. The ratio works regardless of unit, as long as it stays consistent.

Daily calculation needed?

Once a week is enough, end of week. For a whole team, automate the calc from your tracking tool.