The Wizz Air Sofia Marathon 2025 will take place on October 11 and 12, with the start and finish line for all distances set at the iconic Knyaz Alexander I Battenberg Square. On Saturday (October 11), the route will be open for participants in the 5K FIB Mass Run, while on Sunday (October 12), the other distances will take place – the 10K Garmin Run, the 21.1K half marathon, and the classic 42.2K marathon.

A dedicated support zone will be available at the square, and refreshment stations will be set up along the course offering water and food, so that runners can stay hydrated and refuel with energy when needed. Regardless of the distance, proper hydration starts before the race. And during the run itself, the right fluid intake can be crucial not only for performance and physical condition, but also for recovery afterward.

How Distance Affects Hydration Needs

The body starts losing fluids from the very first kilometers of running. Exactly how much depends on body weight, pace, weather conditions, and level of exertion. On average, between 100 and 150 ml of water is lost per kilometer through sweating.

Recommended fluid intake by distance:

5K FIB Mass Run: About 300–500 ml, spread before and after the run. It’s usually not necessary to drink during such a short distance unless the weather is hot.

10K Garmin Run: About 500–700 ml. It’s recommended to drink some water shortly before the start and take advantage of at least one station along the course.

21K Half Marathon: Between 1 and 1.5 liters. It’s important to drink regularly – small amounts every 3–5 km. At this distance, it’s advisable to combine water with isotonic drinks, especially if the run takes over 90 minutes.

42K Marathon: Between 2 and 3 liters of fluids, depending on body weight and finish time. Marathoners must pay attention to body signals and use every hydration station wisely.

Isotonic Drinks – When and Why

Isotonic drinks contain electrolytes (sodium, potassium, magnesium), which are lost through sweat, as well as carbohydrates that help maintain energy levels. These drinks are especially useful during longer distances (21K and 42K) and in warm weather. It’s recommended to start consuming them in the early stages of the race, alternating with water. However, it’s important to get your body used to them during training.

Hydration During Training

Just like any other part of training, hydration requires planning and adjustment. It’s important to drink enough water throughout the day – not just around running sessions. For longer or more intense workouts, isotonic drinks can be included, particularly in hot conditions.

Runners should also monitor the color of their urine – pale yellow is a sign of good hydration. Body weight before and after a session can also serve as a guide: if you’ve lost more than 2% of your body weight, it likely means you didn’t consume enough fluids or didn’t distribute them effectively during exertion.

Hydration Before the Race

The evening before the race: It’s important that the body is well-hydrated with water and light isotonic drinks, but without overdoing it – the goal isn’t to “flood” the system, but to provide a solid foundation.

The morning of the race: It’s recommended to drink between 300 and 500 ml of water about two hours before the run. This gives the body enough time to absorb the fluids and helps avoid the need for an emergency bathroom visit just before the start. Another 100–200 ml can be consumed about 30 minutes before heading to the course.

Fluid Intake After the Finish

After crossing the finish line, runners should avoid drinking large quantities of water all at once. It’s better to sip slowly and in small amounts, alternating between water and isotonic drinks. Restoring electrolyte balance is especially important after long runs. In addition to fluids, the body also needs a bit of salt and carbohydrates – so a banana, pretzels, or a sports drink are good options.

Common Myths About Running and Hydration

“If you’re not thirsty, you’re hydrated.”
Thirst is a delayed signal. It’s better to hydrate preventively, especially during longer runs.

“The more water, the better.”
Excessive water intake, especially without electrolytes, can lead to hyponatremia – a potentially dangerous condition where sodium levels in the blood are too diluted.

“Isotonic drinks are only for professionals.”
Every runner, especially during long or hot races, can benefit from a balanced intake of electrolytes and carbohydrates.

“It’s better not to stop for water – you’ll lose time.”
Taking 5 seconds at a water station can pay off in the final kilometers when your body is nearing exhaustion.

Wizz Air Sofia Marathon is not just a sporting event – it’s a true challenge for body and spirit. Proper hydration is one of those seemingly small things that can make a big difference between a safe and enjoyable experience and one that becomes overwhelming and exhausting.