Why hydration and nutrition matter in long-duration events
In prolonged events the body faces constant losses of water, electrolytes and energy reserves. Maintaining a balance between hydration and carbohydrate intake is key to sustaining physical and cognitive performance, preventing cramping, premature fatigue and reducing the risk of more serious problems such as severe dehydration or hyponatremia. The correct strategy is not the same for everyone: it depends on the duration of the event, the climate, the intensity of the effort and the individual characteristics of the athlete.
Basic physiological principles
During prolonged aerobic activity, muscular and hepatic glycogen is consumed; if carbohydrates are not replenished, performance decreases and the sensation of "fatigue" appears. At the same time, water and sodium are lost through sweating; the amount can vary widely among individuals. Dehydration reduces effective blood volume, increases body temperature and raises the perception of exertion. In addition, electrolyte balance is essential for neuromuscular function and nerve transmission.
Factors that modify requirements
- Duration and intensity of exercise: the longer the duration and intensity, the greater the energy and water demand.
- Environmental conditions: heat and humidity increase sweating; cold can decrease the sensation of thirst and mask losses.
- Individual characteristics: body weight, sweating rate, acclimatization, gender and level of preparation influence needs.
- Availability of replenishment: ease of drinking or eating during the race conditions the strategy.
How to calculate and plan hydration
Before designing the strategy in competition, it is useful to know one's own sweating rate: weigh the athlete before and after representative workouts and count liquids ingested during the session. A mass loss of 1 kg is equivalent to approximately 1 liter of sweat lost. The target intake is usually between 300 and 800 ml/hour depending on sweat rate and gastrointestinal tolerance, but should be individualized. In addition, including electrolytes - especially sodium - helps to maintain plasma volume and neuromuscular function.
Prevention of hyponatremia
Excessive drinking of water without sodium replacement can dilute the plasma and lead to hyponatremia, a dangerous condition especially in events lasting many hours. To avoid this, combining isotonic drinks or salts in hydration and adjusting intake to thirst and estimated losses is safer than drinking rigidly by fixed volume. In very long races it is advisable to plan a regular intake of sodium along with carbohydrates.
Nutrition during the competition: type and rhythm of intake
The objective is to provide rapidly absorbed carbohydrates to maintain blood glucose and delay glycogen depletion. For efforts between 1 and 2.5 hours 30-60 g/h of carbohydrates are recommended; for longer events (2.5-3+ hours) the figure can be increased to 60-90 g/h, combining different types of sugars to improve absorption (e.g. glucose + fructose in appropriate proportions). The texture and form (gels, drinks, soft bars or light solid foods) are chosen according to the gastrointestinal tolerance of the athlete.
Types of carbohydrate sources
- Sports drinks: hydrate and provide carbohydrates and electrolytes, convenient when simultaneous replenishment is needed.
- Energy gels and bars: energy dense, easy to carry; it is important to take them with water to facilitate their absorption.
- Real food: bananas, bread with honey or small bites may be well tolerated by some athletes in long races.
- Combinations: alternating drinks with solids or gels can reduce monotony fatigue and help maintain caloric intake.
Practical strategies before, during and after
Prior to the race it is advisable to be well hydrated and with optimal glycogen deposits, which implies a diet rich in carbohydrates 24-48 hours before and avoid pre-competitive dehydration. During the competition follow a regular intake pattern (e.g. every 15-30 minutes small sips of drink and every 30-45 minutes a gel or food depending on needs). After finishing, the objective is to replenish fluids, sodium and carbohydrates to facilitate recovery: a drink with carbohydrates and some protein in the first two hours favors glycogen synthesis and muscle repair.
Rehearse in training sessions
Testing the nutritional and hydration strategy during long training sessions is essential: each stomach reacts differently and what works in theory can cause real discomfort. Testing amounts, times and types of products allows you to adjust tolerance, avoid surprises and create a routine that leads to automatic behavior on race day.
Warning signs and how to respond
It is important to distinguish between normal thirst, fatigue and symptoms that require intervention. Dizziness, confusion, persistent nausea, severe cramps, marked decrease in performance or excessive loss of body weight are warning signs. In case of moderate dehydration, providing isotonic fluids and some sodium content helps; in case of suspected hyponatremia (swelling, confusion, convulsions) urgent medical attention is necessary and avoid administering large volumes of water alone.
Practical recommendations and examples
An indicative guideline for a 4-6 hour race: start well hydrated, take 150-300 ml every 15-20 minutes if sweating is high; consume 60-90 g of carbohydrates per hour by combining drinks and gels (e.g. a drink with 6-8% carbohydrate plus a gel every 45-60 minutes with additional water). Add 300-700 mg of sodium per hour in very hot or sweaty conditions. Adapt amounts according to tolerance and measure pre/post workout weight to adjust replenishment rate.
Final tips
- Plan and test your strategy in advance.
- Don't wait until you are thirsty to drink if your sweat rate is high.
- Combine carbohydrates and electrolytes to optimize absorption and performance.
- Listen to your body's signals and act on unusual symptoms.
With individualized planning and pre-testing, it is possible to maintain performance in long endurance events while minimizing risk. The key is to know your own losses, choose products that you tolerate and adapt your intake to the conditions of the event. This way, you will reach the end of the race in better shape and recover faster.
