When you're dehydrated, the strain feels harder than it actually is! An experience that almost every athlete has already had. Sweating is one of the most important mechanisms to protect the body from overheating. Intensive and long-lasting endurance units, especially at high temperatures, can result in high sweat losses. What does this mean for the fluid balance? Corinne Maeder explains.
Intensive and long-lasting endurance units, especially at high temperatures, can result in high sweat losses. Perspiration loss per hour of sport varies from 0.3 to over 2 liters depending on the intensity of exertion, environmental conditions, level of training, body weight, genetic condition and other factors. Lack of fluids or water (dehydration) is one of the most common causes of exhaustion and reduced performance during prolonged endurance exertion. Even a loss of fluids of 2-3% of body weight during exercise (related to the weight before the start of exercise) can reduce physical and mental performance.
Proper fluid intake is therefore important before, during and after exercise. Three simple rules that any endurance athlete can easily implement:
- Before training/competition, your fluid balance should be balanced
- Drink regularly during exercise
- Make up for your fluid deficit after exercise for optimal regeneration
What is the optimal amount to drink during exercise?
Recommendations for hydration during exercise have changed dramatically in recent years, ranging from "don't drink" (early 1970s) to "drink the maximum amount you can tolerate" (1996).
The actual fluid requirement during training/competition depends on various factors, such as climatic conditions, individual perspiration rate, duration and intensity of exertion. The optimal amount to drink is therefore different for every athlete, and previous recommendations have now been refuted. Both drinking too much and not enough can impair athletic performance!
However, general drinking recommendations can be helpful for many of us for sporting activities > 60 minutes: drink approx. 400-800 ml of liquid per hour, regularly in small sips (e.g. approx. 150 ml every 15 minutes). In cool weather and light exercise, the hourly requirement is in the lower recommended range, while in warm temperatures or with high exercise intensities, more should be drunk.
There is no easy way to accurately determine individual fluid requirements during exercise. A practicable formula, which is also used by competitive athletes, is as follows:
Outside of training, the color of the urine serves as a simple indicator of the status of the fluid balance: if the urine is light yellow, the fluid balance in the body is correct. Slightly darker urine (roughly the color of apple juice or beer) is a typical sign of underhydration or dehydration. However, it should be taken into account that certain foods (e.g. beetroot), multivitamin preparations or antibiotics can influence the urine color, which means that this parameter should no longer be used as a guide.
It is not only important "how much" is drunk, but also "what"
For short endurance sessions, water or a calorie-free drink is the ideal choice. During longer periods of exertion, many athletes like to quench their thirst with so-called isotonic sports drinks. An isotonic drink contains the same osmolality (270-330 mosmol/kg water) as human blood or blood plasma and is therefore absorbed by the body particularly quickly. Osmolality is the osmotically effective “particle concentration”, which is defined by the components sugar and electrolytes, among other things. Isotonic drinks (such as a homemade mix of a special juice and water ratio or isotonic sports drinks) are therefore special carbohydrate-electrolyte solutions. They improve fluid intake during exercise and thus help maintain endurance performance during longer sessions.
Tips for choosing the right sports drink
- The intensity and duration of the load is crucial! For short units or fat metabolism training, calorie-free drinks are usually useful. For longer and/or more intensive loads, on the other hand, carbohydrate-containing electrolyte drinks are the right choice. Sodium (component of table salt) is sweated out most quantitatively and is therefore an important component of sports drinks. Sodium is essential for water retention in the body, a regular fluid balance and for muscle and nerve function
- It must be well tolerated! Therefore, test what is ideal for you personally
- It has to taste good! Choose a drink that tastes good to you, otherwise you tend to drink too little
Avoid monotony! Different flavors provide variety