As a marathon approaches, it's crucial to pay close attention to your diet and nutrition . Hydration is a key element for ensuring optimal performance and avoiding risks such as dehydration. Proper hydration throughout your race is essential for maintaining good hydration levels and sustaining your prolonged effort . However, be careful not to over-hydrate! In this article, we'll 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 a marathon runner?
Water plays a crucial role in maintaining bodily functions, notably regulating temperature, lubricating joints, transporting nutrients, and eliminating metabolic waste . During a race like a marathon , the body loses a significant amount of water through perspiration. Depending on individual characteristics, athletes can lose 1 to 1.5 liters of water per hour of exertion through sweat, and sometimes up to 3.7 liters per 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 water as a percentage of body weight equals a 10% decrease in performance! A well-designed and personalized hydration strategy is therefore essential to prevent dehydration, maintain peak performance, and avoid problems that can occur during races, such as dehydration, heatstroke, and cramps.
Factors influencing water requirements during a marathon
Indeed, several factors must be considered during a marathon. Runners must pay particular attention to the duration of their effort , as the needs will differ between a marathoner who finishes in 2 hours and one who takes 5 hours. Climatic conditions , such as hot or humid weather, and each runner's ability to retain water in their body , must also be taken into account. For example, during a race in high temperatures above 25°C, hydration needs will be greater compared to a race held in winter at 5°C. Water loss through perspiration will be significantly higher during a race in hot conditions, thus requiring a greater fluid intake to maintain proper hydration. Furthermore, the intensity of the effort and the distance covered in kilometers also influence the need for milliliters of water per hour of running. Water requirements vary from one runner to another depending 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 sugars like dextrose, play an important role in maintaining the body's fluid balance.
These electrolytes (especially sodium) are lost in large quantities through sweat during a marathon. It is therefore necessary to replenish these lost fluids to avoid muscle cramps, fatigue, and other problems related to electrolyte imbalance .
The risks associated with inadequate hydration
Dehydration
As you probably suspect, dehydration poses a major risk in a marathon, especially if the runner doesn't drink enough water to compensate for the fluid and electrolyte losses due to perspiration. Various symptoms can indicate dehydration, such as fatigue, decreased energy, lack of concentration , and in more severe cases, muscle weakness, dizziness, and fainting . Dehydration also leads to an increase in body temperature and can therefore result in heatstroke.
To avoid all these problems, it's essential to drink small sips of water regularly throughout the race and before you feel thirsty. In fact, the sensation of thirst isn't always a reliable indicator of your body's hydration level, especially during intense physical exertion. That's why it's better to drink small sips regularly than to gulp down your entire water bottle!
Overhydration
Yes, hydration is essential. However, drinking too much water can also be dangerous to your health! Indeed, excessive water consumption without electrolyte intake can dilute the sodium in the blood, leading to hyponatremia . This can cause various symptoms such as nausea, vomiting , headaches, confusion, seizures, and in some severe cases, coma or even death (For your information, a marathon runner in Boston died in 2002 from hyponatremia).
That is why it is important to maintain a good balance by choosing suitable 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's important to know that you need to have tested hydration strategies beforehand, prior to your goal! During your long runs (necessary for marathon training), try to consume the same foods and the same volume of water as you plan to consume during your marathon! This will improve your digestive system's ability to eat and drink during exercise.
Before the marathon
Even before race day, it's advisable to focus on hydration . Proper hydration in the days leading up to the race will help your body prepare! Runners are advised to drink between 5 and 7 ml of fluid per kilogram of body weight per hour, starting 2 to 4 hours before the activity, to ensure adequate fluid reserves . Runners should also avoid drinking large quantities of water just before the start, as this can lead to frequent urination or, in more serious cases, digestive problems during the race, which can negatively impact athletic performance.
During the marathon
During a marathon, it's recommended to hydrate with water or sports drinks at regular intervals , every 10 to 15 minutes. Taking small sips of liquid regularly helps maintain consistent hydration without overloading the stomach. Runners should also adjust their hydration based on the temperature and their level of perspiration . The warmer it is, the more important it is to drink.
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 overhydration .
After the marathon
After a run, 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 someone who has lost 2 kg should consume 3 liters of water post-exercise (2 x 1.5). Foods containing carbohydrates and sodium are particularly effective at accelerating rehydration and muscle recovery . In practical terms, it is crucial to continue hydrating 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 hydration while providing essential nutrients.
