Optimizing Hydration
The Physiology Behind How to Hydrate as an Endurance Runner & the Calculations to Guide Your Gulps
Photo by Tristan Brown
By Alyssa O’Krent of AOK PT
As we stride into the peak of summer, it's crucial for endurance runners to understand the vital role hydration plays in performance and overall health. At AOK Physical Therapy, our goal is to optimize our athletes’ performance and health. Optimized hydration helps regulate body temperature, lubricates joints, and transports nutrients, which are all essential for optimal performance, especially during prolonged activities like running.
The Physiology of Hydration
When you run, your muscles generate heat. To dissipate this heat and maintain a stable core temperature, your body sweats. Sweating is an effective cooling mechanism, but it also leads to significant fluid loss. This fluid loss, if not adequately replenished, can result in dehydration, impairing both physical and cognitive function.
Dehydration affects the body in several ways:
Reduced Blood Volume: This makes the heart work harder to pump blood, reducing the efficiency of nutrient and oxygen transport.
Electrolyte Imbalance: Loss of electrolytes through sweat can lead to muscle cramps and weakness.
Increased Core Temperature: As dehydration progresses, the body's ability to cool itself diminishes, raising the risk of heat-related illnesses.
Impaired Muscle Repair and Recovery: Water is essential for cellular functions, including muscle repair. Dehydration slows down the delivery of nutrients and oxygen to muscle tissues, impeding their ability to repair and recover.
Increased Injury Risk: Dehydrated muscles are less elastic and more prone to strains and tears. Joint lubrication is also compromised, increasing the risk of joint injuries.
Hydration Strategies for Endurance Running
Pre-Run Hydration
Aim to drink 0.5 ounces of water per pound of body weight in the 2-3 hours leading up to your run. It is most ideal to consume the majority of this water in the early part of this window.
Example: A 150-pound runner should aim to drink 75 ounces of water pre-run.
Timing: As a morning lark, I often wake up one hour before my run starts. A more realistic target in this case would be around 16 ounces of water to avoid discomfort.
Electrolyte Intake During the Run
Aim to consume about 600 mg of sodium per hour during the run to replace lost sodium, potassium, and other vital minerals.
One LMNT electrolyte packet, for example, provides 1000 mg of sodium, 200 mg of potassium, and 60 mg of magnesium.
Example: For a 150-pound runner:
Hourly Intake: Since LMNT provides 1000 mg of sodium per packet, you would need roughly ½ packet per hour to meet the 600 mg requirement.
During the Run
Consume 0.03 ounces of water per pound of body weight every 15 minutes.
Example: A 150-pound runner should drink approximately 4.5 ounces of water every 15 minutes. One gulp of water is approximately one ounce, so this would be about 4-5 gulps every 15 minutes..
15 minutes: 4-5 gulps
30 minutes: 4-5 gulps
45 minutes: 4-5 gulps (and so on)
Post-Run Hydration
Drink 1.5 times the amount of weight lost during the run. A simple way to estimate this is by weighing yourself before and after the run. Each pound lost should be replaced with 24 ounces of water.
Example: If a 150-pound runner loses 2 pounds during the run, they should aim to drink 48 ounces of water post-run.
Practical Tips for Staying Hydrated
Carry Water: Use a hydration pack, belt, or handheld bottle to ensure you have water readily available.
Monitor Urine Color: A light, straw-colored (or young chardonnay) colored urine indicates good hydration, while dark yellow suggests you need more fluids. If your urine ever changes to a dark brown, seek medical attention immediately.
Stay ahead of your thirst: Thirst is a late indicator of dehydration, so don’t wait until you’re thirsty to drink. Establish a hydration schedule and stick to it.
By following these hydration strategies and incorporating electrolyte intake, you can ensure that your body is well-prepared to handle the demands of endurance running, especially in the heat.
