Tag Archives: hydration

Hydrating for Exercise

Sixty percent of our total body weight is water.  Water carries nutrients to cells and helps maintain our body temperature through sweat.  Staying fully hydrated helps our heart and muscles work more efficiently.

With the temperatures rising and summer running approaching, I thought it would be fitting to talk about staying hydrated before, during, and after exercise.  Drinking only when you’re thirsty should not be your goal.  Thirst occurs when we have already lost 1-2 liters of fluid!   So, to stay properly hydrated, it’s important to drink fluids regularly, rather than relying on thirst.

When we lose just 2% of body weight due to dehydration, our aerobic performance suffers.  In order to perform our best and feel our best, we should be fully hydrated before, during, and after exercise!

Prior to Exercise

The majority of people begin exercise fully hydrated.  It is recommended to drink 17 to 20 ounces of water two to three hours before exercise and another 8 oz. about 20 minutes before beginning.  (If the color of your urine is dark yellow, more fluids are needed).   I always have a cup of coffee before running as I’m sure many runners do!  The good news is “caffeine intake has little effect on hydration status with exercise.” 

During Exercise

The purpose of fluid intake during exercise is to prevent dehydration (decreased body fluid) and hyponatremia (low sodium level in the blood).  Here are some guidelines to follow:

  • Try to drink the same amount of fluid that you lose in sweat.  An easy way to determine this is to weigh yourself before and after exercise.  Everyone is different and has different sweat rates but it is advised to drink 8-16 oz. per hour.  (Compared to men, women have lower sweat rates and reduced electrolyte losses).
  • During exercise sessions lasting 90 minutes or longer or if heavy sweating occurs, fluids with sodium are recommended.  Sports drinks are very helpful in replenishing sodium loss.  Another alternative is to consume extra sodium with food before a long exercise session.
  • To minimize fatigue during exercise, consume a sports drink that contains carbohydrate.  Also, if you plan on exercising for longer than an hour, it is recommended to take in carbohydrate with your fluids.  Muscle glycogen stores are depleted with prolonged exercise.  To sustain performance levels and prevent tiredness, you should try to get 30-60 grams of carbs that are quickly absorbed for every hour of training.  Sports drinks come in handy during endurance exercise, as they can replace fluids, sodium, and glucose.  There are many different types of sports drinks and it’s best to use trial and error to figure out which brand you like and see that it doesn’t cause stomach issues.  Most races have a sports drink available during the event. If you plan to take advantage of this, then you should find out what brand is being used and practice with it during training to make sure it works for you.

Post Exercise

After exercising, your goal should be to make up for any fluid imbalance that occurred during your training.  This includes water to restore hydration, carbs to restock glycogen stores, and electrolytes to boost rehydration.  Symptoms of severe dehydration are nausea, vomiting, or diarrhea.  If this occurs, you may need to have fluids replaced intravenously (put directly into a vein).

Most athletes can fully rehydrate with their usual meals, snacks, and fluids.  If you plan on training within 12 hours or less after your session, you should try to drink about 1.5 liters of fluid for each 2 pound lost.

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It’s important to note that the human body is able to tolerate substantial changes in fluid intake while exercising and at rest with little or no effects on health.  Because of this, most recreational exercisers will never experience hyponatremia or severe dehydration.  Prolonged or intense exercise in extreme heat does increase health risk.

To be safe, feel good, and perform your best, it is essential to drink water throughout the day and try to maintain body water stores.  Don’t just rely on thirst.  Make water easily available, bring a water bottle with you when your on the go, or even set a reminder on your phone.  Take charge, have a plan,  and drink up!

How do you make sure you’re drinking enough fluids?

Do you like sports drinks?  What is your favorite?