Bruce Protocol
The Bruce protocol is a diagnostic test
Cardiology diagnostic tests and procedures
The diagnostic tests in cardiology are methods of identifying heart conditions associated with healthy vs. unhealthy, pathologic, heart function.-History:...

 used in the evaluation of cardiac
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

 function, developed by Robert A. Bruce
Robert A. Bruce
Robert Arthur Bruce was an internationally recognized cardiologist and a professor at the University of Washington...



Before the development of the Bruce Protocol there was no safe, standardized protocol that could be used to monitor cardiac function in exercising patients. Master's Two-Step test was sometimes used, but it was too strenuous for many patients, and inadequate for the assessment of respiratory and circulatory function during varying amounts of exercise. Most physicians relied upon patients' complaints about exertion, and examined them only at rest.

To address these problems, Bruce and his colleagues began to develop a treadmill
A treadmill is an exercise machine for running or walking while staying in one place. The word treadmill traditionally refers to a type of mill which was operated by a person or animal treading steps of a wheel to grind grain...

 exercise test. The test made extensive use of relatively new technological developments in electrocardiographs and motorized treadmills. A Bruce exercise test involved walking on a treadmill while the heart was monitored by an electrocardiograph with various electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

s attached to the body. Ventilation
Ventilation (physiology)
In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...

 volumes and respiratory gas exchanges were also monitored, before, during and after exercise. Because the treadmill speed and inclination could be adjusted, this physical activity was tolerated by most patients. Initial experiments involved a single-stage test, in which subjects walked for 10 minutes on the treadmill at a fixed workload. Bruce's first reports on treadmill exercise tests, published in 1949, analyzed minute-by-minute changes in respiratory and circulatory function of normal adults and patients with heart or lung ailments.

In 1950 Bruce joined the University of Washington
University of Washington
University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...

, where he continued research on the single-stage test, particularly as a predictor of the success of surgery for valvular or congenital heart disease. Later he developed the multistage test, consisting of several stages of progressively greater workloads. It was this multistage test, a description of which was first published in 1963, that became known as the Bruce Protocol. In the initial paper, Bruce reported that the test could detect signs of such conditions as angina pectoris, a previous heart attack, or a ventricular aneurysm
An aneurysm or aneurism is a localized, blood-filled balloon-like bulge in the wall of a blood vessel. Aneurysms can commonly occur in arteries at the base of the brain and an aortic aneurysm occurs in the main artery carrying blood from the left ventricle of the heart...

. Bruce and colleagues also demonstrated that exercise testing was useful in screening apparently healthy people for early signs of coronary artery disease.

Typically during a Bruce Protocol Heart Rate and Rating of Perceived Exertion are taken every minute and Blood Pressure is taken at the end of each stage (every three minutes).

There are Bruce Protocol Tables available for Maximal and Sub Maximal (more practical with the majority of the non-athletic or competitively athletic population) efforts (see below).

Bruce Protocol (Sub Maximal Table)

Stage Minutes % grade km/h MPH MET
Metabolic equivalent
The metabolic equivalent of task , or simply metabolic equivalent, is a physiological concept expressing the energy cost of physical activities as multiples of resting metabolic rate and is defined as the ratio of metabolic rate during a specific physical activity to a reference rate of...

1 3 10 2.7 1.7 4.7
2 6 12 4.0 2.5 7.0
3 9 14 5.4 3.4 10.1
4 12 16 6.7 4.2 12.9
5 15 18 8.0 5.0 15.0
6 18 20 8.8 5.5 16.9
7 21 22 9.6 6.0 19.1


The Modified Bruce protocol starts at a lower workload than the standard test and is typically used for elderly or sedentary patients. The first two stages of the Modified Bruce Test are performed at a 1.7 mph and 0% grade and 1.7 mph and 5% grade, and the third stage corresponds to the first stage of the Standard Bruce Test protocol as listed above.


The test score is the time taken on the test, in minutes. This can also be converted to an estimated VO2max score using the calculator below and the following formulas, where the value "T" is the total time completed (expressed in minutes and fractions of a minute e.g. 9 minutes 15 seconds = 9.25 minutes). As with many exercise test equations, there have been many regression equations developed that may give varying results. If possible, use the one derived from a similar population and which best suits your needs.
  • VO2max (ml/kg/min) = 14.76 - (1.379 × T) + (0.451 × T²) - (0.012 × T³)

  • Women: VO2max (ml/kg/min) = 2.94 x T + 3.74

  • Women: VO2max (ml/kg/min) = 4.38 × T - 3.9

  • Men: VO2max (ml/kg/min) = 2.94 x T + 7.65

  • Young Men: VO2max (ml/kg/min) = 3.62 x T + 3.91

ref: ACSM's Health-Related Physical Fitness Assessment Manual

Underlying Heart Rate Formulas

the typical way we calculate MHR is with the formula 220-age. This formula is a bit controversial because it doesn't reflect the differences in heart rate according to age. The underlying heart rate formula most often used for the Bruce is outdated Karvonen formula (below).

A more accurate formula, offered in a study published in the journal, Medicine & Science in Sports & Exercise, is 206.9 - (0.67 x age) which can also be used to more accurately determine VO2 Max, but may produce significantly different results.

A diagnostician (e.g., personal trainer, doctor, athletic trainer, nurse, medical professional, dietitian, etc.) may be best served to conduct the test twice using both parameters and forumlas.

Karvonen method

The Karvonen method factors in resting heart rate (HRrest) to calculate target heart rate (THR), using a range of 50–85%:
THR = ((HRmax − HRrest) × %Intensity) + HRrest

Example for someone with a HRmax of 180 and a HRrest of 70:

50% intensity: ((180 − 70) × 0.50) + 70 = 125 bpm

85% intensity: ((180 − 70) × 0.85) + 70 = 163 bpm
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