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Ben Samuels

Performance Nutritionist

Fueling Rock 'n' Roll Marathons

We’re delighted to be the official energy gel partner to Rock ‘n’ Roll Marathons! Discover how to fuel your marathon performance with our world-class nutrition.

The Rock ‘n’ Roll Marathon Series makes running fun, combining travel and entertainment to provide a world-class event atmosphere. Whether you are looking to run a new PB, raise money for charity or complete a personal goal, getting your nutrition right around training and racing could be the key to enjoying race-day. As Official Energy Gel Partner to the Rock ‘n’ Roll marathon series, we’ll not only be fueling runners on race day but also providing you with world class knowledge, starting with how to fuel for your marathon:

Train as you race

When event day comes around there is no doubt that carbohydrate will be the preferred fuel for marathon running. To prepare for this you should practice your race-day nutrition strategies in training. However, as a runner we must consider the role of fat in fueling running performance. The percentage contribution of carbohydrate and fat to overall energy production is largely determined by exercise intensity and duration. Your high-intensity intervals and tempo sessions will be carbohydrate dependent. Whereas, easy miles and recovery runs can be fueled using our own body fat stores.

A well-designed training plan should include the following sessions in your training week:

  • Low-intensity running with restricted carbohydrate availability
  • High-intensity intervals fueled by carbohydrates
  • Race-day sessions where the full fueling plan below is practiced
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GO Isotonic Energy Gels

With the importance of carbohydrate for race-day evident, fueling during a marathon is key. This can be achieved through our GO Isotonic Energy gels, allowing you to split your energy and hydration plans. The tonicity of a solution refers to its concentration. This concentration affects how easily and quickly water and carbohydrate empties from the gut and is absorbed into the bloodstream. Ultimately this will affect how quickly the gel can be used as an energy source. Hypertonic solutions have a higher concentration than then fluid in the body, whereas hypotonic solutions have lower concentration. A higher concentration requires additional water to digest and can cause gastrointestinal distress, a lower concentration empties quickly from the stomach but delivers little energy. An isotonic solution has the same concentration of dissolved particles as the fluid in the cells within the body, promoting high carbohydrate delivery (1) without the need for water.

24-48 Hours Before Race Day

The days leading up to a marathon present a good opportunity to loading glycogen into the muscle to use as energy during running. Carb-loading in preparation for a marathon can be achieved through an increase in carbohydrate ingestion for the 1-2 days before your race. Aim to increase your carbohydrate intake to 3.6-4.6 grams per pound of body mass (8-10 grams per kilogram of body mass) per day, including: a carbohydrate source with all main meals, carbohydrate snacks between meals and use carbohydrate based drinks during the day. Utilising primarily high glycaemic index (GI) carbohydrates will promote superior glycogen storage versus low GI carbohydrates (2). The below plan provides an example of how an athlete could load with ~550g of carbohydrate:



Food Source

Carb Quantity (g)


2 cups of cereal, two slices of white toast, thick spread of jam and a glass of fruit juice.



1 medium banana



2 toasted bagels, choice of filling



Home-made fruit smoothie



2 cups of cooked white pasta, chicken breast, tomato based sauce, 2 slices of garlic bread



1 tin of rice pudding + 250ml fruit juice




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Your breakfast acts as a key meal on race day, to top up energy stores and ensure you are fully fueled for the start line. High glycaemic index carbohydrate choices would be superior to promote glycogen storage and subsequent utilization during running performance (2), aiming for 0.45-1.36g of carbohydrate per pound of bodyweight (3). Your breakfast should reflect this and include normal breakfast food: cereals, toast, bagels, jam, fruit juice. Breakfast should be 2-3 hours before the start of the race to allow for full digestion and prevent any chances of gastrointestinal distress while running.

You should aim to start running in a hydrated state, pre-hydrating with 2.3-4.5ml of fluid per pound of body weight in the 1-3 hours before the race. This can be split between breakfast and the build-up to the race. Fluids should include key electrolytes to promote fluid absorption and retention, meaning fewer stops for the toilet during the race (3).

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Using GO Isotonic Energy gels to meet your energy requirements will enable you to tackle the marathon with individual energy and hydration plans, giving you the best chance to optimally fuel and hydrate on race-day:

Our body’s carbohydrate stores are limited to around 400-500g and can be depleted within 60-90 minutes of intense running, resulting in fatigue and hitting the wall. Carbohydrate intake during the race is required to maintain performance and keep you fueled through to the finish line. You should aim to take in 60g of carbohydrate per hour of running, from the first hour. This can be achieved through 3x GO Isotonic Energy gels. Isotonic Energy gels deliver 22 grams of carbohydrate and GO Energy + Caffeine gels deliver 22g of carbohydrate and an additional 75mg or 150mg of caffeine to reduce the perception of effort when running is at its hardest (4), usually during the final hour of a marathon. Your Rock 'n' Roll marathon fueling plan:

Your hydration strategy on course should be designed with the goal of preventing greater than 2-3% body mass loss through fluid losses (6). As we sweat we lose both fluids and electrolytes, to maintain performance we need to replace both during the race. Sodium is the most important electrolyte as it helps to stimulate thirst, improve fluid palatability and promote fluid absorption and retention (5). As a general recommendation aim for 500ml of fluid per hour, then drink to thirst in addition to this. Fluids should include a sodium content of 30mmol/L, in line with fluid ingestion recommendations during exercise (7).

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Hard marathon racing depletes muscle glycogen stores, causes muscle damage and results in fluid loss. Your recovery nutrition should therefore focus on energy, muscle repair and rehydration. Consider these areas for your Rock and Roll marathon recovery:

Refuel and Repair
The capacity of your muscles to absorb and store nutrients is increased after exercise (8), so it is important to replace carbohydrates and provide protein and electrolytes within at least 30 minutes of finishing. This can be done with “real food” options; however, this is not always possible or palatable immediately after a marathon. 

Take on a full carbohydrate based meal (e.g. pasta, rice, potato, breads) within 1 hour of finishing the marathon. This should also include a source of protein (e.g. chicken, fish) and plenty of vegetables.

To ensure that you are fully recovered from the marathon, aim to replace 150% of the fluid volume lost through sweating (9). Consume this fluid in the hours post-event.


  1. Vist, G. E., & Maughan, R. J. (1995). The effect of osmolality and carbohydrate content on the rate of gastric emptying of liquids in man. The Journal of Physiology, 486(2), 523.
  2. Burke, L. M., Hawley, J. A., Wong, S. H. S., & Jeukendrup, A. E. (2011). Carbohydrates for training and competition. Journal of Sport Sciences, 29(sup1), S17-S27
  3. Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the academy of nutrition and dietetics, dietitians of canada, and the american college of sports medicine: Nutrition and athletic performance. Journal of the Academy of Nutrition and Dietetics116(3), 501-528.
  4. Killen, L. G., Green, J. M., O’Neal, E. K., McIntosh, J. R., Hornsby, J., & Coates, T. E. (2013). Effects of caffeine on session ratings of perceived exertion. European Journal of Applied Physiology, 113(3), 721-727.
  5. Stachenfeld, N. S. (2014). Sodium Ingestion, Thirst and Drinking During Endurance Exercise. Sports Science Exchange, 27(122), 1-5.
  6. Armstrong, L. E., Herrera Soto, J. A., Hacker Jr, F. T., Casa, D. J., Kavouras, S. A., & Maresh, C. M. (1998). Urinary indices during dehydration, exercise, and rehydration. International Journal of Sport Nutrition8(4), 345-355.
  7. Coyle, E. F. (2004). Fluid and fuel intake during exercise. Journal of Sports Sciences, 22(6), 39-55.
  8. Phillips, S. M., & Van Loon, L. J. (2011). Dietary protein for athletes: from requirements to optimum adaptation. Journal of Sports Sciences29(1), 29-38.
  9. Baker, L. B., & Jeukendrup, A. E. (2014). Optimal composition of fluid‐replacement beverages. Comprehensive Physiology, 4, 575-630.
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