In the 1953, Professor Jerry Morris and his colleagues published a ground-breaking study, finding that drivers of London's double-decker buses, compared to conductors, were more likely to have cardiovascular disease and die suddenly from blood clots in the heart. The bus drivers were sedentary throughout their shift, while the conductors were actively climbing up and down stairs during their shift. As a follow-up, Morris found that postal workers, who walked and biked to deliver the mail,...
