Weather Woes

"By the time you're thirsty, you're already dehydrated," says Jeanne Grant, a registered dietitian at the University of Washington Medical Center's Nutrition Clinic. To compensate for dehydration, the body increases heart rate due to the decreased blood return to the heart. Restricted blood flow leads to constriction of blood vessels in the skin; this constriction reduces your body's ability to dissipate heat.

To avoid dehydration, drink early and often -- about 2 quarts of water a day. Before exercise, which tends to blunt thirst even more, drink 1 to 2 cups of water. During long hikes and bike rides, try to drink another cup or two every 20 minutes. Avoid alcohol and caffeine, which are diuretics and can dehydrate the body. Sports drinks are okay if you are exercising longer than an hour, Grant says, but in most cases water is fine.

A late afternoon thunderstorm can sometimes do more than ruin a hearty hike or a good round of golf.

Lightning kills up to 200 people a year in the U.S. and most strikes hit in July and August. Golfers on the back nine, swimmers, hikers caught above the timberline, and ball players are a few favorite targets.

Lightning's high voltage -- which seldom causes burns -- can stop your heart and breathing. The heart often starts again by itself, but breathing doesn't. CPR can be a real lifesaver.

Most people who get struck, however, survive, says Brian Zachariah, M.D., of the University of Texas Southwestern Medical School. Survivors can suffer hearing loss, fractures, cataracts, paralysis, memory loss, or even personality change.

To be safe, avoid outdoor exercise in the late afternoon if skies are stormy. Strikes are most common late in the day. Take cover at the first flash, no matter how far away the lightning seems.

If you're caught in a lightning storm, avoid being the tallest object in an open area. Seek shelter or lie down in a low area. If you're on a golf course, don't huddle with your partners or near your clubs under a tree. Lightning traveling down a tree has a "splash effect" that can zap through you and a foursome, says Dr. Zachariah.

Hikers and walkers should lie down in a low spot. Don't hide under an overhang; lightning may curl around the rock to strike. If you are swimming, get out of the water.

We know temperature extremes can make even the perkiest people wilt, but running shoes?

In very hot temperatures (90 to 95 F.), shoe stability suffers, says University of Oregon researcher Barry T. Bates, Ph.D. A stiff shoe becames more flexible, which is bad news for the many runners who require stiff shoes to prevent overpronation. Runners who overpronate (a foot rolls inward) often develop foot and knee problems.

Advises Bates: "If you do a lot of running, are prone to injury, and live in a climate with large temperature differences, switching with the seasons from one type of running shoe to another might prevent injuries."

Shoes with gel- and air-filled components are less affected by temperature changes, says Bates.