The role of carbohydrates in endurance sports

The role of carbohydrates in endurance sports

The speed read: Why carbs matter and how much you should take in

Carbs are energy and during training and especially competition, your body requires fuel to perform at its maximum. The state of science on carbohydrate intake during endurance sports emphasises the importance of both quantity and type of carbohydrates consumed. The science has shifted over the last 10 days from recommending a maximum of 60 grams/hour to 90 grams/hour to 120 grams per hour [7]. With some anecdotal evidence of fuelling stratergies of 150 grams/hour working for individuals. Along with the quantity of carbohydrates, there are two other considerations. Firstly the combination of glucose and fructose in ratios such as 2:1. I prefer rather 1:0.8 for even higher performance supported by more recent scientific studies but also my personal experience. The ideal ratio for you is of course dependent on individual needs and the intensity of the exercise. Secondly, what else is added to the product? In my experience each extra ingredient increases the risk of GI distress. A tailored approach will significantly enhance your performance by optimising energy availability while minimising gastrointestinal issues.

The starting point: What carbohydrates are and why we need them

Carbohydrates are one of the three macronutrients, along with proteins and fats, that provide energy for your body. They are organic compounds made up of carbon, hydrogen, and oxygen, and come in three main types:

  • Sugars: Simple carbs like glucose, fructose, and sucrose, found in fruits, honey, and table sugar.
  • Starches: Complex carbs found in grains, potatoes, and legumes.
  • Fibre: A form of complex carbs that aids digestion but isn't digested into energy directly.

When consumed, carbs are broken down into glucose (a simple sugar), which is absorbed into the bloodstream and used as energy by cells. Glucose is also stored as glycogen in the liver and muscles, where it can be rapidly converted back to glucose when the body needs quick energy.

Why endurance athletes need carbohydrates:

  • Primary Energy Source: Carbohydrates are your body's preferred and most efficient source of energy during high-intensity exercise. During endurance activities the body burns through its glycogen stores to fuel muscle activity.
  • Sustains Performance: During prolonged exercise, glycogen levels deplete over time, leading to fatigue. Eating carbohydrates during training or competition helps delay this, allowing you to maintain a higher intensity for longer.
  • Rapid Energy Supply: Simple carbohydrates, especially those found in sports drinks, gels, and fruits, are absorbed quickly, providing a fast source of energy during competition or long training sessions.
  • Spares Protein and Fat Metabolism: When enough carbs are available, your body uses them first, sparing protein (which is needed for muscle repair) and fat (which provides slower, less efficient energy) from being used for fuel.

In sum…

  • Carbs delay Fatigue: Carbohydrates help prevent early exhaustion by providing readily available energy.
  • Carbs support Recovery: Post-exercise, carbs help restore your depleted glycogen stores, which is critical for your recovery and readiness for the next session.
  • Most importantly - Carbs enhance your performance: Studies show that athletes who maintain high levels of glycogen perform better in long-distance and endurance sports.

The issue: Why it matters how much you take and how to find the your personal optimum

The absorption of carbohydrates is facilitated by specific transport proteins in the intestine. SGLT-1 transports glucose, while GLUT5 is responsible for fructose absorption. When glucose intake exceeds approximately 60 grams per hour, the SGLT-1 transporter becomes saturated, which can lead to gastrointestinal discomfort if additional carbohydrates remain unabsorbed in the intestine[1][4]. To mitigate this risk and enhance overall carbohydrate utilisation, combining glucose with fructose in the right ratio allows athletes to exceed the traditional absorption limits without experiencing adverse effects[4]. Another important factor for digestibility is of course the pureness and quality of the carbs. Only the really needed ingredients should be in your gel or powder and these should be all natural and tested ingredients.

Now, if you need a low carb (e.g. 30g) or high carb (e.g. 90g plus) per hour intake depends on a series of personal factors, the environment you are training or competing in (e.g. its temperature and humidity). You can define your optimal carb amount (and the amount of additional electrolytes) through our customisation calculator at www.pureformance.com/customize

The ‘so what’: my recommendations on carb intake for your training and race

If you are a hobby athlete that is not competing seriously, honestly you can forget about all the expensive pro stuff. If you just run a 15k race of a half-marathon, eat a banana for each half-an-hour of exercise. A banana? Yes, an average banana will provide you (on top of many other useful things like vitamin C, B and others, calcium and magnesium) with 25-30 grams of carbs.

Now, if you are more ambitious and really want to maximise performance the ideal dosage matters - and believe me, it matters a lot!

Endurance athletes have long recognised the importance of carbohydrates for optimal performance. Recent research has refined our understanding of how to maximise carbohydrate intake during endurance activities, particularly focusing on the types and ratios of carbohydrates consumed.

Carbohydrate requirements during exercise

The general recommendations:

  • Athletes are generally advised to consume between 60 to 90 grams of carbohydrates per hour during prolonged exercise. But this can be sometimes also just 30 grams, depending on your environment and even be increased to up to 120 grams plus per hour for highly trained individuals or during very intense efforts[2][5].

Glycogen loading:

  • In the days leading up to an event, athletes may engage in glycogen loading, consuming 10 to 12 grams per kilogram of body mass per day for 36 to 48 hours prior to competition. This practice aims to maximise muscle glycogen stores, enhancing endurance capacity[2].

Optimal carbohydrate r and glucose and fructose combination:

  • Research indicates that combining glucose and fructose can enhance carbohydrate absorption and oxidation rates compared to glucose alone. The optimal ratio has been debated, with findings suggesting two primary ratios:
    • 2:1 Glucose:Fructose: This ratio has been traditionally recommended as it allows for higher carbohydrate delivery (up to 40% more) to working muscles than glucose alone[4].
    • 1:0.8 Glucose:Fructose: My personal experience but also more recent studies suggest that this ratio may be slightly more effective for achieving high exogenous carbohydrate oxidation rates, particularly at higher intakes during exercise[1][2].

Why release delay of carbohydrates is so important in our view:

After having worked with Nigel Mitchell, in my view one of the world’s leading sports food scientists, we think we have cracked the code how to ensure that the carbs are entering your bloodstream in a more homogenous way and not in spiky tranches. After many runs and personal trials we have managed to find an optimal combination of glucose and fructose delivery. By combining different forms of glucose polysaccharides with fructose we think we have the optimal balance between digestibility and carb release.

Source: 

[1] MNSTRY Know-how. The Optimal Carbohydrate Ratio – Does It Exist? Available at: https://know-how.mnstry.com/en/the-optimal-carbohydrate-ratio-does-it-exist/

[2] Gatorade Sports Science Institute. Dietary Carbohydrate and the Endurance Athlete: Contemporary Perspectives. Available at: https://www.gssiweb.org/sports-science-exchange/article/dietary-carbohydrate-and-the-endurance-athlete-contemporary-perspectives

[3] Luan, D. et al. A Comparative Observational Study of Carbohydrate Intake and Endurance Performance. Scientific Reports, 2023. Available at: https://www.nature.com/articles/s41598-023-51048-6

[4] TORQ Ltd. Understanding Glucose:Fructose Ratios. Available at: https://www.torqfitness.co.uk/news/understanding-glucose-fructose-ratios

[5] Ambishious. How Endurance Athletes Can Use Carbs to Boost Performance. Available at: https://ambishious.co.nz/carbohydrates/

[6] Jeukendrup, A. The Optimal Ratio of Carbohydrates. Mysportscience. Available at: https://www.mysportscience.com/post/the-optimal-ratio-of-carbohydrates

[7] Urdampilleta, A. et al. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners. Nutrients, 2020, 12(5), 1367. Available at: https://www.mdpi.com/2072-6643/12/5/1367

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