As a physiotherapist, one of the most common conversations I have with people isn’t about whether training is good for them — it’s about how much is enough, and how much is too much. Training harder can make you fitter and faster, but only if your body is prepared for that load. Push too far, too fast, and the risk of injury can rise.
One of the most useful tools we have to manage this balance is the Acute to Chronic Workload Ratio (ACWR).
What Is Acute to Chronic Workload Ratio?
ACWR compares how much training you’ve done recently (acute load) to how much training your body is used to (chronic load).
• Acute workload = training load from the last 7 days
• Chronic workload = average weekly training load over the last 4 weeks
The ratio tells us whether your recent training spike is appropriate or potentially risky.
How Do You Calculate Training Load?
A simple and practical method is using session RPE (Rate of Perceived Exertion):
Training Load = Session Duration (minutes) × RPE (out of 10)
For example:
• 60 minutes of running at 7/10 RPE
• 60 × 7 = 420 units
This method is widely supported in the literature and is easy to use without fancy technology. You would calculate this number for every session and add them together to get weekly totals.
Calculating ACWR: A Simple Example
Let’s say your last 7 days (acute load) total 2,100 units.
Your last 4 weeks average (chronic load) is 2,000 units per week.
ACWR = Acute Load ÷ Chronic Load
2,100 ÷ 2,000 = 1.05
This puts you in a very safe and effective training zone.
What Is the Ideal Range?
