Friday, October 10, 2008

Getting More Out Of Your Calories

The amount of food you should aim to consume each hour of a really long ride should be determined by your carbohydrate choices.  Of course more carbs equals more fuel, however this equation only works if your absorption can keep up with your intake.  As I've said before, this fuel should come from a combination of energy drinks and some form of solid food. 

Studies show that the maximum rate at which glucose can be absorbed, or oxidized, into your bloodstream is 1 gram per minute, which equals 60g per hour.  However, other studies indicate that if you consume a 2:1 ratio of glucose and fructose, your body increases the oxidization rate to 1.5g per hour.  This is a 50% increase!  It's speculated that because the different sugars follow different pathways of absorption, your body is tricked into converting more than it normally would.

All of this is explained in greater detail by a qualified dietitian in the following article from bicycling magazine.

Why does this matter?  If it's not already obvious, the more energy your body can absorb, the more energy you will have for riding.  This is particularly useful in long races.  In the Warny for instance, you'll burn about 6500 calories (which equals ~1600g of carbs).  Replenishing these calories is not an easy thing to do while racing at 40-50km/hr (remember, some of those are stored from your pre-race carb loading ).  Pay very close attention to the TYPES of sugars you're ingesting (2:1 glucose to fructose) as this will play a massive part in getting you to the end of the race feeling fresh and strong.  Most people are running on EMPTY at the end of big races.  Not you, because you've read this and now know better!

I will soon post a spreadsheet that tells you what my nutrition and eating strategy is before the Warny.  It takes into account where the feed stations are, how long it will take to get to each of them, what will be in my feed bag, and the mix of carbs in each of the choices.  I'm not saying it's necessarily right for you, but it'll give you an idea of the job ahead and you'll see that drinking water and gels alone isn't going to cut it for a long ride like the Warny.


The Woodduck said...

Great stuff Wade. Looking forward to reading this. Just have to make sure that my food makes it over the Westgate this year!