Safe and Effective Carbohydrate Loading

Many athletes, recreational or serious, have their pre-event traditions. All-you-can-eat pasta dinners, including unlimited refills of Gatorade, often fill the evening before the big day. Should this be considered just a fun tradition that many recreational athletes make it out to be or is there truly something to saturating muscles stores with glycogen that serious athletes are seeking?   Carbohydrate loading is defined as a dietary technique designed to promote significant increase in the glycogen content to delay the onset of fatigue.

During high intensity and endurance, carbohydrate is the primary fuel used by the muscles. In lower intensity, carbohydrates may not be the major source of fuel, but they are required for the effective metabolism of fat, which is. Thus carbohydrates are the limiting factor in exercise, meaning  when carbs are depleted in either case, performance is dramatically reduced.  

Carbo Loading

Traditional “carbo-loading” involves a stage of prolonged exercise and an exceedingly restrictive diet during the depletion stage, followed by intense carbohydrate loading.  From any viewpoint, this involves a switch from a normal balanced diet to an extreme. Extremes often stimulate a controversial debate and there thus both a positive and negative side should be weighed up. Some simple facts on carbohydrate metabolism can help you decide to what extent and what method carbohydrate loading may be appropriate for you.

Side Effects  of Carbo Loading

The lack of carbohydrates combined with high bouts of exercise during the depletion stage of traditional carbo-loading could elicit hypoglycemia (signs are weakness, lethargy, and  irritation). Prolonged intense exercise during the depletion stage could also lead to muscle trauma which in fact would impair the storage of glycogen rather than enhance it. Furthermore, carbohydrate loading could lead to the destruction of muscle fibers by excessive glycogen storage.

Several lab studies have reported abnormal electrocardiograph patterns in individuals who use the classic method.  Besides the irregular heartbeats and sudden loss of blood pressure, diarrhea, cramping, and nausea are often symptoms associated with drastic diet changes.

Glycogen is hydrophilic, meaning that it attracts water. This means that with each extra gram of glycogen stored, an extra 3 grams of water is stored too. Extra body weight is associated with the increased water content and extra energy is used to lift the extra water weight. Positively, the extra water content may help regulate body temperature by being available as a source of sweat. Athletes who compete in endurance sports, such as marathons or long-distance cycling, may thus benefit throughout their training, particularly in the heat, yet they may not want to have extra weight to carry. For athletes that require flexibility, such as gymnastics, weight lifting, and sprinting, if muscles are packed solid with water, this may cause stiff muscles and loss in flexibility.

Type of Carbohydrate Loading

The type of carbohydrate loading may also make a difference to saturation of glycogen.  Sports products and simple carbohydrates, such as Gatorade, PowerAde, and sports gels, are easily digested into glucose and are effective for glycogen sparing appear during an endurance event. Carbohydrates from a complex source, such as pasta, bread, and cereal, may be more effective for training periods before an event, rather than during the event, for maximizing glycogen storage.

Some early research may support the traditional technique of depletion and loading however more recent research shows that this strict routine is unnecessary. Simply changing to a very high carbohydrate diet, combined with 1 to 2 days of rest will effectively increase muscle and liver glycogen.  Furthermore, it has become evident that if an appropriate amount of carbs are consumed over the entire week rather than concentrating on the last day or two before an event, there is little glycogen difference between the 2 techniques.

Carbohydrate Loading Recommendations:

Due to this particular controversy, there are obviously a number of variations of glycogen packing before an event. In summary, it is important to consider that the benefits should more than offset the extra water weight, the possibility of inflexible muscles. For those wishing to experiment with the extreme depletion methods, the possibility of hypoglycemia and irregular heart rates is a health risk.

A generally recommended safer variation on traditional carbo-loading is as follows:
Day 1: deplete exercise
Day 2 high protein/high fat, low carbs, tapering exercise
Day 3: high protein/high fat, low carbs, tapering exercise
Day 4: high protein/high fat, low carbs, tapering exercise
Day 5: high carbs, tapering exercise
Day 6: high carbs, tapering exercise or rest
Day 7: high carbs, rest
Day 8 : Competition
High carbs is considered to be 8 – 10 g carbs per kilogram of body weight.

However, 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, will give you the energy to perform well for most training periods and competition events.