Acute chronic work load ratio

A lot of injuries we see here at NK Active, are related to training errors and overtraining. Keeping with our mottoes of get active, stay active and move forward, there is a tool you can use to help try and prevent overtraining hopefully due to the risk of injuries.

Typically people use the 10% rule. Increasing their active by 10% a week. However there are issues using the 10% rule when activity levels are low and also when they are high.

Let’s introduce the acute chronic workload ratio.

The acute chronic workload ratio was developed by Dr Tim Gabbett, a human physiologist.

The acute chronic workload ratio looks at your activity levels over a four-week period, looking at 4 weeks chronic workload and then one acute weeks workload.

Should the ratio be greater than 1.2 there is an increased risk of injury and greater than 1.5 is significant increased risk of injury.

This is a great tool to use on returning from injury and also future planning of activity levels. It doesn’t just have to be useful mileage, it can be used for time and intensity levels.

The Acute Chronic Workload ratio calculator

We are have created the acute chronic workload ratio for everyone to use, just type in your weekly data into the boxes, click calculate and will instantly work out your cute chronic workload ratio.

For the Intensity calculation just times the length of the activity by the effort level (0-10 scale, 0 = no effort 10 = maximum effort)

For example 50min run at 7/10 would give an intensity level of 350

When filling in the ACWL ratio the 4th week is always the highest value, then work backwards.

For example if your biggest week mileage was 40 miles, this would go in week 4, then fill in the previous 3 weeks mileage in the other boxes.


Greater than 1.2. = increased risk of getting an injury. 

Greater than 1.5 = Significant increase of getting an injury.


You can download Dr Tim’s work, here is a free PDF.


We would like to thank Dr Tim Gabbett for allowing us to use his work.