So I was headed for a short run this afternoon and my 5 year old said he wanted to come. I told him I was running a long way and wouldn’t be able to bring him back. He said “I don’t care, I’m coming with you!” I figured we’d run a little while and he’d get tired and we’d run back so he could go back to the house. 1 mile in and 10 minutes later he was still going. We took a short walking break and got back to running within 100 meters. We ended up running 2 miles together. He’s a whopping 40 pounds, not an ounce of fat, very active and basically runs everywhere he goes. He also talked my ear off the whole time. Told me it was the best part of his day getting to run with me. Now, part of his motivation was probably that his 7 year old brother quit 3 times in the first 800 meters and then bailed out. Anyway. My question is, does anybody have a rule of thumb for distance:age? I’d love for him to continue tagging along on my short runs but I don’t want do it if there’s a chance at bone/tendon/growth plate etc. damage at his age. I’ve found very little info on line other than ones stating he should be running no more than 400 meters. This kid does that in the house on an average morning getting ready for school. I’m just wondering if anybody has any personal experience with their own kids or other kids in general.