You've been training for months. You've spent more early mornings in running shoes than you have tucked up in bed; you've done short runs, long runs, quick ones and slow ones, all of them at paces ranging from 'race' to 'rather not actually, thanks'.
But despite all the hours of putting left after right, if you're not prepared to provide your body with the fuel it needs along the way to the finish line, you won't get there half as quickly as you'd planned. A race nutrition strategy is as important to your success as registering on time and doing up your laces.
But while those are things to do on the day, the time to start forming your mid-run habits is a long time before you're limbering up on the start line. It should start now.
Wall To Fall
Regardless of whether it's a gel, a drink, a bar or even just sweets that you're knocking back on the move, you're doing it for one very visceral reason - the wall. The wall is what marathon runners hit in the second half of the race, usually somewhere between 18 miles and the finish. They feel lightheaded, fuzzy and utterly without energy. In short, they would much prefer to just potter off home for a nice bath and a lie down than cover the many miles that remain.
"When running, you burn through your main source of stored energy - glycogen - very quickly, and the faster you go the more quickly you burn it," says Level 4 UK Athletics coach and Runner's World Contributing Editor, Nick Anderson (fullpotential.co.uk). "With shorter races you need to remain hydrated for optimal performance, but you don't have to worry about completely depleting your carbohydrate stores. "However, once you're out there for longer than 90 minutes to two hours you can expect to see a depletion of those glycogen stores. You will slow down dramatically and 'hit the wall'."
So, simply put, if your body runs out of glycogen, to keep running it has to resort to its only other fuel source - stored fats. Processing fats requires a lot more oxygen, leading you to slow down to a jog or even a walk, so that more of the oxygen you breathe in goes towards breaking down fats, than your working muscles. From the wall onwards it's a mental battle to the finish line. Which is rubbish.
Fortunately, with the right mid-race nutrition you don't have to experience the full horror of the body-wall interface. In fact, by maintaining your glycogen levels your body need never come near anything vaguely brick-like whatsoever.
"It's a combination of people running too hard and not using the right nutrition," says Anderson. "Someone who has trained well and has a good nutrition strategy should be able to run even splits throughout a marathon and run the same time for the first half as the second."
Fundamentally, your marathon nutrition strategy is to take carbohydrates on board every 40-45 minutes that you're on the road. Whatever distance you're running, if you're going to be running for longer than an hour you should be putting in some fuel. So for the full distance you may need five to six refuelling breaks, for a half perhaps just two and on a 10K most people will have finished before their body needs anything.
Isotonic energy drinks and gels are very rapidly absorbed, as your body is understandably extremely keen to grab what it needs. Just don't wait for a telegram telling you quite how desperately it needs it.
"The classic mistake is to feel woozy and then reach for a drink or a gel," explains Anderson. "They are packed with sugars and complex carbs, both of which work quickly. But if you wait until halfway to take something on then it's too late."
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