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How much energy do you have – and of what type?

Posted By: Ward / Category: long distance endurance

When you think about survival fitness, or just the ability to complete a marathon or an ironman you need to become aware of how much energy storage you have and of what type. And maybe more importantly how far these energy stores could take you if you are performing a low level task such as walking or a higher energy task such as running.

Two hikers in the Mount Hood National Forest
Image via Wikipedia

I won’t discuss the energy system that are the main contributors to events that last less than 1 or 2 minutes, but instead concentrate on the ‘endurance’ energy systems.

glucose and glycogen stores:

——————————————————————–Provides energy for:

—————————————————————————-walking                     running

blood glucose:                            20 g                 15 min                       4 min

liver glycogen:                             80 g                 1 hour                      18 min

muscle glycogen:                    350-700 g         5 – 10 hours             2 – 3 hours

Adipose tissue (fat)           9,000 – 15,000 g        11 days                     3 days

So you can see even if you add up all the glucose/glycogen stores that come from consuming carbs you don’t have enough for completing a marathon in a time that most people are capable of. Most people will complete a marathon in  2.5 to 5 hours and a major part of ‘hitting the wall’ is when you run out of glycogen muscle storage. And obviously any longer events such as ultramarathons, hiking, or ironman events you require fat burning – and you better be good at it.

Despite this fact there are not many of the sport trainers telling you about the importance of the ability to use fat or that this can be trained. If you want to be able to perform well in long endurance events, do a long hike (be it for pleasure or to survive) you want to become an efficient fat burner. Additionally, this might help you lose fat, which is of prime importance for many people.

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