As a marathon approaches, it is important to pay close attention to your diet and nutrition. Hydration is therefore a key element to ensure optimal performance and avoid risks such as dehydration. Hydrating adequately throughout your race is essential to maintain good hydration levels and sustain your prolonged effort. Be careful not to drink too much, however! In this article, we will provide hydration strategies for marathon runners, taking into account the specific needs of each individual during such a long race!
Understanding hydration needs during a marathon
What is the role of hydration for marathon runners?
Water plays a crucial role in maintaining bodily functions, including temperature regulation, joint lubrication, nutrient transport, and elimination of metabolic waste. During a race like a marathon, the body loses a significant amount of water through perspiration. Depending on the individual, athletes can lose 1L to 1.5L of water per hour of effort through sweat, and sometimes up to 3.7L/hour in extreme conditions! Uncompensated fluid loss can lead to a decrease in physical and cognitive performance. It's worth noting that a 1% loss of body weight in water equals a 10% decrease in performance! A well-developed and personalized hydration strategy is therefore essential to prevent the risks of dehydration, maintain high performance, and prevent problems that can occur during a race such as dehydration, heat stroke, and cramps...
Factors influencing water needs during a marathon
Indeed, various factors must be taken into account during a marathon. Runners must pay attention to their duration of effort, as the needs will not be the same for a marathon runner who finishes in 2 hours and one who finishes in 5 hours. Climatic conditions such as hot or humid weather and each runner's capacity to retain water in their body must also be considered. For example, during a race in high temperatures above 25°C, the needs will be greater compared to a winter race at 5°C. Water loss through perspiration will be significantly higher during the race in hot weather, thus requiring a higher fluid intake to maintain good hydration. Furthermore, the intensity of effort and the distance covered in kilometers also influence the need for milliliters of water per hour of running. Water needs vary from runner to runner depending also on their weight, metabolism, and training level.
It also seems necessary to understand that hydration is not limited to water alone. Electrolytes, such as sodium, potassium, and magnesium, as well as sugar like dextrose, play an important role in maintaining the body's water balance.
These electrolytes (especially sodium) are lost in large quantities through sweat during a marathon. It is therefore necessary to compensate for this water loss to avoid muscle cramps, fatigue, and other problems related to an electrolyte imbalance.
Risks associated with inadequate hydration
Dehydration
As you probably suspect, dehydration is a major risk during a marathon, especially if the runner doesn't drink enough water to compensate for hydro-electrolytic losses due to perspiration. Various symptoms can be signs of dehydration, such as: fatigue, decreased energy, lack of concentration, and in more severe cases, muscle disorders, dizziness, and fainting. Dehydration leads to an increase in body temperature and can therefore result in heat stroke.
To avoid all these problems, it is crucial to regularly drink small sips of water throughout the race and before you feel thirsty. Indeed, the sensation of thirst is not always a reliable indicator of the body's hydration status, especially during intense physical exertion. That's why it's better to drink small sips regularly than to gulp down your entire water bottle at once!
Overhydration
Yes, hydration is essential. However, drinking excessive amounts of water can also be dangerous for your health! Indeed, excessive water consumption, without electrolyte intake, can dilute sodium in the blood, leading to hyponatremia. This can cause various symptoms such as nausea, vomiting, headaches, confusion, seizures, and in some severe cases, a coma or even death (For your information, a female marathon runner in Boston died in 2002 due to hyponatremia).
That's why it's important to maintain a good balance by choosing appropriate drinks such as sports drinks that contain electrolytes, helping to replace minerals lost through sweat.
What are the different hydration strategies for a marathon?
It is important to have tested hydration strategies beforehand for your goal! During your long runs (necessary for marathon preparation), try to consume the same products and the same volume of water as you plan to consume during your marathon! This will help improve your digestive system's ability to eat and drink during exercise.
Before the marathon
Even before race day, it is advisable to pay attention to your hydration. Indeed, hydrating well in the days leading up to the race will prepare your body! Runners are advised to drink between 5 and 7 ml of fluid per kilogram of body weight per hour, 2 to 4 hours before the activity, to ensure an adequate fluid reserve. Runners should also avoid drinking large quantities of water just before the start, as this can lead to a frequent need to urinate or, in more severe cases, digestive problems during the race, which can harm the performance of athletes.
During the marathon
During the marathon, it is recommended to hydrate with water or energy drinks at regular intervals, every 10 to 15 minutes. Drinking a few sips of liquid regularly helps maintain constant hydration without overloading the stomach. Runners should also adapt their hydration based on the temperature and their sweat rate. The hotter it is, the more important it will be to hydrate in larger quantities.
Hydration packs and belts can be practical accessories to ensure you drink enough without having to stop too often at aid stations. These accessories also allow you to control the amount of water consumed and avoid overhydrating.
After the marathon
After the race, rehydration is essential to restore the body's fluid balance and promote rapid recovery. It is recommended to drink approximately 1.5 times the amount of fluid lost during exercise, meaning that a person who has lost 2 kg should consume 3 liters of water post-exercise (2x1.5). Products containing carbohydrates and sodium are particularly effective for accelerating rehydration and muscle recovery. Specifically, it is crucial to continue to hydrate regularly in the hours that follow, to compensate for fluid loss and prevent dehydration, while water-rich foods, such as fruits and vegetables, can also contribute to fluid intake, while providing essential nutrients.
