Guest post by:
T. Ryan Littlejohn
Athletic Trainer
MUSC Health Sports Medicine

Everyone knows that water is good for you, right? It helps regulate body temperature and allows the body to function normally, but did you know that too much is just as dangerous as not enough? Learning the symptoms of dehydration and hyponatremia (depletion of sodium in the body) can be essential in protecting yourself and others during activity. The signs of dehydration can include: thirst, headaches, nausea, chills, vomiting, cramps and decreased performance. Early signs of hyponatremia, also known as water intoxication, may include irritability and headaches, but can also cause swollen hands and feet, nausea, vomiting and seizures.  If these symptoms are present, treatment should be sought out immediately. Man & woman drinking water from bottles

Determining your sweat rate is a great way to make sure you are ingesting the correct amount of fluids. This information should not replace your health professionals advice, but is a good starting point for assessing hydration. To find your sweat rate follow this example.

Sweat Rate = (A + B) ÷ C
A= Pre-exercise weight – Post-exercise weight in ounces. (1 pound=16 ounces)
B= Fluid consumed during activity in ounces (1 cup=8 ounces; 1 gulp=1 ounce)
C= Exercise duration recorded in hours.

Example: During Tims outdoor activity he worked out for 60 minutes and drank 8 ounces of fluid.  His pre-exercise weight was 150 pounds and post exercise weight was 149 pounds.
Sweat rate = (A+B) ÷ C
A 150 -149=1 pound loss (16 ounces)
B Consumed fluid 8 ounces
C Worked out for 60 minutes=1 hour
Calculation: 16+8=24 ounces per hour or 12 ounces of fluid every 30 minutes

Tim should plan to drink at least 24 ounces per hour to stay hydrated.* This will allow his body to perform well at a high level during exercise.  

* Note this could change depending on outdoor conditions.