ehydration is when our body loses more water than what it consumes due to factors like hot weather, certain diseases, exercise etc. As the body fluid level goes down your metabolism also gets negatively affected. However, three to four percent reduction in body water loss is usually tolerated by the human body. A loss ranging between five to eight percent can lead to lightheadedness and fatigue. Extreme thirst along with mental and physiological deterioration occurs if the loss exceeds ten percent. Fifteen to twenty percent loss of body water can lead to death. Oral rehydration can help you come out of mild dehydration. 
Reasons for Dehydration in Runners
1. Poor access to fluids
If fluids are not easily available or accessible during training sessions or during races, dehydration sets in.
2. The intensity of the activity
As an athlete’s intensity of training increases, more water is lost through sweat and the lesser time he may get to rehydrate himself.
3. Lack of proper hydration at the onset of a race or exercise session
If the hydration level at the beginning of an exercise or training session is not appropriate then rapid dehydration may take place in runners.
4. Training or running in hot weather
This leads to an excessive amount of sweating and thereby rapid dehydration.
5. Many practice sessions on the same day
Multiple practice sessions increase the body’s need for fluids.
6. Higher sweat rate or larger body frame
Those who sweat more or are bigger in size lose more fluid, so need to replenish more.
7. Poor access to meal
As we consume a large number of fluids with our meals, our hydration level is disturbed if our normal eating patterns are disturbed.
8. Variation in tolerance toward fluids
Individual differences occur as far as one’s capacity to consume the amount fluid he has lost during running is concerned. So rather than drinking a large amount at one go, you can consume fluids slowly over a period of time. 
Signs of Dehydration in Runners
- Feeling thirsty
- Dryness of skin, mouth, and eyes
- Increased rate of heart
- Reduced motivation
- Mental fatigue
- Over sweating indicating loss of electrolytes and energy
- Under sweating indicating heat exhaustion
How to Stay Hydrated
Following are the various ways to keep yourself hydrated on Hot and Humid Day:
- Way to Stay Hydrated
- Daily Hydration
- Consume Water and Water Rich Fruits and Vegetables
- Suitable Hydration Drink
- Replenishment of Electrolytes
- Be Cautious With Sports Drinks
- Count Your Total Intake of Fluids
- Start Hydrating Beforehand
- Total Amount of Water to Be Consumed Before the Race
- Amount of Water to Be Consumed by Long Distance Racers
- Fluid Carrier
- Amount of Water to Be Consumed After the Race
- Check Your Urine’s Colour
- Hydration and Nutrition for Race Day Preparation
- Tips for Runners for Racing on a Hot and Humid Day
1. Daily Hydration
Hydrating yourself daily is the best way to avoid dehydration or its warning signals
2. Consume Water and Water Rich Fruits and Vegetables
You should not only drink eight to ten glasses of water a day but also eat fruits and vegetables having high water content. These include spinach, cucumber, tomatoes, radish, watermelon, cauliflower, iceberg lettuce, broccoli, and capsicum.
3. Suitable Hydration Drink
Choose an appropriate hydration drink. Its sugar content should be less than ten grams and sodium content should be between 250 to 350 grams. Hydrate yourself before and after your training session and after every twenty minutes when training. 
4. Replenishment of Electrolytes
Your hydration product should also replenish your primary electrolytes i.e. magnesium, calcium, potassium, and sodium as well as minerals that you lose with your sweat while running.
5. Be Cautious With Sports Drinks
Many sports drinks are high in sugar which is detrimental for our health. So, you have to be careful.
6. Count Your Total Intake of Fluids
Long distance runners need to keep a track of their total intake of fluids during the entire stretch including how much they have consumed before and after their exercise.
7. Start Hydrating Beforehand
A runner who will be covering more than ten miles needs to start hydrating himself or herself many days before the actual race. Drink lots of non-alcoholic fluids and water and rest well. 
8. Total Amount of Water to Be Consumed Before the Race
Before your race begins, you should be drinking a minimum of 16 ounces of water or non-caffeinated drinks. However, it should not exceed 24 ounces as then your urge to eliminate may also be initiated.
9. Amount of Water to Be Consumed by Long Distance Racers
Long distance runners should drink a minimum of six ounces of water or other fluids within every twenty minutes. It should not exceed eight ounces. If you run for more than thirty minutes consume a sports drink to replenish your lost minerals and sodium while running. 
10. Fluid Carrier
Use a fluid carrier to carry fluids along with you while running just in case there is no availability of any during your race.
11. Amount of Water to Be Consumed After the Race
Post your race, drink a minimum of 20 ounces and a maximum of 24 ounces of water or any sports drink for proper hydration of your body. 
12. Check Your Urine’s Colour
The color of your urine is an indicator of your hydration level. If it is dark yellow, you need more water. As it turns lighter your hydration level is just fine. 
13. Hydration and Nutrition for Race Day Preparation
Stay well hydrated. Your fluid consumption should be such that you pass urine after every two or three hours. If the color of your urine is light yellow, then you have appropriate hydration. Overhydration, on the other hand, can disrupt your normal electrolyte balance. So, if you are urinating after every one hour you should slow down your intake of fluids.
Do not try anything new the day before and just stick to what you have been eating during your training or what suits your stomach.
In case the race is being held in a new site, do advance meal planning to be sure you get your favorite foods. Alternatively, you can carry your food.
The biggest meal on the day before should be your lunch and you should concentrate on getting ample carbohydrates. This will also give your body ample time to digest it.
Do not overload carbs on a prior night as it may make you feel bloated on race morning. Do not consume gas forming or high fiber foods like bran, beans etc.
Alcohol will dehydrate you and alter your sleep so don’t consume it. 
The day before the event consumes extra fluids which could be nutrient rich fluids like pure juice, non-fat milk or just water. On the morning of the race, just two hours before the actual event consume two cups of fluid. Your kidneys will get ample time to work on the liquids and therefore you will get enough time for emptying your bladder before the race. Half an hour before your race just drink 5 to 10 oz. of sports drink or water. 
As every runner or athlete has a unique need for hydration, you need to weigh yourself pre and post-training session. This will help you get an estimate of the amount of fluid your body, in particular, requires to stay hydrated. You need to drink 16 oz. of extra fluid for each pound, you lose during an activity. 
You need to drink 24 oz. of fluid post your activity per pound lost during the activity. The weight difference pre and post will help you determine if you are over-hydrated. Once the race ends first drink to mitigate your thirst and then drink accordingly. 
14. Tips for Runners for Racing on a Hot and Humid Day
Choice of clothing has to be appropriate: as you need to stay cool during the race wear something that is comfortable, fits you loosely and absorbs your sweat. Apply sunscreen and use a cap and sunglasses if possible.
While you were training the weather condition may have been more pleasant so your expectation or running goals would have been different. In adverse conditions like very hot and humid days prior to beginning your race you need to modify your goals, your pace etc. Research has revealed that lowering your speed by 20 to 30 seconds per mile with every five degrees Fahrenheit rise above sixty degrees is beneficial for a runner to finish without getting exhausted or dehydrated. 
While crossing aid stations, pick two cups one for drinking and another for splattering on your head to cool yourself. Certain races also supply you with some cooling amenities like hoses that spray over runners or cooling sponges etc. You can use these if required.
Follow guidelines to properly hydrate yourself. Take a sports drink with electrolytes to promote absorption of water by your body.
a. Homemade Sports Drink
The aim of a sports drink is to replenish the electrolytes especially sodium that athletes lose along with sweat. Lack of sodium or hyponatremia in athletes causes muscle cramps, nausea, and fatigue. Sports drinks help them to maintain apt electrolyte balance along with hydration level. 
b. Citrus Sports Drink
Two teaspoons of lime
A quarter cup of orange juice
A teaspoon of lemon juice
Three tablespoons of agave syrup
Combine all these and blend well to consume. You can even combine a batch of this juice with two cups of seltzer in a twenty-ounce sports bottle. Put the lid, shake and mix. 
c. Strawberry Lime Sports Drink
A quarter cup of limeade
A quarter cup of sugar
Four to six mashed strawberries
A quarter cup of hot water
Two tablespoons of lime juice
A pinch of salt
Three and a half cup of cold water
Dissolve the sugar in hot water and then add all the ingredients together well and it is ready to drink.
d. Watermelon Slush
Seven or more cups of seedless watermelon cubes
A quarter cup of sugar
A little bit of salt
Twenty-four ounces of plain seltzer water.
In a blender blend all the ingredients and it is ready. To make it thinner in consistency you can add more of seltzer. You can pour your sports drink in popsicle molds, freeze them and pop in when training in hot and humid weather.
e. Sports Drink of Various Flavors
The following sports drinks can be prepared in five minutes and can serve one. If you will be running or training in very hot and humid climates, then you can prepare an extra batch to freeze it and add the ice cubes in your bottle containing the sports drink.
- Orange and maple combo: You require a cup full of orange juice that is free from pulp, two cups of water, two tablespoons of pure maple syrup and some sea salt.
- Apple cider and cinnamon combo: You need a quarter teaspoon of cinnamon, one and quarter cups of pure apple cider, sea salt and two cups of water.
- Pomegranate and mint mix: a cup of pomegranate juice, two cups of cooled and unsweetened mint tea, a tablespoon of fresh lemon juice and sea salt.
In a water bottle combine the ingredients of your chosen flavor, shake well and drink. 
f. Chia juice
A cup each of warm water
Any organic juice
Three tablespoons of chia seeds.
Add chia seed to warm water and stir it well. As the seeds enlarge to cover the container. Let it soak overnight in the fridge. In the morning, you get a thick mix to which you need to add your favorite organic juice, mix well and drink. Chia seeds have ample potassium, antioxidants, calcium, omega 3 fats and protein which make it a good addition to a sports drink. 
g. Organic Sports Drink
Three-fourth cup of organic orange juice
Two organic lemons
Two organic limes
Half a teaspoon of Himalayan pink salt
A little bit of cayenne
A three-fourths teaspoon of calcium magnesium powder
Eight cups of water
Three tablespoons of honey.
In a big pot take one cup of water and add salt, honey, calcium magnesium powder and cayenne. Blend it over low heat and let it cool. Squeeze the juice out of the limes and lemons and mix with the orange juice. Mix all the ingredients together and store in the refrigerator. This drink is rich in electrolytes, calcium, magnesium and vitamin C to replenish and hydrate you.