The Bruce Protocol Treadmill test is mainly used for evaluating cardiac fitness and function. This test was designed by Dr. Robert Bruce in 1963, and was initially used for assessing patients with heart diseases. The test has now become a popular way of testing VO2 max in athletes and others as well. VO2 max is closely related to aerobic endurance. It is also an important factor for determining a person’s capability to perform sustained exercise.
Procedure of the Test
The Bruce Protocol Treadmill Test is performed on a treadmill. The test begins by running at an incline or gradient of 10% and speed of 2.74 km/h. The incline and speed of the treadmill is increased every three minutes. Generally the incline is increased by 2% at every level. The level is increased as follows:
- Level 1 - 10% Incline at 2.4 km/h
- Level 2 - 12% Incline at 4.02 km/h
- Level 3 - 14% Incline at 5.47 km/h
- Level 4 - 16% Incline at 6.76 km/h
- Level 5 - 18% Incline at 8.05 km/h
- Level 6 - 20% Incline at 8.85 km/h
- Level 7 - 22% Incline at 9.65 km/h
- Level 8 - 24% Incline at 10.46 km/h
- Level 9 - 26% Incline at 11.26 km/h
- Level 10 - 28% Incline at 12.07 km/h
As the Bruce Protocol Treadmill test is a maximal fitness test, you have to run continuously until you are tired. The result is the maximum time in minutes spent on the test. VO2 max is calculated using a formula and the recorded minutes. Due to this, the test is also known as an indirect test. The total time (T) on the treadmill is measured as a part of a minute. For instance, 9 minutes and 30 seconds will be noted as T=9.5. Results of this test are measured using different formulas for women and men.
VO2max = 4.38 x T – 3.9
VO2max = 14.8 – (1.379 x T) + (0.451 x T2) – (0.012 x T3)
The Bruce Protocol Treadmill Test is used by athletes to analyze their performance by comparing present results to past ones. This test is commonly used by coaches and athletes for checking the general level of endurance. It is also used as a non-invasive test method by doctors. It helps to determine any abnormalities that maybe present in the heart muscle’s electrical "firing patterns."
Modifications to the Test
The Bruce Protocol Treadmill Test has been slightly modified for sedentary and elderly patients. This modified test begins at a lower workload compared to the standard test. Here, the first level is performed at 0% incline and 2.74 km/h. The second level is done at 5% incline and 2.74 km/h. The third level matches the first level of the Standard Bruce Protocol Test.
The standard Bruce Protocol Test is also performed in clinical environments to determine other parameters like ECG readings and blood pressure. In these cases, the test is known as an exercise tolerance test or stress test. The Bruce Protocol Test should be performed with adequate safety supervision, accommodations and physician approval for best results.