Hydration is important on runs. However, carrying water on a run is not always the easiest thing. Water bottles are clunky to hold and sometimes do not hold enough fluid. The solution: a hands-free hydration pack. Hydration packs for runners come in the form of either a vest or a waist pack. Both allow you to comfortably carry fluids on a run. This article will guide you through everything you need to know for how to choose and use a hydration pack for running, plus some recommendations on some of the best hydration packs for runners.
Why use a Running Hydration Pack?
Hydration packs allow you to access fluids at any point during your run. As explained below, having easy access to fluids throughout your run minimizes the risk of dehydration.
Unlike holding a water bottle in your hand, a hydration vest or hydration waist pack encourage good running form. Carrying a water bottle may feel fine at first, but over the miles, the added weight at the end of a limb can throw off your form. A hydration pack that is centered on your torso will not alter your stride.
Additionally, the bottles and reservoirs used in hydration vests are reusable. You can reduce waste (and cost) from using single-use plastic bottles.
Trail runners can highly benefit from using a hydration pack. In addition to carrying fuel and fluids, you can stash extra layers of clothing, emergency aid kits, and poles.
Should I Carry Water on a Run?
Yes! A good rule of thumb is to carry water on any run longer than 60-75 minutes. In summer, you may find you need to carry water on shorter runs, especially if it is an interval or tempo run.
When you sweat during a run, you lose fluids. Marathoners can lose 27-41 ounces of sweat per hour in pleasant conditions (60 degrees) and even more in hotter conditions. If you lose too many fluids without replacing them, you can become dehydrated. Dehydration decreases your blood volume, which means your heart rate increases to maintain blood flow to the working muscles.
Dehydration beyond 3% of body weight lost in sweat impairs performance. Once you lose more than 5% of your body weight in sweat, performance can decline as much as 30%. When you drink water or sports drink on a run, you can improve your time to exhaustion. This means that you are less likely to tire out too early on your long run or in your race. The trade-off is clear: carrying water on a long run improves performance, while neglecting hydration will create sufferfest. (Here’s more about how to feel good on long runs.)
Beyond improving performance, hydrating during a run can minimize the risk of gastrointestinal upset. Dehydration slows down gastric emptying rate by up to 20-25%, which means that fuel and fluids will sit on your stomach for longer. The longer they sit, the more likely are you to experience GI upset.
You should especially carry water with you on a run in the heat. Dehydration occurs more rapidly when it is hot outside. Once you become dehydrated, your body’s ability to lose heat is impaired, and your core temperature spikes more rapidly. Even if you are heat acclimated, you will not tolerate the heat well if you become dehydrated on a run.
It is worth noting that you do not want to excessively hydrate on a run. A sports drink can encourage thirst and fluids absorption, while also minimizing the risk of hyponatremia (low sodium levels in your blood). Take fluids with you and drink throughout the run, but avoid chugging large quantities the entire time.
Should I Run a Marathon with a Hydration Pack?
You should always first check the rules and regulations of your particular race. Some races do not permit hydration vests for security reasons. Some do allow hydration waist packs even if they do not allow a vest. If a hydration vest is not permitted at the race, you can train with it, but do not want to use it on race day.
When a race permits hydration packs, the choice becomes personal preference. If you prefer to be able to drink at any point, you may want to wear your hydration vest. Additionally, if you use a sports drink mix not offered on the course, a hydration pack makes it easy to carry your sports drink of choice in the race. If you are fine using the aid stations on the course, then no need to race with a hydration pack. A hydration vest also makes it easy to carry all of your gels.
Some runners do choose to bring hydration packs when they are running a marathon in the heat. Using a hydration pack ensures adequate hydration when fluid needs are increased in the heat.
Trail marathons and ultra-marathons are different. Most trail races allow – and encourage – hydration packs. In a trail race, aid stations may be spaced further away. You need to be able to carry your own fluids in a trail race. (Here’s more on what you need to know when transitioning from road to trail races.)
How Large of a Hydration Pack Do You Need for Running?
If you are a road runner, you likely can use a smaller pack. You can certainly use a larger pack if you prefer. If you have a larger pack for the trails, it can work just as well on the roads. (Even large packs are fairly light when not completely filled).
However, if you plan on long trail runs, you may want a larger hydration pack. Salomon’s website recommends packs of 6-12 liters for trail runners. This large size allows you to carry a first aid kit, Mylar blanket, extra layers, and plenty of food and fluids for hours of adventure.
Should You Use Bottles or a Hydration Bladder?
Gone are the days of the heavy Camelbak backpack. Hydration packs for runners now offer multiple options for how to carry water on your run. You can choose a hydration pack with bottles, a large bladder (reservoir), or both.
The biggest difference between bottles and a bladder is the ease of cleaning. Take it from someone who uses a hydration bladder often for long hikes – they are difficult to clean. The difficulty of cleaning increases if you use an electrolyte mix (which is encouraged for running). The electrolyte mix can leave residue in the hose. You can buy special tablets to aid with cleaning, but ultimately the bladder is harder to clean than bottles.
Hydration pack bladders (or a combination of a reservoir and bottles) will allow you to carry more fluids. Most bottles will only hold up to 500mL each. A bladder can hold several liters.
Ultimately, the choice of bottles or a bladder in your hydration pack comes down to personal preference. You want to feel comfortable and have enough fluids wiht you.
How Should a Running Hydration Pack Fit?
Ultimately, a hydration pack should sit comfortably when you run. Both hydration vests and hydration waist packs allow adjustments to optimize fit. Once fitted, a running hydration pack should stay relatively in place. You should not notice excessive bouncing when you run. Additionally, a well-fitting hydration pack should not cause chafing. A hydration waist pack should not sit too tight on the race; too tight of a fit can cause gastrointestinal upset or muscle cramps. If you experience bouncing, chafing, or other discomforts, you may want to try a different brand.
You should also be able to easily access your fluids while running. With a hydration vest, you should easily be able to drink from the flasks. The vest should sit high enough that the flasks are within easy reach to hydrate. A running hydration waist pack should keep the bottle within easy reach, such as in the middle of the low back or front of the hips.
How to Clean a Hydration Pack
Whether you use bottles or a reservoir, a hydration pack should be cleaned regularly. If you use sports drink mix or any electrolyte supplement, you will need to clean the water container after each use. Otherwise, mold may grow.
Always check the manufacturer’s instructions. Some bottles can go in the dishwasher on the top shelf. Other bottles and many reservoirs need to be washed by hand. All you need is dishsoap, a bottle brush, and a bottle drying race.
(If your bottles or reservoirs do grow mold, you can usually buy replacement bottles without needing to buy a new hydration pack.)
Best Hydration Packs for Runners
The Nathan Peak Hydration Waist Pack carries more fluid with more comfortable than the traditional waist packs. This fanny pack style hydration pack sits a larger hard flask on the low back. For a waist pack, this is relatively comfortable. My one gripe (echoed by my husband) is that it can be tricky to find the optimal fit where the pack does not ride up without over-tightening the belt. However, with enough trial and error, you can find the fit most comfortable for you.
If you only need a small amount of fluids (such as water for a summer speed workout), the Salomon Agile belt allows you to discreetly carry a small soft flask. This unisex belt sits along the hips, with the flask tucked flush along the belt. The result is minimal bouncing. While I have not tried this one personally, runners I coach have tried it and rave about it.
The Salomon Adv Skin Hydration Vest comes in a variety of sizes, from 5 to 12 liters. It is available in both women’s and unisex sizing. The vest carries two 500mL front bottles. Based on the size you get, you also fit a bladder into the back reservoir compartment. The fabric is soft and highly breathable, even in the heat of summer. The Salomon hydration packs are some of the best for trail runners due to their large capacity.
The Salmon Adv Skin 12 is my personal hydration vest of choice. As a narrow-chested woman, this vest stays in place. I had trouble with other vests bouncing, but the Salomon Active Skin is so comfortable that I barely notice it on long runs. There are multiple accessible front and side pockets, along with a large back zippered area. Since I have a long torso, I did purchase the unisex size instead of the women’s size. I also use it on short hikes, cross-country skiing, and cycling.
The Ultimate Direction Race Vesta is a lightweight hydration vest. Similar to the Salomon hydration vest, the Ultimate Direction hydration vest comes with bottles and space for a bladder in the back compartment.
As a tall and small-chested woman, I found the women’s size vest to feel a bit short and slightly too wide at times. It would sometimes bounce around and I did chafe a few times.
However, I found that this vest did adjust well for body size changes during pregnancy and postpartum/breastfeeding. During pregnancy and postpartum, this hydration vest sat comfortably. The UD hydration vest was one of my most frequently used pieces of running gear during pregnancy.
Other than my unique fit issues, the Ultimate Direction hydration vest had several desirable features, including breathable material and several accessible pockets.
Sources: Jeukendrup, A. & Gleeson, M. (2016) Sport nutrition (3rd edition). Human kinetics.