Wednesday, 22 October 2014

Carb Loaded? Not today thanks

With 3 days to go before a big marathon thoughts usually stray to the subject of carb loading.

When I ran on carbs I always found carb-loading to be widely misunderstood. The intention is supposed to be to increase the ratio of calories consumed from carbs as opposed to fats or proteins, the general idea being to increase the consumption of low GI carbs (and lower the consumption of fats in particular) in the last few days so as to steadily build up muscle glycogen stores.  

Most carbs are not low GI and fructose (fruit, juices and 50% of table sugar) doesn't get converted to muscle glycogen very well, so they are a bad idea when carb-loading.  Some folks think you need to eat a lot and others not. Some say eat big meals, other say graze.  

It’s all actually rather complicated, and represents a change that you have possibly not tested unless you are a regular distance runner. And when you consider that carbohydrate loading is estimated to improve performance over a set distance by just 2-3%, is it really necessary? Add this to the ubiquitous advice "Don't try anything new just before Marathon day" and you may have a big dilemma to deal with. My advice: don’t try it unless you have tested it first.

Clearly carb-loading is a thing of the past for me on LCHF but it is interesting to consider if there are any last minute dietary changes that fat-adapted runners like me should be adopting. Prior to a big race should we eat more fat, less protein or even, dare I say it, more carbs?

Some fat burning runners chose to train low and run high. They will train on LCHF but load up on low GI carbs the day before and use gels during the race to supplement their fat burning. I have to confess I don’t really understand this fully as insulin generated by eating those gels may directly block our ability to burn fat during exercise. Are these people actually training better and longer on fat but racing purely on carbs?  Mark Sisson of Primal Living talks about this approach here:

Others, such as Bruce Fordyce, a prolific ultra-marathon runner and past winner for the Comrades Marathon will eat normally on LCHF up to race day, have nothing before the race except a cup of coffee with cream and then run for many hours on water alone.

For now I prefer, like Fordyce, to change nothing.  Just eat normally and re-hydrate normally. I have practiced the early breakfast routine that gets my breakfast of eggs & bacon digested before a 9 a.m. start and that  is what I will be doing again come Saturday morning.

1 comment:

  1. Fascinating to wonder about the benefits (or not) of pre-race carb loading. Personally, I still like a huge bowl of porridge on the morning of a race and a sugary drink before the start. I'd love to see someone try the same Park Run (or ideally something longer) with varying pre-race feeding stategies. There may be too many variables to make sense of the results though and the lack of "blinding" is problematic. Still, if you've a bit of spare time.....!!