A variety of treadmill fitness and stress tests are available, but the commonly used treadmill ramp test is the Bruce protocol. It is the easiest to administer and is widely available in clinical and fitness locations. It assesses maximum oxygen uptake, or VO2max. It is a maximal test, so participants will exercise until they are physically unable to continue.
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This test can be used for all populations, such as average adults, athletes and older adults. For average adults and athletes, this test is meant to estimate VO2max, or maximum oxygen uptake. This is the amount of oxygen in milliliters your body can use per kilogram of body weight per minute. Results of VO2 max are expressed as mL/kg/min. The Bruce protocol is a stress test for older population to assess their risk for cardiovascular disease or abnormalities. Older adults use an EKG with nodes placed on their chest so a professional clinician can monitor heart patterns.
The Bruce protocol consists of a maximum of 10 three minute stages, according to Sports Fitness Advisor. Participant starts walking on the treadmill at 1.7 mph and an incline of 10 percent. Every stage the grade is increased by 2 percent. The speed is increased every stage starting at 1.7mph, and then to 2.5 mph, 3.4 mph, 4.2 mph, 5.0 mph, 5.5 mph, 6.0 mph, 6.5 mph, 7.0 mph and the tenth and final stage is 7.5 mph with an incline of 28 percent. This is the highest stage, but since it is a maximal test and the participant persists until they are too tired to continue, it will likely end long before it reaches that stage.
The time it takes to complete the test is the direct measurement in estimating VO2max. The exact formula provided by the American College of Sports Medicine is VO2max=14.7614.76 - (1.379 × T) + (0.451 × T²) - (0.012 × T³), where T is the time at which you stop the test. Or you can use a calculator (See References). The higher the VO2 max, the healthier you are considered. For participants having a stress test with EKG, the doctor monitors heart patterns. If the participant can exercise at up to 85 percent of their maximum heart rate without abnormal EKG patterns, they are considered healthy.
VO2 max is maximal oxygen consumption, but it also is a predictor of early death. Having low VO2max can be an indication that you need more cardiovascular activity to make your heart and lungs stronger and more efficient. The American Council on Exercise states that VO2max for average college age males and females should be 42 mL/kg/min and 38mL/kg/min respectively. According to a study in the "British Medical Journal," the Bruce Protocol has a 70 percent success rate in predicting coronary artery disease, or heart disease in older adults, making it one of the most effective methods.
The Bruce protocol should not be administered in older population or those suspected of heart disease. If the participant has had an acute myocardial infarction within four to six days, unstable angina, or chest pain in the last 48 hours, uncontrolled hypertension over 220/120mmHg, or recently had aortic surgery, do not administer test.
- Top End Sports: Bruce Protocol Stress Test
- “British Medical Journal;” Exercise Tolerance Testing; Jonathan Hill, Adam Timmis; May 2002.
- Sport Fitness Advisor: The Bruce Treadmill Test
- "Advanced Health and Fitness Specialist Manual”; American Council on Exercise; 2009