Blog 4: The Energy Systems

In the human body there are complex number of chemical interactions that turn our consumed food into energy that can be utilised to keep us functioning and moving. These are way beyond the scope of this blog.

So, I will keep it simple in relation to getting more of what you want from your cycling.

The importance of the energy system utilised is how long it is possible for the individual to sustain an effort level while using that system. 

For example the carbohydrate available within the muscle cells can last for around 10 seconds of a maximal effort, while the fat stores within the average healthy person's body could sustain them at a very low level for potentially more than a week.

The relevance of this is that if an individual is pushing as hard as possible the effort level will reduce quite quickly, this could be followed instantly (in some cases) by a period of exhaustion, while the body recovers and attempts to replenish the energy stores.

Another example would be a series of efforts that are sufficiently below the level of exertion leading to exhaustion to not have an immediate and apparent effect on the individual, but over a period of time, without the required level of recovery, lead to failure. 

Perhaps this could be likened to riding up a hill that you have been able to ride up at given speed comfortably in isolation, but after having ascended other climbs first you find your self needing to slow down on the normally easy hill.

The two example workouts below show graphically the different fuel sources utilised by this particular individual over time at a given heart rate.

The illustration to the left shows the individual working in their Zone 1 and how this will likely yield 2/3 of the fuel utilised from Fat. 

This would perhaps be a gentle ride by a canal (the flattest ride I could imagine)

However, the illustration to the right demonstrates an interval session with the individual working in Zones 2 & 3, requiring more energy and utilising a greater level of Carbohydrate for fuel. 

This could equate to a long climb with a series of alternating gradients.

While carrying out sport specific exercise and being aware of your own heart rate and the primary energy system utilised, you will have a much more accurate indication of your own need for recovery and ability to repeat the efforts.

Also over time, you should be able to produce more power (more output) in a given Zone (at a given heart rate), in effect become more efficient.

It is also worth noting that, while energy being produced may primarily from Fat stores, it will not be exclusive and vice versa.

As a gross generalisation though;

Fat Stores                   = Endurance

Carbohydrate Stores = Instant Energy

Again, it comes back to knowing where you are, how your body is using it's stores and how you can best work with your physiology to increase your cycling performance, enjoyment or both.

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