It doesn't take long to get dehydrated when running in the heat, and if you're thirsty it’s already too late.
So before you head out for your summer run, whatever the distance, be sure to apply sunscreen, dress in light colored clothing and drink a lot of water (you could even start the day before). Try to carry water with you or plant some along your route because dehydration will surely cramp your style. Some warning signs that you should look for when running in the heat are increased thirst, dry mouth, confusion and weakness or dizziness.
Unless you have conditioned your body to consistently run in hot weather, you will not be able to maintain your pace, so keep an eye on your heart rate and listen to your body.
As the mercury rises, your body will begin to sweat earlier as you exert yourself. Your body contains about 60% fluid, with almost half of this residing in the muscle cells. During vigorous or prolonged exercise such as running, large quantities of water and electrolytes are lost through sweat, as the body promotes heat loss. Smaller quantities of water are also lost through breathing (respiration).
Individual sweat rates and fluid losses vary widely. As a standard rule of thumb, U.S. News & World Report suggests the following formula: Your weight x 0.5 = ounces of water to be consumed per day. For example, 200lbs x 0.5 = 100.0 ounces per day. This is more than the historical eight glasses of water per day. The American College of Sports Medicine recommends adding 12 ounces of water to your daily intake for every 30 minutes that you plan to work out.
The rate of sweating also varies depending on such factors as the intensity of running exercise, air temperature, humidity and your body’s exposure to sunlight. Therefore when running in the heat, an adjustment has to be made to increase your fluid and electrolyte intake to compensate for obvious depletion. Hydration has to be ongoing in order for you to survive a run in the summer. So drink more fluids prior to running where the elements play more of a factor in your body performance.
Many clinical studies have been carried out to explore the effects of dehydration on exercise performance. At 2% water loss or more the following impacts have been observed:
Dehydration can reduce exercise performance (speed and power output)
Dehydration can reduce the time to exhaustion
Dehydration increases the perception of exercise difficulty
Dehydration can reduce mental performance such as alertness, concentration, visual, motor skills and decision-making
Dehydration and sodium loss can lead to muscle cramps
Dehydration is a risk factor for heat exhaustion and heat stroke which are both serious conditions
Understanding the signs and symptoms of dehydration and managing it early will stop any further injury or illness to you. Dehydration influences several aspects of exercise in a negative way. Rises in core temperature, early fatigue, and decreased performance are some factors that are present in a dehydrated runner. Water is the primary method of rehydration. Overall hydration is beneficial not only to exercise and athletic performance, but also physiologic functions.
So what should you do after your hot run? Lay in the air conditioning? Take a cold shower? Jump in your neighbors’ pool?
First, you should aim to correct any fluid loss depleted during your run. Rehydration should include water to restore hydration status and carbohydrates such as oranges or bananas to replenish glycogen stores.
Based on volume and osmolarity, the best fluid to drink after running to replace fluids that are lost via sweating may not be water - try Pedialyte instead.
Including carbohydrates in your rehydration solution may improve the rate of intestinal absorption of sodium and water, and aid in replenishing your glycogen stores. Replenishing glycogen stores will enhance performance in subsequent exercise sessions (Casa et al., 2000). It's important to keep in mind the recommended daily values for carbohydrates and not to exceed those limits while rehydrating.
It's critical that runners maintain a healthy state of hydration through proper fluid uptake prior to, during and after intense exercise. So stay safe this summer, listen closely to your body and drink plenty of water!