Wednesday, September 8, 2010

Low Carb Equals Monster Fuel
This is a fascinating N=1 test of low carb impact on performance with a CrossFitter.

The intro will be showcased in this post, the low carb experiment will follow.
"Every now and then, an excellent piece of scientific research comes along and forces many of us to reevaluate our positions or question what we thought we knew. This happened to me last May when a paper entitled "Antioxidants Prevent Health-Promoting Effects of Physical Exercise in Humans" was published in the Proceedings of the National Academy of Sciences. The following conclusion can be found in the abstract of the paper:
"Consistent with the concept of mitohormesis, exercise-induced oxidative stress ameliorates insulin resistance and causes an adaptive response promoting endogenous antioxidant defense capacity. Supplementation with antioxidants may preclude these health-promoting effects of exercise in humans".
Essentially, the antioxidants are quenching the reactive oxygen species (ROS), which prevents oxidative damage and blunts the expression of ROS-sensitive transcriptional regulators of insulin sensitivity. This means that ingesting large quantities of antioxidants prevents you from improving your insulin sensitivity, which is a major benefit of exercise (another study on ROS and insulin sensitivity was published during the writing of this blog post).
I was somewhat taken aback to find out that a daily intake of 1.0 gram of vitamin C and 400 IU of vitamin E could negate the insulin sensitivity gained through exercise. I wasn't taking any vitamin supplements at the time because of research indicating that multivitamins are essentially useless, maybe even harmful. Nevertheless, this whole thing really got me thinking about insulin sensitivity and brought back memories of this interesting post I had read on Arthur De Vany's blog. The research discussed in the post demonstrates that insulin sensitivity is not improved when a PWO meal of carbohydrate is employed to replenish glycogen stores. Hmmm…that sounds a lot like the vitamin C/E paper doesn't it? Some more research on the subject of post-workout carbs led me to this excellent post by Mark Sisson, which was followed by this equally interesting post. At this point, a lot research seemed to indicate that PWO carbohydrates were not necessary, maybe even detrimental, and that a PWO meal of protein, although desirable, was also not absolutely required. Within 24 hours, Glycogen stores should be sufficiently replenished for another workout thanks to gluconeogenesis (new creation of glucose) from dietary protein and lactate as long as the levels of dietary protein (for muscle repair and glucose synthesis) and fat (for fuel) are adequate. However, gluconeogenesis takes place in the liver and only a fraction of the glucose makes its way to the muscles. This means it would probably be wise to consume some carbohydrate from vegetables to help replenish muscle glycogen. Vegetables are preferable given that they don't contain the toxin fructose and they come packed with vitamins, antioxidants and a variety of phytochemicals."

No comments:

Post a Comment