Summer has officially begun, and that means heat, heat, and more heat. And if you’re a runner, that translates to a heck of a lot of sweat. It’s always important to hydrate properly, but it becomes crucial in the summer as larger amounts of fluid loss can be dangerous if not replaced adequately. But how do you know when to drink water, when to drink sports drinks, and when to add even more help like salt tabs? Read on to learn when your body needs what, so you can hydrate smartly and safely this summer!
WHY DOES YOUR BODY NEED WATER?
The human body is around 70% water. It is an important part of the cells that make up every organ in your body, it is used to warm and cool you, and it is necessary to maintain a large enough volume of blood to supply oxygen to all of your tissues. You lose water through urination, sweat, and respiratory losses. Respiratory losses are happening 24/7 because you lose a little bit of moisture with each exhale. All of these losses are happening all the time, and they increase due to factors like caffeine (more loss through urine) and heat (more loss through sweat). In order to keep your body in its happy, euvolemic (normal volume) state, you need to replace these losses.
HOW MUCH WATER DO YOU REALLY NEED?
The Institute of Medicine has determined that the average woman needs about 2.7 Liters (or 9 cups) of water per day. The important thing to keep in mind, though, is that you need enough to replace your losses. The amount of water you lose depends on your activity level for the day, the temperature outside, and the humidity in the air you breathe. A glass of water isn’t the only way to replace these losses, either. You get water from any liquid you drink, as well as foods.
IS THERE SUCH A THING AS TOO MUCH WATER?
There can, in fact, be too much of a good thing. Over-hydration can be a serious issue as well, especially for endurance athletes. Your body likes a very particular range of salt in the blood, and normally it can adjust many mechanisms to keep it in this range.
When you run for a long time, especially in the heat, sometimes your sweat gets rid of too much of the salt. On non-race days, you consume food with salt in it and so the lost salt is replaced. In a race, though, you may not be eating at all. If you replace the salty water lost (sweat) with salt-free fluid (plain water), you throw off the body’s salt concentration.
This may sound minor, but it can have serious consequences. Different studies have found that anywhere from 13-29% of athletes have low levels of salt in their blood (called hyponatremia) after common endurance events, including marathons. Most cases are minor, but severe cases can be life-threatening.
The important thing to remember is that when re-hydrating after sweat loss, be sure to drink some things with electrolytes in them, not just plain water. The most important electrolytes to replace are sodium and potassium, because they are used for so many things in your body. These can be found in any common sports drink, like Gatorade, as well as salt tabs or coconut water. Almost every single food you eat has plenty of sodium, and you can get some potassium from items like bananas, potatoes, and avocados.
WHERE IS THE HAPPY BALANCE?
Hydration, like many important aspects of a happy body, is all about balance. You want to replace what you lost, with something similar in concentration. If you are sweating a lot, be sure to ingest some electrolyte-containing drinks or foods along with your water after the race. For cooler days or shorter distances, water is usually fine.
Most importantly, listen to your body. When you’re thirsty, drink. Start with water and add in electrolytes when you’re sweating more. Be careful, pay attention to fatigue or cramping (which can be early signs of dehydration), and replace what you lose.
Stay hydrated and safe out there this summer!
“Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate” Institute of Medicine. Institute of Medicine of the National Academies. 11 February 2004. Web. 24 March 2014.
Wall, Bradley, A., Greig Watson, Jeremiah J. Peiffer, Chris R. Abbiss, Rodney Siegel, and Paul B. Larsen. “Current hydration guidelines are erroneous: dehydration does not impair exercise performance in the heat” British Journal of Sports Medicine (2013). BJSM. Web. 24 March 2014.
Rosner, Mitchell H. and Justin Kirven. “Exercise-Associated Hyponatremia” Clinical Journal of the American Society of Nephrology. 2. 1(2006): 151-161. CJASN. Web. 24 March 2014.
Any other hydration tips? What’s your biggest challenge to staying hydrated?
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