Nutritionally, I strive to eat mindfully and intuitively. The problem with hydrating in athletics is that an athletes' thirst mechanism often fails as a proper signal for fluid loss because of the intensity of exercise. Also, the mind can mask the effect of thirst, allowing an athlete to lose a dangerous amount of water.
More: 15 Hydration Facts for Athletes
What Is a Dangerous Amount of Sweat Loss?
Dehydration is defined as losing 2 percent of your body weight from sweating, but even losing 1 percent can significantly impair your physical performance by raising your body temperature and causing your heart to beat three to five times more per minute.
Dehydration takes away from an athlete's mental edge, physical ability, and can be deadly if your body loses its ability to cool itself down, or if heat illness occurs.
More: How to Avoid Dehydration on Race Day
How Can Sweat Loss Be Monitored?
A great way to monitor hydration is through the color and quantity of your urine. In marathon training and endurance sports, it is important to pay special attention to your sweat loss.
Your rate of sweat loss is individual and influenced by factors such as age, temperature, genetics, gender, and fitness level. In order to know how much sweat you lose during exercise, weigh yourself nude before one hour of exercise and then again right after.
More: What Does Your Sweat Taste Like?
This can determine the amount of water you need replace (80 to 100 percent) of what is lost. Approximately 16 ounces or 0.5 kilograms of water should be consumed for every pound lost.
Maintaining proper fluid balance is essential during exercise, when your muscles generate 20 times more heat than at rest. There is no one-size-fits-all recommendation for fluids, so pay attention to your own sweat loss and hydrate accordingly.
Source: Sports Nutrition Guide Book by Nancy Clark
More: What to Drink, How Much and How Often
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