Q: Ask the Coaches: Heart Rate for a Marathon heart rate A Part of Hearst Digital Media.
A: There is no specific target heartrate zone for marathons, since it depends on how fast (read "hard") you are willing to run. Joggers can finish marathons while never exceeding 65-70%, while the average Kenyan is probably running the whole distance at several beats above 85%.
To have at least a slight idea of your zone for race day, do some planned Marathon Pace runs at exactly race pace of from from five to ten miles, to establish a likely zone. Even knowing this, however, I don't recommend running a whole marathon on just HR's because it is a very tricky matter that could lead to positive splits and a real head banger crash into the wall if you are unfamiliar with what you are doing.
On race day, a number of Magic Intangibles affect your heart rate. These intangibles, including your taper, carbo loading, aid stations and fellow runners at your pace, will make it possible for you to run easier at goal pace than you have in practice. Your HRM reads lower than expected, so you speed up to bring your HR up to the goal range, and pay for it later when you run out of glycogen and have to slow.
The solution then is to not run a marathon on effort alone until you have run several and have correlated your training heart rates with your actual rates at each mile on marathon day.
