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- Alex Hutchinson (@sweatscience)
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My column in today’s Globe and Mail takes a look at some recent field research on carbo-loading the day before a marathon:
[…] To find out whether this revised advice works in practice, researchers in Britain followed 257 London Marathon participants for five weeks prior to the race, collecting data about their training and eating patterns. The runners had an average age of 39 and an average finishing time of 4 1/2 hours. The results were published in the International Journal of Sports Medicine.
Sure enough, day-before carbohydrate consumption mattered. Runners who ate more than seven grams of carbohydrate for every kilogram of body weight (g/kg) ran 13.4 per cent faster than a comparable group of runners who ate fewer carbohydrates but were otherwise identical in terms of age, body mass index, training and marathon experience. Surprisingly, the amount of carbohydrate consumed during the marathon didn’t matter as much. [READ THE WHOLE ARTICLE HERE]
Most people don’t realize what an enormous amount of carbohydrate you have to take in to maximize your glycogen stores — which is why only 12% of the runners in the study hit the 7 g/kg threshold. Trish McAlaster did a nice job with an accompanying graphic showing just how much you’d need to eat and drink to hit 5 g/kg (the average in the study), 7 g/kg, or 10 g/kg (which is the amount suggested for elite athletes). Note that I’m not suggesting you should actually eat four plates of plain pasta for dinner — this is just to put the amounts in context!
[CORRECTION: Reader Mike LaChapelle just pointed out that the math doesn’t add up in the graphic. The “threshold” lunch should include 500 ml of sports drink. That being said, I should clarify that I’m not recommending these menus as exactly what you should eat; it’s aimed at giving a sense of the quantities involved. In real life, I’d go for more variety, and include things like fruit and vegetables!]
But looking at the leading time is a somewhat narrow approach, since it just reflects the freakish talents of one individual in each year. So here’s data, from 
So the basic trends are similar, but not identical. Look at the last three years, for example. From the top time, you might think marathoners are getting slower; but the second graph shows clearly that — as anyone paying attention to the marathon lately can attest — the depth of fast performances has been increasing steadily and sharply. I’ll bet the 2011 numbers will continue that trend.