MINNEAPOLIS -- Summer's simmering conditions and strenuous work are a potentially fatal combination.

HEAT SAFETY Section: Summer Weather Interactive: Sun Safety FROM OUR PARTNERS Guide: All About Heatstroke First Aid: Emergency Treatment Kids: Summer Heat Safety

Heat stroke, which is often linked to inadequate fluid intake, can alter the body's cooling system and the mechanisms it uses to deal with heat stress.

Heat stroke is defined as a core body temperature in excess of 105 degrees with associated central nervous system dysfunction. When the heat cannot be dissipated, severe problems can result.

Complications include respiratory distress, intravascular coagulation, renal or liver failure and seizures.

Older adults, people who are obese and people born with an impaired ability to sweat are at high risk of heatstroke. Other risk factors include dehydration, alcohol use, cardiovascular disease and certain medications.

Stay safe and watch for these signs.

• Rapid heartbeat
• Rapid and shallow breathing
• Increased or lowered blood pressure
• Cessation of sweating
• Irritability, confusion or unconsciousness
• Fainting, which can be the first sign in older adults

Avoid heat stroke by staying away from caffeinated beverages. Caffeine dehydrates the body. Avoid carbonated beverages, which can cause bloating and deter you from drinking enough water.

Wear light-colored clothing in the sun and stay in cool, shaded areas when possible. If you have to remain in the sun for extensive periods, protect your skin with sun block.

Doctors stress the importance of water. Adults should consume 17 to 20 ounces of water before an activity. Drink 7 to 10 ounces every 10 minutes during the activity, and try to take in 24 ounces within two hours of finishing a workout.

Remember -- sodas and alcoholic beverages are not substitutes for water.

If you suspect that someone is suffering from heat stroke, move the person out of the sun and into a shady or air-conditioned space. Dial 911 and blanket the victim with damp sheets.