Perfecting Your Marathon Nutrition Plan

Marathon Nutrition Plan Pre-session and During session fuelling 

Marathon nutrition planning plays a critical role in exercise performance, and effective pre- and intra-exercise fuelling can help you get more from every training session by sustaining energy levels, delaying fatigue, maintaining performance, and supporting recovery. The body primarily relies on two fuel sources to provide energy for exercise: carbohydrate and fat. The contribution from these two macronutrients will depend on the type of activity you take part in. During high-intensity exercise, such as sprinting or hard endurance efforts, carbohydrate becomes the predominant fuel source, whereas during lower-intensity exercise, a greater proportion of energy is derived from fat. As a result, daily carbohydrate requirements vary according to the intensity and duration of exercise and can be adjusted from day to day depending on your training.

How much carbohydrate do you need for marathon training?

Level of Training	Amount of Carbohydrate Required
Light (rest days/ low intensity exercise)	3-5g/kg of body mass/day
Moderate (around 1hr of moderate intensity exercise)	5-10g/kg body mass/day
Heavy (1-3hrs of moderate-to-high intensity exercise	6-10g/kg body mass/day
Very heavy (>3hrs moderate-to-high intensity exercise)	8-12g/kg body mass/day

The table above shows carbohydrate needs for marathon training range from 3-5g/kg body weight on rest days up to 12g/kg on the heaviest training days.

How to Fuel before Marathon Training Sessions:

Carbohydrates should be the priority in a pre-exercise meal. For shorter training runs, consuming a carbohydrate-rich snack beforehand is likely sufficient. Some great options include a banana, a slice of toast/ crumpet/ bagel with honey or jam, or a cereal bar. These foods are rich in easily digestible carbohydrates and therefore provide a readily available source of energy for exercise.

For longer training runs, or on marathon race day, a larger carbohydrate-rich meal should be consumed approximately 1-4 hours before exercise. This meal should be relatively low in fibre and fat to reduce the risk of gastrointestinal (GI) discomfort. If your main meal is eaten 2-4 hours before the start of exercise, it can be beneficial to consume an additional carbohydrate-rich snack 30-60 minutes beforehand to top up energy stores. Examples include a banana, a handful of dried fruit, a snack bar (e.g., Soreen or Squares bar), a few sweets or a few sips of sports drink. 

What Nutrition can you Consume During your Marathon Training Sessions:

Body stores of carbohydrate are limited; therefore, consuming carbohydrate during exercise provides additional energy, helping to delay fatigue and maintain performance. The amount of carbohydrate that is recommended to be consumed during exercise depends on the duration.

• < 30 mins duration: no need for additional carbohydrate.

• 30-75 mins duration: may benefit from a small amount of carbohydrate consumption.

• 1-2 hours duration: research demonstrates that consuming 30-60g of carbohydrate per hour during exercise lasting 1-2 hours can improve performance.

• >2h duration: it’s recommended that athletes consume >60g of carbohydrate per hour, up to 90g per hour during exercise lasting >2.5h. This should be in the form of multiple transportable carbohydrates. Here, the co-ingestion of two different types of carbohydrate, which use different transporters (e.g., glucose and fructose), will maximise absorption and utilisation.

Carbohydrates during exercise can be consumed in a variety of different forms. Gels are often a popular choice, but you could also try energy gummies/ chews, sports drinks or solid foods. If you’re opting for solid foods, then these should ideally be low in fibre, fat and protein to reduce the risk of GI issues. Some great options are bananas, dried fruits or energy bars. Taking on carbohydrates during exercise can be tricky and takes some getting used to. Start with small amounts and build it up gradually. 

What about fibre?

Dietary fibre is a type of carbohydrate, which, unlike other carbohydrates, are not digested in the small intestine, and instead reach the large intestine. Fibre plays an important role in digestive health, helps to prevent constipation and can reduce the risk of some diseases. In contrast to the public health guidelines of at least 30g of fibre a day, it’s recommended that athletes consume 25-35g a day. Despite the benefits of fibre, regular intakes above 35g per day may have negative effects, such as increasing the likelihood of GI discomfort, or promoting feelings of satiety, making it challenging to consume sufficient total energy intake.  

What about hydration?

Body water is required for several physiological functions, including the transportation of oxygen and nutrients throughout the body, as well as the regulation of blood volume, blood pressure, and body temperature. When dehydration occurs, sweat rates lower. Sweating is a primary cooling mechanism; therefore, a decrease in sweat rates can lead to a rise in core body temperature. This has several negative effects on both health and performance, including impaired cardiovascular function, accelerated depletion of carbohydrate (glycogen) stores, and increased mental fatigue.

Individual hydration needs can vary considerably depending on factors such as sweat rate, exercise intensity, environmental conditions (e.g., temperature and humidity), and clothing worn. A practical way to monitor hydration status is by observing urine colour and volume. Pale urine in adequate volumes generally indicates good hydration, whereas dark-coloured urine and low urine output may suggest dehydration.

Perfecting your Marathon nutrition strategy

Prior to race day, you should aim to simulate race-day conditions for 2/3 of your long training runs. This means having the same pre-run meal/ snack and taking on the same type of carbohydrate (i.e., gel, bar, whole foods), the same quantities of carbohydrate, and the same intervals between carbohydrate sources that you plan to use during the race. Regularly sipping on fluids throughout sessions should also be practised. Nutrition is highly individual, and what works well for one athlete may not work for another. Practising your race-day nutrition during training allows you to identify the strategies that best support your performance while minimising the risk of gastrointestinal discomfort.

Written by Ella Myers ANutr, MSc and Head of Sports Nutrition at PGC1-Coaching.

This blog was written by Ella Myers who holds a BSc in Nutrition Exercise and Health and is currently finishing her Masters in Applied Sports Nutrition. Having won numerous academic awards during her undergraduate degree Ella has also had her research published. Ella balance her studies alongside working with athletes from and through PGC1-Coaching as well as athletes at the St Mary's University Elite Training Centre. Ella is available to work with you directly on your nutrition and help you take the next steps in your performance. You can find out about her service offering using the link here.

References/ further reading:

Burke, L. M., Hawley, J. A., Wong, S. H., & Jeukendrup, A. E. (2011). Carbohydrates for training and competition. Journal of Sports Sciences, 29 Suppl 1, S17–S27. https://doi.org/10.1080/02640414.2011.585473 

Convertino, V. A., Armstrong, L. E., Coyle, E. F., Mack, G. W., Sawka, M. N., Senay, L. C., Jr, & Sherman, W. M. (1996). American College of Sports Medicine Position Stand. Exercise and Fluid replacement. Medicine and Science in Sports and Exercise, 28(1), i–vii. https://doi.org/10.1097/00005768-199610000-00045 

Jeukendrup A. E. (2004). Carbohydrate intake during exercise and performance. Nutrition, 20(7-8), 669–677. https://doi.org/10.1016/j.nut.2004.04.017