Hydration Foundation


It’s heating up out there. If you’ve got your sights set on a fall race – which we all hope happens as scheduled! – you might already be getting into some long, tough workouts. Set yourself up for success with a solid hydration strategy to combat the hot weather.

Why do we care about hydration? Water is the medium in which your cells carry out chemical reactions. It helps maintain your body temperature, shuttling heat away from your muscles as they work hard on a run, as well as carrying oxygen and glucose to your cells to keep you going. Meanwhile, electrolytes – sodium, potassium, calcium, magnesium, chloride – are necessary for our cells to function properly. Even a slight variation in electrolyte balance can have serious health consequences, so athletes must have a solid hydration plan in place to avoid electrolytes getting too high or too low. In hot weather when we lose more fluid and electrolytes through sweat, hydration becomes even more important.

You might already know that the easiest way to check your fluid status is to take a look at the color of your urine (gross, but also helpful). Pale yellow indicates good hydration status, while darker urine (or no urine) can indicate dehydration. Other signs of dehydration include dizziness, fatigue, rapid heartbeat, extreme thirst, confusion, and lack of sweat. If you experience this on a run, stop exercising. Get yourself into a cooler place and start rehydrating and refueling immediately.

Your best bet, of course, is to avoid these symptoms altogether. To do that, start hydrating well in advance of your run. When you have a run scheduled in warm weather, make time to hydrate the day before, including some form of electrolytes. If you’re not a fan of sports drinks, try salty liquids like broth or soup. On the day of your run, aim for ~16-24 oz of fluid 2-3 hours beforehand, and another 8 oz within 30 minutes of starting out.


Drinking fluids throughout the run is also important. If your stomach does okay with regular sports drinks like Gatorade, these are fine; however, sometimes the high concentration of sugar can actually pull water into your gut, which not only defeats the purpose of hydrating but also causes GI distress. Similarly, “sugar-free” options can also sometimes cause an upset stomach – many contain sugar alcohols, which are known to cause diarrhea. A low-carb (no more than 3-4% calories from carbs) choice is usually a safe bet if you’re prone to tummy trouble. Not a fan of sports drinks? Salt tabs are okay, but you need to be sure to drink enough fluid along with them, or you again risk pulling water into your GI tract instead of keeping it in your body.

Of course, it’s possible to overhydrate as well. This is one of the reasons I suggest drinking more than just plain water during a long run. Ingesting too much fluid can cause a drop in the sodium level of your blood, which can lead to mild symptoms (headache, nausea), all the way up to cerebral edema and death. Seasoned athletes should be able to use thirst as a primary indicator, but when exercising in hot conditions you also need to use common sense, because it’s much easier to become dehydrated. Ultimately, you want to consume fluids early and often, but you don’t need to replenish every ounce you sweat off during the run, either. Keep yourself hydrated enough so that your performance is not compromised, without overdoing it.


One way to gauge how much fluid you need to replenish is to perform a sweat rate test. Weigh yourself in the same dry clothes before and after your run (not the clothes you run in, which will absorb some water from your sweat). For every pound you have lost during the run, you need about 3 cups of fluid to rehydrate – plus the amount you drank on the run.

Your hydration status can be affected by many different variables, including the temperature, what time of day you’re running, GI issues, hormones (ladies – during the last two weeks of your cycle, your sense of thirst is reduced, so you need to cue yourself to keep up your hydration), body size, and more. Test out different products to find one that sits well with your stomach, so you are ready to go for your toughest runs. Above all: plan ahead, so you can keep going as the thermometer creeps up!


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