Calorie Buring Mystery

Posted by on March 12, 2012

This weekend I did my first decent length ride of 2012. It is common for me to get in one 100 mile ride and several 20-80 mile rides over the summer.  This weekend it was a short of 42 miles. After I was done I started to think about the difference there are between riding and running. Most of these had to do with the impact on the body. One of them came down to the calories burned doing each activity.

On my ride this weekend I burn over 4000 calories. I was surprised that I only drank water and had one 3 Musketeers candy bar. I started thinking of how much different that is than a long run for me. I can’t seem to run more than 16 miles without some kind of issue with calorie intake. I don’t get enough and usually end of paying for it.

Running certainly is more of an impact activity with your legs pounding the ground with each stride. Biking doesn’t have any hard impact on your legs. So I can get why the body wears down quicker when running than biking. I read that a 150 pound person hits the ground with about 1200 pound of force with each step.  But what I don’t understand is my ability to burn the calories biking and still be able to continue when I can’t do the same when running.

Why is it that I can bike 40+ miles on just water and a single candy bar but I can’t seem to run 20+ miles without having to intake calorie every 20 minutes of so? When I do a long run I have started to intake a gel every 20 minutes. That means about every 2 to 2.5 miles I consume some kind of calories.

I can run 10-12 miles on nothing more than water when training. Anything longer than that and my body runs out of calories and thus depletes my energy. I read the body stores about 1500 calories and those can be burned before having to replenish them. After that I think you start to burn fat. So I can see why I need to intake gels and other food when running long distances.  But based on calories why is it I can far exceed the 1500 calories and keep going. It is really just the impact or running compared to biking?

For me on long runs I need to start in taking calories before I get to the 8 mile mark.  I need my body to start processing those and have them ready by mile 11.  If I know I am going 20+ miles I better be eating as much as I can as soon as possible. I have never felt that I have enough energy on 16+ mile runs. This is something I hope to master this summer. It is one of my goals to get comfortable knowing when I need to eat and more importantly how much I need to take in based on the distance ahead of me. Right now it is a total mystery to me. As I start off the running season by doing my first ultra distance races I know I am going to need to have a few failures in order to crack the nutrition nut. I don’t think it is something that will come easy to me. In fact, it is going to be painful!  I have never DNF a race before. I spent 4 years in the Army and the 82nd Airborne Division and never dropped out of a run before. Never.  But I also don’t consider myself to have a high endurance level either. I have always been a fast twitch athlete.  Distance was never easy for me.

Maybe someone can shine some light on the subject of burning calories and why I can burn more than twice the calories when biking and need very little in the form of additional calories. If anyone has any ideas or insights let me know.

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