ACWR & Injury Prevention Masterclass

Most running injuries do not happen because of one bad step or one unlucky day. They happen when we ask our body to do significantly more work than it is prepared for.

If you run 20 kilometers a week for a month and suddenly jump to 45 kilometers in a single week because you felt great on Monday, your tendons and joints take a massive hit. You might not feel it immediately, but two weeks later your knee or shin starts aching.

Sports scientists created a simple ratio to catch this before it turns into pain: the Acute-to-Chronic Workload Ratio, or ACWR.

Your Acute Workload is the total stress you have put on your body over the last 7 days. This represents your current fatigue.

Your Chronic Workload is your average weekly stress over the last 4 weeks. This represents your established fitness base.

By dividing your acute fatigue by your chronic base, you get your ACWR number:

If your number sits comfortably between 0.80 and 1.30, you are in the training sweet spot. You are making consistent progress without overloading your tissue.

If your number spikes above 1.35 or 1.50, your fatigue is way ahead of your preparation. This is when your risk of injury jumps dramatically.

In Caden, we calculate your ACWR automatically every time you log a workout, showing you a smooth 60-day visual curve so you always know when it is safe to push and when it is time to rest.