By Becca Bush, MK, CSCS
As summer sets in and the temperature rises, hydration becomes a point of interest for all who participate in outdoor physical activity. Active individuals should take special precaution during hot summer months to ensure that dehydration doesn’t compromise the body’s performance.
Here are a few general guidelines to consider regarding hydration and physical activity:
At least four hours before exercise, individuals should drink five to seven milliliters per kilogram of body weight (mL/kg) of water or sport drink. For example, if an athlete weighs 100 pounds (45.5 kg) they should drink 200-300 mL of liquid prior to exercise. As a reference point, eight ounces of liquid is about 240 mL. As the weight of the individual increases, the fluid recommendations also increase.
For events lasting less than one hour, water is an appropriate beverage to consume throughout. Fluid replacement during exercise is specific to the individual. Refer to the American College of Sports Medicine’s Position Stand for recommendations specific to body size, sweat rates, type of work, etc. Generally, individuals should create customized fluid consumption plans that prevent body weight reductions greater than two percent from baseline weight. For example, if an athlete weighs 100 pounds (45.5 kg) before exercise, they should drink at least enough fluids to ensure their body weight does not go below 98 pounds.
Sports drinks are good beverages to consume when an event lasts longer than one hour. However, fluids that are too high in carbohydrate content should not be consumed. Fluids containing four to eight percent carbohydrate and 250 mg sodium are preferred.
To determine % carbohydrate:
Take a look at the nutrition label on a sports drink.
Find milliliters (mL) per serving and grams (g) of total carbohydrates on the label.
__Total Carbs (g)/__ x 100 = % carbs
Serving Size (ml)
_ 14 g__ x 100 = 5.8% carbs
If time permits, the athlete should consume normal meals and beverages (with adequate electrolytes) to restore normal hydration. Those who need rapid and complete recovery from excessive dehydration can drink ~1.5 liters (L) of fluid for each kilogram of body weight lost. For example, an athlete that loses two pounds (0.9 kg) can drink 1.36 L or about 46 ounces of fluid.
Stay hydrated this summer!
Sawka, M., Burke, L., Eichner, E., Maughan, R., Montain, S., & Stachenfeld, N. (2007). Exercise and fluid replacement. Medicine and Science in Sports and Exercise, 39(2), 377-390. Retrieved from http://journals.lww.com/acsmmsse/Fulltext/2007/02000/Exercise_and_Fluid_Replacement.22.aspx
About the Author:
Becca Bush holds a Master of Kinesiology degree from Boise State University and a Bachelor of Science degree in Exercise Science from Southern Utah University. She holds a professional certification from the National Strength and Conditioning Association as a Certified Strength and Conditioning Specialist. She has worked in both sports performance and in corporate wellness settings. Among her clients are world champion BMX athletes, NFL players, Summer and Winter Olympians, and NCAA collegiate athletes. She also trains program managers, software engineers, developers, and other motivated clients with fitness goals.