Scenario: The athlete is a 28-year-old male wanting to run marathons. He is in good health. He
has been running 5K and 10K races for the past two years but is afraid of “hitting the wall” or
experiencing some other exhaustive phenomenon.
1. The physiological response of carbohydrate loading in sports.
Carbohydrate loading is a strategy used by many athletes to increase glycogen storage for
more energy during athletic events. Carbohydrate loading is most often used by endurance
athletes to provide energy for long duration or high intensity activities. Carbohydrates are the
main source of energy for the body so loading up on carbs before an event can provide
athletes with large amounts of energy. Carbohydrates are stored in the muscle and liver as
glycogen where they are broken down to provide energy in the form of ATP. Carbohydrate
loading increases stored muscle glycogen, which allows exercise to be prolonged and
performance to be improved.1
2. The process of carbohydrate loading.
Carbohydrate loading typically involves several days of consuming excess carbohydrates
prior to an athletic event. There are many ways to accomplish carbohydrate loading
depending on the athlete, type of event, and duration of event. Carbohydrate loading can be
performed anywhere from 1 to 7 days before an event. The process of carbohydrate loading
involves a high carbohydrate diet a couple days prior to the event while also tapering off
training during the week before.2 This helps an athlete store as much glycogen as possible
before an event.
3. The advantages and disadvantages of various carbohydrate loading techniques.
Carbohydrate loading can benefit an athlete who must perform for 90 minutes or longer by
providing extra glycogen.2 Carbohydrate loading can also benefit athletes who compete in a
hot climate by releasing water as glycogen breaks down.2 While carbohydrate loading is
mainly used for endurance events, it can also be used to benefit bodybuilders by promoting
muscle definition from maximum glycogen storage. While carbohydrate loading has been
shown to be effective for long distance runners, it is not known how often this process can be
repeated while still getting the same results. Other disadvantages of carbohydrate loading can
include increased body weight from the water inside carbohydrates, discomfort with
digestion, and blood sugar changes. Depending on the athlete and type of event, carbohydrate
loading can be beneficial in providing increased energy for endurance events, but athletes
still have to be careful with this technique.
4. The timing, amount, and listing of appropriate food sources for carbohydrate
loading.
The timing and amount of carbohydrates depends on several different factors. Carbohydrate
needs for athletes depend on their body size, length of activity, intensity of activity, and more.
Carbohydrate consumption increases and exercise decreases in the days leading up to the
event. For example, 6 days before the event an athlete can train for 90 minutes while
consuming 5 grams of carbs per kilogram of body weight. Once an athlete gets 2-3 days out
from an event, training decreases to 20 minutes and carbohydrates increase to 10 grams per
kilogram of body weight. The day prior to an event, an athlete does not train and consumes
10 grams of carbohydrates per kilogram of body weight. Sources of carbohydrate rich foods
include bread, pasta, rice, fruit, oatmeal, english muffins, bagels, potatoes, and many more.
5. Any additional information needed to explain the why, how, when, and what of
carbohydrate loading.
Multiple studies have shown significant improvement in overall performance from
carbohydrate loading. Carbohydrate loading improves speed and endurance while also
preventing athletes from feeling fatigued and tired during events. This nutritional strategy can
be a huge difference maker for an athlete’s performance.
References
1. Andrews, J. L., Sedlock, D. A., Flynn, M. G., Navalta, J. W., & Ji, H. (2003). Carbohydrate
loading and supplementation in endurance-trained women runners. Journal of Applied
Physiology, 95(2), 584–590. https://doi.org/10.1152/japplphysiol.00855.2002.
2. Dunford, M., Doyle, J. A., & Killian, L. (2022). Nutrition for sport and exercise. Cengage.
