When all is said and done, however, people with marathon fever end up in good health with no lingering side-effects. But something all runners need to watch out for, regardless of age or physical condition, is dehydration. If hydration isn’t part of your training plan before, during, and after the race, dehydration can sneak up on you as a thief in the night, and it often goes unnoticed until it’s too late. Then come the cramps, the stomach pain, and the runs.
Our bodies sweat…a lot
Whenever we exert our bodies, we sweat, thus beginning a chain reaction that results in decreased running performance if our bodies aren’t rehydrated with the appropriate liquids.
When we sweat, several things occur.
- Blood volume decreases, which in turn, results in less blood returning to the heart
- The amount of blood the heart pumps decreases
- Less oxygen-rich blood reaches working muscles
- Less energy is produced aerobically
- You must run at a slower pace
During a long race, the goal for hydrating your body is to minimize dehydration without over-drinking, but first, let’s start with the basics.
What is dehydration?
Dehydration occurs when you use or lose more than 2 percent of your body weight and your body doesn't have enough water and other fluids to carry out its normal functions. This results in a 4 to 6 percent reduction in running performance.
What are the warning signs?
Some of the warning signs of dehydration include:
- Headaches
- Thirst
- Flushed skin
- Premature fatigue
- Increased body temperature
- Faster breathing and pulse rate
- Increased perception of effort
- Decreased exercise capacity
- Muscle cramps
And later signs include dizziness, increased weakness, and labored breathing.
How to monitor hydration?
Another item to think about during your training is how to monitor your hydration. One of the easiest ways to monitor hydration before and after a run is to check your urine color. If your urine is a straw or lemonade color, you’re in good shape. But if it’s darker yellow — an apple juice color — you’re dehydrated. (And note: If your urine is a bright yellow color, that is usually the result of taking a multivitamin.)
Another way to monitor hydration is by calculating your sweat rate. This is done by taking your pre-exercise body weight and subtracting from it your post-exercise body weight (recorded in ounces). Add that number to the amount of fluid consumed during exercise. Lastly, divide that number by your exercise duration (recorded in hours).
Your sweat rate is important because dehydration sets in differently depending on how fast you’re running. For fast runners, thirst lags behind and may be a late indication of dehydration, but for slower runners, thirst indicates the onset of dehydration.
So, what is the best way to replace fluids?
Before Exercise
Begin exercise well-hydrated. Four hours before exercise, drink ____ ounces of water or sport beverage for every pound you weigh. For a 150-pound person, that’s about 350 ml or 1.5 cups. Beware of over-hydration, since it increases the need to void during activity and provides no advantage.
During Exercise
Drink — don’t pour liquid over your head. Drinking cools from the inside out. If your run is less than an hour or involves low to moderate activity, stick with water. If you’re in for the long haul (more than an hour) sports drinks with 4-7% carbohydrate are the best in order to replace carbohydrates and electrolytes.
After Exercise
To rehydrate after your workout, drink 16-24 ounces (2-3 cups) of fluid for every pound of body weight lost during exercise. Consider thirst, urine color, fluid intake, sweat loss, and body weight changes. And remember: It’s better to drink small amounts throughout the day than a lot all at once.
So now that you’re an expert on how to stay hydrated, let’s sum it all up.
- Don’t drink only water. Alternate with sports drinks.
- Drink when you’re thirsty, but don’t force yourself. Stay hydrated, but not overhydrated.
- Weigh yourself before the race, and write your weight on the back of your bib. This will be helpful for medical staff if you need attention at the finish line.