We’ve all probably heard of carb cycling, but what exactly is it and how does it work? Before delving deeper into this tactic used by athletes of all disciplines, we need to understand the role that carbohydrates play in the body, especially when it comes to training and exercise.

What role do carbohydrates play in athletic performance?

Carbohydrates play a vital role in exercise and performance, particularly during prolonged or high intensity bouts, where carbohydrates will be the primary source of energy. A study by Currell, Conway & Jeukendrup (2009) in soccer players showed that ingesting carbohydrates improved kicking accuracy by 3.5%, dribbling by 3.2% and agility by 2%. In addition to this, figure 1 highlights the amounts of carbohydrate in the muscle before and after a soccer game. As you can see, the amount of carbohydrate dramatically reduces throughout the game as energy is expelled, which could significantly reduce performance. Consuming enough carbs before, during and after exercise can therefore help to increase performance by ensuring our muscles have the energy they need to function at their best no matter what we’re demanding of them; however, this doesn’t mean that more carbs are always better!

 

What is carbohydrate cycling?

Carb cycling, or carbohydrate periodisation as it’s also known, looks to optimise performance by adjusting carbohydrate intake day to day depending on the daily requirements e.g., more carbohydrates on longer / harder days and fewer carbohydrates on shorter / lighter days. This is important for athletes because every training day will be different, therefore your food intake (in particular carbohydrates) should reflect this by also adjusting day to day. When you consider the fact that elite athletes can have around 1400-1800 eating occasions per year (Stellingwerff, Morton & Burke, 2019), this means there are 1400-1800 opportunities to impact your performance through your nutrition strategy… In simple terms, what you eat matters, as it will directly impact how your body can cope with what you’re demanding of it.

Why cycle carbohydrate intake?

The reason carbohydrate periodisation is considered a fundamental nutritional priority is because it allows the athlete to appropriately fuel for training and competition, whilst also influencing areas such as body composition (e.g., reducing body fat) and training adaptations (Impey et al, 2018).

As shown in figure 1, carbohydrate availability in the body can reduce dramatically throughout training / exercise, therefore keeping levels topped up is important when it comes to maintaining performance. However, there may be situations whereby a high carbohydrate availability could be counterproductive. For example, if your goal is to reduce body fat then you need to target using fat as an energy source. High intensity exercise and high carbohydrate availability can reduce how much fat your body uses for energy, as your body will naturally look to get its energy from carbohydrate stores in the first instance. Therefore, reducing carbohydrate intake on a lower intensity day to match the physical requirements gives your body the opportunity to prioritise fat as its primary energy source. In addition to this, excess carbohydrates on low intensity days could also lead to unwanted weight gain and potentially unfavourable body composition.

Carb cycling/ periodisation is therefore a good strategy if the reduction of body fat is your primary goal, as well as important if you’re an elite athlete whose nutrition strategy needs to be adapted day-to-day to adequately meet the demands of training.

Carbohydrate cycling in practice

How carb cycling is done is entirely dependent on you and your own needs / goals, as well as your typical training schedule. A simple way to implement a carbohydrate periodisation strategy is to use the traffic light system:

Green – High carbohydrate intake

Generally, a total daily intake of > 7 grams per kilogram of body mass is considered a high carbohydrate intake.

To work this out, multiply your bodyweight (kg) by > 7 (e.g., 75 x 7 = 525 grams).

To work out the amount carbohydrates per meal you need, divide your total daily intake by how many times you eat (e.g., 525 grams / 5 feedings = 105 grams per feed).

Amber – Medium carbohydrate intake

Total daily intake of 5 grams per kilogram of body mass.

Red – Low carbohydrate intake

Total daily intake of < 3 grams per kilogram of body mass.

 

Start by mapping out your training sessions in a table. From this you can then start to match the carbohydrate requirements to the training demands. For example, below shows a typical training week for a team sport.

Generally, it is recommended to work around the match day (in this example Saturday). The day before a game (e.g., Friday) will be a high carbohydrate day to ensure that your body has enough fuel for the match. The day after (e.g., Sunday) will also be a high carbohydrate day to restore the carbohydrates used during the match. The rest of the week will then be adapted based upon the training requirements. In this example Monday is a medium carbohydrate day to fuel the field and weight session, but to also prepare for the high intensity session on Tuesday. Tuesday is a high intensity field session therefore breakfast and lunch are high carbohydrate meals. However, Wednesday is a complete rest day and so requires a minimal carbohydrate intake. This is reflected by tapering carbohydrates on the Tuesday evening and minimising carbohydrate intake throughout the whole of Wednesday. Thursday is a medium carbohydrate day to fuel the lower intensity session and weight training. Thursday can also be used to keep carbohydrate stores topped up in preparation for the carbohydrate load on Friday.

References

  • Currell, K., Conway, S., & Jeukendrup, A. E. (2009). Carbohydrate ingestion improves performance of a new reliable test of soccer performance. International journal of sport nutrition and exercise metabolism19(1), 34-46.
  • Impey, S. G., Hearris, M. A., Hammond, K. M., Bartlett, J. D., Louis, J., Close, G. L., & Morton, J. P. (2018). Fuel for the work required: a theoretical framework for carbohydrate periodization and the glycogen threshold hypothesis. Sports Medicine48(5), 1031-1048.
  • Krustrup, P., Mohr, M., Steensberg, A., Bencke, J., Kjær, M., & Bangsbo, J. (2006). Muscle and blood metabolites during a soccer game: implications for sprint performance. Medicine & Science in Sports & Exercise38(6), 1165-1174.
  • Stellingwerff, T., Morton, J. P., & Burke, L. M. (2019). A framework for periodized nutrition for athletics. International Journal of Sport Nutrition and Exercise Metabolism29(2), 141-151.