If you’re an avid runner, then you might be familiar with how quickly dehydration can impact your running performance. So then you start to wonder how to carry water while running…

Starting a run, you often feel good and ready to hit a new PR. As you continue running, however, especially in the heat or on longer runs, you may start to feel sluggish, cramp, or even get a headache, and suddenly, you aren’t sure how long the run will last.

You might take a break and think back on if you drank enough fluids recently. If you realize you might have been lacking in your electrolytes, it’s likely that our pesky friend dehydration has arrived at the party. 

Now, if you are thinking, “yep, I have totally been there!” then you are also probably thinking, “what can be done to prevent that?” and “how do I help myself once I become dehydrated?”. Well, sit tight because we have got you covered! 

We will discuss the 6 impacts of dehydration on running performance if you should drink electrolytes while running, and how to carry water while running to help decrease your risk of dehydration. Additionally, we will touch on what causes dehydration, why runners are at increased risk, and what symptoms to look out for!

What Causes Dehydration?

To start with a little background, as an adult, about 55-60% of your body is made up of water. Water also makes up most of your brain, heart, bones, muscles, kidneys, skin, and lungs. So, as you can imagine, we need to stay hydrated to make sure all parts of the body can stay functioning as they need to!

Dehydration ultimately stems from not drinking enough water/hydrating beverages or losing water too quickly through things like sweating, diarrhea, or vomiting.[1] 

As a runner, you are oftentimes at increased risk of dehydration. With running (especially long distances) comes sweat. Our bodies sweat to cool down during exercise, and when we sweat, we lose water and electrolytes (e.g., sodium, potassium).[2] Not to mention many times, people go on runs outside, which means heat may cause additional water losses, increasing the likelihood of dehydration. 

It is crucial that you implement hydration into your daily routine, so you don’t experience the impact of dehydration on running performance. 

Signs and Symptoms of Dehydration

How do you know if what you are experiencing is dehydration? The tell-tale signs to look out for include: [1,2]

  • Premature fatigue
  • Headache, confusion
  • Dark-colored urine
  • Dry mouth/lips
  • Muscle cramps
  • Rapid heart 
  • Chills
  • A sudden decrease in running speed

Typically, after drinking water or an electrolyte-rich beverage, most people feel better 10-15 minutes later. If your dehydration symptoms persist after attempting oral rehydration, you may be experiencing moderate-severe dehydration and require IV rehydration.[1]

6 Impacts of Dehydration on Running Performance

It has been found that dehydration of ≥2% body weight loss results in a significant decrease in endurance performance.[3] Even though this is known, dehydration is still a common issue in athletes/runners.

A study was conducted that looked at the hydration status of university/club-level athletes. Out of 430 athletes, they found that 31.9% (137) completed exercise while dehydrated, and 43.6% (187) were dehydrated after training/competition. This is just one small example of how often athletes are dehydrated. 

Now that we know how common dehydration is let’s talk about the 6 impacts dehydration has on running performance.

1. Lower Endurance Capacity 

The most important thing to note in regard to dehydration’s impact on endurance capacity is its correlation with heat.

Dehydration’s impact on endurance is largely exacerbated by high temperatures of 40℃ (104℉). At 40℃ and a 4% body mass loss, there was a ~23% decrease in endurance performance. When temperatures decreased (30℃, 20℃, 10℃, dehydration’s impact lowered to 12%, 5%, and 3% respectively.) [4]

Ultimately, dehydration coupled with high temperatures resulted in shorter exercise time to exhaustion, reduction in exercise intensity, or both. [5]

This relationship between hydration and environment temperatures is important to note. If you know it is going to be hot outside and you haven’t been hydrating well, it may be a good idea to move your run inside, decrease the length of your run to <1 hour, or skip the run for that day and focus on hydrating.[4,5]

2. Decrease in Oxygen Utilization 

Dehydration of 2-4% of body mass generally reduces VO2 max, otherwise known as the amount of oxygen your body can utilize during exercise. Multiple studies have found a correlation between the level of dehydration and reduction in VO.[5]

It is important to note that the higher the environment temperature, the greater the reduction in VO2 max was. 

Dehydration is also associated with decreased stroke volume (the volume of blood pumped by your left ventricle with each contraction). [5] A decrease in stroke volume is one of the main reasons why your VO2 max may decrease.

Why are we concerned with a decrease in VO2 max? Because the more oxygen you can use during high-intensity exercise, the more energy you can produce. In other words, VO2 max is a great indicator of physical fitness, and we would like to prevent dehydration from lowering it.

3. Poor Motor Coordination 

Motor coordination is your body’s ability to move multiple parts to perform a specific action. In the case of running, having motor coordination allows you to move both your arms and legs at the same time, allowing you to run. 

Dehydration has been found to impact certain parts of the brain, such as the thalamus and basal ganglia. These areas of the brain also play a role in motor coordination. So, when your body gets dehydrated, these areas of the brain cannot work as well. This results in poor motor coordination, which is likely to hinder your running performance. 

Additionally, it is thought that dehydration has a negative impact on processes involved in higher-level decision-making. This has been found to hinder decision-making and reaction times.

It is important to add that in these studies, dehydration had the greatest impact on cognitive performance and motor coordination when >2% body weight loss was present.[6] 

4. Muscle Cramps

The research behind muscle cramps and dehydration is related to an excessive loss of electrolytes rather than an overall loss or deficiency of water. Athletes who drank too much water and not enough carbohydrate-electrolyte beverages were even found to have muscle cramps.

As touched on before, when you sweat, you lose water and electrolytes. Electrolytes play a large role in nerve and muscle function, so if these electrolytes are not replenished, they can result in exercise-associated muscle cramps (EAMCs). [7,8] 

Overall, EAMCs are associated with various causes, not just electrolyte imbalance/deficiency. With that said, research has found that carbohydrate-electrolyte beverages may allow athletes to compete for a longer period of time before EAMCs occur and prevent EAMCs from happening in low-intensity exercise. 7]

Now, during exercise, where the amount of sweat produced is more than the fluid and electrolyte absorption, carbohydrate-electrolyte beverages may help delay the onset of the cramps. Still, they will not prevent them from happening.[7] Keep on reading, and we will touch on if you should drink electrolytes while running.

5. Hyperthermia 

Hyperthermia is defined as an abnormally high body temperature. Earlier in the blog post, we mentioned sweating during exercise helps us cool our bodies down.

When we get dehydrated, we can no longer decrease our body temperature by sweating. This is dangerous because this means we can no longer regulate our own body temperature.

An excessive increase in body temperature (hyperthermia) not only results in early muscular fatigue and cramping but puts you at risk for heat stroke, which can be life-threatening in severe cases. [9,10] The CDC defines heat stroke as the body temperature rises to 106 or higher within 10-15 minutes. If this occurs, please seek medical attention immediately.[10]

6. Decreased Muscular Power

Whether dehydration has an impact on muscular power varies in research. Overall, most studies agree that dehydration does negatively impact muscular power, but to a very small degree.

It is thought that the reason dehydration may lower muscular power is due to the impact it has on the body’s neuromuscular system. The neuromuscular system refers to how our nervous system and muscles work in harmony to control movement in the body. 

The impact dehydration has on our neuromuscular system seems to be minimal, though, resulting in a small impact on muscular power. A study found that in 67% of participants (177), muscular power was decreased when dehydrated. However, the decrease was minimal at 1-3%.[5]

Can You Over-Hydrate?

I know, I know…..we have spent this whole article talking about why it is important to stay hydrated. Plus, we’re yet to cover how to carry water while running. But can too much of a good thing be bad?? Let’s discuss this.

Yes, of course, it is important to drink water and stay hydrated, BUT it is also important to include electrolyte beverages into your hydration routine as well.

Drinking too much plain water can result in a dilution of the sodium in your blood. This condition is called hyponatremia.[11]

According to the Cleveland Clinic, hyponatremia is actually the most common electrolyte abnormality seen in patients. The severity of this condition depends on how rapidly your sodium levels are diluted, but the neurological symptoms can range anywhere from mental confusion to seizures to comas. Other general symptoms include muscle cramps, nausea, vomiting, headache, and fatigue.[11]

Please keep this in mind when you are hydrating throughout your day, especially if you are a runner/active!! Keep reaching for that water throughout the day but don’t forget to add some electrolytes in there as well.

Should You Drink Electrolytes While Running?

To expand on the importance of electrolytes, let’s dive into whether you should drink them while you are running.

The short answer to this question is yes and no.

If your run is a shorter one (30-60 minutes), water should be an appropriate beverage choice while running. [5,7] It is still a good idea to have some electrolytes after, especially if you are prone to sweating a lot. 

If your run is 60 minutes or longer, it’s definitely a good idea to drink electrolytes throughout your run. The longer you exercise, the more prone you are to dehydration and/or water/electrolyte losses. As mentioned above, dehydration can be detrimental to your running performance. Drinking electrolytes during your run is a great way to not only avoid the decrease in endurance and cognitive performance associated with dehydration but to prevent hyponatremia as well! [5,7]

Cans of NOOMA Organic Electrolyte Sports Drink, one of the best electrolytes for athletes

In addition to staying hydrated, it is good to implement certain foods to support muscles and joints as well as other tips and tricks to promote recovery and reduce muscle soreness after runs.

What Electrolyte Beverage Should You Pick?

There are TONS of electrolyte beverages out there, and it may feel overwhelming trying to find the best one for you. Now, no need to open a new tab and Google “best electrolyte drinks.”

Instead, we have a whole post on the 17 Best Electrolyte Water Brands (including NOOMA, our favorite, with a 30% off code!) that explains when, why, and what brand and product of electrolytes you should be consuming based on your activity and personal preferences.

Learn how to carry water while running such as a trail runner using a water vest running in the mountains.

How to Carry Water While Running

The key to understanding how to carry water while running is finding the right size belt, filling bottles properly, and understanding proper hydrating strategies during running which are discussed below.

Now that you now the incredible impact of dehydration on running and if you should drink electrolytes while running, its time to dig into how to carry water while running.

We’ve tried countless products, and we’re not only going to tell you how to carry water while running, but how to effectively use the water or your electrolyte beverage to avoid stomach issues or impaired performance.

How to Carry Water While Running Steps:

1. Choose a running belt with a wide band or a vest if you’re going super-long

A narrow band will bounce around and is less likely to stay in place. A high-quality band or vest that is wider and has more surface area in contact with your body is able. to stay secure and have less bounce. The key is surface area. The more belt in contact with your body, the less bounce!

But, keep in mind that more surface area may cause more warmth or setting so, think of your activity and how much you really sweat. Ultra runners probably need a vest while most recreational runners going for less than 2.5-3 hours would do well with a high-quality running belt with insulated bottles.

2. Don’t overfill

We have to be brutally honest and remind you that taking too many fluids or too much bouncing of your belt is going to change your running mechanics. Doing this consistently over time can lead you to be more prone to injury.

The solution?

Only fill as much as you need to and choose a route that allows you to refill if needed.

Depending on your conditioning and climate, If you’re on. shorter run, it is very likely that only one bottle is needed. So, lighten your load, only take one bottle, and only fill up what you need.

Now, running mechanics are super important right?!?

So, don’t forget to switch which side the bottle is on occasionally. Personally, I switch every 3 miles or so depending on how far I’m going. If you keep it on the same side all the time it will cause a change in running mechanics that can lead to issues in the long run. Michael, the sports PT on our team, has seen clients with hamstring issues from always having their phone strapped to one leg and when they finally had them switch sides occasionally or use a running belt in the center of their back to carry their phone, then finally the issues went away.

Properly alternating sides if using one bottle is a crucial tip to keep in mind if when considering how to carry water while running.

3. You may need less water than you think

It is important to note that research suggests don’t tend to see a decline in performance from dehydration until we’ve lost about 2% or more of our body weight in fluids.

So, for someone who is 125 lbs that would be 2.5lbs of fluid loss and for someone 175lbs that would be 3.5 lbs of fluid loss. Now, ask yourself how long is. your activity going to be, and are you a heavy sweater? Will the humidity be high or will the sun be coming up during your activity leading to accelerated fluid loss?

The fact is, for many runners, most training runs under an hour or even an hour and a half, depending on your conditioning level and climate, fluids aren’t actually needed. And, for those that are going for longer, do you really need 2 or 3 bottles?

If you really want to figure out hos much fluid you need, start to weigh yourself before and after runs to see how much fluid you lose for various distance and carious amounts of heat. Start to get a gauge of what distances and temperatures cause you to lose near or over 2% of your body weight in fluid and start to only carry bottles on runs that will get close to or over that threshold.

Fun fact: Research on cyclists showed that hydrating during 1hr rides decreased performance while hydrating during exercise of 1-2 hrs lead to a modest increase. performance and >2 hrs lead to an increase in performance by at least 3%[13]

3. Alternate Drinking Bottles

If you’re an ultra runner or someone choosing a vest with a water bottle, you may disregard this section. However, if you’re using bottles on a belt, this information is really important.

As we talked about earlier, a crucial thing to keep in mind when carrying water while running (or preferably a high-quality electrolyte beverage) is to try and keep your running mechanics as normal as possible.

To do this, we recommend making sure to alternate the bottle you drink from as you run so the weight stays evenly dispersed across the belt.

4. Use Cold Water (and maybe even insulated bottles or ice!)

Nathan running belt with insulated bottles- if wondering how to carry water while running, this is one of the best ways!

Cold water does have the ability to lower core temperature or at a minimum, help right its rise. A rising core temperature has the potential to wreck training or performance and in a worst-case scenario, lead to heat stroke or death.

So, we recommend and personally use refrigerated water in our bottles.

However, if you’re going for a long run, this water will warm up quickly. So, if you’re going on a long or super-hot run, consider adding a few ice cubes or even using the belt and bottles we use with insulation., Nathan Hydration Insulated Running Belt.

For us personally, if we go for a run for over 2 hours and it’s going to be super hot or humid or both, we’ll add a couple of ice cubes as well.

We’ve also heard of some runners putting just 1/4-1/3 full bottles in the freezer the night before so it creates one solid cube that melts slower. This is definitely a great idea if overheating is an issue for you, you live in an extremely hot climate, or if its an abnormally hot day compared to what you’re used to (the first few hot days of summer can be tough on the body until you acclimatize to it!).

Happy hydrating my friends!


  1. https://my.clevelandclinic.org/health/treatments/9013-dehydration 
  2. https://www.osmosis.org/answers/hypertonic-dehydration 
  3. https://journals.humankinetics.com/view/journals/ijsnem/27/2/article-p158.xml 
  4. https://pubmed.ncbi.nlm.nih.gov/30671905/
  5. https://pubmed.ncbi.nlm.nih.gov/24692140/
  6. https://journals.lww.com/acsm-msse/Fulltext/2018/11000/Dehydration_Impairs_Cognitive_Performance__A.21.aspx
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1150229/
  8. https://my.clevelandclinic.org/health/symptoms/24019-electrolyte-imbalance
  9. https://journals.physiology.org/doi/full/10.1152/ajpregu.00395.2015
  10. https://www.cdc.gov/niosh/topics/heatstress/heatrelillness.html#:~:text=Heat%20stroke%20is%20the%20most,within%2010%20to%2015%20minutes.
  11. https://my.clevelandclinic.org/health/diseases/17762-hyponatremia 
  12. https://pubmed.ncbi.nlm.nih.gov/22763119/
  13. https://pubmed.ncbi.nlm.nih.gov/28497286/