120 g of Carbohydrates per Hour for Maximum Performance – What’s the Truth?
Some manufacturers and athletes claim that consuming up to 120 g of carbohydrates per hour is necessary for peak endurance performance. But what does science say?
How many carbohydrates should I consume during exercise?
Your small intestine has a system for processing glucose (grape sugar) and another for fructose (fruit sugar). By consuming both sugars simultaneously, you can process a maximum of 1.5 - 1.7 g of carbohydrates per kilogram of body weight per hour. These systems depend on salt, which we will discuss later.
For example:
A 60 kg person can likely absorb 90-102 g of carbohydrates per hour. If you only consume pure glucose, the absorption rate drops to 1 - 1.2 g of carbohydrates per kilogram of body weight, resulting in about 60-72 g per hour. This is especially important for those with fructose intolerance.
The weight reference usually pertains to an average body type. A bodybuilder won’t process more sugar just because he has more muscle mass, as the critical organ, the small intestine, does not grow with increased muscle mass.
Conclusion:
This calculation shows that scientifically, the “more is better” advertising claims are often misleading. Consuming too many carbohydrates, especially in the form of sugar, can lead to stomach issues because your stomach may reject the excess.
Are you an ultra-runner? Consider this:
The ISSN (International Society of Sports Nutrition) guidelines for ultra-marathon runners recommend a realistic goal of 30-50 g of carbohydrates per hour during the run. This could be, for example, one gel with about 30 g combined with savoury foods like our veggie purees. This prevents you from getting tired of sweet gels after 4 hours and provides continuous energy while avoiding sugar peaks.
If your body responds well, you can gradually increase the amount. If you manage to consume even 60 g of carbohydrates per hour, you’re doing well. If you aim to compete for first place and push your limits, you should train to consume even more carbohydrates, as higher intensity demands more. But always keep your physical limits in mind – too much can backfire and end your run prematurely.
Training Tip:
Imagine starting a run with a full stomach and deliberately consuming excess carbohydrates during training. Doesn’t sound appealing? Believe me, you’re in good company. In an interview, a pro mentioned intentionally overeating during training so that his gut handles a smaller amount better during the race.
Electrolytes and Fluids: Important for Performance and Digestion
Did you know that on average, we lose 800 ml of sweat per hour during exercise, and symptoms of dehydration can start appearing with more than 2% fluid loss relative to your body weight?
The range of fluid loss usually varies from 0.4-1.8 litres per hour. Therefore, the ISSN recommends drinking 450-750 ml per hour or 150-250 ml of fluid every 20 minutes. For those who sweat particularly heavily, even this may be too little. It’s further recommended that fluids contain 500-700 mg/l of sodium in hot weather, as sodium regulates fluid balance. This corresponds to about 1000-2000 mg of table salt (sodium chloride), which is broken down into sodium in the body.
What does this mean for your training?
General statements can be dangerous. Both too little and too much drinking can be problematic. To determine how much fluid you lose, there is a very simple test. Weigh yourself naked before and after about an hour of activity. If you don’t drink during that time, you can calculate your hourly fluid loss. Repeat this on days with different weather conditions to better understand your range. Once determined, avoid drinking more than this amount per hour.
Unfortunately, sodium loss isn’t as easy to measure as fluid loss. This can only be determined by a doctor or in a lab. Hence, the recommendation is to start with a small pinch of electrolytes, preferably in the form of a capsule. This allows you to precisely control your sodium intake. The amount of sodium should generally never exceed 900 mg per litre. This corresponds to the well-known saline solution used in medicine, which the body can process well. If you can manage with less, that’s great. So start with small amounts and only increase if you still experience cramps, nausea, or dizziness.
Bringing it all together:
To transfer energy from food into your cells for energy production, you also need salt. Some stomach issues are due to too little salt for digestion. Sodium is needed to transfer energy into the cells.
So, train your nutrition and fluid intake including electrolytes just as you train your muscles, and you’ll enjoy more success and fun in sports.
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