The Bruce Test is commonly used treadmill exercise stress test. It was developed as a clinical test to evaluate patients with suspected coronary heart disease, though it can also be used to estimate cardiovascular fitness. See also a general description of Exercise Stress Tests. As this stress test is a maximal test performed commonly on people with heart problems, the test should be performed under the supervision of appropriately trained medical staff.
purpose: to evaluate cardiac function and fitness.
equipment required: treadmill, stopwatch, a 12-lead electrocardiograph (ECG) machine and leads, sticking tape, clips.
pre-test: Explain the test procedures to the subject. Perform screening of health risks and obtain informed consent. Prepare forms and record basic information such as age, height, body weight, gender, test conditions. Perform an appropriate warm-up. Attach ECG leads if required. See more details of pre-test procedures.
procedure: Exercise is performed on a treadmill. If required, the leads of the ECG are placed on the chest wall. The treadmill is started at 2.74 km/hr (1.7 mph) and at a gradient (or incline) of 10%. At three minute intervals the incline of the treadmill increases by 2%, and the speed increases as shown in the table below. (see Bruce Test video examples). The test should be stopped when the subject cannot continue due to fatigue or pain, or due to many other medical indications.
| Stage | Speed (km/hr) | Speed (mph) | Gradient |
|---|---|---|---|
| 1 | 2.74 | 1.7 | 10 |
| 2 | 4.02 | 2.5 | 12 |
| 3 | 5.47 | 3.4 | 14 |
| 4 | 6.76 | 4.2 | 16 |
| 5 | 8.05 | 5.0 | 18 |
| 6 | 8.85 | 5.5 | 20 |
| 7 | 9.65 | 6.0 | 22 |
| 8 | 10.46 | 6.5 | 24 |
| 9 | 11.26 | 7.0 | 26 |
| 10 | 12.07 | 7.5 | 28 |
modifications: There is a commonly used Modified Bruce protocol, which starts at a lower workload than the standard test, and is typically used for elderly or sedentary patients. The fist 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.
exercise stress testing
results: 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) (this formula is the one used for the calculator below)
Women: VO2max (ml/kg/min) = 2.94 x T + 3.74
Women: VO2max (ml/kg/min) = 4.38 × T - 3.9Men: VO2max (ml/kg/min) = 2.94 x T + 7.65
Young Men: VO2max (ml/kg/min) = 3.62 x T + 3.91ref: ACSM's Health-Related Physical Fitness Assessment Manual
VO2max calculator: Enter your total time on the Bruce Test in the box below and click calculate. The time in minutes should be expressed in minutes and fractions of a minute e.g. 9 minutes 15 seconds = 9.25 minutes.
target population: Patients with suspected coronary heart disease, and athletes in sports in which aerobic endurance is a important component, such as distance runners.
advantages: You can also get measurement of maximum heart rate by recording heart rate during the test, which can be used in training programs to set intensity.
disadvantages: Relatively large time and costs required. Specialist training is required to interpret exercise ECG traces.
other comments: The original Bruce protocol was developed in 1963 by Dr. Robert. A. Bruce. Other similar exercise stress test protocols include Astrand, Naughton and Balke.
caution: This test is a maximal test, which requires a reasonable level of fitness. If used recreational athletes or people with health problems, injuries or low fitness levels, please have medical assistance on hand.
Any comments, suggestions, or corrections? Please let us know.
Commenting is closed on this page, though you can read some previous comments below which may answer some of your questions.
The Bruce protocol's stages are both too long (3 minutes) and way too discontinuous to provide an accurate graded measure of aerobic fitness for the general population. It also doesn't provide adequate time to warm up, which can be dangerous for older people who may have heart conditions.
Stage 4, which begins to test the upper level of fitness, requires a speed of 4.2mph up a 16% grade. This is a 14.6 MET level exercise that requires a VO2 Max of over 51, which would put a man aged 36-45 in the top 5-10% for his age category, while Stages 5 (5mph at 18% grade) and 6 (5.5mph at 20%) require that one be able to jog, which many older people aren't trained for and may not be able to do anyway due to foot, knee, hip, or back problems. How many of the people reading this have ever tried to walk at 5mph even on the flat?
Even extremely fit and fast bicyclists, rowers, or runners who don't train on steep hills, or who aren't super lean like elite distance runners, are going to be at a grave disadvantage at even the Bruce's beginning grade of 10%, never mind 16-20% yet these people may be more aerobically fit than the super lean runners who train regularly on steep hills.
The Balke protocol is much better as it is conducted throughout at a fixed speed that is a normal walking pace: 3.3mph for men, and 3mph for women. The grade begins at 0 and is bumped 1% for each minute (except for the first bump, which is 2%). The Balke thus accommodates even people with severe limitations and handicaps, yet provides an accurate graded assessment of their capabilities without washing them out at the first or second stage bump. On the other end of the scale, the Cooper Aerobics Clinic, which has been using the Balke Protocol on many tens of thousands of patients for over 40 years now, and with few adverse results, has a desirable modification to the Balke that tops the grade out at 25% after 25 minutes, and adds .2mph to the speed for each minute thereafter. This makes it possible for superfit people who can keep going that long to add a few minutes before having to switch to jogging that they may not be trained for.
The ECG is to look for ST segment changes such as depression or elevation.
The stages are specifically designed with a clinical setting in mind. Stage 1 is extremely slow and is designed for older patients who can't walk quickly or haven't walked on a treadmill before. The subsequent stages are then made with the intention of increasing the patient's heart rate quickly so they are not walking for longer than 6-12 minutes usually.
The test can only be described as diagnostic if 85% of the patient's heart rate is acheieved and maintained for longer than a minute, however most physiologists (such as myself) will attempt to acheive 100% of the THR and maintain it for a minute in order for the patient to have completed a conclusive test (as conclusive as a normal treadmill can be, but that's another debate).
There are numerous other end points, such as a systolic BP over 230mmHg or diastolic BP over 100mmHg, the presence of a serious/life-threatening arrhythmia, such as VT, AF, VF, an SVT or even left bundle branch block. It may also be stopped if 2mm of ST depression or elevation is noted while the patient is symptomatic OR 3mm of ST depression/elevation with no symptoms reported by the patient.
