How do you know when your running shoes are worn out?

In this video I compare a pair of Altra Flow 2s with 1200 km on them against a new pair of Flow 3s with 20 km. I show you the warning signs to look out for, including new niggles below the knee like a tight arch, sore shins or pain along the outside of your foot, and a simple thumb test you can do at home.

I also explain why I do not follow the usual 400–600 km replacement rule, and what I recommend if you think your shoes might be getting worn out.