In my work with runners on technique and improving their physical abilities as they relate to their technique I use The Yessis System of Improving Performance, and some variant of the 1 x 20 RM strength training program. The runners show significant improvement in their running times, but some have difficulty in bringing down their marathon times more than 5-10 minutes.
To find out why I have them closely monitor their nutrition to determine their fuel for the marathon in preparation for and during the run. In most cases, the runners were found to be following the commonly recommended nutritional protocols which I believe are outdated. Let’s examine the facts.
Long distance runners in general are distinguished by maintenance of their muscle enzymes, while marathon runners are distinguished by the amount and speed of mobilization of lipids (fats) in the blood. In the marathon, the aerobic system provides the energy (ATP) through the use of oxygen.
When energy is produced in glycolysis (when glycogen is broken down for energy in the absence of oxygen) lactic acid is produced which, when the concentration is sufficiently great, shuts down energy production. This is an anaerobic process which takes place in the absence of oxygen. But, muscular activity for the run will continue as long as there is an adequate supply of oxygen or glycogen stores.
The nutrients used by the body as fuel for the marathon include fatty acids (from fats), amino acids (from proteins), and glucose (from glycogen – carbohydrate – breakdown) delivered to muscles by way of blood. Of the three, the breakdown of fatty acids produce the greatest amount of energy (ATP) – more than double what can be produced from the breakdown of carbohydrates and without the production of lactic acid!
Protein breakdown for fuel will occur when the fatty acid supply has been depleted. But keep in mind that your body will always retain about 5-10% fat. The body uses carbohydrates, fats, and protein for fueling the run, but the ratios of use can be changed according to your training and availability of the nutrients in the body at the time that they are required for use.
The general consensus in regard to fueling your body is that you should eat more carbohydrates, fewer fats, and maintain the proteins. Thus, it is not uncommon to read that your diet should contain 60-70% carbohydrates, about 10-20% protein, and 10-20% fats. During the run, carbohydrate-type drinks or gels are used for replenishing the carbohydrate stores.
The rationale for this type of diet, is based on seemingly sound information. Marathoners must have a lean body with minimum levels of fat so that the run is more economical. The heavier you are, the more work the muscles must do which is not economical and causes early fatigue.
What is overlooked in developing a lean body, however, is that the body requires minimum levels of muscle to maintain high levels of muscular endurance. This is especially true of the leg muscles necessary to maintain a long run. The faster you run at a steady pace, the more muscular endurance is needed.
Dieting to eliminate fats and to minimize proteins in the diet may produce a lean body but it also does not allow you to develop the muscular strength needed. If you have true minimum levels of fat, your body will not have sufficient fats to burn during the run.
Keep in mind that the body will reserve minimum levels of fat and cannibalize the muscles to get more energy before it will use up the remaining fat stores. This is why it is possible to see so many extremely thin runners. Most of their muscle has been used to provide energy when they run out of fats and carbohydrates.
Before a long distance run, carbohydrate loading is effective in increasing the amount of glycogen in the body. Often overlooked is the insulin spike that leads to a major let-down when the carbohydrates are depleted. Also, the insulin may help convert some of the carbohydrates to fatty acids.
As a result, the body may now have more fat to burn for energy even though we think it was from carbohydrates. Perhaps this is why, before a race, eating a large carbohydrate meal is considered so effective. Thus it is not surprising that before a major marathon there is a pasta feed the night before. But is it the most effective? The answer is in part two and in Explosive Running.
For more information see Explosive Running, 2nd edition