Even though you are racking up the mileage in marathon training you have to be careful not to over train.
Over-training and overuse injuries are the most common reasons people get hurt and are unable to finish training.
To avoid injuring yourself by over training stick to the 10% rule: Don’t increase your mileage by more than 10% each week. Cool Running says:
“Do not increase either your (1) weekly mileage and/or (2) long run mileage by more than 10 percent a week. Doing so greatly increases the chances of incurring an injury, thereby delaying or stopping your training all together.”
There were weeks in my training that called for me to scale back. After 2 consecutive weeks of super long runs on a Saturday the third week called for me to run significantly less. There is a reason for this, and it’s for your own good. The professional marathon training programs that you find online *from reputable sources like Cool Running, Hal Higdon and Jeff Galloway* are written by people who have ran marathons and who know how to keep runners from getting injured. Stick to the plan even if you can do more! This is hard to do when you feel like you can run further, but it’s for your own good.
Staying healthy and keeping your body happy is hard enough during marathon training, don’t make it harder for yourself 🙂