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Old 06-14-2013, 08:03 AM   #9
Phil Washlow
Member Phil Washlow is offline
Join Date: May 2013
Location: Westchester  IL
Posts: 306
Re: Against the Current

Originally Posted by Bill M. Hesse View Post
This is debatable. It is certainly true you increase fat usage at 50-60% THR, but at the speeds a competitive race is taking place this would false unless of course fat is all you have to use because your glycogen stores are next to nothing. The reason for this is having to engage a combination of muscle fibers and not just slow twitch ones to run at these speeds. The fact that carbohydrates improve athletic performance is near inescapable. Again, it depends as you say on the goals of the OP. I obviously believe carbohydrates are not evil.
At 60% of V02 max (about as high as you can go and maintain for hours, like endurance races) an elite and metabolically efficient athlete can get upwards of 80% of their energy from fat sources. This rate is about 750 cals per hour, 20% is 150 cals. You can store about 500g of glycogen in your muscles which is about 2000 cals, we're looking at 10 hours of safe performance with no glycogen replenishing. There is a product called super starch that can be used to replace glycogen without spiking blood glucose (which would turn off the 80/20 split, as your body can not uitilize as much fat with spiked glucose and insulin). If you go a little slower (lower VO2) you can up that % of fat utilization.

Carbohydrates can make tremendous improvements in athletic performance and strength/muscle gains. But I believe it is necessary to understand how they are impacting our performance and use macro composition to optimize your diet for your desired outcome. IMO just fat loss or just endurance = low carbohydrate consumption. Rapid strength and size gains = higher consumption of carbs (within reason).
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