We are frequently asked some variation of this question by people we coach and friends we train with: “What should I eat?”
Indeed, nutrition before, during and after racing is an important pre-occupation for many runners and triathletes. I suppose that is so because nutrition is so darn tricky–and it can ultimately lead you to your best performance or throw your day off the ledge. To make matters trickier: what works for one person may or may not work for another, so there isn’t a simple formula we can all follow.
But, don’t throw up your lunch just yet! There are some general principles you can apply to help you find your race-day fueling sweet spot. I’ll share some of them here. Note: These tips are geared toward race-day fueling for long distance events: marathons, ultramarathons, and half and full ironmans.
It is important to note that proper race fueling requires good nutrition throughout training and in the days leading to the race. However, pre-race nutrition and “every day nutrition” are not considered in this article. (You can read about daily nutrition here.)
What’s inside of us already
Your body does NOT contain enough stored carbohydrates (via glycogen or glucose) to carry you through a marathon or beyond. At 80-90% of max intensity, we have about 2 hours worth of fuel stored in our muscles (glyocogen) and blood (glucose). But, for most athletes, performance will begin to decline before you get to that two hour mark—unless you restock.
And so was born the gel and sports drink industry.
So, it should be easy right? Just eat a gel, grab some aid station cookies and pretzels, drink some fluids and be on our merry way. Ha! Ha! Not quite so fast, you epicurean daredevil, you!
If you’ve been at this long enough, you’ve likely had at least one nutritional mishap–more likely, you’ve had several. If you’ve ever felt apathetic, anxious, extremely fatigued and so on, you’ve “under” fueled. If you’ve ever experienced stomach cramps, bloating, or vomiting, you may have “over” fueled.
The trouble is that the human GI system is quite variable in terms of the amount and type of fuel it can handle. Some of us treat aid stations like an all you can eat buffet, eating whatever we like with little consequence. While others must carefully learn through trial and error what their stomach will and will not accept during racing. In addition to the individual variability, intensity, duration, climate, and race conditions can also switch up nutritional needs.
So, what to do? You have to train your digestive system just like the rest of your body. The stomach is very jealous of the attention that the heart and the muscles get. It just wants a little bit of love and attention – is that so wrong?
How much and what type of calories depends upon the duration and intensity of your race. Marathons and half ironmans are typically run at a higher intensity than ultra marathons or full ironmans. Therefore, how much you can eat, as well as the type of foods the body will be able to digest easily, will differ to some extent. No matter what the distance: endurance athletes need carbohydrates on race day. So, let’s start there.
In general, carbohydrates are the primary energy source for endurance athletes. Carbohydrates are such an excellent source for athletes because they can be easily broken down and used by our bodies – without the need for much oxygen, which is good because we are using oxygen for other important stuff in the middle of a race ;).
The body stores carbohydrates in the form of glycogen (muscles) and glucose (blood). Glycogen is the main source for endurance energy, while glucose is most useful for helping to keep our mental facilities sharp and for supplying quick bursts of energy (like when you want to pass that person in right front of you).
Athletes have a limited amount of stored carbohydrate energy, as I mentioned earlier. This is why proper recovery nutrition is so important: it ensures that you restock the used stores after each workout. This is also why many tout the benefits of pre-race carb loading: it ensures that those glycogen stores are filled to the top. And finally, this is why we must consume gels, chomps, sports drink and the like throughout our endurance endeavors. We will run out of energy if we don’t.
When some runners talk about hitting the wall, what they might really be referring to is hitting the end of their glycogen stores.
Knowing how much to restock depends, at least in part, on how much carbohydrate you can and need to digest, given the intensity and duration of your specific race. Studies have found that, on average, we can process about 1 gram of carbohydrate per minute, working at about 80% of max intensity. To put this number in perspective, sports gels contain about 30 grams of carbohydrates. Research has found that a minimum of 10 grams per hour is necessary to stave off the bonk.
The consumption of more carbohydrate and calories than the stomach can process will lead to GI issues because the stomach will not be able to process the calories and empty the stomach. The outcome? Bloating, cramps, vomiting and so on.
Additionally, 1 gram per minute is not a “magic” number for everyone. It’s an average, which means most people will need slightly less or slightly more. If you are a smaller female, it is likely you will need less; for a larger male, it is likely you will need more. It is important to note that these numbers are statistical averages and every individual body will need it’s own “sweet spot” of carbs.
How do you know what your sweet spot is? Experiment during training! Find what works and then do it every training session.
Our friend and nutritionist Chris Draper recommends adding and subtracting calorie amounts in small increments. I’ll use myself as an example. I am a 127 pound, 5’3” female. During an Ironman bike, I will consume approximately 300 calories per hour,