Hydrating for exercise and sports performance

author:  Kelly Gill, MS, RD, CSSD, LD


Need clarification on fluid needs surrounding workouts and/or sporting events?  Wonder about the effect of caffeine on hydration and performance?  This blog and infographic provides recommendations for hydration in competitive athletes of all ages, as well as “weekend warriors” (as in those who work out regularly).  It even touches on the effects of caffeine and how to use it, safely, to enhance performance.






Proper hydration is necessary for optimal performance

Whether you play sports at the professional level, the recreational level, or any level in between, or even if you don’t play sports at all but do work out regularly, proper hydration is essential to optimize your performance. If you are not properly hydrated, you can experience the effects of dehydration, as listed below, which will hinder your performance and keep you from being your best.




Symptoms of dehydration:

  • Lack of concentration
  • Early fatigue during training
  • High perceived exertion in training
  • Trouble tolerating heat
  • Delayed recovery
  • Muscle cramps
  • Headaches
  • Nausea and vomiting
  • Elevated heart rate above normal



**The best and most effective line of defense against dehydration is to manage your thirst

Drink when you are thirsty.  Stop when you are not.  Barring medical issues, managing hydration is usually as simple as that.  Everyone wants to know how much fluid they need per day.  Formulas used by professionals just provide only a jumping off point.  There is no precise way to know exactly how much fluid you need.  Plus, your fluid needs change from day to day.

Certain strenuous events, like performing in extreme heat or completing an ultra marathon, etc., warrant further evaluation and a possible work up with a professional!




How much water do I need?

First, listen to your body’s cues for thirst.  Second, confirm your hydration by checking the color of your urine (see the color chart in the infographic above).  Third, pay attention to the signs and symptoms of dehydration as listed above.  Furthermore, here are some specific tips you can follow before, during, and after a game/practice/exercise:


Before activity –

Assess your urine before a sporting event or workout!  Your urine should be pale yellow prior to your activity.  Don’t start a sporting event or a workout in a dehydrated state!!  If you are dehydrated, drink ~16 oz fluid to re-hydrate approximately 30 minutes prior to your activity.  Don’t overdo fluids so that you feel bloated or water-logged.  If you’re already hydrated, then 8 oz of water ~15 minutes before your activity will help to sustain proper hydration for the activity.


During activity –

As a rule of thumb (individual needs may vary, depending on many factors, like type of activity, intensity, heat, and sweat volume and concentration),  ~3-8 oz water (2-3 large gulps) every 15-20 minutes will support fluid needs during your exercise or event.


After activity –

Drink to recover your thirst and ensure pale yellow urine.




Difference between types of fluids:


  1. Water: The best fluid to consume for any activity lasting less than an hour is water.  This should be your default drink.

The reason it’s so great is because it’s pure!  There’s nothing else to factor in.


  1. Sports Drinks: Sports drinks only need to be consumed when exertion lasts more than an hour (possibly less depending on intensity)

The added sugar from sports drinks fuels the muscles while the fluid and added electrolytes help replenish losses from sweat.  However, drinking sports drinks for workouts or sporting events lasting less than an hour provides added calories from sugar that is not necessary and can interfere with any weight management efforts.  

Parents, this message applies to kids, too!  They do NOT need sports drinks during activities where their exertion lasts less than one hour.  There is a benefit to sports drinks in events requiring an hour or more of exertion, or for additional fuel between activities.  Of course, individual needs vary.  Variables to consider include intensity as well as sweat factor.   Fatigue is a clear sign of depleted stores, in which repletion with a sports drink can be beneficial.  However, the process of repletion can take ~15 minutes.  One benefit of training, is learning through your training what your individual needs are and what amount of fluids, added sugar, and electrolytes maximize performance without causing unwanted weight gain or water log.


  1. Fruit juice: High in calories.  Limit to one serving at a time (and really per day!).

Fruit juice provides fluids, sugar, and vitamins/minerals.  While, it contains beneficial vitamins/minerals, it has more sugar (although natural sugar) and calories per ounce than most sports drinks and soda.  So, volume should be moderate.  Ideally, vitamins and minerals would come from whole fruit and not fruit juice!  No one NEEDS to have fruit juice.  Drinking juice is just a matter of preference.  Consumers should know the pros and cons.


  1. Soda: No nutritional benefits.  Some caffeine can enhance sports performance (see below).

Soda does provide fluids, along with added sugar and caffeine.   However, it offers no health benefits.  While some caffeine can enhance sports performance, too much caffeine can have negative side effects (see information below on benefits and side effects of caffeine).  Soda is NOT recommended before, during, or after exercise, as the carbonation can negatively affect performance.


Side Note on Diet soda:

Diet soda is made with artificial sweeteners, which some people find concerning.  I, however, am not so concerned, provided it’s consumed in moderation.  First, diet soda has been around for about 60 years!  With that kind of staying power, it just can’t be ALL bad, can it?  Second, artificial sweeteners are regulated by the FDA.  All artificial sweeteners used in diet soda have been approved by the FDA and are considered Generally Recognized As Safe (GRAS) for consumption.  Third, substantial research (like hundreds and hundreds of studies!!) has been and continues to be conducted.  In fact, artificial sweeteners are studied more than any other food additive.  There is NO evidence of health risks in humans with the use of artificial sweeteners.  With that said, research shows that people who drink diet soda do not weigh less than those who don’t.  While diet sodas are considered safe, they are not necessarily healthy!  Be smart, use in moderation! 



Moving on to caffeine…


I was in line to check out at the grocery store when I heard the lady in front of me announce to the checker, “caffeine is bad.”  Did you know there are some positive benefits of caffeine, when used properly?  Especially when it comes to enhancing performance.  And what’s wrong with enhancing performance, whether it’s at work or at the gym?


Positive Effects of Caffeine (in moderation):
  • Enhances endurance exercise performance
  • Improves reaction time, concentration, and self-perceived energy levels
  • Low doses increase energy expenditure and oxygen uptake without changing perceived effort, exercising heart rate, or fuel usage
  • Delays feelings of fatigue, and lessens sensations of exertion and pain
  • Reduces time to complete a set amount of work


Now, too much can be a bad thing.  Plus, drinking too much can cause you to build a tolerance to it, which is a shame.  Once you’ve built up a tolerance, then you miss out on all the benefits listed above.


Possible Side Effects of Caffeine (in excess):
  • Anxiety / nervousness
  • Overstimulation / jitteriness
  • Mental confusion
  • Elevated resting heart rate
  • Restlessness
  • Inability to focus
  • Gastric irritant
  • Mild diuretic
  • Insomnia / disrupted sleep
  • Addiction (from overuse and reliance)



So, take care to drink caffeine in moderation and avoid building up a tolerance or adaptation to it by not drinking it everyday.  Or drink minimal amounts daily, allowing an “ergogenic” dose just on days you want to enhance performance.  Daily intake of caffeine should be less than 0.5-1.0 mg/lb (1.1-2.2 mg/kg), which is 75-150 mg for a 150 lb person.


For ergogenic effect (performance enhancing) of caffeine, research supports 2-3 mg/kg (136-205 mg for 150 lb person).  Older studies used doses of 5-6 mg/kg, but newer research finds amounts that high are no more beneficial than the 2-3 mg/kg being recommended now (In other words, once performance is enhanced from caffeine, there is not further benefits from taking larger doses). 


 Athletes looking for ergogenic benefit from caffeine, should
  1. save caffeine for competition days
  2. not develop intolerance to caffeine by regularly over-consuming, and
  3. experiment, starting with amount of 2 mg/kg and increase as needed to find that point of noticeable benefit from caffeine. 


**The practice of using caffeine as an ergogenic aid is NOT recommended for adolescents! 


Adolescents gain more advantage from
and increased experience
than from any ergogenic supplement!!



Here’s an idea of how much caffeine is in certain beverages/foods:
  • one 12 oz soda may have between 23-55 mg caffeine (this excludes root beer and lemon-lime sodas, which have 0-18 mg)
  • one 8 oz coffee may have between 85-100 mg caffeine
  • one 8 oz tea may have 10-70 mg caffeine
  • one 3.5 oz milk chocolate bar may have 10-15 mg caffeine
  • Energy drinks can vary widely.  They are not required to include caffeine on the label.  Consumer reports, in December 2012, tested 27 top-selling energy drinks and found them to contain anywhere from 6 – 242 mg caffeine per serving (*consider some drinks have more than one serving per container).

If you’re interested in a more detailed list of caffeine amounts, click here.


Other information on caffeine:


According to a Consumer Reports article from December 2012, five of 16 products tested had more than 20% of the amount of caffeine listed on their label and one of the products had 70% less caffeine than what was on their label.    The other ten were within 20% of the amount listed on their label, which is considered reasonable.

There is no requirement for a product to list the amount of caffeine, and this report found that 11 out of 27 energy drinks don’t even specify the amount of caffeine.

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  • hoteratus.com November 12, 2017 Reply

    The best nutritional plans for athletes will include fluid replenishment that will allow the athlete to train consistently to meet the desired adaptations to training in terms of specificity and progression.

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