Road runner Metroplus

The fa(c)t of the matter

Your body can store energy beyond your imagination - Photo: N. Sridharan  

Running long distance for long periods of time requires a substantial amount of energy. Most recreational runners focus on carbohydrates as an energy resource (hence the infamous carb loading the night before a race). However, in this two part series, we will spend some time understanding the important role FATS can play in fuelling your next race. I have been researching this topic and wanted to share my findings.

As potential fuel sources, the carbohydrate, fat, and protein in the foods that we eat follow different metabolic paths in the body, but they all ultimately yield water, carbon dioxide, and a chemical energy called adenosine triphosphate (ATP). Think of ATP molecules as high-energy compounds or batteries that store energy. Anytime you need energy — to breathe, tie your shoes, or cycle 100 miles (160 km) — your body uses ATP molecules.

Because the body requires less oxygen to burn carbohydrate as compared to protein or fat, its considered the body’s most efficient fuel source. Carbohydrates, such as sugar and starch, are readily broken down into glucose, the body’s principal energy source. Glucose can be used immediately as fuel, or can be sent to the liver and muscles and stored as glycogen. The body constantly uses and replenishes its glycogen stores. As we exercise, our muscle and liver glycogen reserves continually decrease. The capacity of your body to store glycogen, however, is limited to approximately 1,800 to 2,000 calories worth of energy, or enough fuel for 90 to 120 minutes of continuous, vigorous activity.

What if I tell you that you could actually run for more than eight to 10 hours, without eating anything during the run?

Enter the world of FAT! Fat is the body’s most concentrated source of energy, providing more than twice as much potential energy as carbohydrate (9 calories per gram versus 4 calories each per gram). Unlike one’s glycogen stores, which are limited, body fat is a virtually unlimited source of energy for athletes. Even those who are lean and mean have enough fat stored in muscle fibres and fat cells to supply up to 80,000 calories. You go do the math – say you expend 1,000 calories in an hour of running, you can literally run for 80+ hours if you figure out a way to use your body fat as fuel! During exercise, stored fat in the body is broken down into fatty acids. These fatty acids are transported through the blood to muscles for fuel. In order for fat to fuel exercise, however, sufficient oxygen must be simultaneously consumed.

So the question is – How does one tap into this potentially unlimited source of energy available to all?The answer will come up in our next column. Before I end I will leave with one clue for you to think about – body requires more oxygen to burn fat when compared to carbohydrates!

The author is an occasional runner, who is on an eternal quest for a training methodology that would allow him to do less running and yet do well at a marathon event

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Printable version | Jul 20, 2021 4:17:19 PM |

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