Determining Hydration Needs
By Lee Haynes
Saturday morning there was a question on weighing yourself before exercise and afterward and fluids consumption...
We said we'd get the correct answer, from USA Fit...
What is the best method for calculating the amount of fluid a person needs during exercise?
- Baseline fluid requirements for non-exercising individuals can be calculated by weighing the person in lbs and dividing that number by 2:
- Wt (lbs) divided by 2 = minimum daily requirement of fluid for a non-exercising individual represented in ounces
- Example: 140 lb male
- 140/2 = 70
- 70 ounces fluid replacement necessary for daily maintenance
- Exercising individuals need to build on the minimum daily fluid requirement. The most accurate method for determining fluid replacement for an exercising adult is by weighing themselves before they run and weighing themselves again after they run. The change in weight represents the amount of fluid necessary to achieve an accurate fluid balance.
- Example: 140 lb male
- Pre-exercise weight: 140 lbs
- Post-exercise weight: 139 lbs
- 1lb of weight loss = 16 ounces of fluid to be replaced
This is in addition to the minimum daily requirement
It is also recommended that on hot days and additional 8-20 ounces of fluids be consumed prior to exercise (30-60 minutes before). An easy way to remember how much to drink is to drink often, aiming for at least 5-8 ounces of a sports drink every 10-20 minutes during exercise lasting longer than an hour or anytime the weather is warm. Optimal fluid replacement for most runners is 500ml/hr.
