Prepping for your big race: how to carbo-load the right way

Being wary of every new nutritional fad is always a good idea, but one method that has stood the test of time is carbo-loading. First implemented in the late 60’s, carbo-loading is, essentially, eating a tonne of carbohydrates before a ride or race to increase your performance. The key however, is to do it correctly.

Carbo-loading aims to massively increase the levels of glycogen available for your muscles to use during exercise, resulting in an increase in performance. However, when you eat the carbs, and how much of them you actually consumed, can both have a drastic effect on the performance enhancement you receive.

Carbohydrate loading is only officially recommended for rides over 90 minutes. This is because, at any point in time, your body has enough glycogen stored for about 90 minutes of endurance exercise, and for anything longer, your natural supplies begin to run low. However, many studies have shown significant improvements from carbo-loading for shorter races.

A pre-race meal containing 4.5 grams of carbohydrates per kg of body weight has been shown to increase the maintainable VO2 max by 10% (2) – this translates to a 2-3% increase in cycling performance over a 4-hour event (3).

Before a race, there are two critical points for carbohydrate fueling: your pre-race meal, and what you eat immediately before you start. You should aim to eat your pre-race meal four hours before your ride. This avoids a period of time known as transient hypoglycemia. After you ingest any meal, your body triggers a compensatory release of insulin to compensate for the increased sugars, which can actually decrease performance if you were to start your race during this period. For maximal results, a pre-race meal should contain 4.5 grams of carbohydrates per kilo of body weight – that’s a lot of carbs. For a 70kg athlete that will be 315 grams of carbohydrates. To obtain this with solid foods would be unreasonable, so thankfully, there has been no difference shown between consuming the carbohydrates in solid or liquid form. Whilst this amount of carbohydrates may seem excessive, it has been shown to increase the maintainable VO2 max by 10% (2), which translates to a 2-3% increase in actual cycling performance over a 4-hour event (3). So maybe save this one for race day.


What a solid meal of 315 grams of carbohydrates would look like!

By itself, consuming carbohydrates immediately before exercise does not increase cycling performance (4). However, the massive increase in performance associated with a large pre-race meal can actually be enhanced by consuming a ‘top up’ dose of 45 grams immediately before the race (5). Why this benefit exists is still unclear, but it is thought to do with your body implementing two different metabolic mechanisms to deal with the excess carbohydrates.

Key points to remember:

  • Consume a large, carbohydrate-dense meal, in solid or liquid form, four hours before your race.
  • Top up on carbohydrates immediately before you start.
  • Stay hydrated before and throughout your race.

Remember, dehydration and lack of physical preparation will negate any positive effects of carbo-loading, so train hard and drink plenty of water!

So, consumption of a large pre-race meal, combined with a top up dose just before the race is the best way to immediately improve your cycling performance.  Just remember that being dehydrated and unfit will negate any positive effects observed from increased carbohydrate consumption. So train hard and drink plenty of water!



1 – Coleman, E. (1994). Update on carbohydrate: solid versus liquid. International journal of sport nutrition, 4(2), 80-88.

2- Sherman, W. M., Brodowicz, G. A. R. Y., Wright, D. A., Allen, W. K., Simonsen, J. O. H. N., & Dernbach, A. (1989). Effects of 4 h preexercise carbohydrate feedings on cycling performance. Medicine and Science in Sports and Exercise, 21(5), 598-604.

3- Burke, L. Middle- and long-distance running. In: Practical Sports Nutrition. Human Kinetics Australia, 2007; 109–139

4 – Palmer, G. S., Clancy, M. C., Hawley, J. A., Rodger, I. M., Burke, L. M., & Noakes, T. D. (1998). Carbohyrate ingestion immediately before exercise does not improve 20 km time trial performance in well trained cyclists. International journal of sports medicine, 19(06), 415-418.

5 – Neufer, P. D., Costill, D. L., Flynn, M. G., Kirwan, J. P., Mitchell, J. B., & Houmard, J. (1987). Improvements in exercise performance: effects of carbohydrate feedings and diet. Journal of applied physiology, 62(3), 983-988.

Categories: Nutrition

3 replies »

  1. So if I have a race starting at 6:30am, should I wake up and eat something at 2:30am, or is it best to just have a carb loaded dinner?


    • Hey Claire, your best bet would be to Carbo load with a late dinner, as the benefits can be experienced for up to 12 hours, 4 hours is just the optimal time. It’s vital you get a full nights’ rest before a race! Good luck out there!


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