Monday, July 30, 2012

Hydration and Exercise

  • 75% of Americans are chronically dehydrated. It is probable that similar percentages apply to 90% of the world population.
  • For each 1% loss of water, there is a 10% loss in exercise performance.
  • Lack of water is the #1 trigger of daytime fatigue.
  • Recommended water intake a day is half your body weight in ounces. For all you 200lb guys out there; Are you taking down 100 ounces of water a day?
As evidence by these stats, hydration is vital. Not only to performance, but for everyday life. Water is the essence of life. It is the most important nutrient in our bodies making up roughly 70 percent of our muscle and brain tissue. Only oxygen is craved by the body more than water. Replacing bodily fluids lost be everyday activity, and more specificly exercise, is crucial to helping your body recover and maintain a healthy functioning system.

A little Science to help you understand Hydration and Exercise.
Staying hydrated is essential for everyone, but for athletes and fitness enthusiasts, proper hydration is even more important. Sweat loss rates (how much water you lose during exercise) during hard exercise may be as high as 2-3 Liters per hour. (Sweat rates commonly range between one to four pounds per hour, depending on your sport and environmental conditions) Replacing the sodium, chloride, magnesium, and potassium (Electrolytes) lost during exercise can be done by using water or a variety of  other products. If not done properly, you may experience dehydration which can lead to muscle cramps, headaches, and fatigue in the mildest of circumstances.
A table of what is lost in a liter of sweat
Electrolyte- Average amount/ 2 lbs (1 liter,~1 quart) sweat Food reference
Sodium- 800 mg (range 200-1,600) 32 ounces( 2 standard gatorades) = 440 mg Sodium
Potassium- 200 mg (range 120-600) 1 med banana = 450 mg Potassium
Calcium- 20 mg (range 6-40) 8 oz yogurt = 300 mg Calcium
Magnesium- 10 mg (range 2-18) 2 Tbsp peanut butter = 50 mg Mg
Measuring if you are hydrated can be done by
  1. Monitoring urine volume output and color. A large amount of light colored, diluted urine probably means you are hydrated; dark colored, concentrated urine probably means you are dehydrated. (Unless you have vitamin B in your system which is common in multivitamins.)

2. Weighing yourself before and after exercise. Any weight lost is likely from fluid, so try to drink enough to replenish those losses. Any weight gain could mean you are drinking more than you need.
Fluid Replacement Guidelines
Before Exercise
  •  Drink 17-20 oz. of water or a sports drink (If you feel like your electrolyte levels are low) 2-3 hours before exercise.
  • No need to overhydrate. Your kidneys can only process so much liquid and hydrating 2-3 hours before exercise allows time for your kidneys to process and eliminate the excess.
  • Drink an additional 7-10 oz. of water or sports drink 10-20 minutes before exercise.
  • If you take caffeine, take it 30-60 minutes before you exercise.(see my previous blog for more on this)
During Exercise
  • Begin drinking early during the sporting event . Even minimal dehydration compromises performance. (Small sips on a regular basis are the best way to go)
  • In general, drink at least 7-10 oz. of water or a sports drink every 10-20 minutes.
  • Remember to drink beyond your thirst to maintain hydration. Optimally, drink fluids based on the amount of sweat and urine loss. (Again try not to gulp 10 ounces at once.)
  • If exercising longer than 60 minutes, drink 8-10 fl oz of a sports drink  every 15 - 30 minutes. (These carbs help maintain normal blood glucose levels so you are able to enjoy sustained energy)
After Exercise
  •  Within two hours, drink enough to replace weight loss from exercise. If your workout was longer than 60 minutes, your electrolyte levels need to be replenished with something containing sodium, potassium, magnesium, and calcium.
  • Drink 20-24 fl oz water or liquid for every 1 lb lost.
  • Consume a 3:1 ration of carbohydrates to protein drink or meal within the 2 hours after exercise to replenish glycogen stores. 
  • Kevin

No comments:

Post a Comment