How to Hydrate for running
When running for more than 30 minutes, you'd better hydrate along the way. For every 1% dehydrated you get, your performance can suffer up to 5%.
You Will Need
* A bathroom scale
* A water bottle
* And a sports drink
* A water bottle pack that cinches around the waist
Step 1: Weigh yourself
Weigh yourself naked as you're getting dressed to run.
-Tip: Before you take a step, chug a tall glass of water.
Step 2: Fill your bottle
Fill up a water bottle with water for runs shorter than an hour. If going longer, fill it with a sports drink.
Step 3: Pack your bottle
Either hold the bottle in your hand, or carry it in a pack around your waist.
Step 4: Hydrate
Drink about 20 ounces of fluids ever hour. The hotter it is the more you'll need to drink.
-Tip: If it's scorching and you know you'll need more than 20 ounces of fluids every hour, carry two water bottles, one filled with a sports drink.
Step 5: Weight yourself again
When you return home, strip off your clothes, dry yourself completely, and weigh yourself again.
Step 6: Assess your hydration
If you've lost weight, you need to drink more during your workout. For every pound less, drink 16 more ounces next time you run.
Hyponatremia, or over-hydration, is considered a bigger threat to marathon runners than dehydration.