ACWR for runners: Which injuries it can (and can’t!) predict

Somewhere in the last fifty years, running acquired a rule: “Don’t increase your weekly mileage by more than 10 %”. The 10 % rule gets mentioned all the time, but nobody is quite sure where it came from. It’s a rule of thumb, a nice and easy thing to remember, it sounds sensible and it’s easy to calculate. But the 10 % rule has 0 % scientific evidence going for it, quite worse in fact: almost 20 years ago a randomised control trial concluded that the 10 % rule makes no difference whatsoever to prevent running injuries (Buist et al. 2008).

Running frequency chart

We recently added a new chart on the Trends page showing how many days per week you’ve been running, on a rolling 7-day basis. Sports science studies have shown that weekly run frequency is linked with injury risk, especially for those running only once or 6-7 days per week. The data suggests a balance between frequency and mileage is important for injury prevention.