Hydration 101 for Runners

A woman taking a water break during her run.
Choose the health content that's right for you, and get it delivered right in your inbox

Our bodies are about 60 percent water. So, it seems like an easy concept that we need to replace those fluids when we lose them through sweat and exercise. But much like nutrition, there are varying opinions on how much to hydrate, with what and how often.

Hydration can be both simple and complex. Staying hydrated on a daily basis is the best way to set yourself up to be adequately hydrated on your runs. Knowing how to address fluid requirements during runs and races will help you stay safe and perform your best under a variety of conditions.

Hydration Needs and Warning Signs

While your hydration needs are dependent on your sex, height and weight, they are also heavily influenced by the duration and intensity of your activity, the weather conditions and even altitude. Sweat rates differ from person to person, so individuals of similar builds running the same race at the same pace may still have different fluid needs.

But in general, estimates can be used. You can take your weight and divide it by two. That’s how many ounces of fluids you need per day.

As a runner, the goal of hydration is to keep your body primed to run and recover well. At the most basic level, you are trying to avoid the two extremes: dehydration and hyponatremia, defined as a low sodium concentration in the blood. In runners and other athletes, hyponatremia is typically caused by drinking too much water relative to the amount of sodium in your body.

Knowing the warning signs of both of these extreme conditions is important. Though rare, they can become life-threatening if not addressed quickly.

Here are the warnings signs of dehydration:

  • Fatigue
  • Dry eyes
  • Dry mouth
  • Dark colored urine
  • Cramps
  • Headache
  • Muscle Spasms
  • Sweating decreases (or totally stops)

The warning signs of hyponatremia include:

  • Bloating and a feeling of sloshing in your stomach
  • Nausea
  • Incoherence
  • Disorientation
  • Inability to drink more and/or urinate
  • Seizures

Hydration Guidelines

The extreme conditions described above are rare, but they can occur even in experienced runners. Most of the time you’ll fall well within the range of normal hydration, but knowing how to tweak it to your advantage can help you feel and perform your best.

Adequate Hydration

Maintaining adequate daily levels of hydration will set you up successfully for long runs and harder workouts, but what does that mean, exactly? The old adage of eight 8-ounce glasses of water per day may work for some but be too much for others.

If you aim for eight 8-ounce glasses of fluids (not just water), that recommendation becomes more accurate. Remember there is water in what you eat too, especially fresh fruits and vegetables.

Drinking to Thirst

For basic day-to-day hydration and training in moderate weather conditions for shorter distances, drinking to thirst may be okay. But when you’re running in more extreme conditions or over longer time periods, this doesn’t always work. Most of the world’s best athletes follow a more structured hydration plan, and you’ll likely benefit from one as well.

Start your Runs Pre-Hydrated

Low intensity runs less than 60 minutes in length rarely require supplemental hydration. But starting a long run or workout by topping off your hydration stores can help you perform better throughout.

What does this mean in terms of volume? Approximately 2 hours prior to a run, drink about 16 ounces of fluid. This allows time for absorption so your stomach doesn’t feel too full or “sloshy.” Immediately before running, you can top off with another 4 to 6 ounces.

Set a Timer

Drinking to thirst may work for some scenarios, but following a schedule for hydration can be beneficial during a longer training run or race. On the run, it’s easier for your body to ingest and absorb small amounts of fluid more often.

4 to 6 ounces every 20 minutes is an ideal goal to shoot for. If you aren’t sure what this translates to, try measuring it out. It’s often less than you think.

Long Runs vs. Races

Hydration requirements are extremely individual. Long training runs are the time to experiment with your hydration and nail down a strategy. Learn what fluids and supplements you can tolerate in a variety of conditions, so your long run presents no surprises. And when its safe for long races to resume again, prepare by mapping out your water stops ahead of time.

Electrolytes and Salt Supplements

While not all runners supplement with electrolytes or salt, others find benefits in long races and hot conditions. Recommendations for salt vary dramatically from about 300mg up to 1000mg per hour depending on conditions and your body’s specific needs. Higher levels of sodium and other electrolytes may upset your stomach, so test out any potential supplements during your training runs and ask your doctor for more personalized advice.

A Network of Care for Your Whole Health

Hydration doesn’t have to be a complicated and confusing part of your training. Practice early and often to determine what strategies and supplements work to help you feel your best. And if you need help to support your health and fitness journey, our expert network of care is here to guide you with extra safety measures in place to protect your whole health.

Recent Blogs

Women stomach pain
Hernias 101: What You Need to Know
Man seeing doctor wearing PPE
Your Essential Guide to Cancer Screenings by Age
Heart Care with Advanced Technology and Research
Couple reading
Colorectal Cancer: Rising Rates and Changing Trends
7 Most Common Digestive Conditions
View More Articles