Translocation of GLUT4 can also occur due to muscular contractions (2). So, weight lifting alone increases muscular insulin sensitivity - called insulin independent glucose uptake. Because of this fact, this time is ideal to take advantage of the nutrient partitioning (basically means where the nutrients go) effects of training. So, ideally we’re looking at a quick digesting carbohydrate to replenish the glycogen used while training and a quicker digesting protein to provide amino acids due to the increased protein synthesis that comes after training (for up to 36 hours (3)). The quickest digesting carbohydrate, glucose - also known as dextrose or corn sugar or even grape sugar - is probably the best idea. It’s also very cheap, especially if bought in bulk. Maltodextrin is also a good available source. It is known as a ‘complex carbohydrate’, purely on the grounds that it is a glucose polymer consisting of about 3-8 molecules. It is therefore too long to be classed as ‘simple’, and since there is no mid-classification, complex it is. This doesn’t stop it from digesting very quickly and doing the same job to insulin that glucose does. Maltodextrin is also a carbohydrate exploited by supplement companies for this very reason. They can claim it is a complex carb and it’s great in their MRPs. In all truth, it is the guar gum that they put in these products that slow digestion, not the maltodextrin. Any other time of day, just like glucose, it is a poor choice.
Once you’ve got the basic idea of a simple sugar post-workout, then you can experiment using different combinations of glucose and maltodextrin. It is usually recommended to make a 50/50 mix of the two, based on the differing absorption rates of the two carbs. Glucose requires no digestion and so once in the intestinal tract can pass straight through the wall lining. Maltodextrin, however, requires a bit of digestion to split it into the glucose molecules that make it up. The difference of digestion is not really that much in the way of time, but can make a big difference. This is because glucose enters the cell via active transport (4) and only so much can get through at any one time once the receptors are all being utilised. By taking in maltodextrin, the longer digestion and absorption rate means the glucose from the malto is getting to the cell more or less once the first glucose molecules are in. So you’re basically ‘lining the glucose up’.