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The Conductor’s Stairs: How a London Bus Gave Us the Idea of Exercise
In 1949, two men worked on every London double-decker bus. One sat in the cab at the front and drove all day. The other worked the platform at the back, took the fares, and climbed the stairs to the top deck again and again. They were men of much the same social class, and they worked the same shifts on the same bus.
A doctor named Jerry Morris looked at their sickness records and saw a gap between them. That gap became one of the founding results of a whole field of research. It also seeded an idea you carry without noticing: that health comes from a special activity called exercise, done at a special time, in special clothes.
The bus story is usually told as a neat fable: active men lived, sedentary men did not, go for a run. The real story is better. It includes an argument about trousers, a quiet admission that the first result was partly wrong, and a conclusion Morris reached forty years later that the field has since half walked back. Each step of it tells you something about the movement in your own week.
A heart problem nobody could explain
After the Second World War, British doctors faced a puzzle. Coronary heart disease had become a leading cause of death in middle-aged men, and nobody could say why. The usual suspects of the day were heredity, stress, the pace of modern life, and rich food. Physical activity was not on most lists. Much medical caution leaned the other way: after a heart attack, patients were often kept in bed for weeks.
Morris came to this question from an unusual direction. He was born in Liverpool in 1910 to a Jewish family that had left Poland, and he grew up poor in Glasgow. He trained in medicine in Glasgow and London, served in the army in India and Burma during the war, and came back to build a career on the idea that disease has social causes as well as biological ones. In 1948 the Medical Research Council gave him a small unit at the Central Middlesex Hospital to study exactly that. The biographical record at the Royal College of Physicians credits him with showing how much of disease is shaped by the way people live and work.
His method was simple and slightly radical for its time. Instead of studying patients who were already sick, he would study whole groups of working people and ask which jobs went with more heart disease. Occupations were a natural experiment. Society had already sorted millions of men into different daily routines. All he had to do was count.
Thirty-one thousand busmen and one gap
London Transport was a gift for this kind of work. It employed tens of thousands of men in a few well-defined grades, kept careful sickness and absence records, and had its own medical department. Morris and his colleagues, J. A. Heady and P. A. B. Raffle among them, arranged access to those records with the company's chief medical officer. They followed about 31,000 drivers, conductors, motormen and guards aged 35 to 64 through 1949 and 1950, and they traced every case of coronary heart disease through general practitioners, hospitals and death certificates.
The result appeared in The Lancet in November 1953, in two parts. Drivers had about 2.7 first coronary events per 1,000 men per year. Conductors had about 1.9. The difference in the most serious outcomes was sharper. When conductors did become ill, the disease more often showed up first as chest pain rather than as a sudden fatal event, and it tended to come later in life. Sudden deaths were markedly more common among the drivers.
Morris did not stop at one employer. The same papers compared postal workers. Postmen who walked or cycled their rounds had lower rates than the clerks and telephonists who sat at counters and switchboards, and men in intermediate jobs fell between the two. Two different industries, two different types of movement, the same direction of result.
What did the conductors actually do? A later review in the British Columbia Medical Journal puts their load at roughly 500 to 750 stair steps per working day. The original papers do not record heart rates, and nobody timed the climbs. What is clear is the pattern: short, repeated bursts of uphill effort, spread across a long shift, with no gym and no intention behind them.
The original data, 1953
First coronary events per 1,000 men per year
Shock, disbelief, and three years of checking
It is easy to forget how odd this result sounded. The Royal College of Physicians' account says the paper was met with general shock and disbelief. Before it appeared, Morris had spent about three years on the analysis and had invited sceptics to attack the data again and again. That is a man who knew a strange result needs more checking than an expected one.
The obvious objection came fast. Maybe the job did not change the men. Maybe different men chose the jobs. A man who already felt unwell, or who was heavier and less fit, might prefer to sit in a cab. A lighter, more restless man might choose the stairs. The conductors' advantage would then be a fact about recruitment, not about stairs.
Morris raised this possibility himself in the 1953 papers and listed the other candidate explanations, including the mental strain of driving in London traffic. Then he went looking for a way to test it, and he found one in a place no cardiologist had thought to look.
The argument about trousers
London Transport issued uniforms. Uniforms come in sizes. Sizes are written down. So Morris and his team pulled the uniform records of three central garages, covering more than 2,000 drivers and conductors, looking at the waist size of the trousers and the chest size of the jackets.
The result, published in 1956, was uncomfortable for the clean version of the story. Drivers were bigger around the waist and chest than conductors of the same height and weight, and the difference was there even among the youngest men, before years of driving could have done much. In 1967 another researcher, R. M. Oliver, went further back still. He measured new recruits before they started work. His paper found that men entering driver training were already heavier and bigger round the waist than men entering conductor training, partly because they were taller, and that they carried more skin fat even allowing for height. Some of the gap had walked onto the bus with them.
This is the part of the story that usually gets left out, and it is the most honest part. It did not destroy the finding. In the uniform data, drivers still had higher rates of sudden death than conductors of the same size. Body shape explained some of the difference but not all of it. What remained was a smaller, harder-won result, and Morris treated it that way. He did not declare victory. He changed his population.
The move to leisure time
By the 1960s Morris had a new problem. Jobs like the conductor's were a shrinking share of work, and the men who still did them were not a random sample, as the trouser data had shown. If activity mattered, the place to find it in a modern population was no longer the job. It was what people did after the job.
So he turned to the most sedentary group he could find: executive-grade civil servants. These men sat at desks all day, which made their free time the only variable worth studying. In the early studies the men logged what they did, in five-minute blocks, over two days. The first big report, in The Lancet in 1973, followed nearly 17,000 of them. Men who recorded vigorous activity, defined as work at a peak rate of about 7.5 kilocalories per minute, had a markedly lower rate of coronary disease than men who did not.
The detail that matters is what did not show up. According to Simon Kuper's later profile of Morris in the Financial Times, most of these men gardened, and Morris had half expected that to count. In his data it did not. Only the hard stuff seemed to matter.
The narrowing: only vigorous exercise counts
The clearest statement of this came in 1990, in the British Heart Journal. Morris and colleagues followed 9,376 civil servants aged 45 to 64 for a little over nine years. The roughly one man in eleven who often played vigorous sports, cycled a lot, or walked fast, faster than about 6.4 km/h, had less than half the coronary disease of the rest. When the same activities were done gently, the paper reported no link at all, and neither was there one for high totals of general physical activity. A sporting past did not count either. It had to be current.
Morris wrote this up with real care. He noted that the vigorous exercisers were a favourably selected group, the same objection that had followed him since the buses, and showed that their advantage held across the other risk factors he measured. His conclusion was specific: aerobic, vigorous, habitual, with a threshold of intensity below which he could find nothing.
This is the moment the idea of exercise as we know it locked into place. Health came from a deliberate session, hard enough to make you breathe heavily, done regularly, in your own time. Much of the fitness culture that followed, from aerobics classes to heart-rate-zone dashboards, fits inside that frame. Morris did not invent jogging. But his data gave scientific cover to the belief that the workout is the unit of health, and that the rest of the day does not really count.
Notice the irony. His first and most famous result came from men who never did a workout in their lives. The conductors were not exercising. They were working, and the work happened to include stairs.
How it reached your wrist
For a long time, public guidance followed the narrow version. As recently as the WHO's 2010 recommendations, activity was counted only in bouts of at least ten minutes. The logic was close to Morris's 1990 threshold: below a certain dose and duration, it was assumed, the body did not register the effort.
What changed was measurement. Morris had questionnaires and diaries, and people are poor at remembering light activity. Nobody writes down the walk to the printer. When large studies began to put accelerometers on people's wrists and hips, the light movement that diaries missed became visible, and it turned out to carry a signal of its own. The World Health Organization's 2020 guidelines reflect that shift. They still recommend 150 to 300 minutes of moderate activity, or 75 to 150 minutes of vigorous activity, each week. But they dropped the ten-minute rule, said plainly that some activity is better than none, and added advice to cut long stretches of sitting. The short version that circulated was "every move counts".
So the line from the buses to your phone has a curve in it. The step count on your watch, the stand reminder, the stairs badge: these are the conductor's working day, rediscovered by sensors, after forty years in which the science had mostly looked past it. You can read more on the modern evidence for stair climbing and for short bursts of everyday movement in our earlier guides.
Seventy years in one line
How the idea of useful movement narrowed, then widened
The twist nobody expected: work is not the same as exercise
If the story ended there, it would be tidy: right in 1953, too strict in 1990, rescued by sensors. But the evidence has one more turn.
Over the past two decades, large studies of people in physically demanding jobs have often failed to find the benefit you would expect. Heavy manual work, carried on for a whole career, does not reliably show the same favourable associations as activity in free time, and in some cohorts it points the other way. Andreas Holtermann and colleagues called this the physical activity paradox in the British Journal of Sports Medicine in 2018. They offered six possible reasons. Work activity is often too low in intensity to build fitness and too long to allow recovery. It keeps heart rate raised for hours without the rest periods that follow a training session. It involves static postures and heavy lifting rather than rhythmic movement. And workers rarely control when and how they do it.
The paradox should not be read as a finding that work is bad for you, and the research is still sorting out how much of it reflects income, smoking, and the other burdens that come with manual jobs. But it raises a fair question about the busmen. Why did the conductors seem to do well when so many modern manual workers do not?
Nobody can answer that from 1950s records, and it would be dishonest to pretend otherwise. One plausible reading is the shape of their effort. Climbing a bus staircase is short, rhythmic, and hard enough to raise your breathing for a moment. It is followed by rest while you take fares. Hundreds of times a shift, it looks less like a day of labour and more like a scattered set of tiny intervals. That is a hypothesis, not a fact. But it fits both Morris's later threshold of intensity and the modern finding that movement counts, which is a rare thing: a story where both sides of an old argument may have been looking at the same stairs.
What the story is actually evidence for
Strip away the fable and three things remain, and each comes with its limits.
First, how you move through an ordinary day is linked with long-term health, and not only through planned workouts. That was Morris's first result, and modern device-based studies support the broad pattern. These are still observational links. They describe what active people tend to experience, not a guarantee for any one person.
Second, intensity seems to carry weight of its own. Morris's civil servants showed it with diaries, and later studies with better tools have generally agreed that harder effort is linked with more benefit per minute. You do not need long sessions to get some of it.
Third, selection never goes away. The fit choose fitness, the conductors chose the platform, and the vigorous civil servants were healthier to begin with. Morris spent forty years fighting this objection and never fully defeated it, because no observational study can. The right response is not to dismiss the evidence but to hold it at its true weight: strong, consistent, and still a set of associations. A historical frame does not turn 1950s sickness records into proof of what any routine will do for you now.
The man who kept walking
Morris retired as professor of social medicine at the London School of Hygiene and Tropical Medicine in 1975 and kept working there until a few weeks before his death in October 2009, aged 99. In 1996 he received an Olympic award for sport and exercise science. Kuper's Financial Times profile, published about six weeks before he died, described his own routine: years of swimming, jogging on Hampstead Heath from the 1960s, and stairs at work. It is a nice detail, and it should be read as nothing more than that. One long life is a story, not a data point.
What his career does show is a way of thinking. He invited attacks on a surprising result, measured trousers when the obvious objection came, and changed his population when the first one stopped being useful. He also narrowed his conclusion further than later data supported. Keep both lessons: the rigour, and the knowledge that one era's rigour can still miss what the next era's instruments see.
The bottom line
The modern idea of exercise was built on men who never exercised. Their health advantage was real but smaller than the fable, partly explained by who chose the job, and it came from short, repeated, slightly breathless effort spread across a working day. This week, notice the conductor's stairs in your own life: the flights you take, the brisk walk between meetings, the short climbs that make you breathe hard for half a minute. They are not a substitute for regular, deliberate sessions, which still carry the best evidence. But they are not nothing, and the history of the busmen is the history of science slowly learning to count them again. If you have a heart condition or have been inactive for a long time, talk to your doctor before you add hard efforts.
