The Importance of Drinking Water

Many of the pages on CrossFire CrossTraining and Krav Maga’s website mention bringing water to class. This is because water is crucial for the human body to function, especially during hot days or exercise. The human body is made up of 60% water, but cannot manufacture its own supply.1 The only way your body can replenish its water supply is by bringing water in from outside sources, like a water bottle or drinking fountain.


Keeping your body well-hydrated is important to successfully performing many functions your body needs to stay healthy, especially during workouts. Water helps carry nutrients to muscles and waste products away from muscles. Muscles use glucose as fuel to work quickly and efficiently. After using that glucose, muscles create lactic acid as a byproduct. Water makes sure glucose can reach the muscles, then carries away the lactic acid, which helps stop cramps from happening. Even the blood that keeps muscles moving is largely made of water, which helps circulation. Joints, skin and the nervous system all need water to function. Joints are lubricated with water so they can withstand impact.2 Skin – and in turn the whole body – is cooled when sweat meets the air. Water even keeps the nervous system operating efficiently, helping both response time and coordination.3


The temperature of drinking water can be important as well, since water does more than just help your muscles function. Water also helps maintain the body’s internal temperature. Generally speaking, cool water (around 16C, which is typically the temperature of tap water) is recommended for athletes.4 Most people are more likely to drink cool water over other temperatures, thus making rehydration both easier psychologically and physically.5 Cool water can act as a heat-sink for the body, allowing it to cool down after or during exercise. Due to this cooling effect, cool water tends to be soothing.6 Cold water, however, can prolong the body’s satiation and gastric emptying rate, which results in drinking less water than the body needs to rehydrate.7 Warm and hot water puts more stress on the body, as the body will need to spend more energy cooling that water down.8 Cool water, then, tends to be the easiest for the body to digest and use efficiently, especially during workouts.


Knowing when your body requires water can be difficult. Thirst is not a perfect indicator of how much water a body needs. Individuals who only drink to satisfy thirst tend to replace only half of the water lost through sweat and other water losses.9 However, it is also important not to force yourself to drink if you feel full or otherwise ill. Forcing yourself to drink may induce nausea and discomfort while working out. 10 Individuals who sweat profusely, may lose too much water in sweat to drink that same amount of water within a workout period. Forcing yourself to do so may exacerbate the risk of other issues, such as losing too much sodium through profuse sweating.11 If you’re not sure how much water to bring to class, two to three quarts is a good general guideline.12 It is important to bring at least this much if the weather is warmer or more humid than usual.


With all this work to remain hydrated, it is worth noting what dehydration does to the body. While dehydrated, heart rate will increase, body temperature rises, and coordination becomes more difficult. With more severe dehydration, the body may stop sweating altogether, taking away the body’s natural means of cooling itself down. The human body will begin to retain whatever water it has left when it recognizes dehydration. This results in a lack of sweat and bloating.13 Early signs of dehydration can also be recognized in changes in mood and symptoms of fatigue.14 Cognitive performance also slows down, particularly in the realms of vigilance, short-term memory, reasoning and hand-eye coordination.15


Water is incredibly important to the human body, but it is not the only workout drink marketed towards people who exercise. The use and effectiveness of sports drinks are still debated among fitness professionals and nutritionists. Generally speaking, if a cardio workout is less than 45 minutes, then sports drinks are unlikely to help much. A body will lose more water through sweat in that time than it will electrolytes or carbohydrates. Water will also absorb more quickly into the body for immediate use. If a workout lasts more than 45 minutes, sports drinks may prove useful. Be careful when buying sports drinks, however, as anything with less than 5% sugar tends not to contain enough energy to be useful, while anything over 8-10% is sugary enough to potentially cause intestinal cramps and nausea.16 A spilled sports drink can also make the floor sticky and attract insects. If you choose to bring sports drinks into an indoor gym, please make certain it is in a sealable container.


For most people in CrossFire classes, water is the way to go. Taking sips of cool water throughout a workout can help maintain a healthy, hydrated state, as well as lower rising body-temperatures, and support muscles and joints. A water fountain is also available in the MAI studio for quick drinks or to refill your bottle. So grab those water bottles and hit the mats.



  1. Karen Andes and Diane A. Welland, M.S., R.D., The Complete Book of Fitness: Mind · Body · Spirit (New York: Three Rivers Press, 1999), 247.
  2. Ibid.
  3. Andes and Welland, Complete Book of Fitness, 248.
  4. Saeed Khamnei, Abdollah Hosseinlou and Masumeh Zamanlu, “Water temperature, voluntary drinking and fluid balance in dehydrated Taekwondo athletes,” Journal of Sports Science and Medicine 10 no. 4 (2011): 720, PMID 24149564.
  5. Khamnei, Hosseinlou and Zamanlu, “Water temperature,” 722.
  6. G.S. Wimer, D.R. Lamb, W.M. Sherman and S.C. Swanson, “Temperature of ingested water and thermoregulation during moderate intensity exercise,” Canadian Journal of Applied Physiology 22 (1997) quoted in Saeed Khamnei, Abdollah Hosseinlou and Masumeh Zamanlu, “Water temperature, voluntary drinking and fluid balance in dehydrated Taekwondo athletes,” Journal of Sports Science and Medicine 10 no. 4 (2011): 721, PMID 24149564.
  7. P. Butudom, D.J. Barnes, M.W. Davis, D.B. Nielsen, S.W. Eberhart and H.C. Schott II, “Rehydration fluid temperature affects voluntary drinking in horses dehydrated by furosemide administration and endurance exercise,” Veterinary Journal 167 (2004) quoted in Saeed Khamnei, Abdollah Hosseinlou and Masumeh Zamanlu, “Water temperature, voluntary drinking and fluid balance in dehydrated Taekwondo athletes,” Journal of Sports Science and Medicine 10 no. 4 (2011): 721, PMID 24149564.
  8. Khamnei, Housseinlou and Zamanlu, “Water temperature,” 722.
  9. Andes and Welland, Complete Book of Fitness, 247.
  10. Marc Jacobson, “The Effects of Sports Drinks Containing Caffeine and Carbohydrates on Soccer-Specific Skill Performance During Match-Induced Fatigue,” master’s thesis, University of Victoria, 2009, 44, University of Victoria Library Catalogue – Main.
  11. Sandra Fowkes Godek, Chris Peduzzi, Richard Burkholder, Steve Condon, Gary Dorshimer, Arthur R. Bartolozzi, “Sweat Rates, Sweat Sodium Concentrations, and Sodium Losses in 3 Groups of Professional Football Players,” Journal of Athletic Training 45 no. 4 (2010): 369.
  12. Ibid.
  13. Andes and Welland, Complete Book of Fitness, 248.
  14. Harris R. Lieberman, “Methods for assessing the effects of dehydration on cognitive function,” supplement, Nutrition Reviews 70 (2012): 143, doi: 10.1111.
  15. Lieberman, “Methods for assessing the effects of dehydration,” 144.
  16. Andes and Welland, Complete Book of Fitness, 248.

Author: CrossFire Sensei

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