*UPDATE*
Some folks laid the smackdown on John "I am going to cite 70 scientific papers so I look smart but really I'm just a meathead asshole" Kiefer, who decided to write a blog entry (it's on the OP, I refuse to link to it) that endurance exercise, or as the gymrats like to call it "cardio," makes you fat.
Article:
http://gokaleo.com/...1/women-and-running/ Main Point: just because a dude with some exercise degree writes a piece citing actual scientific literature, it does not mean he is citing the literature correctly, or developing theories that are justified based on the published science. If he wanted to write a "here's what I see in the gym everyday and this is what I think, p.s. I have no science to back that up" that would have been fine. Plain observations are an excellent tool to begin hypothesizing and experiments. BUT HE DIDN'T. meathead asshole. excuse me while I go run for four hours and get ginormous wiggly thighs.
Some salient excerpts:
"A main premise of this article is that too much cardio slows the body’s metabolism, especially in women. The author supports this claim with his first collection of citations:...
Five of the eleven citations used here to support steady-state training’s detrimental effects specifically in women relied solely on male subjects [4, 5, 8, 9, 10], and two of those used rats [8, 9]. A sixth looked at mixed subjects [3], though still weighted heavily toward males. When making claims about a specific population, we want studies that use subjects that match the target group as closely as possible. When sex differences exist, we cannot use male subjects to validate processes and outcomes occurring in women. If we ignore this error though and take the group of citations as a whole, it still portrays a very different picture than the one the author is attempting to paint.
The author’s citations highlight that there are responders and non-responders to exercise-induced declines in T3 levels (10 responders to 7 non-responders) [1]. So this problem of reduced T3 does not necessarily manifest in all women all the time. After the initial decline at the start of training seasons, T3 levels started to trend back towards baseline [1, 2]. Others report no change in T3 levels at all [3, 5], in
direct contradiction to the author’s claim."
" 'To this end, your body sets into motion a series of reactions that make it difficult for muscle to burn fat at all[36-41]. Instead of burning body fat, your body takes extraordinary measures to retain it.'
The first sentence is in
direct contradiction to the previous sources given. Citation 35 found a 100% increase in fat use in muscles. Here again, papers 36-41 are investigating the pathways involved in fat metabolism and its use a fuel substrate. None of these sources show a link between endurance training and the muscles’ ability to burn fat beyond the normal transition to rely more heavily on carbohydrate oxidation as exercise intensity increases. The bold claim that the body takes “extraordinary measures” to retain body fat goes uncited."
"The author goes to great lengths to set up cardio as a metabolism-halting, fat-gaining nightmare, yet never mentions the effect (or lack thereof) of one’s diet on this process."