Fuelling The Body Pre, During and Post Training

Carbohydrates are needed to fuel basically every activity and the amount of glycogen stores in  the muscles and your liver has a direct affect on your performance.  A high muscle-gyclogen concentration will alllow you to train optimally.  A low muscle-glycogenconcentration can lead to poor performance and early fatigue.  This means Glycogen is the most important fuel for any form of exercise.  Each different type of carbohydrate produces a different respose in the body.  High carbohydrate diets significantly increase endurance and give you a major advantage over an opponent who is on a low carbohydrate diet.  Sports nutritionalists and exercise physiologists recommend that people who reguarly exercise consume a diet which consists of a relatively high percentage of energy form carbohydrates and a relatively low percentage from fat.  In order to get the most out of your session you must make sure your pre-exercise glycogen stores are high.  If you ensure this it will help to improve endurance, help you train harder and delay exhaustion.  However this method is not always reliable as it assumes an optimal energy (calorie) intake.  It does not supply optimal carbohydrate for those with very high or low intakes.  For example, an athlete consuming 4000-5000 calories per day, 60% energy from carbohydrate (i.e 600g +) would mean that they would exceed their glycogen storage capacity.  On the other hand, for athletes taking in 2000 calories daily, a diet providing them with 60% energy from carbohydrate (i.e 600g) would not contain enough carbohydrate to maintain muscle glycogen stores.

Simple and Complex Carbs:

In practiice, many foods contain a mixture of both simple and complex carbohydrates which can make the traditional classification of foods extremely confusing. 

Simple carbohydrates are very small molecules consisting of one or two sugar units.  They comprise the monosaccharides which have one sugar unit, the monosaccharides are glucose (dextrose), fructose (fruit sugar) and galactose and the  disaccharides which consist of two sugar units which are: lactose or milk sugar (which comprises a glucose and galactose molecule joined together) and sucrose or table sugar (which comprises a glucose and galactose molecule joined together). 

Complex carbohydrats on the other hand have much larger molecules, consisting of between 10- and several-thousand sugar units (which are mostly glucose) joined together.  They include the starches, amylose, amylopectin and the and the non-starch polysaccharides (dietary fibre) e.g cellulose, hemicellulose and pectin.

Glucose Polymers and Maltodextrin:

In between simple and complex carbohydrates are glucose polymers and maltodextrin, which comprise of betweeen 3- and 10 sugar units.  They are made from the partial breakdown of corn starch in food processing.  These are widely used as bulking and thickening agents in processed foods e.g sauces,  baby foods and soft drinks.  They are also widely used in sports drinks and meal-replacement products, owing to their low sweetness and high energy density relative to sucrose.

Not All Carbohydrates Are Equal:

It's tempting to assume that simple carbohyrdrates due to their smaller molecule size can be absored by the body more quickly than complex carbohydrates and produce a large and rapid rise in blood sugar but this is certainly not true.  For example apples (which contain simple carbohydrates) proiduce a small and prolonged rise in blood sugar, despite being high in simple carbohydrates. Plenty of starch foods (which are complex carbohydrates) , such as potatoes and bread, are digested and absorbed very quickly by the body and give a rapid rise in blood sugar.  So the old notion about simple carbohyrates giving fast-released energy and complex carbohydrates giving slow released energy is misleading not true.