Each exercise stage lasts for 3 minutes, after which the treadmill speed and inclination increased. Bruce chose 3 min stages as this provided ‘the optimal compromise between requirements for physiological adaptations and minimal time for expeditious testing’. The protocol starts with a gentle, submaximal stress and gradually progresses to higher and higher workload. The Bruce protocol exercise test is still used as the first-line investigation in patients with suspected coronary artery disease around the world although it has competition from newer non-invasive imaging technologies such as nuclear perfusion scanning and exercise echocardiography which have been shown to have better diagnostic accuracy.
Robert Bruce was born in 1916 and 7 years after graduation became the first chief of cardiology at the University of Washington School of Medicine in Seattle where he spent the rest of his career. His landmark 1963 paper first described the multistage protocol and despite his death 10 years ago his name lives on in the minds of generations of doctors as the ‘Bruce protocol’ treadmill test is used daily around the world.