How Many Carbs Do You Need Per Hour?

Today's #TheWerk post is brought to you by Dana Eshelman. Dana is a Board Certified Sports Dietitian (CSSD) and a USAT level I certified coach. Dana resides in Washington, UT, having recently relocated there from Boulder, CO. Learn more about Dana and her practice (A Dash of Dana) by going to A Dash of Dana or following her on Instagram at @a.dash.of.dana.

-----------------------------

Carbohydrates have hit the center stage in endurance sports. Some endurance athletes are aiming to hit 90+ grams of carbs per hour of training or racing. But, is this the right approach for everyone? Do you need to be pushing the needle on your carbohydrate intake? How much carbohydrate do you actually need? Is more carbohydrate better?

The answer: IT DEPENDS.

It depends on the duration of activity. It depends on your performance goals. It depends on if you are entering that session with low energy availability or well fueled (I hope the later). It depends on your performance level/ fitness. Let’s talk about it! 

Importance of carbs

It is well known that carbohydrates are necessary for you to reach your peak performance potential. But, there is a lot of confusion with numerous sports nutrition products on the market with different serving sizes and it makes it really confusing for you, the consumer. 

What to focus on:

1. How many grams of carbohydrate you will need per hour - this will depend on duration and intensity of activity
2. The type of product you will use to get your carbohydrate - gels, chews, drink mixes, whole food, etc.
3. The source of the carbohydrate you are consuming - glucose, maltodextrin, cluster dextrin, fructose

Glycogen (carbohydrate stored in your muscles and liver) supports 90-120 minutes of exercise with fat being used as a secondary resource. I like to think of fat as what you use in the background. Fat will not help you be able to sustain a high output over a long period of time. You need to be ingesting carbohydrates to prevent yourself from “bonking” or “hitting the wall”.

Carb Utilization

There is a direct relationship between the duration of activity, carbohydrate needs and performance. Meaning, the higher level of output you have (i.e. watts, pace), the more carbohydrates you are using (carb oxidation), therefore the more carbohydrates you need to be consuming to maintain the same level of performance. This is especially important in exercise lasting more than 2 hours.

It is also important to note that the harder the session, the more carbohydrate you will use (carbohydrate oxidation) and the less fat you will use as fuel. This is called the crossover concept or metabolic efficiency point.

Training lasting less than an hour

If you are going into this session with some carbohydrate on board (please eat before your training) then you do not necessarily need to bring along carbohydrates for this session. Exercise lasting 1 hour or less will not deplete your carbohydrate stores, so you do not need to replenish carbs. However, there is evidence that suggest swishing a 6% carbohydrate solution such as Skratch hydration or gatorade in your mouth for 5 to 10 seconds and spitting it out can reduce the rate of perceived exertion and increase total distance covered for all out efforts (ie. a time trial).

Think about those short, spicy sessions that are threshold and above where you are breathing heavily and swallowing food/ liquids is tough. This is where swishing that carbohydrate drink mix (ie. Skratch hydration) for 5-10 seconds can be beneficial. This has been seen to improve performance by up to 3%.

Training lasting 1 to 2 hours

As the duration of exercise increases, so do your carbohydrate needs. In this window, 30-60 grams of carbs per hour is appropriate. The harder the effort and the longer the duration you are exercising, the closer you will fall in the 60 grams of carbs per hour. This is because carbohydrate oxidation increases as your intensity increases.

30-60 grams of carbs per hour will look like:

• 500 ml Skratch hydration (amount: 21 g carb, type: drink mix, source: cane sugar and dextrose)
• 1 Cranks Sports E-Gel (amount: 37 g carb, type: gel, source: maltodextrin and fructose )

Another important piece of the puzzle is your fitness level. As you gain fitness, you are able to sustain higher workloads (i.e. more watts, faster pace) near your threshold for longer periods of time. This means that you are utilizing carbs at a faster rate and will, again, fall at the top end of this range of carbohydrate needs per hour.

Training lasting over 2 hours

Research supports 60 to 90 grams of carbohydrates per hour for exercise over 2 hours. As you increase your carbohydrate intake per hour, you may find that you are experiencing gut distress - nausea, diarrhea, sloshy belly, vomiting. This high dosing of carbohydrates does take gut training to build tolerance, so do not be discouraged if adding in more carbs does not feel great on the first go. Give yourself about 4 weeks for your stomach to adjust.

As you are taking in more carbs and the duration of exercise increases, the focus points of source of carbohydrate and type of carbohydrate come into play. First, we want to look at having multiple transportable carbohydrates (MTCs). The most common MTCs ratios in sports nutrition products are 0.8 fructose to 1 glucose or 1 fructose to 2 glucose. This encourages maximal absorption in the small intestine which will eliminate the aforementioned GI issues.

Example of 60-90 grams of carbs per hour:

• Gu Roctane drink mix (amount: 59 g carb, type: drink mix, source: maltodextrin and fructose)
• 1 Precision Fuel & Hydration gel (amount: 30 g carb, type: gel, source: maltodextrin and fructose)

For exercise lasting under 6 hours, I recommend utilizing sports nutrition products as these are highly digestible when you are working at higher intensity. As you get into exercise lasting 6+ hours, this is considered ultra endurance. The type of carbohydrate is what you will take into consideration next. Increasing the duration means the intensity of your exercise will decrease and you will be able to add in more whole food options. That means you are now looking at consuming some fat and protein in addition to carbohydrates. This is beyond the scope of this article, but I have more information on ultra endurance fueling here.

Takeaways

In my experience, I find more athletes to not be consuming enough carbohydrate per hour. If this is true for you, start training your gut and building tolerance to that 60+ grams of carbs per hour to ensure you are supporting the work you are asking your body to do. This will play a huge role in your ability to perform, your recovery, and your adaptation to training.

If you are consuming adequate carbs and are curious about the emerging research on elite athletes consuming 90+ grams of carbs/ hour, we have more research to do here to prove its necessity in amateur athletes. A meta-analysis found that the greatest performance benefit was seen with carbohydrate intake of 68 to 88 grams carb per hour. When you are consuming more than your gastrointestinal tract can transport per hour, that carbohydrate ends up sitting in the gut (aka gut rot). This is where you see higher incidences of gut issues especially in ultra endurance events. Let’s stick to science. More is not necessarily better.

-----------------------------

If interested to learn more, please contact Dana care of dana@adashofdana.us. Rest assured, Dana takes a holistic approach to nutrition: it is about supporting the complex systems that make up your body and listening to what your body needs so you can take on all that you ask your body to achieve. Dana uses her personal experience as a runner and triathlete as well as her experience in helping hundreds of athletes fuel fiercely so they can reach peak performance in both life and sport!