Hydration for Athletes

I am in the process of studying for the CSSD exam (Certified Specialist in Sports Dietetics) and if it's taught me anything it is how crucial water is for athletes. As a recreational athlete I've experienced first hand the affects of dehydration and if you are an athlete you probably have as well at some point in your life. Losing as little as 2% body weight from water deficit can impair athletic performance as well as make you feel weak, dizzy,and disoriented, not to mention thirsty. While exercising for long periods of time or at intense levels it is usually impossible to maintain water balance, therefore the goal of drinking during exercise is simply to prevent excessive dehdyration (>2%) as well as excessive changes in electrolyte balance which will compromise performance.

The first step is establishing a baseline of water balance. There are measures, such as Urine Specific Gravity, that allow athletes and their coaches to calculate specific hydration states but most recreational athletes do not have access to these technologies. If not, the most practical way to monitor hydration is by measuring body weight. You should have a digital scale that reads at least to the tenth decimal place for accuracy. Be sure to keep your weigh-ins as consistent at possible. Always weigh first thing in the morning, after urinating, and nude for optimal accuracy. Do this for at least 3 days to determine a baseline value. The more days you do this, the more accurate it will be. If you are a menstruating female you will want to weigh for more than 3 days since there is a lot of water weight fluctuation depending on where you are in your cycle.

If you are well hydrated, and in energy balance, your weight should fluctuate no more than 1%. Being in energy balance is very important for this to be accurate. If you are in the process of gaining or losing weight you cannot use this method. Also, keep in mind that if you had a huge meal the night before or if you have been constipated for a few days this will affect your weight as well. If this is the case, measure for several more days until a baseline weight can be established. Once you know your baseline weight, any fluctuations indicate water loss or gains.

You can also use body weight changes during exercise to calculate sweat loss and how much water you specifically need to be consuming during exercise. To do this you will need to weigh yourself immediately before and after exercise, again in the nude if possible. You also need to keep track of how many ounces of fluid you are drinking during this experiment.
The Sweat Loss Formula is:
total estimated sweat loss = (A -B) + (C+D)
where
A= weight before exercise
B= weight after exercise
C= water consumed during exercise
D= water urinated during and after exercise
Remember, there are 16 oz in 1 pound so for every pound lost you will want to drink at least 16 oz of fluid. As an example, if you come up with a sweat loss total of 52 oz make sure to divide that up evenly among 15 minute intervals to determine your hydration schedule. For example, if you exercised 90 minutes, there are 6 15 minute intervals, and 52 divided by 6 equals 8.6. That means drink 8.6 oz every 15 minutes.
If that totally confused you feel free to email me at jensommer55@gmail.com for more info or for help on calculating your specific needs.



Below are the general fluid recommendations for exercise.

Before Exercise: drink 5-7 mL/kg body weight (2-3 mL/lb) at least 4 hours before exercise. (There are 240 mL in 8 oz (or 1 cup-don't you love metric!), or 30 mL in 1 oz).

During Exercise: Refer to sweat rate calculations above to get your specific fluid recommendation or aim to drink 6-12 oz every 15-20 min (18-48 oz/hour).

After Exercise: Drink 16-24 oz of fluid for every pound lost during exercise.