Fainting
Cause: Often brought on by a sudden stop that interrupts blood flow from the legs to the brain.
Treatment: After the fall, elevate legs and pelvis to help restore blood flow to the brain.
Prevention: Cool down gradually after a workout with at least five minutes of easy jogging and walking.
More: How to Avoid the Dangers of Running in the Heat
Heat Exhaustion
Cause: Dehydration leads to an electrolyte imbalance.
Symptoms: Core body temperature of 102 degrees to 104 degrees, headache, fatigue, profuse sweating, nausea, clammy skin.
Treatment: Rest and apply a cold pack on head/neck. Restore salt balance with foods and drinks with sodium.
Prevention: Don't run hard in the heat till acclimatized, and stay well hydrated with sports drinks
More: Runners: Electrolytes and When to Replace Them
Hyponatremia
Cause: Excessive water intake dilutes blood-sodium levels; usually occurs after running for four or more hours.
Symptoms: Headache, disorientation, muscle twitching.
Treatment: Emergency medical treatment is necessary; hydration in any form can be fatal.
Prevention: When running, don't drink more than about 32 ounces per hour; choose sports drinks over water.
More: Hydration Confusion: How Much is Too Much?
Heat Stroke
Cause: Extreme exertion and dehydration impair your body's ability to maintain an optimal temperature.
Symptoms: Core body temp of 104° or more, headache, nausea, vomiting, rapid pulse, disorientation.
Treatment: Emergency medical treatment is necessary for immediate ice-water immersion and IV-fluids.
Prevention: Don't run hard in the heat until acclimatized, and stay well hydrated with a sports drink.
More The New Rules of Hydration
More: 4 Ways to Thrive When Running in Hot Weather
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