Hydration Tips for Endurance Runners

Managing both hydration and nutrition while running is important, yet it’s almost as challenging as running itself. Understanding basic hydration and nutritional needs is just the start of developing a plan. Practicing them in training is necessary for dialing it in to match your individual needs and developing a successful race-day strategy.

Allan Misner, NASM CPT and host of the 40+Fitness Podcast, and I discussed hydration and nutrition over two podcast episodes, which you can find here: https://40plusfitnesspodcast.com/podcast/

Listen to episode 487 – Nutrition for Running – Part 1, released on May 17, 2021, and episode 488 – Nutrition for Running – Part 2, released on May 24, 2021.

Allan and I discuss the most common, current guidelines for hydration and nutrition, which I’ve outlined below. However, both hydration and nutrition remain a highly individualized strategy. Our specific needs may not always fall so neatly into a precise calculation or even common guidelines. Practicing hydration and nutrition in training is essential for learning what works best for you and supports your running or athletic activities.

Drink Water on a Daily Basis – Your Starting Point

We all know drinking water is necessary for good health, athlete or not. There are many established guidelines for water intake. The Road Runners Club of America (RRCA) calculation for a daily water goal is:

Body weight in pounds x 0.55 = ounces of water to drink daily

For a 150-pound athlete, that calculation equates to 82.5 ounces, which is a little over 10 (8oz) glasses of water per day.

This calculation offers a good starting point; however, we all differ in age, gender, size, activity level and other physiological aspects. Someone accustomed to drinking 2 or 4 glasses of water per day shouldn’t jump up to 10 glasses even if the calculation suggests to do so. There’s no guarantee that your body will function better after increasing water consumption so greatly. Instead, gradually adjust water consumption and observe how your body responds over time.

It is common knowledge that humans can go as many as three days without water before risking organ failure or death. Because, drinking water is essential to human life, that alone suggests that the risk for dehydration is serious business. However, the threat, or maybe the fear, of dehydration has caused the pendulum to swing in the opposite direction.

Hyponatremia is the result of drinking ‘too much’ water and is just as dangerous as dehydration. Drinking excessive amounts of water can reduce sodium levels in the bloodstream. People with a higher sweat rate may experience additional sodium losses, diluting the sodium content in the bloodstream even further, possibly to dangerously low levels.

Both dehydration and hyponatremia cause fatigue, nausea and headaches. Dehydration presents itself with weight loss, dizziness, vomiting and dry mouth. Hyponatremia presents as weight gain and confusion/disorientation. Both can and do land runners in the race day medical tent or hospital.

Please note that the weight loss and gain that I reference is an identifier, like taking a temperature to determine whether someone has a fever. Someone who drinks too much water will be heavier, while a person not drinking enough will be lighter than when they started the race. Weigh-ins were once a part of ultra-race check-in stations, but are no longer standard practice.

Studies have shown that a fluid loss of 1% will adversely impact circulatory performance and decrease performance levels. A decrease of 2% makes these consequences even more significant. Runners lose fluid through sweat, urine and breath. Sodium and potassium are also lost through sweat, which is why electrolyte drinks are important for athletes.

Electrolyte drinks are made up of water with varying amounts of sodium, potassium, magnesium and calcium. The purpose of electrolytes is to control fluid balance, regulate blood pressure, muscle contraction and maintain acidity or pH of the blood.

What and How Much to Drink Before, During and After Running

The big question that everyone wants to know is what to drink and how much? RRCA offers a great starting point and the timing has a purpose. Drinking before a run primes the body for what is about to take place. Drinking during the run maintains as close to a hydration homeostasis as can be achieved based on the activity and the body’s response. Drinking afterwards replenishes what was lost during the activity.

  1. Before running: RRCA suggests that runners drink 10-16 ounces of water or sports drink about 1-2 hours before a training run or race, then topping off the tanks with 4-8 ounces right before starting.
  2. During running: RRCA suggests that runners drink 4-8 oz of water or sports drink every 15-20 minutes (4 oz, every 15 min = 16 oz/hour). For a 2-hour half marathon, for example, a runner might drink as much as 32 ounces.
  3. After running: RRCA suggests that runners drink 24 oz of water or sports drink for every pound of body weight lost during the run.

How much do YOU need?

As I mentioned, these guidelines are the RRCA suggested starting points. Now, you need to experiment to determine what feels good to you. Drinking that volume of fluid would send me into every port-o-potty on the race course. It’s simply too much liquid for my body to manage. Instead of counting ounces, consider these factors:

  1. Urine color: While not scientific, urine should be pale in color. A more pronounced color suggests dehydration. This isn’t a foolproof way of determining how hydrated or dehydrated you might be, but it’s something to evaluate.
  2. Drink regularly and often: Drinking to thirst is a common strategy, but not foolproof. Most people don’t feel thirst in cold weather like in the heat, yet hydration is just as important in winter as in summer. In addition, runners may be more focused on the finish line than on how they are feeling and miss the warning signs of dehydration. It’s also been argued that if you are thirsty, then it’s already too late and difficult to recover from dehydration in time to preserve the rest of the race. Incorporate a strategy, such as drinking at each mile or two or three. Or choose to drink at each aid station. Practice how often you drink in training and, if successful, use that strategy on race day.
  3. Observe your sweat rate: Weigh yourself before a training run, after using the bathroom, and without clothes. Immediately after running, dry off as much as possible, remove sweaty clothes, then weigh yourself again. The difference in weight corresponds to the approximate amount of water lost. Online sweat rate calculators and laboratory services can guide you toward a personalized sweat rate estimate which can offer insight on how much you need to drink while on a run. Also observe any white dust or grit on your body or clothing. This grit, if not dirt from a trail run, may be the electrolytes lost in sweat after the sweat has evaporated. This suggests electrolyte drinks might play a larger role in your hydration strategy.

We all sweat at different rates and lose electrolytes in our sweat, also at different rates. With a little experimentation, you will be able to determine an estimate as to what to drink, how much and when. There are laboratories that will conduct sweat tests if you have the money and inclination to do the testing. Even so, I suggest consulting your doctor first for guidance.

In the meantime, the best thing you can do is use a paper or digital journal and practice different hydration strategies in training. Begin to monitor what you eat and drink on a daily basis. In addition, begin to take detailed notes of what and how much you drank before, during and after a run. Include notes on weather, perceived rate of exertion, other mental and physical feelings (thirst, hunger, fatigue, etc.), how much you sweat and how many times you used the bathroom. Over time, you will begin to notice trends and be able to hone in on a hydration strategy.

Not all Electrolyte Drinks Are the Same

Read the labels on several electrolyte drinks for the type and amount of each electrolyte mineral, sugars, carbs and other things like caffeine or protein. This is particularly important to compare against your daily diet and the running fuel you may choose. If you get a lot of sodium during your daily diet, for example, you may not need as much in an electrolyte drink. In addition, some of the running foods, gels or gummy chews, may also have the same nutritional items. Too much caffeine, sodium or sugar could present digestive problems during your race. Both natural and artificial sugars can quickly accumulate causing what I like to call a ‘sugar bomb’, sending you to the port-o-potty with gastric distress. Experiment with what agrees with your stomach and have a few options you can tolerate. Bring your own hydration to a race if they don’t offer your preferred drink on the course.

Alternating water with electrolyte drinks is good strategy. In addition, drink water with running-specific or real food and use water to rinse out your mouth, if needed. The accumulation of sugar can also cause issues in the mouth. The buildup of sugar on the teeth and tongue is distracting and can lead to palate fatigue and soreness. The soreness makes it difficult to continue eating or drinking during the race and you might get even further behind on hydration and nutrition.

Experiment to Find Your Customized Hydration Strategy

What you need for hydration is uniquely you. Think of it as a customized hydration strategy. Use the hydration tips that we discussed in the podcast and as summarized in this blog post as a starting point. Then, adjust hydration and nutrition to meet your unique needs. Please reach out to me through Strong-Soles.com or my social media pages with any additional questions. Happy running!