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On Your Marks, Get Set... Guzzle!
You have just finished a long run, it is a warm sunny day, you are sweaty and your face is beat red, so you reach for that ice cold water bottle and begin to guzzle! Nothing beats fluids when you exercise. Nothing beats fluids at any point of the day for that matter. Fluids are a crucial nutritional practice for optimizing performance as well as maintaining good health and well-being. Water is the largest component of the human body, making up 50 to 70% of the body's weight (about 10 gallons, or 40 liters). For this reason, water plays several key roles in numerous processes in the body. It takes part in many chemical reactions as a solvent, reactant or product and transport medium. Water plays a role in temperature regulation through perspiration and evaporation; it helps remove waste products such as excess sodium and urea (a by-product of protein metabolism containing nitrogen) via urine; it helps form the lubricants found in the joints of the body and is the basis for saliva, bile and amniotic fluid. It is apparent that regular hydration is important to maintain vital bodily procedures and therefore, dehydration should not be taken lightly.
Fluid Needs
Adults need about 1 milliliter of water per kcal expended, adding up to be the common prescription of 2 liters (8 cups) per day. We consume about 1 liter of water in various liquids such as fruit juice, tea, milk and water itself. Foods such as fruits, vegetables and soup, can supply another liter of fluid. The body operates on an "import/export" system, meaning, fluid intake closely matches fluid lost. Fluid is periodically lost during the day by way of sweat glands, urine, feces, respiratory tract and skin. (Fluid loss varies depending on environment, temperature, body type, metabolic rate, etc.) Here is a chart to better understand this process:
Water Intake
Drink: 4 cups
Water Content in Food: 4 cups
Water Produced from Metabolism: 1.5 cups
Total = about 10 cups
Water Output
Skin (perspiration): 2 cups
Lungs (respiration): 1.7 cups
Urine: 5.5 cups
Feces: 0.6 cups
Total = about 10 cups
Physically active individuals need more than the average requirement because of the volume of sweat lost in physical activity. When exercising, at times an individual can lose greater than 2 to 3 liters per hour; thus, demanding a greater fluid intake, even up to 10 liters per day. It is common to guzzle water after a workout to fill the "quota" for necessary water intake and remain hydrated. In actuality, to best optimize performance and overall health as an active person, it is critical to hydrate before, during and after exercise.
Before Exercise:
Being well hydrated prior to physical activity helps promote physical performance. Dehydration is a definite disadvantage when exercising often causing slower responses, muscle cramps and early fatigue. A practical tool to assess hydration status is to monitor color and volume of urine. Darkly colored urine that is relatively of small volume is a strong indication of dehydration. The thirst mechanism is not a reliable tool to assess level of hydration, as this is the body screaming, "I am dehydrated! Drink something!" At this point, it is too late.
Besides obtaining plenty of water through regular drinking and eating, it is recommended that individuals drink about 500 milliliters (about 16 fl. oz.) of fluid about 2 hours after exercise, allowing time for the body to absorb and process. In addition, drink 250 to 500 ml (8 to 16 fl. oz.) about 15 minutes before activity. This will promote adequate hydration as well as lower core temperatures and heart rates during exercise. If exercising outside in warm temperatures, add another 250 to 500 ml (8 to 16 fl. oz.) 30 to 60 minutes before exercise.
During Exercise:
While exercising, individuals should drink at regular intervals to consume fluids at a consistent rate to replace water lost via sweating. To remain well hydrated, individuals should drink about 1 liter (32 fl. oz.) during each hour of activity. This should be consumed in intervals of at least 125 to 250 milliliters (4 to 8 fl. oz.) every 10 to 20 minutes. When exercise exceeds 1 hour, fluids containing carbohydrates and/or electrolytes (example: Gatorade) are recommended during exercise.
After Exercise:
Fluid replacement after exercise is critical for quick recovery. The best scenario for fluid replacement is guided by way of monitoring water loss. If an individual weighs him or herself prior to the exercise session and then immediately post exercise, an estimate of water loss can be determined. For every 0.5 kilograms (or 1 lb) of water loss during exercise, 500 to 700 milliliters (16 to 20 fl. oz.) is needed to re-hydrate. For example, if an individual weighs 63.5 kilograms (140 lbs) prior to an exercise session and then 62.6 kilograms (138 lbs) post exercise, he/she needs to consume 1000 to 1250 milliliters (32 to 40 fl. oz.) to re-hydrate [1 kg (or 2 lbs) x 500 to 700 ml (or 16 to 20 fl. oz.) = 1000 1250 ml (or 32-40 fl. oz.)].
Being that sweat contains sodium and electrolytes, sports drinks are highly recommended to replace these losses. The best scenario for post exercise rehydration is to drink sports drinks containing 14 to 16 grams per 250 milliliters (8 fl. oz.), which is about 6% carbohydrate. Avoid sports drinks with more than 8% carbohydrate since they exit the stomach slower.
Tips for Maximum Hydration:
- Always carry fluids with you wherever you go
- Know the warning signs of dehydration: fatigue, light headedness, headaches, dry mouth, dark urine, muscle cramps
- Drink by schedule - not by thirst
- Know your sweat rate by weighing before and after exercise
- Drink 500 to 700 milliliters (16 to 20 fl. oz.) for every 0.5 kg or pound of weight lost after activity
- Replace fluid and sodium losses to achieve complete re-hydration
- Put more in your stomach than on your head!
- Avoid alcoholic and caffeinated beverages which have diuretic properties
Hopefully, while reading this article you have been sipping on your water bottle but if not... on your marks, get set... GUZZLE!
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