Glycemic Index
It is well documented that the level of intensity that a player is capable of performing at is directly related to their glycogen stores (energy stored in the liver and muscles). It is therefore no surprise that players will attempt to keep these stores as ‘stocked up’ as possible by consuming carbohydrates prior to exercise. However it is not just the consumption of carbohydrates that is important, it is also the kind of carbohydrate, as some can be used for a short-term energy solution while others provided a more prolonged source. A simple process that can be used by players to determine what time span it takes for the carbohydrates to provide energy is to look at the foods Glycemic Index. The Glycemic Index has been devised to categorise items of food into a ranking system that illustrates how quickly it can increase blood glucose levels. Foods are classified into 3 group’s dependant on whether they are considered to be high, medium or low Glycemic index;
- Low GI - less than 55
- Intermediate GI - between 56 and 69
- High GI - higher than 70
The process to determine a foods ranking on the index is quite a simply procedure. An individual fasts overnight and then proceeds to consume 50-100 grams of the desired food, within a laboratory environment. Measurements of the individual’s blood glucose level are then taken over the next two hour period. From the recordings a graph can then be plotted to show how the individuals blood glucose levels are affected by the food chosen compared to that of the same amount of pure glucose.
It is possible for a player to use the index as a useful tool when planning not just pre and post training/competition meals but also their daily diets.
| Meal | Glycemic Index | Portion Size |
|---|---|---|
| Breakfast | Moderate (or high depending on time until activity) | Dependant on how close to training or competition |
| Lunch | High | Regular |
| Dinner | Low (or high if consumed after activity) | Regular |
| Snacks | Any – dependant on time of day and schedule | Small |
| Pre-match / training | High | Regular (but not too big) |
| During | High | Small |
| Post-match / training | High | Larger |
Examples of the Glycemic index of some daily consumed foods
| Food Item | Glycemic Index | Classification |
|---|---|---|
| French Baquette | 95 | High |
| Gatorade™ | 89 | High |
| White Bread | 75-80 (brand dependant) | High |
| Pretzels | 83 | High |
| Jelly Beans | 80 | High |
| Cornflakes | 70-80 (brand dependant) | High |
| Mars Bar ® | 68 | Medium |
| Cottage Pie | 65 | Medium |
| Raisins | 64 | Medium |
| Split Pea Soup | 60 | Medium |
| Cranberry Juice | 56 | Medium |
| Popcorn, Sweet | 55 | Low |
| Spaghetti (boiled 15 mins) | 44 | Low |
| Tomato Soup | 38 | Low |
| Red Lentils | 27 | Low |
| Plain Yogurt | 15 | Low |
| Hummus Dip | 6 | Low |
There will be times when players will not only require the understanding that carbohydrates are useful but also which are the best sources of energy for certain times. Therefore they should be equipped with the knowledge contained within this page that they are capable of planning and preparing their own meals and diets.