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.