check this site
http://www.abcbodybuilding.com/magazine03/dextrose.htm
and
http://www.abcbodybuilding.com/magazine/windowofopportunity.htm
or read this
During the post-workout phase of training our bodies are in a hypoglycemic stage. Blood-sugar and insulin levels have drastically dropped. Immediately following exercise natural GH concentrations struggle to increase as insulin levels try to rebound from its current highly catabolic state.
A simple carbohydrate supplement combined with the post-workout window of opportunity will give immediate rise to blood glucose levels and cause a state of hyperglycemia. This will force a increase in the production of insulin! In other words simple carbohydrates will lay the smack down on cortisol production.
The newly increased quantity of insulin in the blood will drive much needed glucose (and amino acids) through the receptor sites in the muscle cell at an insane rate.
These elevated stages of blood glucose will begin causing further secretions of Growth Hormone, the key hormone responsible for producing Insulin Growth factor.
Why simple carbohydrates? Increased absorption rates, and an abruptly induced insulin burst. The faster you can get glucose into your bloodstream and muscles, the less protein destroyed and the more glycogen stored.
This is the one time of the day when you want to stay clear of complex carbs. Complex and fibrous carbs simply take way too long to digest and will not give optimal insulin release to offset muscle catabolism.
You also want to stay far away from any fat and fructose sources post-workout. Fructose will not replenish muscle glycogen but rather will replenish liver glycogen. Fat severely delays digestion because it metabolically requires so many more processes to break down.
Another vital key to post-workout nutrition is insulin sensitivity. Creating stronger insulin sensitivity is the primary way to get the most out of your post-workout simple carbohydrate intake.
Jacob covers how to do this in his 13 Weeks to Hardcore Fat Burning “The Diet” article. I highly recommend adhering to the list of ways to increase insulin sensitivity he describes in that article whether you are on a bulk or cut. It will make your insulin spike, via simple carbs, that much more potent.
Only certain types of simple carbohydrates will replenish muscle glycogen. These are carbohydrates in the form of glucose/dextrose.
The basis of our simple carbohydrates (post-workout) should come from sources that register high on the glycemic index. A range of 100-130 will work the best for our purposes. Dextrose or Maltodextrin are the two sources of simple carbs I recommend to ingest post-exercise.