Marathon Heart Rate

by Michael
(Australia)

Marathon heart rate, meaning what heart rate to run on during the marathon can be quite a challenge to find out.

Michael sent this question :

G'day

I planning on running my first marathon in a few weeks and am keen to know if there is an optimal heart rate at which I should run at on the day?

I'm 35 and plan to run the event in about 4hours...

I've clocked up about 500km since Feb in preparation.

Thanks
Michael

Hi Michael,

Great question. A challenge when it comes to marathon and heart rate is based on two things :

1) Race adrenaline.
2) Cardiac drift.

Marathon Race Day Adrenaline

I have seen this quite a few times. Because of the race day adrenaline kick, the heart rate seems off for the whole first part of the marathon race. It is very difficult to actually know exactly where to "be".

Cardiac Drift

Now, this is complicated further by cardiac drift. Cardiac drift sets in and gives you a "false" higher heart rate if you perform over a large number of minutes at a fairly high intensity as the marathon. The result is that it is difficult to determine the heart rate for the last 10-15 km of the race.

The result of these two is that you have two different challenges in two different parts of the race. The bottom line is : I do not recommend to rely solely on heart rate for your first marathon. Maybe your second when you have "data" from the first one.

Instead I would do like this :

For the next weeks now run at least once or maybe twice weekly on a track or a path where you have exact marks of how fast your are running. Use this to "teach yourself pace"

Then for the marathon, go out at a pace that let you pass the half marathon in about 2:03-05 and then try and run a negative split, with 1:55-57 for the last half marathon part.

If you have trained the pace on beforehand and get in a "steady" feel at this pace then this is much better than running with heart rate. Take a look at the picture above - to remember the splits on the way, note down every km/mile "passing time" for a 4 hour marathon on the way with a pen on your arm.

That way you will have full control and this is much better than a pure marathon heart rate focus.

Good luck to you !

best regards,
Marius

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