Hydration in Trails

Hydration in Trails

Road running versus trail running differs in a variety of ways from the terrain and elevation to accessibility to basic functional needs like fueling and water. It is important before venturing off on your trail run to know the differences and to be well-prepared in case of issues or an emergency. To avoid dehydration and injuries, we discuss the importance of properly hydrating and the best solutions to stay hydrated on your trail runs. 

To maintain proper hydration during a trail run, one must remember that the importance of hydration begins before going out on the run as well as during and after the run. So it is essential to keep in mind to drink water regularly throughout the day because even when exercise is not a factor, many experts recommend drinking about 8 glasses a day. Of course, these recommendations change with increased energy expenditure, sweat loss, and warmer weather all playing variable parts. Therefore, the accurate hydration throughout the day can certainly increase and vary per the individual. 

We have outlined some basic guidelines on how to stay hydrated during a trail run, yet it is best to experiment to determine your adequate hydration needs and to what best suits you. Also, check out our previous article on marathon fueling and hydration here.

Before your trail run: It is advised to consume 12 to 16 ounces within an hour before your run. 

During your trail run: Up to 60 minutes, most activities will not require additional water if having been properly hydrated before the run. However, once surpassing 60 minutes and also depending on your sweat rate and the weather, it is advised to have between 12 to 24 ounces per hour. 

After your trail run: It is best to rehydrate inversely to what you lost in sweat during your run. An easy solution to determine how much fluid you lose during exercise is to calculate your sweat rate. 

How to Calculate Your Sweat Rate

To measure your sweat rate perform the following steps when going out for a greater than 60 but less than 90-minute trail run.

1. Hydrate! Drink water and urinate as you normally would before your run.

2. Weigh yourself! Right before you leave for your trail run, measure and record your weight. 

3. Run time! Go for your trail run. When performing this test, make sure not to drink fluids or urinate while you are running. 

4. Weigh yourself again! After your trail run, wipe off excess sweat and measure and record your weight again. 

5. Math time! Multiply 16 ounces for each pound lost or each kilogram lost by 1000 milliliters to calculate your sweat rate. 

The calculation is beneficial in providing a frame of reference while you are out on your trail run. You can now estimate how much water you may need to consume each hour and how much to carry with you, as you will not have many opportunities to get access to hydration stations while out in the woods and mountains. This estimate is also helpful in reducing under and overhydration to avoid additional problems. So now to figure out what are the best ways to carry your water while on a trail run?

The running market is inundated with options for carrying fluids. We determine the pros and cons of each to help you decide the best solution for you. 

The Handheld Options:

The handheld options can be either a bottle or collapsible flask and are true to its name, they are held in your hand. 

Pros: Potentially lightweight and makes for easy access to hydrate. 

Cons: Can lead to muscular imbalances. They are not ideal for long races or rugged terrain where you may need your hands to be free. 

Fuel Belts:

These are packs worn as a belt around your waist that can have one to multiple bottles and pockets for storage. 

Pros: Leaves you hands-free. Usually, the belts have additional storage for other key items you may need to carry like your phone, keys, gels, credit cards, etc.

Cons: The weight of the bottles may cause bouncing and shifting of the belt. The pressure of the belt could also lead to potential gastrointestinal issues or skin chafing on bony areas like the spine. 


These packs are smaller in size than a traditional backpack and are snugger to the body. They can carry a hydration bladder and/or bottles and they also provide additional pockets for storage. 

Pros: Leaves you hands-free. Provides lots of options for multiple hydration containers and extra space for storage of essentials and packing of small and thin layers of clothing like a windbreaker or extra pair of socks.

Cons: Can get heavy, cause friction, and can make you hotter.

Finding the best hydration carrying option is like finding the right pair of shoes. It may take time and several tries with different options to get the right fit and style that works best for you. Speaking with your local running retail shops and reading customer reviews online may be the best place to start. 

Here are a few things to consider:

How long is your trail run? 

For a run that is greater than 60 minutes, one bottle is sufficient. Greater than 90 minutes you may need multiple containers for water and an additional sports drink. 

How challenging are your trail runs?

Depending on the terrain and difficulties, you may need to have your hands physically free to climb and ascend a trail.

Do you like to be hands-free on your trail runs?

A personal preference, but the longer you carry something the risk the item will become heavy, annoying, or a nuisance. 

What essentials are you carrying with you on your trail runs?

Consider what you bring on your trail runs like keys, phones, money, gels, etc. This may determine if you need additional pockets and storage.

Will you have access to refilling your hydration containers?

If there is accessibility for stations that allow water refilling, the lighter your carrying load could potentially be. 

What will the weather be like on your trail run?

The warmer the weather, the likelihood you will need more fluids to carry.

Taking the time to answer these questions can certainly help you narrow down the right choice for you. And if you are still confused, bring the answers to your local running retailer and they can help point you in the right direction.