Don’t Be Dehydrated: Key Hydration Tips

Is there anything better than an ice cold glass of water after a long training run or bike ride in the summer time (maybe a nap too)? When we are talking about performing optimally on your run, there is nothing more important than staying properly hydrated during, and not just after. Dehydration can slow you down, and increase recovery time and stress on your body. Do you know how much fluid you should be drinking on your run? Let me help you figure it out.

Sweat rate: Step one in figuring out how much H2O you should be drinking is to determine your sweat rate. To do this, you should weigh yourself naked right before and after exercise, adding back in any fluid you drank on the run. Any weight difference is the amount of water lost as sweat (1 lb = 16 oz fluid). So if you lost 2 lbs, then that equals 32 oz of water lost as sweat. If you drank 8 oz during your run, you add that back in, and it means you lost 24 oz (32oz – 8oz) or 1 1/2 lbs. The next time you run that distance you should plan to drink 80-100% of the amount lost to stay hydrated. You don’t want to drink to discomfort, but you should shoot for regular fluid intake throughout your run to eliminate excess fluid sloshing around in your stomach. Practice drinking fluids during training, so  that you can get an idea of how much fluid your body can comfortably tolerate.

Thirst: Thirst can be decreased during exercise or even overridden by the brain. You may have lost 1% of your body weight before you even feel thirsty, which is 3 cups (24 oz) for a 150 lb person.  A 2% weight loss meets the definition for dehydration, and a 3% loss can impair performance and cause you to lose mental focus.

Daily hydration checking: Check the color and quantity of your urine every day. If you have small amounts of dark urine, then it means your body is concentrating metabolic wastes and you need to drink more. Vitamin supplements can cause urine to be darker, so the overall amount can sometimes be a better judge than color.

Signs of chronic dehydration: Fatigue, headache, and lethargy—these symptoms commonly occur during the hot summer months.

Electrolytes: Replacing electrolytes, specifically sodium is very important when you are exercising for over an hour. Plain ol’ water will do for exercise under an hour. Sodium losses can range from 800 mg to as high as 1600 mg per quart (32 oz) of sweat. People who are not as acclimated to heat and are less fit will sweat higher amounts of sodium. Muscle cramps can also be associated with dehydration, so if you sweat more than the average person, try to consume sodium containing fluids while exercising, because it will help you retain fluid. If you find it difficult to drink enough to stay hydrated, sodium containing foods can help stimulate thirst and retain fluid. Target intake is 250-500 mg of sodium per hour, which is the amount in 20-40 oz of Gatorade.

Hyponatremia: A dangerous condition that occurs when blood sodium levels become dangerously low from diluting the blood with too much water. Hyponatremia tends to affect those who exercise longer than 4 hours in the heat; it’s good to avoid plain water before an event, and eat salted foods and fluids prior to exercise like pretzels, salted oatmeal, and soup. You should also consume salty food during the event, and stop drinking water if your stomach is sloshing during the run.

Fluids before exercise: Shoot for 5-7 ml/kg or 2-3 ml/lb (one oz = about 30 ml) four hours prior to exercise. This will allow excess fluids to be eliminated prior to exercise or an event. Drinking a beverage with sodium, or having a sodium containing snack can help you drink more and retain fluid.  Over-hydrating can make you need to use the bathroom during a run, and dilute your electrolytes. Drink again 5 to 15 minutes pre-exercise.

Fluids during exercise: Prevent excessive dehydration, more than a 2% weight loss, while exercising. If you are exercising for more than 3 hours you really should know your sweat rate to prevent dehydration. Best hydration ratio: per 8 oz of fluid = 110-170 mg sodium, 20-50 mg potassium, and 12-24 grams of carb, which is about 50-95 calories. Drinks like Gatorade and Accelerade have the right combo of sodium, potassium, and carbs. If you prefer another glucose source like dried fruit or gummy candies, both Nuun and GuBrew tabs have the appropriate amount of sodium and potassium without additional calories from carbohydrates.  You should consume 30-60 grams of carb (120-240 calories) per hour when exercising hard for longer than an hour to maintain normal blood glucose and sustain a workout.

Fluids after exercise:  Drink 50% more than you lost to enhance recovery from dehydration. Most people can recover with normal meals and water. Sipping over a longer period of time is more beneficial than drinking a large volume in one sitting, because your body can only absorb so much fluid at once.  After a big event you should continue to hydrate over the next 24 to 48 hours.

Foods/Drinks that are hydrating: You don’t need to exclusively focus on water for rehydration; there are a lot of vitamin and mineral rich foods that have a high water content and count towards rehydration.