's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

30 minute refueling "window" after exertion(6 posts)

30 minute refueling "window" after exertionNatC
Aug 15, 2003 2:58 PM
You know how everyone says that after riding you have a 30 minute "window" during which your body easily absorbs glucose, and after that 30 minutes that window shuts? What physiological event happens at the 30 minute mark that causes the shift in metabolism? Does anyone know if that time period is based on any actual scientific studies, or if it's just one of those pieces of information passed verbally from one person to the next (kind of like the 8 cups of water per day thing)?
read and decide.eayste
Aug 15, 2003 3:20 PM
Right on...NatC
Aug 15, 2003 3:56 PM
Thanks, that was the kind of info I was looking for. It appears the physiology has actually been tested. I didn't see where it mentioned the mechanism, although one article alluded to increased insulin as a result of exertion. It seems though that the authors of the three articles disagree on the time frame, varying between 1 hour, 4 hours, and 6 hours.
Right on...Jon Billheimer
Aug 15, 2003 5:33 PM
The "window" is about two hours and is due to the presence of glucose transporter enzyme production due to exercise. At thirty minutes, enzyme production is still high, then tapers throughout the remaining 90 minutes to non-exercise levels.
Glycogen synthase?NatC
Aug 15, 2003 6:17 PM
I think glycogen synthase is the name of the enzyme that carries out the conversion. I think it's also epinephrine-mediated, so maybe one's adrenaline levels during exertion modulate the glycogen window? Si o no?
Aug 15, 2003 5:35 PM
Yeah . there are a few scientific school of thoughts about the Glycogen window and all have difference theories on what works and how it.
But I think it's mainly an individual thing , kinda like bike frames , that everyone is different even on a metabolic level . So the window time is different for everyone.
For me , it's about 90 mins.
I have a slower metalbolism and weigh 200 lbs.
My 140 pound friend on the other hand. His window is about 15 mins.
So there are alot of varieties on the issue,
As for the mechanism . I think it has to do with the Digestive and endocrine systems.
On how your body turns your food into energy and how it uses it to replenish what it lost.