Endurance and your body’s Energy System

Endurance and your body’s Energy System

So what is meant by Endurance? On this episode of 32Gi Sports Nutrition; Mark Wolff breaks it down, and has a great analogy to explain it. We also look at the Energy System and how your body fuels itself during exercise. So what is the best fuel source? Hear more here.



Thanks for joining myself, David Katz, Mr. Active and Mark Wolff, on another episode on the 32Gi Sports nutrition podcast. Today we look at endurance which is so critical when it comes to the relationship with nutrition and what you putting in. So Mark that’s my first question to you today, what is meant by endurance?

MW: I think if we have a look at a medical definition of endurance, it’s really an activity over a prolonged period of time. The way I put it to some body builders that I was educating around endurance was, ”how many reps of squats did you do today?” The common answer would be, “I did 12 reps and I did three sets of squats.”

What is meant by Endurance

When I look back at what we did that morning which was a hill session on the bike, I said we actually did about 2000 one legged squats in a period 60 minutes. If you think about it in those terms it’s really putting your body under a bit of physical stress, quite a lot of physical stress and it’s basically maximising the usage of your muscles over a prolonged period of time.

That’s really what endurance is it’s not just about physical activity you’ve got to also put it into a perspective of thought, of concentration. I mean if you talking about endurance sometimes endurance actually deals with concentration span.

Even if you are cricket player and you have got to stand on a field all day long whether you’re playing a one day or a test match; you need to understand that there needs to be focus as well.

That is another form of endurance. So endurance covers the physical aspect but as well as mental focus as well and it’s really over a prolonged period of time. I think that really, really sums it up.

DK: Well Mark you’ve got a great analogy where you liken endurance and the need to fuel yourself to a journey.

Preparing for your endurance journey

MW: So I use an analogy where I look at a motor vehicle for example. If we look at a motor vehicle; it’s got a body, it’s got a shell, it’s got an outer body and it’s got an engine. If you look at a human being we’ve got organs inside which you could actually equate to being our internal engine.

I always ask people when they enter an endurance event; for example they’re doing a marathon or they’re doing an ultra-marathon whatever event they’ve selected. I ask them, “is your own vehicle in good working condition to go on this journey?” Because you’ve selected a destination which is obviously the finish line. It could be a couple of months before and now you’re going on a journey and you need to get to that destination.

If we look at a motor vehicle and you going on a long, long trip for example. I always ask people, “what do you look at before you go on a long trip?” People will always tell me, “that’s quite simple; the vehicle needs to be serviced, I need to check the tyre pressure. The oil and the water need to be checked. You need to check windscreen wipers, because obviously if there’s a rain storm on route and your windscreen wipers aren’t working, that will be an issue as well.”

Then one of the things that you also need to look at is the petrol tank full? Because I mean if it isn’t, how are you going to actually go on this journey. So if these things aren’t checked chances of you making it to the finish line or to your destination are very, very slim. You are going to go off path if there are any underlined things with the vehicle.

Can you tell if your engine is in good condition?

So one of the things I always ask people is, “how do you know your own vehicle, your own human body is in good working condition?” What I often recommend is that first of all you know from the outside. We get visual perspective of exactly are we in good shape or aren’t we?

Sometimes it’s not a true reflection of what’s going on in the inside and on the outside we might be in good shape. But on the inside we don’t know what’s happening with our own engines and that’s a very much neglected part. People are so quick to go and service their vehicles when they need it or to fill up with petrol.

I often ask people well what kind of fuel are you putting into your own body, and are you sure your organs are in good working condition? So in this case I always recommend going for a medical. Going for a full check-up and making sure your own body is in good working order to be able to go on this journey.

Which I call endurance because it really is a journey, it’s a long journey. You need to make sure that your vehicle is in good working condition to get to your destination which is your finish line.

DK: Well Mark most vehicles only having one fuel tank when we look at our personal energy systems you look at three fuel tanks; your glycogen, your fat and your protein. Tell us a bit more about these fuel sources and how important they are.

3 main fuel tanks of your body

MW: I think the energy system is very critical and people might tell you there is four or five tanks. In a vehicle we do have a reserve tank which usually comes on after the main tank is finished; we get a little light indicator that we need to fill up with fuel.

In the human body I would say that there are really three main fuel tanks of which really two are the main fuel tanks. Those are what you’ve just mentioned; glycogen, fat and protein.

Glycogen and fat are really the two tanks that we want to look at as far as fuelling goes. The reason I say that is because those are the two tanks that primarily fuel the body during endurance sport, during physical activity. How does it work?

How Glycogen stores work

Glycogen first of all they are our own natural energy stores, our carbohydrate stores. Basically they are stored in the muscles and also stored in the liver. Generally glycogen is utilised under high intensity exercise.

So if we not getting enough oxygen into the system you’ll find that you primarily using glycogen as a source of fuel. There is a way to spare glycogen and that is obviously to take in carbohydrates.

You cannot spare it indefinitely. You’ve got the ability to spare glycogen up to a certain percentage. Probably we look around the 30% mark, by taking in some carbohydrates to help support that. Generally the glycogen stores or the glycogen tank is limited.

In actual fact you looking at about 2000 calories probably with topped up glycogen stores. If you working out how many calories you are burning per hour; you will probably see that takes the average person around an hour and a half. A well-trained athlete maybe two hours and maybe a little bit longer.

Why Fat is such a powerful fuel source

If we look at our fat stores, those are our largest natural stores available in the human body. In actual fact we are looking at around 40000 calories of storage. So that is a major fuel tank.

It’s a known fact that the human being can probably run around 55 marathons on his fat stores alone. It’s a very, very powerful form of fuel. It is obviously stored in the body in different areas.

So we look at subcutaneous fat which is sitting under the surface of the skin with the intramuscular trivialise. There’s fat available in the body. Obviously depending on what you consuming you might have some free fatty acids also available for fuel within the system as well.

So why do we say fat is so powerful and it’s very simple. One gramme of carbohydrates is four calories; one gram of fat is around nine calories. So you talking about more than double the amount of fuel from fat as opposed to carbohydrates.

If you can harness that you’ve got the ability to actually utilise a very powerful form of fuel. That’s what we try and teach people to do, to become more fat efficient. I call it actually minimalistic fuelling in a way. But to become a more fat efficient athlete would definitely benefit you in endurance sport.

Obviously during exercise or especially during a race and a high intensity exercise; there’s going to be a range of intensities that the human body goes through. During those ranges of intensities there will be a percentage of glycogen and fat that are utilised.

As the intensity becomes higher and higher and there’s less oxygen coming to the system, your glycogen levels will be utilised more. As the intensity drops down more you’ll find that fat can become more available. But again it depends on how you want to tap into those fuel tanks. What you consume will definitely play a critical role in determining how to tap in there.

I’ll just use a simple example. You do spike your blood sugar and then you go off hoping to burn off fat. You just won’t because the first thing your body wants to do is get rid of that blood glucose, before it actually starts to tap into the fat stores. As opposed to somebody who goes out there and trains on water. They’ll probably get into a fat burn state a lot quicker.

So what you consume will also determine which tank you can access. But we will be talking about; training, racing, distance, time and intensity in order to be able to select the right nutrition strategy to fuel those various types of efforts, in another podcast.

Why you don’t want to use your Protein stores

One of the tanks that we haven’t really spoken about is the protein tank. Probably one of the main reasons is that it’s not an ideal fuel tank to access. The last thing you want to do is actually catabolise protein in the muscle in order to be able to utilise this fuel. It does happen in ultra-endurance events.

We will talk about how this can be mitigated where the focus should be on the two primary fuel tanks. Which are considered to be your glycogen and your fat. We’ll get into that in a lot more detail because it gets very, very technical. There’s a lot of information that we can share with you around that.

DK: Not something you want to be doing, eating into your muscles to use them as energy. Mark another fantastic podcast. Thanks for joining Mark Wolff and myself David Katz Mr. Active, we’ll be back next week with some more fantastic information for you when it comes to nutrition.

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