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Nutrition tips for marathon running

Nutrition tips for marathon running

Unlock marathon success with top nutrition tips for pre, during, & post-race. Fuel your run to the finish line!

Unlock marathon success with top nutrition tips for pre, during, & post-race. Fuel your run to the finish line!

Christophe Roosen

Christophe Roosen is the co-founder and coach of Trenara. Runs a marathon in 2:31:34.

Nutrition is key when it comes to maximizing race-day performance. Let me guide you through some nutritional topics, based on expert advice and my own personal experience with that scientific advice.

  1. Nutrition (the week) Before the Marathon

Preparing your body for a marathon begins looong before you hit that starting line. It's not just about the miles you log but also about how you fuel them. I’m a big fan of the Science of Sport Podcast and listened very carefully to their episode about ‘The Science of Nutrition in Sport’. Prof. Graeme Close has a clear advice: “fuel for the work required”. Eating is the only way to create energy (read: produce ATP) inside your body. But writing about how to eat during your 12-week training plan, would bring us too far. Maybe another time.

Proper nutrition is your ‘secret’ weapon for energy, endurance, but also recovery. Let's dive into the strategies that will prime your body for peak race-day performance.

Carbohydrate Loading: Maximizing Energy Stores

Carbohydrate loading is a strategy used by runners to maximize the storage of glycogen (=energy source) in the muscles and liver. It’s like ensuring you’ll start with a full battery.

The latest science around nutrition suggests to up your carb intake starting 3 days before the marathon. There’s no need to deplete your glycogen stores, which was popular in the eighties and nineties.

  • Day 1: up to 7-8 grams of carbs per kilogram bodyweight

  • Day 2: up to 8-10 grams of carbs per kilogram bodyweight

  • Day 3 – the day before your race: up to 6-8 grams of carbs per kilogram bodyweight

  • Marathon day breakfast: 3-4 grams of carbs per kilogram bodyweight

For example: I’m at 68,5kg, so on day 2 I’m aiming at 685 grams of carbs at max and at least 548 grams.
And while my advice would be to opt for complex carbs during the year, here I’d suggest to go for the ‘white’, simple variants: white bread, pasta and rice. Easy digestible, less fibers. Also: these carbs should replace fats and proteins. You should not add those extra carbs on top of your normal diet, that's an important note that Asker Jeukendrup underlines.

Glycogen (thus carbs, thus sugars) are the most optimal form for energy production for your body, when maximizing performance is your focus. Hitting the wall, a well-known term in marathon running, describes how it feels when your body runs out of glycogen. From then on, you need fats to produce energy and fats aren’t as energy-rich as carbs, thus forcing you to run (much) slower.

Balanced Meals: Building a Nutrient-Rich Foundation

While carbs are in the spotlight in that specific 3-day period before your marathon day, a balanced diet is key during the rest of the year. Ensure each meal includes a good balance of carbohydrates, proteins, and fats. Proteins aid in repair and recovery, while fats provide long-term energy.

Hydration Strategies: Fine-Tuning Fluid Intake

Hydration is a delicate balance critical to optimal performance and health. Scientific research suggests that while it's essential to stay hydrated, overhydration (or hyponatremia) can be as detrimental as dehydration, especially for endurance athletes. The key is to drink according to thirst, not exceeding it, to avoid both as well dehydration as overhydration.

  • The Science of Thirst: Thirst is a reliable indicator of your body's need for fluids. Several studies indicate that the body's natural thirst mechanisms are adequately equipped to guide fluid intake during exercise. This approach prevents both dehydration and the risk of hyponatremia, a condition caused by low sodium levels from excessive water intake (which can be deadly!).

  • Pre-Marathon Hydration: In the days leading up to the marathon, aim for a consistent intake of fluids that keeps your urine light yellow, often a sign of proper hydration. This doesn't mean overdoing water consumption but rather increasing it slightly to ensure hydration levels are optimal. This is especially important for marathon runners, as starting a race even slightly dehydrated can impact performance and increase the risk of heat-related illnesses.
    Include beverages like electrolyte solutions (like Oral Rehydration Solutions, ORS in short, type of drinks designed to quickly replace fluids and salts lost during exercise) that help maintain a balance of fluids and electrolytes, certainly in hot weather conditions. Your body/muscles need(s) salt to function well.

  • Remember that you will put on some weight during that last couple of days before the marathons: each gram of carbs is stored with 3 to 4 grams of water. And while the additional water weight might seem like a drawback, it's actually beneficial for us marathon runners in the context of energy availability and hydration. The benefits of having accessible energy and being well-hydrated far outweigh the temporary increase in weight.

When I talk about my marathon weight, I refer to my bodyweight of the morning on the first day of carb loading.

Avoiding New Foods: Stick to What You Know

The days leading up to the marathon are not the time for dietary experiments. Stick to meals and ingredients that you know your stomach ‘loves’. Introducing new foods can result in unexpected digestive issues on race day. That’s why I’ve grown my own pre-race rituals for the Valencia Marathon: each year I visit the same (Italian) restaurants, eat the same French bread and jam, … Having that fixed ritual also comforts me.

  1. Nutrition During the Marathon

Fueling during a marathon isn't just about preventing hunger - I can guarantee you: when you’re hungry, it’s already too little too late! It's about maintaining energy levels and supporting your body's physiological needs, so you can, ultimately, cross the finish line with a strong performance. The right nutrition strategy during the race can make a significant difference in not only results but also your experience of it! Let's explore how to keep your body energized and properly fueled from start to finish.

Hydration: Listening to Your Body's Cues

As told before: listen to your body. Thirst is an indicator that your body needs fluids, but don't wait until you're parched. Study at what points the aid station will be placed on the course. Check if they’ll offer water in cups or small bottles – it really makes a difference, because drinking from a cup needs some practice.

Energy Gels and Chews: Timing is Everything

Energy gels, chews, and other quick-absorbing carbohydrate sources are crucial. They're designed to give you a quick energy boost without weighing down your digestive system. Lately, over the past couple of years, science suggests that you might aim for more than 60gr of carbs per hour to fuel your performance. 90gr, and in cycling/triathlon even 120gr, aren’t a rare sight anymore.

You have to test this beforehand. Know that 60gr per hour can be reached via a 2:1 glucose:fructose ratio, but that glucose digestion is limited. When you want to go 90gr, you have to opt for a 1:0,8 ratio.
When it comes to timing (and you’re aiming at 60gr): when you have a gel that offers 24gr of carbs, you should aim at taking one gel per 20 minutes. Not three at once – seems only logical, but this way I’m sure you guys and girls know what my advice is.
My last couple of gels (1 or 2), again as per expert advice, contain some caffeine to boost the mental game as well. 

We’ve talked about this in our The Running Crew podcast, Dutch only, and got a valid remark from our listener, Gerrit. While we support taking fructose during certain longer training sessions and races, fructose will raise triglycerides levels in your blood and may contribute to fatty liver disease.
Again: fuel for the work required. The carbs you need for marathon running, are not needed for a 5k race or a recovery run.

Electrolyte Balance: More Than Just Water

Sweating isn't just about losing water; it's also about losing electrolytes, which are crucial for muscle function and hydration. Incorporate electrolyte replacements into your race plan, either through drinks or gels. This will help you avoid cramps and maintain your performance throughout the race.

Practical Tips for Race Day Nutrition

As I often suggest in the training descriptions during the 12-week training plan: practice your nutrition strategy during your long training runs to ensure there are no surprises on race day. I myself aim to be always self-sufficient when it comes to energizing my race: I carry all my gels myself. Missing an energy-rich drinking solution or gel from a supporter can have a huge impact.

Remember, the goal is to maintain energy levels and hydration without overloading your digestive system. Smaller, but frequent sips are preferable to consuming large amounts at once. Fueling during the marathon is a critical component of your race strategy. By planning your hydration and energy intake, experimenting with different products during training, and listening to your body's signals, you'll be well-equipped to tackle the physical and mental challenges of the marathon.

  1. Nutrition After the Marathon

The race against recovery begins the moment you cross that line. Proper post-race nutrition is essential. Not just for recovery but also for maximizing the benefits of your hard-earned effort. Here’s how to refuel and repair your body after the marathon.

Immediate Post-Race Nutrition: The 30-Minute Window

The first 30 minutes after finishing are critical for recovery – although I’ve heard in a Fast Talk Labs podcast that it isn’t as crucial for men as for women.

Your muscles are primed to replenish glycogen stores and start repairing muscle damage, making it the perfect time to consume a mix of carbohydrates and protein. This isn't just about replenishing what you've lost; it's about seizing a window of opportunity for optimal recovery.

After Valencia 2023, Loes, my girlfriend, had some protein bars with her. But my jaws were that cramped that I couldn’t eat them. I’ll go for a shake next time.

Rehydration: Restoring Fluid Balance

Replacing lost fluids is your first priority post-race, but remember to sip slowly to give your body time to absorb the fluids effectively. Water is essential, but drinks that include electrolytes, especially sodium and potassium, can help restore the electrolyte balance disrupted by hours of sweating. Again: the color of your urine is a good indicator of your hydration status; aim for pale yellow 🎨

Recovery Meals: The Next 24 Hours and Longer-Term

Your post-race meal should continue the recovery process with a balanced mix of carbohydrates, proteins, and fats. Whole foods are your best bet: a lean protein source, complex carbs, and fats. These meals support muscle repair, inflammation reduction, and replenishment of glycogen stores.
But: don’t forget to treat yourself. You’ve also earned that cake and/or ice cream.

Listening to Your Body

Appetite may fluctuate in the days following a marathon. It’s normal to feel ravenous or have little appetite at all. Listen to your body and eat according to hunger cues, focusing on nutrient-dense foods to support recovery.

Staying Hydrated

Continue to prioritize hydration as your body recovers. Water supports every metabolic function and nutrient transfer in the body and is essential for efficient recovery.

The marathon may be over, but your recovery is just beginning. By following these nutrition strategies after your race, you support your body's recovery process, laying the foundation for your next training cycle or race. Remember, recovery is as crucial to your body and performance as the training itself. Treat it with the same respect.

To conclude

That’s it! Hope you’ve found this a useful read. As I wrote at the beginning of the post: nutrition is key to maximizing your race-day performance. You’ll need a conscious approach to tackle this topic and make room for trial and error during the preparation phase.
Last Monday I ran my first ultra (58k) and during 2,5 to 3 hours I was able to digest 90gr of carbs per hour. But after 3 hours, I found it difficult to take gels at the same intervals. But it’s a first step in ‘training the gut’.

Share your thoughts on our socials. How do you prepare for fueling your marathon?
And for those who got to the bottom of this post: should we incorporate some nutritional advice in the app as well?Let us know on Instagram.

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