Hydration, Sodium, Potassium and Exercise: What You Need to Know

By Perrin Braun, August 1, 2022

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What’s a small thing you can do that can have a big effect on your performance? Drink enough water. Our bodies are mostly comprised of fluid, which means that every cell, tissue, and organ needs enough water to function. While plain H20 is the most important part of hydration, you also need electrolytes like potassium and sodium to perform at your best.

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Why should you pay attention to hydration?

Hydration is necessary to maintain peak performance. Water regulates your body temperature, lubricates your joints, and transports nutrients throughout your body. Staying hydrated is particularly important during exercise because you lose water through sweat. The longer and more intensely you work out, the more necessary it becomes to get fluid into your body. When you don’t replenish your fluids, it becomes harder for your heart to circulate blood.  A decrease in blood and plasma volume can contribute to muscle cramps, dizziness, fatigue, heat stroke, and heat exhaustion.

In addition to water, your body loses electrolytes when it sweats. Chloride, potassium, and sodium are major electrolytes, which are minerals in your blood, urine, and bodily fluids that contain an electric charge. Your body’s cells use electrolytes to carry electrical impulses that help your cells communicate with each other and give you the ability to taste, see, smell, touch, and hear. InsideTracker measures potassium and sodium in your blood to help you maintain your well-being  and to reach your personal fitness potential.


Do athletes have any special hydration requirements?

If you’re an athlete, how much water should you drink? The answer varies depending on how much and how intensely you exerciseand how much you sweat. However, there are ways to gauge whether you’ve hydrated enough.

One way is to monitor your urine. Light-colored urine means you’re probably adequately hydrated, but dark, concentrated urine can indicate that you’re not drinking enough water. Weigh yourself before and after workouts – weight loss that occurs directly after a workout is likely to be caused by a fluid reduction.

During the first hour of exercise, you should rehydrate with water. Many athletes use these basic guidelines from the American College of Sports Medicine as a reference point, and then adjust their water intake to fit their hydration needs:

At least 4 hours before exercise, drink about 2-3 milliliters (mL) of water or a sport beverage per pound (lb) of body weight. For instance, a 150-lb athlete needs to drink 300-450 mL, which equals about 10-15 ounces of liquid Consume approximately 8 oz of fluid every 15 minutes After exercise, consume about 16-24 fl oz of fluid for every pound of body weight lost during exercise. To read more about how much water you should be drinking, read our detailed blog about the topic

Hydrating before, during, and after exercise

Why is sodium important for hydration?

Many people associate sodium with high blood pressure, heart disease, and canned foods, but it serves important functions in keeping your body healthy:

  • Maintains fluid balance in your cells
  • Helps to transmit nerve impulses throughout your body
  • Helps muscles contract and relax

Because sodium is found in so many foods, it’s fairly uncommon to develop a sodium deficiency unless you’re having a bout of excessive vomiting or diarrhea. If you’re losing a lot of water, you’re probably also losing a lot of sodium too. Symptoms of a sodium deficiency include muscle cramps, fatigue, dizziness, nausea, and inability to concentrate. Drinking too much fluid, especially plain water, can result in hyponatremia, a dangerous condition in which there is not enough sodium in your body fluids. If the deficiency really becomes serious, the body can go into shock and the circulatory system can collapse. 

Conversely, if our diets contain too much sodium, our body tissues tend to retain water. For reference, the 2012 American Heart Association recommended that people consume no more than 1,500 milligrams of sodium a day – just a bit more than 1/2 teaspoon of salt. For comparison, a medium order of fast food French fries contains about 260 milligrams of sodium. A recent study reported that Americans are consuming even more sodium – 8% more in 2010 than in 2001. Consuming too much salt can cause the kidneys to retain water, which can sometimes result in increased blood pressure, stroke, and heart disease. 


Why is potassium important for hydration?

In addition to helping to maintain a proper fluid balance in your body, potassium also performs the following functions:

  • Keeps the blood from clotting
  • Maintains the body’s pH balance
  • Carries nutrients to the cells
  • Protects the stomach lining from the damage that could be caused by stomach acids
  • Maintains healthy blood pressure
  • Promotes heart health
  • Preserves bone health

Athletes should be especially concerned with their potassium intake; potassium plays a role in the storage of carbohydrates to fuel your muscles. In addition, the frequency and degree to which your muscles contract depends heavily on having the right amount of potassium in the body. When you don’t get enough potassium in your diet, or when the movement of potassium through the body is blocked, your nervous and muscular systems can become compromised. The Adequate Intake (AI) for potassium is 4.7 grams per day, but most Americans don’t consume enough potassium in their diets.

Food sources of potassiumOne reason for our low potassium levels is that Americans generally don’t eat enough fruits and vegetables. Bananas are a great source of potassium which helps to promote muscle recovery. Fresh fruits, especially citrus and melons, and vegetables, especially leafy greens and broccoli, are also rich in potassium.  You can also find the mineral in fish, most meats, and milk. Sweet potatoes and legumes like lima and kidney beans are also high in potassium.

Because you lose potassium through sweat and urination, you need to be consuming these potassium-rich foods each day, especially if you’re an athlete. Low potassium levels can reduce your energy and endurance. A recent Australian study with highly trained athletes showed that drinking a caffeinated beverage immediately before exercise can help to maintain adequate potassium levels in your blood and delay fatigue during your workout.

Your body will definitely let you know if you’re not hydrated. If you’ve been experiencing muscle cramping or high levels of thirst, get your potassium and sodium levels checked with an InsideTracker Plan. If your potassium or sodium levels are not optimal, InsideTracker will provide you with recommendations about what to change in your diet, and introduce you to some new foods that can help.

Don't let dehydration hinder your performance. Download this guide now for more hacks to enhance your endurance, 


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