Most marathons and large triathlons have pre-race pasta dinners. Even athletes who don't attend the dinner make reservations weeks in advance at the closest Italian restaurant. Many athletes walking around the race expo are munching on Power Bars and carrying large bottles of Gatorade, refilling them often.
Is the pasta just a cheap race meal for the directors to put on or is there something to the practice of ingesting large amounts of carbohydrates before a big race?
Carbohydrate Loading Defined
As it turns out "carbohydrate loading" is a well known dietary practice designed to load up the muscles with glycogen prior to an athletic event. The carbohydrate loading theory was that if you deprived the body of glycogen and depleted it's stores, when you began taking in carbohydrate again, the body would store more than normal - supersaturating the muscles. As fatigue accompanies the draining of glycogen from the muscles, loading up on glycogen is thought to delay fatigue, a very welcome side effect for a marathon runner. This practice was developed in 1967 by Gunvar Ahlborg, a Swedish scientist.
The primary fuel used by your muscles during high intensity exercise and endurance events is carbohydrates. Your body gets the carbohydrates it uses for energy from the glycogen it has stored in the liver and muscles.
During lower intensity exercise fat is the major source of muscle fuel. However, carbohydrates are required to metabolize the fat so carbohydrates still play a role when you are exercising at low intensities.
What this means to you is that whether you are exercising at a low intensity or high intensity - carbohydrates are a limiting factor in your performance.
How can you keep carbohydrates from limiting your performance? This is the idea behind carbohydrate loading - to keep carbohydrates from limiting your performance.
"Traditional" carbohydrate loading involved completely depleting your body of carbohydrates, then saturating your body with carbohydrates. During the depletion stage the athlete follows a restrictive diet and intense exercise and during the loading stage, the athlete loads up on carbohydrates.
No matter how you look at it, this plan is a departure from a normal, balanced diet. Carbohydrate loading has it's critics and defenders so do your homework rather than blindly following a plan. This article gives you some simple facts to help you decide whether and to what extent to incorporate carbohydrate loading into your training plan.
Side Effects of Carbohydrate Loading
A big side effect of carbohydrate depletion is that your energy is also depleted. I once went on a three day body builders diet in which you only eat tuna for 3 days. This diet is supposed to "lean you up" for competition and is also used kick off a new training season. I can't for the life of me remember why I thought this would be a good idea but I believe I thought I would "detox" or lose a few pounds before marathon training season. By midway through the second day I was so stupid I couldn't spell my own name. This was a clear indication to me of the signs of hypoglycemia - weakness, lethargy, and irritation. (Interestingly, the amount of carbohydrate required by the brain and nervous system are enough to deplete your liver of stored glycogen in 24 hours, so you can imagine how sharp your brain function would be during carbohydrate depletion.)
As you taper for your race, your workouts are probably along the lines of short and sharp. Short enough to allow you to recover and sharp enough to keep your muscles primed for racing. A carbohydrate-depleted fog is not what I think of as sharp.
As you prepare mentally for your race, you want to be positive, not irritable.
If you exercise intensely during the depletion stage, you could experience muscle trauma which would impair your muscle's ability to store glycogen rather than enhance it. If that isn't enough, the loading stage could actually harm muscle fibers by pushing them to store excessive glycogen.
Several lab studies have reported abnormal electrocardiograph patterns in athletes who follow this strict depletion and loading phase pattern.
A second side effect of carbohydrate loading is weight gain. Glycogen is hydrophilic, meaning that it attracts water. When you stuff your muscles with glycogen, the glycogen attracts water into your muscles. With each extra gram of glycogen stored, an extra 2.6 grams of water is stored. When carbohydrate loading you will gain weight. Even following a modest carbohydrate loading plan, you may arrive at the start line a few pounds heavier. Don't be alarmed by this. This is also due to the decreased exercise during your taper. On the positive side, the extra water may help regulate body temperature by being available as a source of sweat.
For endurance athletes the trade-off to consider is whether the extra water will be a help (could be particularly true in hot weather) or a hindrance (extra energy required to carry extra weight).
Athletes whose sport requires flexibility, such as gymnastics, weight lifting, and sprinting should be aware that muscles packed with water may be stuff and limit flexibility.
Type of Carbohydrate Loading
The type of carbohydrate you take in during the loading phase may not make much difference in how well the muscles are saturated with glycogen.
In one study involving runners, the runners' normal diets were modified by increasing either their protein intake, their intake of complex carbohydrates or their intake of simple carbohydrates. The 'complex' carbohydrate group added bread, potatoes, rice or pasta to their diet.. The 'simple' carbohydrate group increased their carbohydrate intake with chocolates. Running times improved for both groups who increased their carbohydrate intake. The complex carbohydrate group improved their running times by 26%, while the simple carbohydrate group improved by 23%.
The group who increased their protein intake made no improvements in their running times. What this study confirmed is that increasing carbohydrate intake improves performance, the type of carbohydrate doesn't make a difference.
Carbohydrate Loading Methods
The original carbohydrate loading method was to strip the body of glycogen by exercising to exhaustion 6-7 days before the endurance event. For the next 3 days, the athlete consumes a diet of less than 10% carbohydrate.
The athlete again exercises to exhaustion but for the last 3 days before the event consumes a diet of 90% carbohydrates. The idea was that the body would hold onto the glycogen in the last 3 days, supersaturating the muscles with glycogen.
Some early research may support this method however more recent research shows that this strict routine is unnecessary. (and perhaps harmful, see the first section)
Studies have shown that simply increasing your carbohydrate intake to 75%, combined with 1 to 2 days of rest will effectively increase muscle and liver glycogen.
Carbohydrate Loading Recommendations:
The amount of additional carbohydrate your body can store is dependent on your diet and your conditioning level. For an untrained individual who consumes a high carbohydrate (75%) diet, glycogen stores during a loading phase may increase up to 490g. For an athlete training on a daily basis who consumes a moderate carbohydrate diet (45% carbohydrate), the amount of glycogen able to be stored is 330 g. However, for a well-conditioned athlete who consumes a high carbohydrate diet (75% carbohydrate), his/her total carbohydrate reserves may increase up to 880 g. Clearly the conditioned athlete's muscles are much more efficient at storing carbohydrates than the unconditioned person.
A well-conditioned athlete may need to do little more than consume a higher quantity of carbohydrates in the three days before competition to receive full benefit.
Eating a consistent diet that is 55-65% carbohydrate will allow you to replace muscle glycogen stores on a daily basis and not just the night before an event and will give you the energy to perform well for most training periods and competition events.