I promised you a Sports Nutrition Series, so here you go…. the first installment!!

Hydration is extremely important in an athlete’s ability to train, compete, and recover. Even slight dehydration (1-2% body weight loss) can have a negative impact on performance.

“No other nutritional intervention comes close to providing the performance-enhancing effects of staying well-hydrated.”Bob Murray, PhD FACSM

Why is dehydration bad? It causes impaired heat dissipation, which causes a rise in body temperature and increased strain on the cardiovascular system. Your heart beats faster, you use up glycogen faster, your brain function becomes impaired, and exercise just plain feels harder. It can also cause overall fatigue and lethargy.

Standard fluid recommendations have traditionally stated ‘drinking to thirst’ is adequate to prevent dehydration. However, this is largely based on sedentary adults, not endurance athletes or heavy exercisers, who typically need more fluid. The American College of Sports Medicine covers their bases by saying learn your personal needs, which can be done by weighing yourself pre and post exercise.

It’s tough to state an actual number or amount of fluid that is recommended since it varies person to person. Essentially, the volume of fluid consumed should be based on sweat lost. Some people sweat a TON and some not at all. The amount of fluid these two types of people need would be different. Fluid should be replaced at a rate close to or equal to sweat loss. Learning how much you sweat can help prevent dehydration. For example, you weigh yourself right before exercise and right after, and notice a 2lb weight loss- this means you should drink an additional 32 ounces of water during your next training so you don’t become dehydrated. [1 pound (16oz) of body weight lost = 1 pint (16 fl oz) of sweat lost] If you weight 150+ lbs try not to lose more than 3lbs. Do this by drinking regularly throughout exercise. Water can be turned into sweat in 10 minutes!

Thirst alone is not the best indicator of dehydration. You get thirsty when your body senses a decrease in body water, or an increase in sodium concentration, meaning you’re only thirsty once you’ve experience a fair amount of loss. Basically that means the sensation of thirst doesn’t match the body’s need for fluid all that well, especially for exercising athletes. Also, fluid quenches thirst before body levels have been fully replaced.

Excessive fluid consumption can also causes a problem by diluting the body’s sodium (called hyponatremia). It’s much rarer than dehydration, but it’s important to be aware of, especially in endurance events.


Things that cause decreased fluid intake:

– Uncomfortable sensation of fluid in the stomach

– Poor access to fluid during exercise

– Lack of education

Ways to increase fluid intake:

– Easy access (nearby, easy container to drink out of)

– Train gut to tolerate more fluid

– Consume fluid at regular intervals

– Make it taste good- improving flavor can increase consumption

– Cool it down – temperature of a beverage has negligible effect on body temperature, but most people will drink more of a cooler beverage

What should I do during training?

– Learn your sweat rate

Practice drinking!

What should I do during an event?

– Put what you’ve learned in training to use

– Drink on a schedule to avoid dehydration or distraction from drinking

How do I know if I’m drinking enough?

Honestly, the answer’s in the toilet. Check the color of your urine.

– It should be fairly clear and of good quantity

– You should urinate every 2-4 hours

– Your morning urine shouldn’t be dark or concentrated

Urine color chart:

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If your urine is darker than number 3, drink more!(Chart developed by L. Armstrong, PhD)

Plain water is adequate during exercise that lasts less than hour. Sports drinks may be a good option in exercise lasting longer than 60-90 minutes. I’ll address sports drinks next time!!


Want something more specific than ‘learn your needs’? Here’s an estimation:

Start off hydrated: Drink 2-3ml per pound body weight 4 hours before exercise. (That’s about 10-15 ounces for someone weighing 150 pounds.) Don’t try to overhydrate- you can only absorb so much at one time and you’ll just pee it out.

Drink regularly during exercise. Have an idea how much fluid you usually lose. Take a couple gulps every 15 minutes.

Replace lost fluid: After exercise, drink 50% more fluid than you lost in sweat. Sipping slowly allows better absorption.

So there ya have it. Obviously there’s a lot more to say about that, but there’s an overview for you. How do you stay hydrated?!