Despite writing last week that fat should make up approximately 30 per cent of a runner's diet, make no mistake, carbohydrate is the preferred fuel for distance runners.

Carbohydrate can be used more efficiently for ATP (energy) production and is simply easier to convert to energy than fat or protein.

The reason our bodies do not rely solely on carbohydrate for energy is due to our poor ability to store great quantities of this fuel source. We can store some carbohydrate as glycogen in our muscles and liver, and as glucose in our blood, the total of which will last us for less than two hours of very easy running.

But as we run faster and faster, the glycogen lasts less and less time. Not even the Olympic champion can store enough to run a full marathon solely on carbohydrate.

Which is why I recommend that all distance runners train to improve their ability to burn fat (glycogen/fat fuel mixture), in order to spare the glycogen and make it last longer.

Since fat does not burn as readily as glycogen, all runners slow down when glycogen stores become depleted. It, therefore, makes good sense to make it last as long as possible.

Our bodies even require carbohydrate to burn fat. We've all seen runners who have hit "the wall" in the marathon, with their glycogen stores completely exhausted. In such a state they are often able to do little more than walk the remaining miles. Without carbohydrate, even jogging can become nigh impossible.

So, bear in mind, as you run faster and faster, the rate at which muscle glycogen becomes the sole fuel also increases, and what you feel as fatigue in the later stages of a long race is mainly due to the depletion of your muscle glycogen stores.

Research shows that even a single 100-metre sprint can reduce muscle glycogen by 20 per cent!

You now understand the importance of carbohydrate as a fuel source to a distance runner. Probably, some would want to set this article aside to go and eat some right now. But hold on a minute.

Try and avoid the "more is better" principle, because eating too much carbohydrate comes with a nasty penalty; any excess will simply be converted to body fat and become extremely difficult to access as fuel.

So, instead of making a mental note to consume more carbohydrate than usual, let's consider whether you might be eating it at the wrong time.

A popular misconception among runners who train once per day is that they have the 24-hours between workouts to restore their muscle glycogen in time for their next run.

Not so. Research now shows that in actual time you only have about 45 minutes after a hard workout to optimally replenish your store of muscle glycogen, and halt the muscle damage that is the natural consequence of exercise. Eating the right nutrients at the right time will dramatically improve how well your muscles recover and, more importantly, how they perform next time you go running.

Almost all athletes believe that their fitness improves during exercise. This is not completely true.

Sure, during a workout we provoke our bodies to adapt in ways that provide us with increased power, or endurance, but the adaptations that actually make us perform better next time out occur during the recovery between training sessions.

How well those adaptations take place, and how well you improve week after week, are highly influenced not only by your training but also by your pre- and post-workout nutrition. More next week.

Enjoy your running.

johnwalsh42195@yahoo.it