Carbohydrates – a Triathlete’s Best Friend

By Steve A
October 26, 2011 on 12:28 pm | In Nutrition Tips | No Comments

In the world we live in today there is an increasing talk about carbohydrates. The truth is that carbohydrates really are the endurance athlete’s best friend, without them we could not swim, bike or run with any bit of enjoyment or proficiency.  Without carbohydrates, our capacity for endurance would just about disappear. So the question on everyone’s mind is how many carbohydrates do I need? To answer this we first need to understand what carbohydrates are and what they do in our bodies.

What is a Carbohydrate?

To the endurance athlete, carbohydrates are basically either glucose, fructose or some combination of the two (there are more types of carbohydrates, but for this we are only going to talk about those two). Carbohydrates can be linked together to form different types of sugars or chemical structures such as sucrose (glucose linked with fructose), also know as table sugar. Carbohydrates can also be linked together to form more complex molecules like Amylose or Amylopectin which is basically a long string of glucose molecules linked together and are commonly found in plants.  Carbohydrates are found in foods like fruit, bread, pasta, potatoes, rice, grains and sweets. Carbohydrates can be classified as either Simple, like in cookies and soda, or Complex, like in whole wheat bread or pasta.

What does it do in the body?Carbohydrates begin to break down into a digestible form once they enter the mouth. Your saliva contains an enzyme called amylase that begins to break down complex carbohydrates into a more simple form preferred by the small intestines. Next, carbohydrates are moved down into your stomach where they are further broken down into a digestible form called chyme. This mix of partially digested food is then released slowly into your small intestines where it is broken down further into the simplest form, glucose. Glucose now can be absorbed into your blood stream. Once glucose is in circulation, your muscle cells and liver can begin to uptake glucose with a little help from our friend insulin. Inside the cell, glucose is either made into glycogen for storage or used for energy in glycolysis during exercise. Once glucose has entered glycolysis, it can be used to make energy anaerobically for a short period of time or it can be used to fuel the citric acid cycle at medium to medium high aerobic efforts. Depending on your exercise intensity, your body will begin to burn a blend of fat and carbohydrates. Carbohydrates are not 100% essential, but for an endurance athlete they are critical. Without carbohydrates, it would take a long time to restore glycogen levels to an acceptable range after training.

How much do I need?

Now that you have the gist of what a carbohydrate is, we can discuss how much an endurance athlete needs. Typically an endurance athlete needs 50-65% of their diet from carbohydrates, with less than 10% of those carbohydrates coming from a simple form. Here is what I recommend:

Training time                      Carbohydrate grams/pound body weight

1 hour/day                          2.7-3.2 g/lb

2 hours/day                        3.6 g/lb

3 hours/day                        4.5 g/lb

4 hours/day                        5.4-5.9 g/lb

As an example, if I am a 180lb man and I am training 2 hours per day, 180lb x 3.6g/lb=648 grams of carbohydrates. I recommend splitting these up through each meal of the day, so for 5 meals that is 129g per meal. Since there are 4 calories per gram of carbohydrate, that is about 520 calories per meal from carbohydrates.

The beautiful human machine is complex and there is no owner’s manual, but hopefully this helps you understand how things work a little better. Now go out there, eat carbs and train hard!

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