How to Fuel on Long Runs

Long runs are a staple in almost every run training plan. As most runners know, long runs are not just about running for a long time. How you fuel on long runs contributes to how well they go – and how good you feel running longer distances in marathon and half marathon training

How to Fuel on Long Runs

Why Should I Fuel on Long Runs?

When running at a submaximal pace, your body uses aerobic metabolism to produce energy. Aerobic metabolism relies on oxygen, carbohydrates, and lipids (fats). You get oxygen from breathing. Your body has robust fat stores, but these only account for a fraction of aerobic metabolism. A majority of the energy comes from carbohydrates, which are not easily stored. 

Assuming you ate prior to your run (and here’s why you want to do that!), your body will likely have enough glycogen stored for 1.5 to 2 hours of exercise at a moderate intensity. You want to start supplying your body with easily available carbohydrates before it depletes those glycogen stores. You will have more energy, avoid that dreaded bonk, and perform better when you take in carbohydrates during runs longer than 1.5 hours in duration. 

Other benefits of long fueling include:

  • Quicker recovery
  • Less muscle breakdown
  • Better within-day energy availability and hormonal regulation
  • Lower risk of injury

How Much Fuel Should I Take?

According to a 2019 journal article in the International Journal of Sport Nutrition and Exercise Metabolism, the recommended intake during runs longer than 90 minutes in duration is 30-60 grams of carbohydrate per hour – with some athletes needing up to 90g/hour. That’s roughly two to three gels per hour (although you don’t have to use gels!). 

The longer the run, the more vital it is to take in adequate fuel. So, 30 grams of carbs per hour may be fine on a 1.5-2 hours, but you may higher amounts per hour as runs exceed 2.5 hours. 

During higher intensity long runs (such as long runs with marathon pace segments), you may find you need more fuel. The higher the intensity, the more carbohydrates your body utilizes for energy production. 

How Much Does Fueling Impact Performance?

Significantly! A 2014 study published in the International Journal of Sports Nutrition and Exercise Metabolism compared runners who fueled freely during the Copenhagen Marathon with those who consumed 60g of carbs per hour. The runners were of equivalent fitness, yet those who fueled with 60 g of carbs per hour completed the marathon an average of 11 minutes faster. 

Of course, you aren’t aiming for PRs in your normal weekly long run. However, fueling on your long run can help you finish with confidence – and that confidence builds throughout training.  

Gut Training Can Help

You may be thinking that 30-60 grams of carbs per hour sounds like a lot. You do not have to start there! Gut training is the theory that you can teach your stomach to handle more fuel during runs. Your stomach is a muscle and can be trained! Begin with what you can handle, then gradually introduce more over time. 

Don’t Forget Fluids & Electrolytes

Replenishing fluids and electrolytes is vital on long runs! Amongst other reasons, dehydration increases GI upset, so you want to minimize dehydration. For more on electrolytes on long runs, reference this article.

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What’s your preferred long run fuel?

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6 Responses

  1. 30-60 grams of carbs per hour does sound like a lot. If I think back to my recent trail race, I don’t think I fueled that much.
    I have a long run on Saturday and I will have a closer look at exactly how many carbs I eat. Thanks for this, Laura!

  2. As my long runs have been getting longer I’ve been trying to take a little more fuel during my runs. I tend to take the lower end of the recommended amount (30 g/hr) so I need to get that up a little. I also want to experiment with some different kinds of fuel. I’ve been using Science in Sport which has worked pretty well, and sometimes Honey Stinger gels.

  3. Fueling has always been a challenge for me, mostly because of GI issues. When I found Tailwind, I was pretty happy, but during some of my longer races, I developed nausea. I have yet to find the perfect fuel!

  4. Fueling can be really challenging. For longer, slower runs I tend to be good for up to 90 min as you mention. When I know I am going longer, I start fueling at 4-5 miles. It definitely takes lots of trial and error to find you sweet spot

  5. Sounds like I might need to increase my fueling. I don’t think I get quite as much as I need. I’m so glad you shared this!

  6. Lately I’ve been experimenting with fuel that has a little more protein/fat than gels and drinks. I have issues with my sugar dropping, including lightheadedness sometimes, and I’m finding success by adding a few almonds or by making my own gels using dates, chia, and some nuts.

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