簡單的"伏地挺身"數:一直是"健適"之好指標/
. Breakthrough: How Working Out Can Alter Your DNA
Scientists discover that physical activity leads to beneficial changes in gene activity, even after a single workout
Well
An Enduring Measure of Fitness: The Simple Push-Up
As a symbol of health and wellness, nothing surpasses the simple push-up.
Practically everyone remembers the actor Jack Palance performing age-defying push-ups during his Oscar acceptance speech. More recently, Randy Pausch, the Carnegie Mellon professor whose last lecture became an Internet sensation, did push-ups to prove his fitness despite having pancreatic cancer.
“It takes strength to do them, and it takes endurance to do a lot of them,” said Jack LaLanne, 93, the fitness pioneer who astounded television viewers in the 1950s with his fingertip push-ups. “It’s a good indication of what kind of physical condition you’re in.”
The push-up is the ultimate barometer of fitness. It tests the whole body, engaging muscle groups in the arms, chest, abdomen, hips and legs. It requires the body to be taut like a plank with toes and palms on the floor. The act of lifting and lowering one’s entire weight is taxing even for the very fit.
“You are just using your own body and your body’s weight,” said Steven G. Estes, a physical education professor and dean of the college of professional studies at Missouri Western State University. “If you’re going to demonstrate any kind of physical strength and power, that’s the easiest, simplest, fastest way to do it.”
But many people simply can’t do push-ups. Health and fitness experts, including the American College of Sports Medicine, have urged more focus on upper-body fitness. The aerobics movement has emphasized cardiovascular fitness but has also shifted attention from strength training exercises.
Moreover, as the nation gains weight, arms are buckling under the extra load of our own bodies. And as budgets shrink, public schools often do not offer physical education classes — and the calisthenics that were once a childhood staple.
In a 2001 study, researchers at East Carolina University administered push-up tests to about 70 students ages 10 to 13. Almost half the boys and three-quarters of the girls didn’t pass.
Push-ups are important for older people, too. The ability to do them more than once and with proper form is an important indicator of the capacity to withstand the rigors of aging.
Researchers who study the biomechanics of aging, for instance, note that push-ups can provide the strength and muscle memory to reach out and break a fall. When people fall forward, they typically reach out to catch themselves, ending in a move that mimics the push-up. The hands hit the ground, the wrists and arms absorb much of the impact, and the elbows bend slightly to reduce the force.
In studies of falling, researchers have shown that the wrist alone is subjected to an impact force equal to about one body weight, says James Ashton-Miller, director of the biomechanics research laboratory at the University of Michigan.
“What so many people really need to do is develop enough strength so they can break a fall safely without hitting their head on the ground,” Dr. Ashton-Miller said. “If you can’t do a single push-up, it’s going to be difficult to resist that kind of loading on your wrists in a fall.”
And people who can’t do a push-up may not be able to help themselves up if they do fall.
“To get up, you’ve got to have upper-body strength,” said Peter M. McGinnis, professor of kinesiology at State University of New York College at Cortland who consults on pole-vaulting biomechanics for U.S.A. Track and Field, the national governing body for track.
Natural aging causes nerves to die off and muscles to weaken. People lose as much as 30 percent of their strength between 20 and 70. But regular exercise enlarges muscle fibers and can stave off the decline by increasing the strength of the muscle you have left.
Women are at a particular disadvantage because they start off with about 20 percent less muscle than men. Many women bend their knees to lower the amount of weight they must support. And while anybody can do a push-up, the exercise has typically been part of the male fitness culture. “It’s sort of a gender-specific symbol of vitality,” said R. Scott Kretchmar, a professor of exercise and sports science at Penn State. “I don’t see women saying: ‘I’m in good health. Watch me drop down and do some push-ups.’ ”
Based on national averages, a 40-year-old woman should be able to do 16 push-ups and a man the same age should be able to do 27. By the age of 60, those numbers drop to 17 for men and 6 for women. Those numbers are just slightly less than what is required of Army soldiers who are subjected to regular push-up tests.
If the floor-based push-up is too difficult, start by leaning against a countertop at a 45-degree angle and pressing up and down. Eventually move to stairs and then the floor.
Mr. LaLanne, who once set a world record by doing 1,000 push-ups in 23 minutes, still does push-ups as part of his daily workout. Now he balances his feet and each hand on three chairs.
“That way I can go way down, even lower than if I was on the floor,” he said. “That’s really tough.”
沒有留言:
張貼留言