The bus study that started exercise science
In 1953, a London doctor compared the men who drove double-decker buses with the men who ran up and down the stairs collecting tickets.
The short version
- Jerry Morris found bus conductors had about half the heart attacks and sudden deaths of bus drivers.
- The conductors climbed hundreds of stairs a shift. The drivers sat.
- A later check found conductors were slimmer even when hired, a clue that other factors were at play.
The study
Jerry Morris and colleagues published their study of London Transport workers in The Lancet in 1953. Drivers sat for their whole shift. Conductors walked the bus and climbed the stairs of double-decker buses all day. The conductors had roughly half the rate of heart attacks and sudden cardiac death. A similar pattern showed up between postmen who walked their routes and office-based staff.
The twist
Morris kept digging. His team checked the uniform sizes issued to new hires and found conductors already had smaller waists than drivers on their first day. So some of the difference may have come from the kind of person who took each job, not only from the stairs. Today this is called confounding.
How it held up
Decades of later research, including trials, confirmed that physical activity lowers heart disease risk. Morris’s original comparison wasn’t perfect, but his core idea was right, and he went on to study leisure-time exercise in office workers.
The modern version
Today’s question is less about jobs and more about sitting time. A 2023 study found five-minute walks every half hour of sitting improved blood pressure and blood sugar. See our movement guide.
Sources
Educational information, not medical advice. Read our medical disclaimer.