Most 5K training programs have you running about ~18 miles a week. A full marathon is 26.2 miles in a DAY. That's quite a difference. If you ran every day with

Most 5K training programs have you running about ~18 miles a week. A full marathon is 26.2 miles in a DAY. That's quite a difference. If you ran every day with no rest days, for 24 miles a week (per your post)...that's almost a 5K a day. I never said that was a definitive number. Hence the "~." There are other studies that back up this idea. As for your last sentence...no one here said anything about that. No one even said it would cause "bad health" to run a full marathon. However, when you run long distances, it has tremendous effects on parts of your body that are prone to injury and strain. Women long distance runners even have fertility problems. The human body was not meant to run long distances as the person I was replying to suggested. It's not "healthy" when contrasted with lower distances. Running itself is good.