Dehydration: Curse of Summer (And Winter) Running

For endurance athletes, few things are more enjoyable than a good workout or a race in pleasant weather conditions.

But the summer months can also help foster the worst curse for runners – dehydration.

The loss of the body’s fluids can abruptly not only ruin a training effort or a competition, but it can cause more severe problems, even death.

“Most people assume that their bodies will warn them before they become dehydrated, usually by intense thirst,” said Dr. Mark Fredrick, a physician in Costa Mesa, Calif. “Unfortunately, that signal can be masked. Often when a person loses fluid quickly, the normal thirst mechanism is overwhelmed, and dehydration or heat stroke can set it with little or no warning.”

According the standard averages, a person loses four liters of fluid through daily activities. Fluids and food consumed usually replace the normal losses, while evaporation of sweat from the skin raises the rate of cooling.

But certain factors – exercise, sweating, diarrhea, exposure to high temperatures and exposure to high altitudes – can significantly increase the required amount of replacement fluids required.

Exercise and sweating cause the large percentages of fluid loss and can result in dehydration rapidly. Even mild cases of dehydration, especially if accompanied by diarrhea, vomiting of high temperature, can acutely affect the body’s ability to maintain a proper balance of fluids.

“Parents should carefully monitor children’s outdoor play and fluid intake in heat,” said Dr. Jerome James, a pediatrician, also in Costa Mesa, Calif. “When exertion raises the body’s core temperature, the brain stem engages cooling mechanisms, which allow the blood to be cooled and the sweat glands to produce sweat.

“On very hot days, however, it is easy to overheat (heat exhaustion) because the ability to sweat is reduced, and the sweat that is produced cannot evaporate. This is a serious problem in people of all ages, but children are especially vulnerable.”

Common symptoms of heat exhaustion are fatigue, exhaustion, nausea, lightheadedness and possible heat cramps, and recovery is not always easy. But there are recommended treatments, the most common of which is to replenish the body with sodium-enhanced tepid cold water. The recommended solution is one teaspoon of salt dissolved in a liter of water. A tablespoon of sugar or a sweet drink mix added to the solution can also help restore energy.

Taking preventative measures is the best way to avoid heat exhaustion. Recommendations include:

  • Drink enough to replace lost fluids, including a well-known practice of among endurance athletes of drinking before being thirsty;
  • Maintain a slower pace during exercise, adapting to the heat;
  • Avoid exercising in the middle afternoon hours, normally the hottest part of the day;
  • Wear cotton clothes that allow air to pass through the fabric and sweat to evaporate;
  • Wear a brimmed heat.

In severe instances, heat stroke can occur rather than heat exhaustion, a condition that can be life-threatening in as a little as 30 minutes, according to Dr. Fredrick.

“When the core temperature of the body rises rapidly, the brain with dilate the blood vessels in the skin in an attempt to cool the blood,” said Fredrick. “The skin becomes red and hot, but still may be wet. In the ill or elderly, heat stroke may produce dry skin from dehydration. The person may also be disoriented, combative, argumentative and even hallucinatory.”

In the event of possible heat stroke, recommended guidelines include:

  • Cool the head and neck and, if possible, place an ice pack at the neck, armpits and groin;
  • Remove all non-cotton clothing;
  • Soak the victim in tepid water, if possible;
  • Fan the victim to increase evaporation of water of the skin;
  • Massage the extremities to return cool blood through the body;
  • Do not force fluids, but continue to cool the afflicted person with hopes they will be able to begin drinking fluids independently.