The most popular exercises in the 1920’s were Walter Camp’s Daily Dozen. Camp, a robust former Yale football star and the inventor of the All-American team, said he got the inspiration for his system by watching lions stretch at the Bronx Zoo. He gave the movements in his ten-minute routine alliterative names—hands, hips, head; grind, grate, grasp; crawl, curl, crouch; wave, weave, wing. “The essential thing is to go slowly,” he advised. A casual test shows that the Daily Dozen will not raise a drop of sweat on a desk-bound forty-seven-year-old writer. The exercises approximate what a moderately serious jogger might do to loosen up before starting real exercise.

Considering the modest investment of effort, the benefits claimed for such exercises were truly remarkable. Constipation and dyspepsia, which seem to have afflicted people back then more than they do now, would vanish. So would sluggish livers, following a few repetitions of the “liver squeezer,” a widely prescribed exercise that involved lying on the back and drawing the knees up to the chin. This was said to wring out the liver like a sponge. Preoccupation with fat was frowned on. “A prejudice against fat amounting to an abhorrence ought to be condemned,” wrote a Boston physician, Samuel Delano, in 1918. But if you did want to lose weight, it was no problem provided you conscientiously practiced the deep breathing that was part of most systems. “Deep, purposeful breathing in the open air prevents the accumulation of fat, as it acts like a pair of active bellows on a furnace fire,” said William J. Cromie, an instructor of physical education at the University of Pennsylvania.

Now and then a voice from the past expresses ideas about exercise not too far removed from present theories. As far back as 1890, a physical culturist named Edwin Checkley came out in favor of running, although he added sadly: “When I run for a few streets on a city thoroughfare, the populace look after me as if I were a ‘freak,’ or as if I were making off with something not belonging to me. …” Perhaps that explains why another pioneer jogger, Theodore Roosevelt, sometimes did his running at night while President, going out from the White House and trotting around the Washington Monument. Among medical men, Dudley A. Sargent, who directed physical education at Harvard from 1879 to 1919, sounded much like physicians today. Sustained, vigorous exertion that stimulates the heart and lungs strengthens the vital systems, he preached.

But where those of middle age or older were concerned, Sargent and the other exercise specialists who agreed with him generally cautioned against really strenuous workouts of the sort their theories seemed to require, such as long runs. Some of the authorities said that “gentle” running was safe, but they really meant “gentle.” C. Ward Crampton of New York, one of the first physicians to sound the alarm over the mounting number of heart attacks among Americans, insisted that the focus of exercise should be to strengthen the heart and that running was well suited for this purpose. But, he said in 1924, sixty-four steps “is sufficient for anyone.” That’s a couple of laps around the living room.

At the time, even that would have been considered overdoing it in some circles. It was commonly believed that everyone was endowed with a fixed, limited supply of “vitality” and that strenuous exercise could lead to premature exhaustion of the supply, followed by invalidism or early death. A 1931 article on exercise in Hygeia , a health magazine published for laymen by the American Medical Association, commented: “It seems that the more prodigiously we give of our vitality the sooner we exhaust it.”

To buttress their case, exponents of this theory seized on every instance of an athlete dying young. Such deaths were not rare in those days; athletes, like nonathletes, could be struck down in their prime by infectious diseases since conquered by antibiotics. But the foes of strenuous exercise claimed in such cases that the athletes had squandered their vitality, weakening their hearts and their defenses against disease. Arthur A. McGovern, the proprietor of a gym in New York, kept a scrapbook of obituaries of athletes who had died by the age of forty, presumably to show clients who might be tempted to push themselves too hard.