Is the issue with chronic cardio the reason for health problems blamed on super fitness endurance athletes or...
Could it be long term chronic carbohydrate intake?
Anyone know of any studies done on low carb chronic cardio?
I doubt a search would turn up much. There's a reason that endurance runners eat a lot of carbs: they need the starch to fuel the enormous oxidative-glycolytic energy demands in the muscle cells. (And my understanding is that both elements contribute to ill effects: the running spikes cortisol levels and the carbs do all the things we already know they do).
This is an extremely complex question, because there are simply too many variables that would require a massive controlled study to come to an acceptable conclusion. The study linked from panu only addresses elite marathon runners and completely ignores the impact of the diet. We all know that carbohydrate quality is of the utmost importance and makes every difference our health, and runners are notorious for consuming massive quantities of crap carbs, which I believe is the likely culprit for the health issues described in that study. Is it the carbohydrate consumption alone that causes problems, regardless of quality? I think Kitavan paradox can shed some light on that question.
But I have to ask, Stephen, are you a runner who is worried about the long term effects of running on a low carb paleo diet? Here are a couple links that you may or may have not seen that addresses the issue better than I ever could:
Excessive carbohydrate intake could be a factor, but so could the intensity of exercise. Relationships of Heart Disease Risk Factors to Exercise Quantity and Intensity
"Men and women who ran faster (ie, at greater intensity) had lower blood pressures; triglyceride levels; ratios of total cholesterol to high-density lipoprotein cholesterol; BMI ... "
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