low gi cars prior to exercise

Nemesis7884

New Member
low glycemics carbs prior to exercise

--------------------------------------------------------------------------------

the following text is from the thinkmuscle newsletter - what does this basically mean low glycemic carbs are superior prior to exercise in terms of fat burning?? what about digesting time? would you apply this knowledge just to use for cardio sessions where fat burning is the main goal or also before wheightlifting?

The title of the study is “Ingestion of a high glycemic index meal increases muscle glycogen storage at rest but augments its utilization during subsequent exercise.” (1) The study was set up as follows, on two occasions, 14 days apart, seven trained men ran at 71%VO2 max for 30 min on a treadmill. Three hours before exercise, in a randomized order, subjects consumed either a high GI or low GI carb breakfast. The low GI breakfast consisted of 80 g bran flakes, 200 ml skimmed milk, 360 g canned peaches in own juice, 300 g apples and 500 ml unsweetened apple juice. The high GI breakfast consisted of 60 g corn flakes, 240 ml skimmed milk, 100 g white bread, 30 g raspberry jam, 265 ml Lucozade original energy drink, 587 ml water. Both meals provided about 175g carbs and 21 grams of protein. Both meals provided the same number of calories.
The two meals had significantly different effects on substrate utilization during exercise. Once again, I’m not going to explore the performance angle of this study. Instead I want to illustrate the impact that GI can have on fat burning. Here is a graph (1) from this study demonstrating what proportion of glycogen and fat were used during the subsequent treadmill session.
Although there was a trend for less disruption of fat burning during rest, the real effects were seen during the workout. During exercise, total carbohydrate oxidation was 12% lower during the low GI trial with a compensatory increase in fat oxidation compared with the high GI trial. Although the total number of calories burned were similar, the proportion of fat burned was significantly higher. This after eating the same amount of carbs (175g) before exercise!
 
Back
Top