Heart Rate Training – Part 4 – Burning the Fat.
If you have not read parts 1-3 of the series on heart rate training, you can click on the following links:
Most of us are familiar with the concept of braaing or barbecuing, for non South 
African readers. You simply take some coals, place some fire lighters under them, set the fire lighters alight and within 45 minutes or so, you are ready to cook. Anyone getting hungry?
You have two primary fuel systems; we can liken them to coal and firelighters. Coal/charcoal represents your fat reserves, and fire lighters represent your glycogen stores.
Your fire lighters are soaked in flammable fluid. They are fun to light and give off a huge flame. Athletes relying on glycogen look the same; they sprint up hills, fly past on bicycles and heat things up in the pool. The only problem is that you have less glycogen than you do fat, and so that burst of speed is unsustainable.
Charcoal or briquettes are different. They are a bit boring to watch, but are able to burn on and on. Athletes relying on their fat systems will be able to keep going without ‘burning out’. If you have ever hit the wall during an event you will know exactly what I am talking about. I still bear the psychological scars of going out too quickly during a marathon and getting to the 34 km mark and feeling like the entire universe had conspired to make me run slower than a tortoise. People have come up with all sorts of terms to describe this, some of my favorites include:
– I ran round the corner and a bear jumped on my back.
– Someone asked me to push a piano to the end of the race which I agreed to do.
– I was just about to overtake a runner when rigor mortis set in.
– A gnome was hiding behind a bush and shot my legs out with a shot gun.
This is where heart rate training comes in: Your heart rate is a wonderful indicator of how hard your muscles/furnace is burning.
50-70% max Hr – Fat is your primary source of nutrition.
70-80% max Hr – approx. 60% carb and 40% fat mix.
80-100% max Hr – primarily glycogen.
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The giant computer that sits between your ears needs lots of glycogen to function. One of the negatives of hitting the wall, or, that moment when you seriously run out of fuel, is that it becomes more difficult to think properly. That puts you in greater danger of having an accident on your bike or running into a lamp pole. If you have ever run a marathon and got to the 35 km mark and battled to work out how far you have to run, your brain is running short of fuel. “Mmmm”, you think to yourself, “42Km – 35Km leaves me with, um, 10Kms worth of running…” You really need to slow down at that point and get some food into you. Grab a gel or drink some coke and then take it slowly so that your body can recover itself. You can become a danger to both yourself and to those around you, especially if on a bike.
Hope this helps,
Regards,
Mike Roscoe. 
Kinesiologist.
