Carbohydrate loading for endurance events
Most long-distance and ultra runners use a carbohydrate loading (or 'carb loading') strategy prior to their events. But before I give you an example of how carb loading can be achieved, let’s understand why it is worth following a carbohydrate-rich diet and the type of events for which this is necessary.
What is the difference between glycogen, carbohydrate and glucose?
Glycogen comes from carbohydrates (a macronutrient), but is technically not a carbohydrate. When you eat foods and drink fluids that contain carbohydrates, your body digests the carbohydrates and turns them into glucose which then can be used for fuel. In contrast, glycogen is the stored form of glucose.
Why are carbohydrates (CHO) so important for endurance running?
During long-duration efforts, an athlete performs at low or moderate intensity. The energy source for muscle contractions at these intensities are CHO, fat, and protein (and we utilise these energy sources in that order). CHO is the most readily available energy source and thus negatively affects our performance when we run out of CHO stocks (which we all know as 'bonking' or 'hitting the wall').
What does CHO loading mean and how is it beneficial for performance?
Through CHO loading we can increase our muscle glycogen to its maximum prior to an event by following a CHO-rich diet for about two days prior to the event. Studies have established the performance benefits CHO loading has on performance (see Haley et al. 1997). The purpose of CHO loading is to increase energy availability and to complete an endurance event with less fatigue.
Which events require CHO loading?
When performing a medium-intensity effort it takes about 2 to 2h30 to empty glycogen storage, therefore it is beneficial to CHO load for events of a duration greater than 2 hours. This means that a race that takes you less than 2 hrs to complete does not require any CHO loading, or that CHO loading has a positive effect on your performance in these "short-distance" races.
Now that you understand why and when it is important to CHO load, how should CHO loading be achieved?
- Start your CHO rich diet 36-48hr prior to your event
- Increase your CHO intake to 10-12g a day per kg of body mass. For example, a person that weighs 75 kg should consume 750g-900g of CHO per day.
It is important to note that your daily overall caloric intake should not (or slightly) increase, which means that you have to reduce fat and protein intake!! You may notice a weight gain on the scale, which is due to the increase in glycogen stores and the water bound to it. So do not worry about that number on the scale!
An example of CHO rich diet:
Breakfast: Bran & fruit cereal Low fat milk Orange juice Toasts & jam Snack: Fruit muesli bars Honey in tea or coffee Lunch: Bread rolls Ham slices Cheese Lettuce, tomato, cucumber Fruit Snack: Sports drink Fruit Toasts & jam
Dinner: Chicken Veggies Rice Low fat yogurt
Enjoy your pre-events meals!
" C is for cookie that's good enough for me" Cookie Monster.
HAWLEY, J.A., PALMER, G.S. & NOAKES, T.D. 1997, 'Effects of 3 days of carbohydrate supplementation on muscle glycogen content and utilisation during a 1-h cycling performance', European journal of applied physiology; Eur J Appl Physiol Occup Physiol, vol. 75, no. 5, pp. 407-12.
Wright, D.A., Sherman, W.M. & Dernbach, A.R. 1991, 'Carbohydrate feedings before, during, or in combination improve cycling endurance performance', Journal of applied physiology (1985); J Appl Physiol (1985), vol. 71, no. 3, pp. 1082-8.