The Bruce treadmill test has now become a standardized procedure used to evaluate the cardiovascular fitness of athletes… or anyone else for that matter.
The original Bruce protocol was developed by DR. Robert. A. Bruce in 1963.
This protocol for a multilevel treadmill test was developed as a means to detect chest pain and discomfort in patients as well as any evidence of possible heart attacks or ischaemic heart disease.
The test is now used:
- For athletes or coaches, to check the development of a sportsperson’s general endurance or, what is known as VO2max. VO2max is simply the most amount of oxygen that a person can consume and utilize and is measured by the volume of oxygen per minute per kg body weight per time (mL/kg/min).
- For patients with suspected coronary heart disease. The Bruce treadmill test can be used by doctors as a non-invasive test procedure to determine whether there are any abnormalities in the electrical “firing patterns” of the myocardium (heart muscle).
When it’s used in a medical context a treadmill test like this is often referred to an Exercise Tolerance Test or Exercise Stress Test.
The Bruce Treadmill test simply refers to the protocol used. Other protocols include Naughton, Astrand and Balke.
At 3-minute intervals both the speed and incline of the treadmill are increased. This can be better explained with the help of the following table…
|The Bruce Treadmill Test Protocol|
|Level||Time (mins)||Speed (km/hr)||Grade (%)|
So, from the chart above, we see that the test starts at 2.74km/hr at a gradient or incline of 10%. At minute 3 the speed is increased to 4.02km/hr and the gradient increased to 12%.
This is a maximal test – which means that the individual must continue until they are fatigued. Needless to say in a clinical setting, other parameters (such as blood pressure and ECG readings etc.) are used to determine the end of the test.
The Bruce Treadmill Test is also what’s known as an indirect test. It only estimates VO2max using the formula below (as opposed to direct tests that use gas analysers to measure respired gases)…
VO2max = 14.8 – (1.379 x T) + (0.451 x T2) – (0.012 x T3)
VO2 max = 4.38 x T – 3.9
In both cases T denotes the time in minutes spent on the treadmill. For example 10 min and 45 sec would be expressed as 10.75 minutes. Athletes can analyze their performances by comparing past and present test results.
They can also compare them to other athletes in their sport, although VO2max is certainly not the only indicator of performance – even in endurance sports.