Marathon Training 101: Hydration

Marathon Training 101: Hydration

Knowing about hydration and your body's signals is incredibly important for athletes, especially before and during a big event. Learn what your body needs everytime it sweats and how you can prevent dehydration.

Sweat and Sweat Rate

Sweating is a cooling process the body undergoes to protect cells and dissipate heat created by exercise. Did you know your muscles can generate 20 times more heat when they are working hard versus when they're at rest? The body combats this heat by releasing water, sodium, chloride and modest amounts of potassium (which makes up sweat) to cool off.


Remaining hydrated while exercising is crucial. If you wait until the feelings of thirst hit, it may already be too late. When you feel thirsty, your body has lost significant amounts of fluid, causing sodium levels in the blood to become more concentrated, signally thirst. According to Nancy Clark, MS, RD, by the time your brain signals thirst, you may have lost 1 percent of your body weight, or 1.5 pounds of sweat for a 150 pound person. This 1 percent loss corresponds with the need for your heart to beat an additional three to five times per minute. On the other hand, dehydration is defined as a 2 percent loss of your body weight, which puts additional strain on the heart during exertion.

Recent research has shown mild levels of dehydration may not be harmful to runners. Allowing thirst to guide your water intake will prevent severe dehydration from setting in and, as long as you have water accessible while you're running, you can stay adequately hydrated. I do suggest drinking water throughout the day, especially the day before a long run or race.

Common symptoms of dehydration include headache, nausea, brain fog, difficulty with exercise, lethargic, fatigued, dry/sticky mouth, thirst, constipation, dizzy, lightheaded and dry skin. Stay hydrated!

Be aware that over-hydrating can also be a dangerous condition. Do not drink large amounts of water before a race, as this can dilute the amount of electrolytes in your body, leading to upset stomach, low levels of sodium, bloating, nausea and, in some cases, seizures and organ failure.

Keep hydrated by drinking your NutriBlasts! You can hydrate by including ingredients packed with water and electrolytes and using coconut water or filtered water as your liquid base.

OurHydration NationBlast is a perfect recipe that'll help boost your hydration levels.

Registered Dietitian, Certified Specialist in Sports Dietetics

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