ATLANTA (AP) _ Feeling faint? Cross your ankles. Squeeze your knees. Grip a ball. Simple muscle-tensing exercises like these can keep you from passing out, say researchers who did a scientific study of the problem.
Lots of people have fainted at least once in their life, usually with little consequence other than embarrassment.
But for some, it's a frequent occurrence that is especially dangerous if it happens while they are driving or if they have jobs like piloting airplanes.
``If they have one episode during a flight, they have a problem,'' said Dr. Nynke van Dijk of the University of Amsterdam, who led the study with financing from the Netherlands Heart Foundation and presented results at a meeting of heart doctors in Atlanta.
Exercise has many benefits, but this is the first scientific study testing specific techniques for fainting.
``They are very cheap, have no known side effects as far as we know and are very easy to teach patients,'' she said.
Fainting is a reflex that can be triggered by stress, dehydration, low blood pressure, certain medications and many other factors. The heart strenuously contracts, the heart rate falls and blood pressure drops. Blood drains from the head and pools in the abdomen, causing the patient to lose consciousness and collapse.
``It's a very common complaint in doctors' offices,'' and a problem that many patients find frightening, said Dr. Matthew Wolff, cardiology chief at the University of Wisconsin-Madison.
Van Dijk and fellow scientists wanted to see if people who feel a fainting spell coming on could do exercises to raise blood pressure and abort it.
They studied 223 frequent fainters ages 16 to 70. About half were given the usual counseling about avoiding stress and other triggers of fainting and increasing salt and water intake to raise their blood pressure.
Others were taught three exercises:
_ Leg crossing, at the ankles while squeezing the thighs together and tensing abdominal muscles.
_ Hand gripping, by interlocking fingertips and pulling arms in opposite directions.
_ Arm tensing, by rhythmically squeezing a soft ball while also tensing thighs and abs.
Over the next 14 months, about one-third of those taught the exercises had a fainting spell compared with half of those who weren't taught the muscle-tensing methods.
People who learned the exercises actually described using them to cut short a spell of lightheadedness, van Dijk said.
She taught her patients the exercises in half an hour, and said many variations are possible _ tighten your thighs and butt ``like dancing the tango,'' she recommended.
``The stuff really works,'' and doesn't involve drugs or any risk, said Dr. James Stein, another University of Wisconsin cardiologist.