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10 Essential Facts About Race Nutrition You Should Know

I’ve been a triathlon coach since 2015 and in the sport since 2007. Many folks say that Nutrition is the 4th discipline of triathlon because it can make or break your race. I got to say that I agree with this. I’ve seen so many athletes start out strong, especially in iron distance races, then bonk during the run because their nutrition isn’t working.  Fine-tuning your nutrition strategy the right way can have a huge impact on your race day performance. Here are 10 essential facts about race nutrition you should know,  some of which might surprise even the most seasoned triathlete.


1. Overhydration Can Be Harmful

1.It's common to think that drinking tons of water before a race is beneficial. However, overhydration can lead to the loss of essential electrolytes resulting in hyponatremia, a serious and even deadly condition caused by an excess of total body water when compared to total body sodium content. Serious hyponatremia can cause seizures, coma and even death. Instead, drink normally add an extra glass of water with your meals. In the days leading up to the race, consider sodium preloading to boost blood plasma volume. Drinking 16 ounces of a strong electrolyte solution 90 minutes before the race start can help retain extra fluid in your bloodstream. This allows you to take in extra fluid, absorb it in the bloodstream through the gut along with extra sodium and hold it in the blood. This technique is good for racing in heat or athletes with high sweat rate or athletes who tend to cramp a lot.


2. Train Your Gut

Practicing your race nutrition during training is crucial. I tell my athletes to practice their nutrition for every single long ride and run. It's okay to fuel aggressively on carbs during key training sessions (slightly more than normal amounts) to train your gut to handle a higher volume of carbs. This practice allows you to reduce your carb intake slightly on race day without compromising your performance.


3. Listen to Your Body

Adjusting your fuel and hydration intake during a long course race is vital. Recognize signs that you may need to increase or decrease carbs, fluids, or sodium. For instance, cravings for sugar or lightheadedness indicate a need for more carbs, while feeling bloated or stomach upset suggests you should back off. Thirst, dry mouth, and a higher-than-normal heart rate signal a need for more fluids, whereas frequent urination, bloat, and peeing frequently might mean you need less.

Signs you may want to increase your sodium intake include cramping muscles and craving salt. Signs you may need to take in less sodium can be that salty food tastes “off”, you are craving plain water, you have dry cotton mouth, or you have an upset stomach. Some of these obviously overlap so the key is to practice, practice, practice, your nutrition and hydration often so you come to know what is normal.


4. Personalized Hydration Strategy

Your hydration needs are influenced by physiology, environment, and intensity. Measure your sweat rate to determine your fluid needs. A 2-4% loss of body weight due to dehydration is tolerable before performance starts to suffer. Seeing salt on your clothes, stinging eyes, low blood pressure when standing, and muscle cramps-these are all signs you are a salty sweater. Knowing your sweat numbers and sodium numbers can be a game changer for your performance. Consider a sweat sodium test to understand your sodium loss and adjust your electrolyte intake accordingly. Reach out to to get your sweat sodium test.


5. The Right Carbs Matter

For long-distance races, aim for 60-90 grams of carbs per hour. Use gels, chews, and sports drinks, but avoid relying solely on liquid carbs, especially for anything over a 2-hour effort. If you want to eat real food, make sure you tested it during training so you know how your body will react to it. (i.e. Snickers Bar) It’s important to know the amount of carbs per hour you need to take in, the kind of carbs, (gel, energy bar) and the source of carbs, such as fructose, glucose hydrogel, slow-release carb etc. The optimal glucose to fructose ratio is 2:1, which enhances carb absorption.


6. Fuel Early and Aggressively

Start fueling early on the bike to prevent muscle glycogen depletion, especially on a long course effort.  Front-loading carbs on the bike (adding extra during the bike leg) ensures you have energy stored for the run. Consuming more carbs early on allows you to run harder and sustain performance when it is harder to eat.

 7. Separate Carbs and Fluids

For short course races, you can put all your fueling in one bottle to include sports drink with carbs and electrolytes. For long-course races, it's better to separate your carb intake from your fluid intake. Use bottles for fluids and electrolytes and carry carbs in your pockets. This approach prevents overconsumption of sugars and helps avoid feeling sick and bloated.


8. Fueling for Shorter Distances

Even in Olympic and Sprint triathlons, fueling and hydration are crucial. You will want to drink to replace sweat loss and take in a certain amount of fluids if your carbs are coming from your drinks. Use a carbohydrate-electrolyte drink on the bike with sodium and supplementary gels as needed. Sodium is not a huge factor for Olympic distance unless heat is a factor. Front-loading on the bike is essential as it's easier to eat and drink while cycling than running. For Sprint races, it is the fueling and hydration you’ve done before the start that matters. Take a gel 15 minutes before the start of the swim and preload with a sports drink with sodium to top off your liquids. I always put a bottle on my bike during transition for the last 2 miles of the bike before I dismount to T2.


9. Carb Loading Before the Race

Effective carb loading occurs in the last 48 hours before the race. Your last meal’s purpose is to top off your liver glycogen. Reduce fat, protein, and fiber intake, and expect to gain a few pounds from the extra glycogen storage. This weight gain signifies successful carb loading and optimal glycogen stores. It’s ok to take in an additional boost of carbs 15 min before race start- like an energy gel. Fifteen min is a good time to get from your gut to your bloodstream.


10. Importance of Sodium

Sodium is the main electrolyte lost in sweat and is crucial for maintaining hydration and performance. Electrolytes are minerals that dissolve in your body fluids such as magnesium, potassium, sodium, calcium. Sodium is the predominant one and most important. Replacing adequate amounts of sodium goes hand in hand with how much fluid you need to replace and how much sodium you are losing in your sweat. Personalized sodium intake, based on sweat loss, ensures you replace the right amount of sodium along with fluids.



Mastering race nutrition involves more than just winging it; it requires strategic planning, practice, and listening to your body's needs. From sodium preloading to personalized hydration strategies, these insights can enhance your race day performance. Remember, nutrition is the fourth discipline, and getting it right is key to achieving your best results. Know your sweat and sodium numbers. Know how many grams of carbs you can tolerate per hour. Knowing these numbers matters and can help you optimize your performance and cross the finish line strong. Happy racing!


Have you thought about hiring a coach for your next race? Click the purple button below, fill out the short form, and I will set up a call with you to talk about your race goals!


Mary Timoney

Ironman University Certified Coach

USA Triathlon Coach

TriDot Coach

ACSM Trainer





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