Hydration and its Effects on Exercise & Athletic Performance

Part 1 – The Signs and Symptoms of Dehydration

The truth is that up to 75% of the population in America is walking around dehydrated. When we exercise, we lose even more fluids and if they aren’t replaced, then chronic dehydration can occur which leads to a host of problems. Some of the well-known signs and symptoms of dehydration such as thirst, muscle cramps, dry mouth, dark-colored pee, nausea and dizziness are indicative of severe dehydration – when we are very under-hydrated. We really need to focus our attention on the earlier signs and symptoms and be proactive in our hydration strategies. 

Studies show that the simplest thing we can do to improve exercise & athletic performance is to maintain proper hydration. In this Part 1 of a 3 Part series on hydration and exercise performance we are going to first focus on how to determine if we are not well hydrated – exploring the signs and symptoms of dehydration.  In Part 2 we will explore the biological mechanisms of why hydration is important for exercise and what happens when the body is hypo-hydrated or dehydrated.  (Spoiler alert – it puts us at major risk for injury and impaired results!) Part 3 will focus on our unique fluid needs and how to calculate how much we need to be consuming before, during and after our workouts. This information is applicable for those at any level of physical fitness or for any level of intensity of workouts.  


Even Athletes are Dehydrated!

Science has concluded that the hydration status of our body has a direct effect on exercise & athletic performance. Yet, studies have shown even the people who endure the most intense physical activity, namely athletes, need continual reminders to drink the right amount of fluids.   As evidenced in a recent study that showed although it is well-known in most all athletes (97.6%) that dehydration decreases performance.  Yet this knowledge doesn’t always lead to correct behavior, as 66% of NCAA Division I athletes at a single university were found to be in a state of hypohydration (Volpe et al., 2009).  These high rates of hypohydration have also been found in other studies in athletes and in the general public.  How can we still be under hydrated when we “know” how important it is? 


Knowing What’s Best Yet Not Doing What’s Best 

This phenomena of knowing what’s best yet not doing what’s best can be said about a lot of things and not for just athletes but all people – getting the right amount of sleep is paramount to health but we as a society are not getting enough; eating processed foods is not the best form of nutrition but obesity rates are at epidemic levels.  Being human seems to put us at risk of knowing but not doing, especially in terms of our fluid intake. This is one reason why there is a push for more education and monitoring of hydration in athletics.  But what about non-athletes? Don’t we need a push too?  Actually, studies have also shown that we do too, as we are a ubiquitously hypo-hydrated society.  And anyone who exercises should be especially aware of their fluid intake  – click on this link to learn more about how you can better monitor your daily hydration needs.  Being aware of how much or little you are drinking in a day is the first step to remedy the problem because as the famous functional medicine doctor, Dr. Eric Balcavage says “what gets measured gets managed.” 

 The other side of the coin in addressing the dissonance between knowledge and action is education, specifically understanding the signs and symptoms (your body’s signals to you) of dehydration.  You can be aware that hydration is important but if you are missing the clues your body gives you, you won’t know when it’s time to get some extra fluids. This is especially important when we exercise, as dehydration has a massive impact physiologically on our cardiovascular, skeletal and muscular systems.  Being dehydrated can actually put us at higher risk of actually hurting ourselves!  Stay tuned for more information on this in Part 2.


Proper hydration = Better workout

As mentioned, being in a state of dehydration before, during and after exercise can lead to problems like injury and excessive stress on the body.  It can also lead to a plunge in results. We shouldn’t have to squander the time we do spend working out because we are not hydrated.  A review of the effects of dehydration demonstrated that dehydration could have an impact on strength and power. Cheuvront and Kenefick (2014) reported that just  ≥ 2% dehydration impaired endurance exercise performance.  According to a meta-analysis by Savoie et al. (2015), hypohydration caused muscle strength to fall by 5.5 ± 1.0% (p < 0.05) and anaerobic power fell (-5.8 ± 2.3%).  Simply translated, you are not going to be at your best nor obtain the best results when you are not drinking enough fluids to meet the demands of physical activity.


The Signs & Symptoms of Dehydration 

When we are under hydrated we feel thirsty, which is considered a symptom of dehydration. The feeling or perception of thirst hopefully leads us to increase our fluid intake. But thirst is definitely not the best indicator of dehydration.  It is actually one of the body’s SOS signals that is produced from our master regulator gland in the brain, the hypothalamus, when it senses we are in need of hydration.  That is not to say that thirst is a bad thing, it’s just a signal that our tank is pretty empty. When we are in this state of hypohydration the cardiovascular system is stressed and has reduced physical capacity, placing us at a higher risk for musculoskeletal injury.   Rather than relying on thirst to guide drinking habits, a better strategy is to make sure you are drinking enough water so that you do not experience thirst.  Utilize an app that reminds you to drink water or set the amount of water out on your kitchen counter or on your desk at work where you can visually see how much you need to drink for the day.  

What other symptoms and signs can be monitored? In their best selling book on optimum hydration, Quench, Dr. Dana Cohen & Gina Bria remark that although “there’s no exact science to determine whether you’re chronically dehydrated; there’s no reliable test your doctor can offer or a score by which you can measure your water level.  But there are some good indicators that you may need more fluid in your body.”  Here are some self-tests you can perform to evaluate your hydration status:  

  • Observe your urine – make sure your urine is clear to light yellow in color (straw colored), not dark yellow, which can be an indicator that you need more fluid intake.  Also watch for low urine output.  Dr. Peter Attia, MD recommends that a person should be urinating every 90 minutes to avoid being under hydrated.  
  • Pinch your skin – if it “tents”, meaning it doesn’t bounce back to its normal shape, you may be dehydrated.  (It is best to use the skin on the tops of your hands)
  • Apply pressure to your fingernail for 3 seconds – If it takes longer than 3 seconds for the color to return to your fingernail bed then you could be dehydrated. 
  • Keep Track of Your Weight – Although this may sound excessive, weighing yourself before and after exercise (especially if you’re exercising in a hot climate or for more than 60 minutes) can be helpful to know how much you need to consume to replenish your loss. 
  • Use a Body Impedance Analysis (BIA) device – BIA devices have become very affordable and actually are pretty accurate in determining your hydration status.  Check out FitTrack or RENPHO.  As an added bonus they also measure total weight, fat percentage and lean muscle mass! 

Find out more on water monitoring in our Guide to Daily Water Intake here.

Getting the Best ROI for Our Efforts!

When we truly understand our body’s signs & symptoms pointing towards dehydration, this can guide us into taking better care of our daily fluid needs.  With this knowledge we can move from knowing to doing, allowing us to get the best ROI for the time we spend sweating it out!




  1. Judge LW, Bellar DM, Popp JK, Craig BW, Schoeff MA, Hoover DL, Fox B, Kistler BM, Al-Nawaiseh AM. Hydration to Maximize Performance and Recovery: Knowledge, Attitudes, and Behaviors Among Collegiate Track and Field Throwers. J Hum Kinet. 2021 Jul 28;79:111-122. doi: 10.2478/hukin-2021-0065. PMID: 34400991; PMCID: PMC8336541.
  2. Volpe SL, Poule KA, Bland EG. Estimation of prepractice hydration status of National Collegiate Athletic Association Division I athletes. J Athl Train. 2009;44:624–629. 
  3. Nichols PE, Jonnalagadda SS, Rosenbloom CA, Trinkaus M. Knowledge, attitudes, and behaviors regarding hydration and fluid replacement of collegiate athletes. Int J Sport Nutr Exerc Metab. 2005;15:515–527.
  4. Cheuvront S, Kenefick R. Dehydration: Physiology, assessment, and performance effects. Compr Physiol. 2014;4:257–285
  5. G. Bria, D. Cohen, Quench: Beat Fatigue, Drop Weight, and Heal Your Body Through the New Science of Optimum Hydration. Go Hachette Books, 2019.

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