Long-distance triathlon season—half-Ironman and Ironman events—is in full swing. After many months of demanding training, the final step is appropriate nutritional preparation for race day. This post explains what to do in the days and hours before the start, how to hydrate and fuel during the race, and what to prioritize after finishing to recover from a maximal effort as quickly as possible.
The hydration and fueling strategy before and during competition aims to prevent or minimize the following performance-limiting factors:
• Dehydration: even mild dehydration can reduce performance, cause cramps and increase the risk of digestive discomfort. As dehydration progresses, symptoms worsen and may eventually lead to life-threatening heat stroke.
• Electrolyte imbalance: there is a serious risk of hyponatremia, or low blood sodium. Sweat causes the loss of many electrolytes, especially sodium, so electrolytes must be replaced without drinking excessively—beyond the amount lost in sweat.
• Depletion of muscle glycogen: once muscles run out of glycogen, they cannot continue working at high intensities. This is when athletes hit the dreaded wall and lose energy.
• Hypoglycemia: low blood glucose causes central fatigue and leaves muscles without sufficient energy.
• Digestive discomfort: nausea, vomiting, gas and diarrhea are a genuine nightmare for many long-distance athletes.
THE 2-3 DAYS BEFORE THE TRIATHLON
Muscle glycogen stores are limited and are rapidly depleted when moderate-to-high-intensity effort continues for a long time. To prevent your muscles from running out of fuel during a long-distance triathlon, follow a carbohydrate-loading diet for the 2-3 days before the event. This can double muscle glycogen stores. The diet consists primarily of carbohydrates, maximizing stores so you can draw on glycogen during the hardest stages of the race and depend less on food intake.
To do this correctly, consume around 5-10 g of carbohydrate per kilogram of body weight per day, depending on the athlete and activity, while reducing training to a minimum. For a man weighing around 70 kg, this represents 300-700 g of carbohydrate per day—an enormous amount, so I would lean toward 7 g/kg. Protein and fat intake should be reduced to a minimum. Do not eat your usual diet plus three times as much carbohydrate.
Choose complex carbohydrates such as potatoes, pasta, rice and quinoa that are low in fiber, especially on the final day. Cereal bars, homemade cakes, dairy desserts, fruit juices and plant-based drinks made from rice, almonds, coconut or oats can help you reach the target. Isotonic drinks and maltodextrin can provide additional carbohydrates.
This diet will increase body weight slightly, possibly by as much as 2 kilograms. Do not worry: this is water stored alongside glycogen. You may feel some muscle tension or stiffness, but it should ease at the beginning of the event. The extra water will also help during the race.
Drink enough water and other fluids during these days, because the body needs almost 3 grams of water for every gram of glycogen stored.
Do not overeat at dinner the night before the race. Good sleep is essential, and an excessively large meal may leave you feeling heavy and disrupt your rest.
BREAKFAST AND HYDRATION BEFORE THE TRIATHLON
The hours before the race should ensure you reach the start well hydrated and replenish the liver glycogen used overnight.
HYDRATION:
During the 4 hours before the start, drink around 5-7 ml per kilogram of body weight. For our 70-kilogram athlete, that means 350-500 ml of fluid.
One good option is a glass of isotonic drink (250 ml) immediately after waking. It provides fluid, salts that help retain it and carbohydrates.
You can then have tea with breakfast or another glass of water. Stop drinking around 60-90 minutes before the start to allow time to excrete excess fluid.
BREAKFAST:
Eat breakfast at least 2-3 hours before the start so digestion can be completed. What and how much you eat depends partly on how you feel. Choose only foods you already know you tolerate well; do not experiment or eat anything unfamiliar. Do not overeat because carbohydrate loading is already complete. Ideally, include carbohydrates such as toast with honey or jam, non-wholegrain cereals or soft oats; a banana; and some protein such as turkey, plain yogurt, egg or a small serving of whey. Add coffee, tea or an infusion. Some people prefer a liquid breakfast and prepare a shake with a plant-based drink or milk—only if milk agrees with them—banana, infant cereal and a small amount of whey. The key is to choose something easy to consume and digest.
THE FINAL MINUTES BEFORE THE START:
Be cautious with carbohydrates such as gels, bars and isotonic drinks during the 30-60 min before the race. Some athletes experience reactive hypoglycemia and may begin the event with low blood glucose if they consume carbohydrates in this window. It is therefore best to avoid them during those 30-60 minutes. If desired, take a gel or glass of isotonic drink during the warm-up immediately before swimming; around 10 minutes before the start, there is no longer a risk of reactive hypoglycemia.
HYDRATION AND FUELING DURING THE RACE
The energy cost of an Ironman is estimated at around 8500-11500 kcal. Long-distance triathletes are estimated to consume less than 60-70% of that expenditure. Every triathlete will therefore reach the finish with a major energy deficit, covered primarily by fat stores and muscle glycogen.
The objectives of hydration and fueling DURING the triathlon are:
• Hydrate correctly: around 500-800 ml of fluid per hour. Dehydration is the main performance-limiting factor. Drink the right amount: both excess and insufficient intake are harmful. Never drink more than you lose through sweat, because this increases the risk of hyponatremia.
• Replace salts and electrolytes: 450-1150 mg Na+ per liter of water, using an isotonic drink, salty foods such as turkey, ham or cheese sandwiches and crackers, or the sodium in gels and bars. Salt capsules are generally unnecessary unless you drink only water and your food, gels and bars provide insufficient sodium. Check the sodium content of every product you plan to use.
• Maintain a continuous carbohydrate intake (60-90 g/hour) through isotonic drinks, gels, bars, fruit, dried fruit such as dates, dried apricots or dried banana, and biscuits. If intake exceeds 60 g of carbohydrate/hour, use mixtures of glucose, maltodextrin and fructose. Avoid large amounts of fructose, which can cause digestive discomfort, and avoid glucose or maltodextrin alone above 60 g/hour.
• If a section lasts >4-5 hours, a small protein or amino-acid intake may be useful, using protein bars, BCAAs or small ham, turkey or cheese sandwiches.
Use transitions to drink an isotonic beverage or water with gels.
Eat as much as possible on the bike. Without the impact of running, digestion is easier and nutrients can be absorbed more effectively. Remaining in a very low aerodynamic position while eating can hinder digestion.
On the bike, aim for 60-90 g of carbohydrate per hour. During the run, 40-60 g of carbohydrate per hour is a reasonable goal. The same applies to fluid: you will be able to drink more on the bike than while running.
Practice the strategy thoroughly on long training sessions. Choose only foods, supplements and drinks you already know you tolerate well.
If your stomach feels unwell at any point, allow it to rest briefly without eating or drinking and rinse your mouth with an isotonic drink or cola, holding it in your mouth for
5-10 seconds before spitting it out, taking care that no other triathlete is beside you. Small sips of cold cola may also help settle the stomach.
WHEN YOU REACH THE FINISH
First and most importantly:CELEBRATE! Hug your children, wife, girlfriend, friends, race partner or whoever is there to share the moment. You are a champion.
The first 30 min: the main objective is replacing lost fluid. During the 4-6 hours after the effort, consume 1,5 liters of water for every kilogram of body weight lost during the race. A cold isotonic drink immediately after finishing is ideal because it provides water and minerals—primarily sodium, potassium and chloride—to restore hydration quickly. Plain water is not recommended because it promotes diuresis and could reduce blood sodium further.
30-60 min: replenish glycogen stores and repair muscle with an easily digested food rich in carbohydrates and protein. Commercial or homemade recovery shakes—with milk, fruit, infant cereal, honey, yogurt, whipped cheese or whey protein—are an excellent option because they are liquid, easy to consume after exertion and cold. Consume carbohydrates and protein in a 3:1 ratio: approximately 1-1,2 g of carbohydrate per kilogram of body weight and 0,3-0,4 g of protein per kilogram.
Continue hydrating.
After 2-3 hours: eat another meal containing carbohydrates and protein. Choose easily digested foods that are low in fat and fiber. The prolonged effort has stressed the digestive system, reducing its capacity to digest and absorb nutrients. White rice, pasta and potatoes are good carbohydrate options; choose eggs, chicken or grilled white fish for protein. Eat plenty of fruit to support rehydration while providing carbohydrates, antioxidants and phytonutrients.
Repeat intake every 3-4 hours and continue to rehydrate generously.
AUTHOR: Ana Madroño
