Fat burning Marathon

by Tor

How does one deal with the long runs in the marathon in terms of "fat burning" - drink energy drinks or not ?

"Hi Marius,

I am following your sub 3.00 plan for the Copenhagen marathon this Year. I really like your structured approach in your plans.

Have some questions to the long runs (+2 hours).

My experience is that after about 1.45 hours I get into the fat burning zone. McMillan suggest to do the long runs without any energy intake to really get used to run with lowered carbohydrate stores (muscle glycogen). My experience is on the other hand that my heart rate goes above E1 and into E2 after about 1.45 hours, if I keep the same speed in the long runs without energy intake. Personally I would like to keep the same pace in the end, in order to be mentally prepared for doing so in a marathon as well.

I have therefore two questions to you:

-Should I keep doing the long runs without energy intake?
-Do you think I should reduce my speed in the end in order to keep E1 (heart rate wise) level in the latter part of the exercise as well?

PS! Do not have any desire for weigth loss through running in the fatburning zone (BMI less than 20).

Thanks in advance, Tor"

Answer: Hi Tor, I suggest you do the following : half of the runs go with energy drinks/bars, half of the runs do without and instead slow down.

This is what the Italian marathoners do as well (they even have a third approach - where they double up two long runs at a fairly fast pace the same day and do not eat/drink much/any carbos in between for maximum results)

However, having said that - the main effect of the long runs is not fat burning itself but the muscular adaption to duration.

It can actually certainly be discussed the real effect on the "fat burning" long runs in terms of marathon running. It is VERY hard to run out of glycogen in these easy long runs. To really get into deep ketosis and push the fat metabolism - you'll need 3-5 days of very hard training and only 20-25 grams of carbos to serve the nervous system. I've done this myself, tested the fat metabolism for objectiveness (ketones) and was surprised how much I had to do + how long it took to really get into a "fat burning" phase when in full training.

I wish you all the best with your training !


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