One of the things often overlooked is how to manage your energy. I'm lucky enough to have studied up on managing energy levels from when I hiked my 100k. This post is for those who've not taken anything like this on before, and it is as relevant for walking, hiking, cycling, etc as it is for running IMHO.
I'll make this post in easy to follow language as there are a raft of experts who can go deep into the technical aspects of how your body processes energy and the chemical rates of processes regarding ATP, Glycolysis and Gluconeogenesis (Not just a hat rack, my friends ;-)). No, I'll keep this simple for those who are getting into this from the outset
When it's gone it's gone (for quite some time)
I talked in a previous post about the 'Bonk' and when the tank is empty you are, quite frankly, done. [you can find it in #13 - MAF Tests (click to read it) and I mentioned how I'd expand upon it. Well here it is...
You may have heard of carb loading the days before a sporting endeavour. Atletes typically do this to load the muscles up with glycogen (a form of glucose). This glycogen is the conversion of carbohydrates you eat into a fuel source, stored for your muscles, brain, organs etc. in the liver. Your body will burn fat for fuel (Lipolysis), however the minute your heart rate starts to climb over your personal zone (Maffetone says 180 minus age) then it switches to higher octance fuel - Glycogen (a process called Glycolysis)
Think of it like filling your petrol tank in your car and topping off the tanks.
Like a car, this fuel is preferred by the body because it is made rapidly available to the body when it is exerting itself. And just like a car, the faster you put your foot on the accelerator the faster you use up the fuel.
Your body is exactly the same. The harder you work, the faster you burn up your glycogen stores.
And once the tank is empty, it doesn't fill up in minutes. It fills up in hours (bit like an EV).
This emptying of the tank is one of the top reasons people fail in endurance events. You will likely have seen people collapsing at the dreaded Mile 18 in a marathon. Why? Because they ran the tank dry. They pushed too hard for too long and there was never enough time to replace the glycogen they were burning through.
It's something I've watched and seen first hand. From people blacking out and collapsing (their brain literally shuts down) to just no ability to even get off the floor.
As I understand it, typically an average person running with a HR at 160 bpm has around 2hrs of glycogen in reserve. Then, they're done. (though chances are you get to stay clothed)
2hrs in a marathon is often around Mile 16-18. No coincidence.
Here's why it happens
On an ultra endurance event, if you are typically burning on average 600-1000 calories per hour (depending upon weight, speed, packload, conditions, etc, etc) and you are going for 30 hours non stop, then (if you weigh what I do) you will burn up to 30,000 calories in order to fuel yourself. To give you an idea that is 150 slices of Domino's Pizza you would need to eat to cover all that energy used!!
If you've ever done any kind of distance that is very hard to do when you feel tired, hurt, blistered, sick, etc.
Ultra marathons are often described as eating competitions for this very reason.
Those calories have to come from somewhere.
Pace yourself
This is where effort and pacing are really important. You have to keep your heart rate in the fat burn for fuel zone for as long as possible, and use quick energy (gels, drinks, etc to top up the glycogen). Hills will burn your glycogen fast, as will running too quick or starting too fast. "It's a marathon not a sprint" is a saying for a reason!
My reason for MAF Training and Fat Adaptation
To be fat adapted means that my body needs to become much better at using fat for fuel. The training I'm doing using Maffetone Method is designed to keep my heart rate low while I run at a gentle pace for very long distances, only focusing on fat for fuel. As my diet moves me also towards being fat adapted, I aim to get a better and more consistent energy source from my body fat stores (which are *ahem* abundant right now) in order to avoid the dreaded crash from 'bonking'.
This will take time. 8-12 weeks typically but should reap the benefits when it matters most.
Think of it this way... your body is like a petrol tanker truck. You are the truck, which has it's petrol tank (Glycogen). These tanks are small. Your tanker load is your body fat stores. If you purely burn your small tanks down you will stop. No way to get started until you've refilled. My aim is to create an effective and consistent feed from the tanker itself into my engine which means it can run and run.
I intend to also top off glycogen burned on hard climbs, etc. frequently. There is a saying "eat for the mile to come, not the mile you've run", so taking in small and often simple carbs like glucose/sugar will also be part of my game day strategy. Until then it's fat for fuel all the way.
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