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If You Compete or Exercise for More than an Hour You Need a Nutritional Strategy

In prolonged exercise, athletes burn through considerable amounts of carbohydrates and fluids. If that nutrition is not replenished during the exercise period, performance diminishes.[1]

For instance, some research shows that dehydration of more than 2% of the body mass reduces physical and cognitive abilities.[2,3] That being said, one study evaluating the winners of city marathons found that these elite marathon runners routinely lose 2% to 3% of their body mass in competition.[4] This underscores the idea that general scientific evidence is important, but that nutritional strategies can be individualised, especially at the elite levels.

When Is Nutritional Strategy Most Important During Competition?

A common answer is “exercise lasting one hour or longer.” Research has established the fact that if fluid balance is not maintained during exercise lasting longer than one hour, it can lead to dehydration, increased body temperature, and impaired performance.[5]

How Much Fluid and Carbohydrates Should Be Consumed During Long Exercise?


How Much of a Difference Does This Nutritional Strategy Make?

There are two studies in which athletes following their normal routines were compared to athletes following nutritional strategy guidelines such as the ones above. In one study, cyclists reduced their 64 km times 6.3% following lab-based nutritional strategy guidelines.[7] In that study, each hour, cyclists consumed 60 g maltodextrin and glucose, 30 g of fructose, 0.5 g of sodium, and 0.05 g caffeine. In a separate study, marathon runners decreased their race times by nearly 11 minutes (4.7%) using this nutritional strategy. They had in-race intake of energy gels and water amounting to an hourly intake of 0.75 L of water, 60 g of maltodextrin and glucose, 0.06 g sodium, and 0.09 g of caffeine.

What About Stomach Upset?

  • Athletes should consume 0.4 to 0.8 litres of fluid per hour, depending on individual differences and environmental conditions.[2]
  • Studies recommend 60 g to 90 g of carbohydrates per hour. The higher end of that is for when a combination of glucose and fructose is consumed. [1,6]

tes avoid or minimize nutrition during competitions due to concerns about gastrointestinal symptoms. The study above comparing marathon runners additionally measured this between runners following the lab-based nutritional strategy or the personal, free-choice nutritional strategy. Certain runners experienced significant gastrointestinal symptoms, with or without the nutritional strategy above. The data is somewhat limited, but it looks like the lab-based nutritional strategy does not hurt or help in terms of gastrointestinal symptoms.    


  1. Jeukendrup AE. Nutrition for endurance sports: marathon, triathlon, and road cycling. Food, Nutrition and Sports Performance III. 2013 Aug 21:99-108.
  2. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise. 2007 Feb 1;39(2):377-90.
  3. Shirreffs SM, Sawka MN. Fluid and electrolyte needs for training, competition, and recovery. Journal of Sports Sciences. 2011 Jan 1;29(sup1):S39-46.
  4. Beis LY, Wright-Whyte M, Fudge B, Noakes T, Pitsiladis YP. Drinking behaviors of elite male runners during marathon competition. Clinical Journal of Sport Medicine. 2012 May 1;22(3):254-61.
  5. Montain SJ. Hydration recommendations for sport 2008. Current Sports Medicine Reports. 2008 Jul 1;7(4):187-92.
  6. Burke LM, Hawley JA, Wong SH, Jeukendrup AE. Carbohydrates for training and competition. Journal of Sports Sciences. 2011 Jan 1;29(sup1):S17-27.
  7. Hottenrott K, Hass E, Kraus M, Neumann G, Steiner M, Knechtle B. A scientific nutrition strategy improves time trial performance by≈ 6% when compared with a self-chosen nutrition strategy in trained cyclists: a randomized cross-over study. Applied Physiology, Nutrition, and Metabolism. 2012 Aug;37(4):637-45.

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