Posted by: Duke Raleigh Hospital | July 16, 2018

Hydration: Optimizing Fluids for Best Form and Function

hydration infographic
As the summer temperatures climb and you start training for your fall marathon it’s important to consider an effective fluid plan for longer endurance runs to prevent under and over-hydration.

What to watch for:

Heat Illness
Cause: Under-hydration
Symptoms: Headaches, dizziness, confusion, fatigue, nausea and vomiting.

Hyponatremia (severely low sodium)
Cause: Over-hydration can dilute the amount of sodium (salt) in the blood.
Symptoms: Nausea and vomiting, headache, confusion, feeling tired, irritability, muscle weakness, spasms or cramps, seizures or passing out.

If you experience any of these symptoms of heat illness or hyponatremia, stop running immediately and if symptoms persist seek medical attention.

Fluid losses during activity vary by sweat rate ranging from 400 mL/hour to >2500 mL/hour. Sodium concentration of sweat also varies. Sweating rates fluctuate with the environment and other factors. For example, hot and humid conditions increase sweating and, acclimating level of the participant, their running pace, and level of exertion all affect the sweat rate.

Thirst is an indication that you are under-hydrated. Avoid drinking only when you feel thirsty. Be sure to drink regularly. For longer distance efforts, consider alternating between water and an electrolyte fluid drink or supplements to avoid hyponatremia.

Staying hydrated prior to training efforts should become part of your daily wellness regimen particularly when the heat index is high.

Running partners Jocelyn Wittstein, MD, and Melissa Raddatz, NP, work together at Duke Orthopaedics & Sports Medicine. Dr. Wittstein is Assistant Professor of Orthopaedic surgery at Duke. She specializes in adolescent and adult sports injuries. She has run several marathons and is an age group competitor. She previously coached Team in Training marathon groups in Eastern North Carolina. Melissa enjoys treating athletes and sports enthusiasts of all ages and levels. She ran Division I Cross-Country and Track at William & Mary. She has run a 2:50 marathon and is a five time nominee for New York Road Runners “Runner of the Year.”

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