Carbohydrates for Muscle and Fitness

Carbohydrate is needed to fuel almost every type of activity and the amount of glycogen stored in your muscles and liver has a direct effect on your exercise performance. A high muscle-glycogen concentration will allow you to train at your optimal intensity and achieve a greater training effect. A low muscle-glycogen concentration on the other hand, will lead to early fatique, reduced training intensity and sub-optimal performance.

Following exercise, glycogen stores will need to be replenished as a key part of your recovery process. The most efficient way of achieving this is by consuming a high carbohydrate diet. The optimum amount depends on the nature, intensity, duration and frequency of your training programme.

If insufficient carbohydrate is consumed between workouts, the resulting pre-exercise low muscle-glycogen stores will limit the duration and intensity of your workouts.

Carbohydrates are traditionally classified according to their chemical structure, simple (sugars) and complex (starches and fibres).

Simple carbohyrates are very small molecules consisting of one or two sugar units. They comprise of 1-suger units glucose, fructose and galactose and 2-sugar units sucrose and lactose.

Complex Carbohydrates are much larger molecules, consisting of between 10 and several thousand sugar units mostly glucose, joined together. They include the starches, amylose and the non-starches polysaccharides.

In practice, many foods contain a mixture of both simple and complex carbohydrates, making the traditional classification of foods into 'simple' and complex' very confusing.

For a more accurate effect different foods have on your blood sugar levels, scientists developed the glycaemic index (GI). It is a ranking of foods from 0 to 100 based on their immediate effect on blood sugar levels. The GI of foods is very useful to know because it tells you how the body responds to them. If you need to get carbohydrates into your bloodstream and muscle cells rapidly, for example immediately after exercise to kick-start glycogen replenishment, you would choose high GI foods.

While the GI concept was originally developed to help diabetics control their blood sugar levels, it can benefit healthy people and athletes too. e.g.. consuming a low GI meal 1-2 hours before exercise can help your performance by providing slow-release energy, thereby delaying fatigue. A high GI food or drink consumed immediately after exercise helps restore muscle glycogen faster.

To, date only the GI's of single foods have been directly measured. In reality it is more useful to know the GI of a meal as we are more likely to eat combinations of foods. E.g.. a simple meal, such as beans on toast, you may assume that half the carbs in coming from the bread and half the beans. So you can add the GI values of the two foods together and divide by 2; (70 plus 48) divide 2 = 59.

The majority of studies that examined the effects of pre-exercise meals on performance used 1g carbs/kg body weight, that translates as 50g carboydrates; if your body weight is 50kg.This small meal is best taken about 1 hour before exercise although you should wait 2-4 hours after a larger meal before exercising. Experiment on finding the exact quantity of food or drink that works best for you.

If you are exercising for more than 60mins at a moderate-high intensity, consuming carboydrates during your workout can help delay fatigue and enable you to perform at a higher level. It will help you to continue exercising when your muscle glycogen stores are depleted. An intake of between 30-60g carbohydrate/ hour is recommended by leading researchers. This matches the maximum amount of carboydrates that can be taken up by the muscles from your bloodstream during aerobic exercise.

The best time to start refuelling is as soon as possible after exercise, as glycogen storage is faster during this post-exercise window than at any other time. During the first 2 hours, replenishment is most rapid at approx. 150% the normal rate. During the subsequent 4 hours the rate slows but remains higher than normal, after this period glycogen manufacture returns to its normal rate. Its recommended consuming 1g/ 1kg body weight during the 2 hour post-exercise period.

The bottom line is that if you are training intensely every day or twice a day make sure you consume high GI foods during the first 2 hours after exercise.