Hydration: Know What You’re Consuming


By Erik Bustillo, MS, RD, FISSN, CSC, CPT

Hydration helps performance, dehydration hinders it. Even though we know hydrating is important, we can sometimes forget to drink fluids, or we might do things that are suboptimal for hydration. Being dehydrated is associated with serious negative health and performance side effects, such as:

  • Decreased power output and performance capacity [1]
  • Decreased reaction time [1]
  • Decreased vigilance and ability to perform multiple tasks [1]
  • Decreased kidney function [1]

All of these potential impairments in performance and health can have serious consequences for the tactical athlete (TA). The TA is responsible for the care of others, which requires top performance in all of the above mentioned; TAs also tend to wear heavy gear, which can contribute to increased risk for dehydration.  Unfortunately individuals may not recognize there’s a problem until they are already under hydrated. With this information in mind, it can be helpful to know what might work and what might not for optimal hydration. Below, we will take a look at several commonly consumed beverages and how they may impact performance.

Sports drinks: 

How the beverage impacts hydration They can help improve hydration and performance because of their glucose (sugar), electrolyte, and fluid make up, as described in a position stand by the International Society of Sports Nutrition (ISSN)[2].

How/when to consume 1 cup of 20g carbohydrate approximately every 30-40 minutes if training for more than 60 minutes.

Common misconceptions Not meant to be consumed regularly outside of training or training-like conditions where fluid is lost; often times, athletes consume these beverages like water throughout the day having done zero physical activity.


How the beverage impacts hydration Coffee can function as a hydration tool. It is important to be mindful of the impact coffee has on you as an individual. It may increase the feeling that you need to use the restroom, but this impact is not the same in all people.

How/when to consume This varies per individual and what amount(s) they are used to consuming, but 1 cup of coffee can be safe to consume.

Common misconceptions Coffee is not a diuretic in the form of making an individual have to urinate more.


How the beverage impacts hydration Alcohol shuts off a hormone called Antidiuretic hormone (ADH) production, a hormone that makes us not urinate… this means alcohol increases urination frequency.

How/when to consume For performance, it is best not to consume alcohol before or during training/training-like scenarios.

Common misconceptions Although small amounts of beer may help with rehydration, it is best not to have more than one beer POST training.

Energy drinks:

How the beverage impacts hydration May help improve hydration, depending on what it contains. Similar to sports drinks, some energy drinks may contain sugar; however, energy drinks often contain caffeine as well. 

How/when to consume Best to consume 8-12 ounces before training that will last 60+ minutes, but a better option in this scenario would be a sports drink that contains glucose and electrolytes.

Common misconceptions Contrary to popular belief, energy drinks are not automatically harmful and may help in athletic performance, but the setback is that they are overconsumed by frequent drinkers and this may add unnecessary calories and sugar to one’s diet. [3]


How the beverage impacts hydration Sodas may increase thirst if consumed in large amounts; however, this high sugar beverage may prove beneficial when an individual is training for long periods and needs fast sugar/energy in their body.

How/when to consume During training bouts lasting longer than 90 minutes, drink 8-12 ounces; consider diluting if sodas impact how your stomach feels.

Common misconceptions Nothing to do with hydration, but diet soda does not contribute to weight gain; however, it should still be consumed in moderation.


How the beverage impacts hydration Water is the most important nutritional ergogenic aid (something that helps increase performance) and should be the majority of the fluid consumed by TAs.

How/when to consume Best to consume no less than 2.5 liters daily at a MINIMUM; hydration after 2.5L then depends on physical activity, body size, and sweat rate.

Common misconceptions  1 gallon a day is not standard nor suggested for EVERYONE. Overhydration is also possible.

Don’t Fall for the Myths

There are many misconceptions regarding hydration, so be careful not to fall for them. Instead, refer to the above as a guide to popular liquids and how they may help/hinder the TA. Every person is different and it is best practice to know how these beverages impact the way you feel. Moderation is important with many things in nutrition and we can see that there is a time and place for all beverages; some more optimal compared to others. 


  1. P. A. Hancock & I. Vasmatzidis (2003) Effects of heat stress on cognitive performance: the current state of knowledge, International Journal of Hyperthermia, 19:3, 355-372, DOI: 10.1080/0265673021000054630
  2. Kerksick, C.M., Wilborn, C.D., Roberts, M.D. et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr 15, 38 (2018). https://doi.org/10.1186/s12970-018-0242-y
  3. Campbell, B., Wilborn, C., La Bounty, P. et al. International Society of Sports Nutrition position stand: energy drinks. J Int Soc Sports Nutr 10, 1 (2013). https://doi.org/10.1186/1550-2783-10-1