Nutritionally oriented bodybuilders often use the glycemic index to determine what kinds of carbohydrates they're going to consume at specific times. The glycemic index indicates how long it takes food carbohydrates to arrive in the blood as glucose. It was originally developed
as a tool for diabetics that enables them to adjust their insulin use.
The glycemic index, or GI, initially produced a few surprises. For example, white potatoes, a staple of the typical bodybuilder's diet, act more like a simple sugar than a complex carbohydrate in terms of assimilation into the body. Apparently, the starch in potatoes is rapidly broken down in the intestine. Other foods, such as ice cream, showed lower glycemic indexes than expected. In the case of ice cream this is due to the food's high-fat content, which slows sugar absorption. An essential fact that's often overlooked about the glycemic index is that it only pertains to individual foods. Combining high-GI carbs with other foods changes the situation completely.
Thus, if you eat a white potato with a high-protein food like fish or chicken, you lower the GI of the potato. Another way to lower the GI of a food is to combine it with a high-fiber food or supplement. This time it's the fiber that delays the food's intestinal absorption. Recently, physiologists have suggested eating certain types of carbohydrate foods at specific times to promote recovery after exercise- For example, complex carbohydrates are generally the preferred form because they promote less insulin secretion and less insulin means a more stable blood glucose pattern.
After a workout, however, when your supply of muscle glycogen, a stored form of carbohydrate, is exhausted, your body needs a shot of glycogen synthetase, the key enzyme that works to replenish glycogen. Insulin promotes the activity of this enzyme, and higher-GI foods stimulate greater insulin secretion. The answer is to consume simple, or high-GI, carbs when you finish training. Studies have shown that taking in simple carbs as soon as 15 minutes after a workout produces as much as a 36 percent increase in muscle glycogen resynthesis. The result is greater recovery after a workout.
The same scenario holds true for carbohydrate loading. During the first day of carb loading it's advisable to focus more on high-GI foods, such as simple sugars. Again, the purpose is to give you a head start in muscle glycogen synthesis by promoting insulin and glycogen synthetase activity. What about the carbs you eat before a workout? Will eating high- or low-GI carbs in this case influence blood glucose levels and recovery after the workout ends?
Researchers from the University of Sydney in Australia directed a group of six athletes to eat four test meals that contained carbohydrates with different GIs. The athletes then cycled for 100 minutes on a stationary bike at 65 to 70 percent of their VO2 max rates, or an average intensity The plasma glucose levels of those athletes who consumed the lowest-GI foods were far higher than those of the athletes who consumed high-GI foods. The results showed that the lower the CI of a preworkout food, the higher the blood glucose will be after the workout.
Since the meals were consumed one hour before the workout, insulin played a role in the results. As we know that higher-GI foods by Eliot promote greater insulin release, we can surmise that the insulin released by the high-GI foods lowered blood glucose levels. In practical terms, if you train for more than two hours at a time, is a good idea to consume carbs that have a lower glycemic index before training. This will promote a more stable blood glucose level, which becomes important for maintaining optimal energy levels as the length of your workout increases.