TRIATHLON AND ENERGY COMSUMPTION

We have being experimenting empirically to improve performance by eating the best way possible during a competition.  Our understanding limits us at times.  Columbus was advised not to travel into the ocean because there was an abyss at the end of the horizon.  Even before triathlon started, the competitors were advised not to train so hard because they could die prematurely.  In the 40´s the swimmers trained less than a kilometer a day afraid that they could burn out or could get over trained.  They are telling us not to take more than 200 calories an hour during a competition.  We have given 400 calories during an hour competition with success.  How we go about it?  The ultra-marathoners get up to 100 grams of carbohydrates (350 calories) an hour during a competition.  Let´s keep doing science or let´s keep thinking clearly.

There are well-done studies regarding this matter:

1)   http://arno.unimaas.nl/show.cgi?fid=1598 . This article was done in 1992.  At that time, there was money and people interested in the subject; they studied athletes’ metabolism at 70% of VO2 max and concluded that 60 grams of glucose was the limit metabolized by these athletes, equivalent to 200 calories per hour.  It is very difficult to measure metabolism above the 70% of VO2 max for technical reasons.  At the same time, the authors assumed that at 70% the metabolism was coming from glucose almost exclusively.  A year later, another paper came out mentioning that the metabolism above 70% was coming more importantly from glucose but the contribution of fatty acids was significant, i.e. 85% of VO2 max effort increases the metabolism glucose but fatty acids continues to be metabolized but at a lower rate.

http://www.aleixo.com/biblioteca/obesidade/artigos/Regulation%20of%20endogenous%20fat%20and%20carbohydrate%20metabolism.pdf

I tried to copy the graphic but it is not possible (it is in the article).  I made a sketch instead.

You could see looking at the graph that when the intensity of the physical activity increases, the plasma glucose metabolism increases twice.  From the previous article 1), we know that after an hour of recovery, the amount of exogenous glucose metabolism increases twice after two hours.  Based on these facts, we give 400 calories per hour and our athletes tolerate and perform a good “wet run.”  We have no time to wait for the article that could tell us that we are o.k.  We based our judgments on performance and empirical research.