Aaack!
Hey gang. I read this blog quite a bit. Excellent stuff there on all types of subjects. This one seemed right up our alley of using fat for fuel. Enjoy
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Thanks, Norm. Good article.
--Jimmy
I learned something new from the article.
I always new that as your HR increased, the percentage of your energy derived from fat vs carbs decreased. So, at MAF you are likely burning 60% fat and 40% carb for energy. At a higher HR, but still at a pretty aerobic HR, the split would be 50% fat and 50% carb.
But, although the percent fat burned decreased with increased HR, the actual total fat burned still increased when you got to 50-50.
Based on this, it means that running at an HR where the split is 50-50 has you burning more fat, and for a given time period, you are actually giving your aerobic system a more intense workout. But, you could give your aerobic system the same overall workout by running at MAF, but just for a longer period of time.
So, I knew about the above information, but what I did not know is that if you then went to a 40% fat 60% carb split at an even higher HR, not only does your percent fat used decrease, but the overall amount of fat used also decreases. That surprised me. So, as you get to these HRs you are no longer really exercising your fat burning system as well. Now you are much more about exercising your carb energy system.
Below is the link to the particular page where this is referenced. It shows some interesting graphs on the issue.
http://www.sportsscientists.com/2010/01/exercise-and-weight-loss-part-3-fat.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+blogspot%2FcJKs+%28The+Science+of+Sport%29
The more I read about this, the more I think I made a small mistake, in my interpretation. The charts in the article seems to show that peak fat burning occurs at about 60% vo2 max. I read somewhere else that 60% vo2 max corresponds to about 70% hr max which is close to where MAF is for many people.
So, it does look like the maximum amount of fat burning does occur around our MAF pace. As we go to higher paces, the amount of fat burned as well as the percent of fat burned appears to decrease.
Of coarse, this is just based on averages. The writer of the article indicated that 60% vo2max for one person might be 70% max HR and it might be 60% max HR for another person.
weightloss (likely fatloss), using running as a tool, and concept of burning max number of cals, in this case max number of cals from body fat, per unit of traing session. How to run (what HR, what %, etc) to maximize the effect of loosing bodyfat - here the choice is specificaly burning bodyfat via running.
aerobic conditioning, aerobic fitness, improving running performance, improving marathon times, specificaly
improving the body ability to use own body fat at higher and highjer running speed.
Both above mentioned goals, using same or similar tools using same words, terms etc.
Discussion about one gets allways confused by arguments from the other and wise versa.
Just because to loose weight, somebody has concept of doing it via running and using running to burn bodyfat in the most efficient manner ....
it odes not mean, that the arguments and conclusions are aplicaple to teh goal of improving fat metabolism for the purpose of marathon training....
say you train fat metabolism at the state when sugars are not kicking in yet and opushing this state to higher and higher paces, it has nothing to do with fact, that if the running pace was faster you would burn much more overal fat even the fat % is lower.
what is the goal determines the thinking, the arguments and the use of tools
