Understanding the Energy Systems Part 2

So yesterday was an intro to the fuel systems of the body.  It was brief, but to get the point across, I made it quick and painless.  If you noticed, the two sources for fuel were fat and carbohydrates.  These are broken down according to how fast energy is needed, then they are converted to ATP for muscular contraction.  The relationship between fat and carbohydrates can be seen in the picture.

As you move away from aerobic systems, fat is used less and less as carbohydrates become the main fuel.  Looking at the picture again, you see that the red line represents the wastes.  This is not related to bowel movements in any way (or we would be in big trouble every time we rode!).  The line indicates the accumulation of lactic acid.  When the intensity is low and fat is still a prime fuel, the lactate acid can be flushed from the blood and muscles in a timely manner.

The aerobic base is the point where the highest intensity of your effort can still be maintained to be aerobically efficient.  Remember, aerobic means “with oxygen” so this is still in the lower heart rate zones.  You can actually shift this point with enough aerobic training.  This is the main goal when you say “I need to get my cardio up.”

As you move up the graph, you’ll see the lactate acid increase exponentially.  This is where you reach the anaerobic threshold.  At this point, you stop using oxygen and that burning feeling is rampant.  Training in this zone requires a lot of work and athletes physically cannot spend much time here.  Once you go past this point, you reach your VO2 max.  Quite simply, this is the maximum amount of oxygen the body can take in and use.

By now, you should see a pattern forming here.  Your heart rate zones used for training are directly affected by your anaerobic threshold, aerobic base and VO2 max.  The fuel required must be consumed in sufficient quantities to ensure that you have the body’s “gas tank” full (i.e. eat correctly).  I hope this helps you understand aerobic training a little more.

If you have any questions, don’t be afraid to email me!

Posted on Nov 10 2011, under Training | No Comments »

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