From the New York Times:
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...
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...
Interested in building up your strength using push-ups? You can find a push-up program on the site below designed to gradually increase your strength over 6-8 weeks. Of course, please consult your doctor prior to beginning any exercise program.