The red double-decker buses of London are famous around the world. Less well known is the fact that the first quantitative, systematic medical study of exercise took place aboard them. In the late nineteen-forties, a young British epidemiologist named Jerry Morris was looking through the postmortem folios of a hospital in the East End when he noticed an alarming increase in the frequency of heart attacks during the first half of the twentieth century. Others had seen the same trend but nobody had an explanation. Morris, however, suspected that the frequency of heart attack might correlate with sedentary occupations, and so he turned to the double-decker bus. “If you’ve been to London, then you know,” Bill Hayes, a writer and photographer who is at work on a history of exercise, told me. “The driver sits at the front and drives the bus, and the conductor hops on and off the bus and climbs up and down the stairs taking tickets and getting people to their seats.” Of the thousands of drivers and conductors working on London’s buses at the time, the vast majority were men, and most came from a similar social background. The only substantial difference between them, in aggregate, was their daily activity levels.
Morris spent hours on buses, monitoring how much time the drivers spent sitting (ninety per cent of their shift, on average) and counting the numbers of steps the conductors climbed each day (between five hundred and seven hundred and fifty). Then, with the help of Britain’s newly established National Health Service, he went through the busmen’s medical records. Morris was stunned by how powerfully the data bore out his initial hypothesis: the sedentary drivers were almost twice as likely as the mobile conductors to drop dead of a sudden heart attack. He followed up with what he described as an “epidemiology of uniforms”—a painstaking comparison of the waist size of trousers issued to both groups, at every age—which established that drivers were significantly bulkier around the midsection than their conductor peers. Morris later confirmed a similar correlation in postal workers, with sedentary counter clerks showing a much higher incidence of cardiovascular disease than postmen, who did their rounds on foot or by bike.
When the papers presenting these findings appeared in The Lancet, Morris’s conclusion—that exercise was medically important and that its absence resulted in death and disease—was met with surprise and even disbelief. “Puzzling,” the Aberdeen Evening Express declared, noting that Morris’s studies failed to take into account what were then generally accepted risk factors for heart attack, such as a temperamental propensity toward “nervous strain.” Mainstream medical wisdom held that heart attacks were most likely the result of high blood pressure, and that physical activity had nothing to do with either.

A Pill to Make Exercise Obsolete