Posted on May 13, 2026 at 06:00 AM
You’ve signed up for a half or full distance Ironman race, done your training, and are ready for the challenge. Then comes race day, and somewhere during the run around 8-9 miles or 18-20 miles, depending on the distance, it all falls apart.
Long-distance triathlons are rarely won on the basis of physical fitness alone. Too often, races are lost in the final miles, when athletes run out of breath and are sidelined Gut problemsor having convulsions. The easy explanation is poor physical fitness. The real answer is usually whatever happened before the race started.
Just because he collapsed during the escape doesn’t mean the escape is to blame. Every seemingly small and insignificant decision made in the days leading up to the race, every choice on the bike, what I ate, what I skipped, how much I ate at the wrong time, adds up.
The tricky part is that these errors are subtle, and it’s not always easy to determine what caused the end. These errors do not wave a red flag or announce themselves. But by the time you notice them, they’re there to stay.
Let’s dive into the nutrition mistakes that turn a promising performance into a survival attempt and the strategies you can use instead to finish strong.
Fueling errors during racing
Let’s be honest, fueling for a 5-17 hour triathlon is complicated. If your race has disintegrated due to a Feeding accidentYou’re in good company.
Countless factors can derail even the best laid plans, so let’s start with one of the biggest: how to fuel a bike.
If you remember one thing, let it be this: running is not fueled while running; Running bike fuel. What you eat and drink on the bike has the biggest impact on your run and, ultimately, your race.
Training and fitness are important, but it’s your bike nutrition strategy that determines whether you finish strong or just finish.
The most common refueling errors are starting The race is low on fuel Over or under fueling the bike. Eating a handful of gels or waiting 30 to 60 minutes to eat creates an energy deficit that won’t hit you right away, but it will hit you down the road.
Overfueling carries its own risks. Consume more carbohydrates than you have The intestine is trained to It can lead to a series of problems. Highly concentrated sports drinks or pushing more than 120 grams of carbohydrates per hour without adequate fluids or proper bowel training, slowing gastric emptying, reducing fluid absorption and accelerating dehydration. The result: gastrointestinal (GI) upset, or bowel closure, including nausea, cramps, and bloating.
Your stomach becomes progressively less tolerable as the race goes on. Hoping to catch an escape? good luck. Heat, intestinal fatigue, dehydration, and heightened sympathetic drive combine to slow gastric emptying, making it nearly impossible to absorb fuel at the same rate as on a bike.
By the second half of a run, most athletes can only handle about half the volume of carbohydrates they could handle in the first hour of the bike.
Hydration errors during the race
Eating carbohydrates in the right amount and at the right time is important, but let dehydration creep in, and everything will fall apart.
the Fluid and sodium balance Determines whether carbohydrates will be absorbed or not. Common hydration mistakes include drinking when thirsty instead of drinking Sweat rate Excessive hydration with plain water.
The consequences are brutal: poor carbohydrate delivery to the muscles, elevated core temperature and heart rate, and gastrointestinal distress. What’s worse is that you can’t recover from dehydration mid-race.
Without the proper balance between sodium and carbohydrates, water alone is an ineffective hydrator, and too much can lead to dehydration. HyponatremiaIt is a serious and potentially life-threatening low level of sodium in the blood.
The solution: race-ready fueling and hydration
The longer the race, the more important fueling, hydration, and sodium intake become. Water rehydrates the body, retains sodium, and carbohydrates nourish the body. Together they target all the major limiting factors in endurance performance.
Start refueling within 10-15 minutes of starting the bike. Don’t wait until you feel hungry or “settled” after swimming; By then, it’s already too late. Fuel in smaller, more frequent intervals, approximately every 8 to 15 minutes.
Bike goals:
- Carbohydrates: 60-90 g/hour, up to 120 g/hour with practice and intensity. Aim to reach the top end early, when your gut is sharp.
- Fluids: 20-32+ ounces, adapts to sweat rate and conditions. Goal: Replace ~85-100% of fluid loss.
- Sodium: ~500-1000+ mg/1L water, specifically designed for individual sweat loss.
Running Goals: Plan to eat fewer carbohydrates due to gut jostling, higher heart rate, and increased dehydration as the race progresses.
- Carbohydrates: 50-70 grams/hour
- Fluids: 20-32+ oz/hour, adjusted for sweat rate. Goal: to replace 70-75% of fluid loss.
- Sodium: ~500-1000+mg/1L water, specifically designed for individual sweat loss.
Sweat rate and sodium strategy: Everyone loses fluid and sodium differently. To estimate your sweat rate, compare your body weight before and after your session in race-like conditions and intensity.
Unlike carbohydrates and fluids, which you consume at a relatively constant rate per hour, sodium intake should match your fluid intake. Sodium loss varies widely, but a consistent starting point is 500-1,000 mg per 32 ounces (about 15-30 mg sodium per ounce).
Bike hydration checkpoints:
- better Urinating Frequency: Approximately every 2.5 hours indicates good hydration.
- Overdehydration warning: frequent urination or low sodium intake compared to fluid intake.
- Dehydration Alert: Riding for more than 3 hours without needing to urinate.
Fuel selection error: Your fuel is not mathematically approved
Not all calories are created equal. During moderate to high-intensity endurance efforts, quickly digesting carbohydrates are the preferred fuel source for your muscles and brain.
If your fuel contains fat, protein, or fiber, or relies on a single carbohydrate source, you won’t get the quick, sustained energy your body needs. Race pace. Common offenders include nut butter snacks, trail mix, and many sports or protein bars.
The solution: the right products
Use properly formulated endurance products that contain multiple sources of transportable carbohydrates, especially glucose and fructose.
The ideal ratio is 2:1 or 1:0.8 glucose to fructose, which increases absorption at carbohydrate intake above 60 grams per hour and keeps energy delivery constant. Most modern endurance products are manufactured with both, but don’t assume that; Always check the label for maltodextrin (glucose source) and fructose to confirm.
Race day fueling mistake: Not tested in training
You can’t neglect fueling in training and expect to handle 120g/hr on race day. The intestines adapt as you do FTPGradually with repeated exposure. Testing the fuel just a few times or trying a combination of gels, chews, and sports drinks for the first time during a race offers something new to an already stressful system. It’s a dangerous gamble, with consequences ranging from gastrointestinal distress and cramping to DNFs.
The solution: gut training
Start training your gut at least 10 weeks in advance. Start with shorter workouts, then gradually move to sessions that reflect race day conditions, duration, intensity and climate. Start by eating the amount of carbohydrates and fluids every hour you can tolerate, then increase your dose by 10-15 g every week or two, depending on what you can tolerate.
Bowel training tips
- Train at least once a week, and on every long ride and run, including short runs. The use of microgels, Sports drinksOr the chews or bars you plan to use on race day.
- In hot weather, reduce your carbohydrate target by 10-20g per hour until fully acclimatized, then resume your gut training progression.
Race day logistics
Consider your bike’s bottle and fuel storage capacity, how you plan to carry or access nutrients during the race, and the locations of aid stations and displays. If you don’t succeed in training, you won’t succeed on race day. However, you should always have a backup plan in case you drop a bottle, miss an aid station, or unexpected temperature fluctuations.
Race day pacing mistake: Going out too hard
The quickest way to sabotage your race is to ignore your pacing strategy. Starting too fast, even when you feel great, prematurely depletes glycogen, accelerates premature fatigue, and leaves you struggling to meet energy demands. The result is a painful breakdown that could have been completely avoided. Avoid the trap of letting race day adrenaline set your early pace.
The solution: race simulator training
In long endurance races, discipline trumps ego every time. If you haven’t managed to pull off an aggressive start in simulator sessions, don’t try it on race day. Start conservatively, use observed effort as your guide, and trust your training to your emotions. If you feel good later in the race, it’s a sign of building gradually.
Triathlon coach Julie Dunkel recently covered this topic in depth to provide an overview of how to do this Avoid the biggest pacing mistakes in a long triathlon.
Race week fueling mistake: Under-fueling
During race week, reducing your training load (tapering) is not a green light to cut calories. High performers maintain a A diet rich in carbohydrates During training and race week to accelerate recovery, replenish glycogen, maintain training quality, and maintain gut tolerance.
Cutting carbs or overall energy intake prevents optimal glycogen replenishment, leaving you underfueled and behind before you even start.
The Fix: Carb Loading
Carbohydrate loading It’s one of the most proven performance strategies, and it’s about more than just a spaghetti dinner the night before. The goal is to eliminate race week fuel landmines, maximize glycogen storage, improve hydration, and arrive at the starting line with a digestive system ready to perform.
A practical guide to carbohydrate loading in race week:
- Increase carbohydrate intake to approximately 6-10 g carbohydrate/kg body weight after 48 hours.
- Choose familiar foods that are low in fat, fiber, and easy to digest.
- Maintain protein intake at 1.6-1.8 grams/kg of body weight.
- Hydrate between meals with water mixed with electrolytes.
- Test your breakfast and pre-race meals before long training sessions. Adjust until you know exactly what works for your body.
- Pre-race breakfast: 2-4 grams of carbohydrates/kg body weight, 2.5-4 hours before the start. Sip on sodium-containing fluids before the race, and bring 20-25 grams of carbohydrates (gel, chewable) with you to eat 15 minutes before the start.
Bottom line: Use taper For rest and recovery, not cutting calories. On the last two days, increase carbohydrates, reduce fat and fiber, and stay hydrated.
The good news is that every dietary mistake mentioned here is preventable. Athletes who race well are not only fitter; They are better prepared. Fueling and hydration don’t become race day strengths by accident. Build your training strategy, test it frequently, and arrive at race day with a plan that’s proven to work.
