ADF and Exercise

Here a bunch of good posts from bradpilon.com (author of the book titled "Eat Stop Eat") exercising and fasting (the bottom line is, exercising when fasting is fine and in some cases even better than after having eaten!)

fasting exercise and blood sugar
http://bradpilon.com/healthy-ramblings/fasting-exercise-and-blood-sugar/
Here are two quick “Did you knows?” concerning fasting, exercise and blood sugar.

Did you know that it takes 30 to 60 minutes of running at 75% of your V02 max (for conditioned runners) to get your blood insulin levels down to the same level found in people who have been fasting for 23 hours? (Dohm LG 1986)

Did you know that when scientists studied people who exercised after fasting for 23 hours, their blood sugar levels were actually found to be slightly higher then when the same people exercised after a small meal? (Coyle EF 1985; Dohm LG 1986)

What this means to you- running at 75% of your VO2 max for as long as 70 minutes in well trained runners who had been fasting for 23 hours did not cause hypolgycemia (low blood sugar) So if you like exercising while you are fasted, this research suggests you don’t have to worry about hypoglycemia (as long as your exercise intensity isn’t way above these levels).

And it takes between 30 and 60 minutes of running at a VO2 of 75% to get the same insulin lowering effect as simply sitting around the house after fasting for 18-24 hours.

Two things to think about the next time you are fasting.

other great entries can be found at the links below:

• fasting and exercise (http://bradpilon.com/healthy-ramblings/fasting-and-exercise/)
• fasting and atheltic performance (http://bradpilon.com/healthy-ramblings/fasting-and-athletic-performance/)

The paper being referred to is:

Dohm GL, Beeker RT, Israel RG, Tapscott EB (1986) Metabolic responses to exercise after fasting. Journal of Applied Physiology, Vol 61, Issue 4 1363-1368

Abstract
Fasting before exercise increases fat utilization and lowers the rate of muscle glycogen depletion. Since a 24-h fast also depletes liver glycogen, we were interested in blood glucose homeostasis during exercise after fasting. An experiment was conducted with human subjects to determine the effect of fasting on blood metabolite concentrations during exercise. Nine male subjects ran (70% maximum O2 consumption) two counterbalanced trials, once fed and once after a 23-h fast. Plasma glucose was elevated by exercise in the fasted trial but there was no difference between fed and fasted during exercise. Lactate was significantly higher (P less than 0.05) in fasted than fed throughout the exercise bout. Fat mobilization and utilization appeared to be greater in the fasted trial as evidenced by higher plasma concentrations of free fatty acids, glycerol, and beta-hydroxybutyrate as well as lower respiratory exchange ratio in the fasted trial during the first 30 min of exercise. These results demonstrate that in humans blood glucose concentration is maintained at normal levels during exercise after fasting despite the depletion of liver glycogen. Homeostasis is probably maintained as a result of increased gluconeogenesis and decreased utilization of glucose in the muscle as a result of lowered pyruvate dehydrogenase activity.