Health and Safety The Bruce Protocol Treadmill Test By Elizabeth Quinn, MS Elizabeth Quinn, MS Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics. Learn about our editorial process Updated on February 02, 2023 Reviewed Verywell Fit articles are reviewed by nutrition and exercise professionals. Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by John Honerkamp Reviewed by John Honerkamp LinkedIn Twitter John Honerkamp is an RRCA and USATF-certified running coach, celebrity marathon pacer, and recognized leader in the New York City running community. Learn about our Review Board Fact checked Verywell Fit content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication. Learn more. by Marley Hall Fact checked by Marley Hall LinkedIn Marley Hall is a writer and fact checker who is certified in clinical and translational research. Her work has been published in medical journals in the field of surgery, and she has received numerous awards for publication in education. Learn about our editorial process Print Verywell / Sabrina Jiang Table of Contents View All Table of Contents How It Works Measuring VO2 Max Test Cautions Test Alternatives The Bruce protocol treadmill test was designed by cardiologist Robert A. Bruce in 1963 as a non-invasive test to assess patients with suspected heart disease. In this capacity, is perhaps more widely known as a stress test or exercise tolerance test. Now, the Bruce protocol test is commonly used to help identify a person's level of aerobic endurance. It does this by providing an estimated maximal oxygen uptake or VO2 max. V02 max is a measure of an athlete's capacity to perform sustained exercise and is linked to aerobic endurance. Bruce Protocol Stages The Bruce protocol involves getting on a treadmill and increasing speed and incline every three minutes (in stages). The test stops when you've hit 85% of your maximum heart rate, your heart rate exceeds 115 beats per minute for two stages, or it is deemed that the test should no longer continue. If your heart rate changes more than six beats per minute between the second and third minute of any given stage, you are kept at the same speed and incline for an additional minute. This is because your heart rate has not achieved a steady state. Bruce Treadmill Test Stages, Speeds, and Inclines Stage Treadmill Speed Treadmill Incline 1 1.7 mph 10% grade 2 2.5 mph 12% grade 3 3.4 mph 14% grade 4 4.2 mph 16% grade 5 5.0 mph 18% grade 6 5.5 mph 20% grade 7 6.0 mph 22% grade Measuring VO2 Max With the Bruce Protocol Maximal oxygen uptake (VO2 max) refers to the maximum amount of oxygen that an individual can take in and use during intense or maximal exercise. It is measured as milliliters of oxygen used in one minute per kilogram of body weight (ml/kg/min). The Bruce treadmill test is an indirect maximal oxygen uptake test. It is considered indirect because it estimates VO2 max using a formula and the person's performance on a treadmill as the workload is increased. Other methods of measuring VO2 max are more cumbersome and require the direct collection and measurement of the oxygen volume and oxygen concentration of inhaled and exhaled air the athlete uses while running. Direct testing requires far more elaborate and sophisticated equipment and data collection than the formula based on time on the treadmill. When the Bruce protocol formula is used, T stands for total time on the treadmill and is measured as a fraction of a minute (a test time of 10 minutes 15 seconds would be written as T=10.25); and this formula changes based on sex. The length of time you spend on the treadmill is your test score and can be used to estimate your VO2 max value. During the test, blood pressure and ratings of perceived exertion are often also collected. Men: 14.8 - (1.379 x T) + (0.451 x T²) - (0.012 x T³) = VO2 max Women: 4.38 x T - 3.9 = V)2 max VO2 Max Norms for Men as Measured in ml/kg/min Age Very Poor Poor Fair Good Excellent Superior 13-19 <35.0 35.0-38.3 38.4-45.1 45.2-50.9 51.0-55.9 >55.9 20-29 <33.0 33.0-36.4 36.5-42.4 42.5-46.4 46.5-52.4 >52.4 30-39 <31.5 31.5-35.4 35.5-40.9 41.0-44.9 45.0-49.4 >49.4 40-49 <30.2 30.2-33.5 33.6-38.9 39.0-43.7 43.8-48.0 >48.0 50-59 <26.1 26.1-30.9 31.0-35.7 35.8-40.9 41.0-45.3 >45.3 60+ <20.5 20.5-26.0 26.1-32.2 32.3-36.4 36.5-44.2 >44.2 VO2 Max Norms for Women as Measured in ml/kg/min Age Very Poor Poor Fair Good Excellent Superior 13-19 <25.0 25.0-30.9 31.0-34.9 35.0-38.9 39.0-41.9 >41.9 20-29 <23.6 23.6-28.9 29.0-32.9 33.0-36.9 37.0-41.0 >41.0 30-39 <22.8 22.8-26.9 27.0-31.4 31.5-35.6 35.7-40.0 >40.0 40-49 <21.0 21.0-24.4 24.5-28.9 29.0-32.8 32.9-36.9 >36.9 50-59 <20.2 20.2-22.7 22.8-26.9 27.0-31.4 31.5-35.7 >35.7 60+ <17.5 17.5-20.1 20.2-24.4 24.5-30.2 30.3-31.4 >31.4 Bruce Treadmill Test Cautions Because the Bruce treadmill test is a maximal exercise tolerance test, it requires a physician's clearance and expert supervision. In an untrained individual or an athlete with an underlying heart condition, exercising to a maximal effort can lead to injury or heart events. While performing the test, clinicians monitor the patient's vital signs continuously and stop the test at any sign of trouble. If you take this test, be sure that your testing facilitator has the appropriate clinical expertise and has conducted such tests many times before you step on the treadmill. Alternatives to the Bruce Protocol The Bruce protocol is not the only treadmill test that can be used to assess your cardiorespiratory fitness. Two other options include the Balke & Ware treadmill exercise test and the Ebbeling single-stage treadmill test. Balke & Ware Treadmill Exercise Test Like with the Bruce protocol, the Balke & Ware treadmill exercise test is done in stages; however, these stages range from one to three minutes each. Another difference is that the speed is kept constant with the incline being the only thing that changes. If this exercise test is used, the goal is also to get the heart rate to 85% of its max, this time by beginning at a 0% incline and increasing by 2.5% every three minutes. Again, if any symptoms develop that warrant termination, the test is stopped. Ebbeling Single-Stage Treadmill Test The Ebbeling single-stage treadmill test is designed for individuals who are low-risk and otherwise healthy, yet not physically active. As its name implies, it has only one stage and that stage is just four minutes long. The speed remains constant with the incline raised to 5% after warming up. The speed is determined by the person's heart rate, generally falling somewhere between 2.0 and 4.5 mph (but this can be adjusted after the first minute if needed). If the heart rate varies by more than five beats per minute, the test can be extended another minute to get the final score. Using the Cooper Test 12-Minute Run to Check Aerobic Fitness 6 Sources Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Luong MW, Ignaszewski M, Taylor CM. Stress testing: a contribution from Dr. Robert A. Bruce, father of exercise physiology. B C Med J. 2016;58(2):70-76. American Council on Exercise. Treadmill exercise testing. Poole DC, Jones AM. Measurement of the maximum oxygen uptake V̇ o 2max : V̇ o 2peak is no longer acceptable. Journal of Applied Physiology. 2017;122(4):997-1002. doi:10.1152/japplphysiol.01063.2016 Fletcher GF, Ades PA, Kligfield P, et al. Exercise standards for testing and training: A scientific statement from the American Heart Association. Circulation. 2013;128(8):873-934. doi:10.1161/CIR.0b013e31829b5b44 Khurana E, Oommen ER. Determination of cardiovascular fitness in young healthy medical students. IAIM. 2016;3(10):74-78. Harvard Health Publishing. Harvard Medical School. Cardiac exercise stress testing: What it can and cannot tell you. Additional Reading Heyward VH, Gibson A. Advanced Fitness Assessment and Exercise Prescription, 7th Edition, The Cooper Institute for Aerobics Research, 2014. Kenney WL, Wilmore JH, Costill DL. Physiology of Sport and Exercise. Human Kinetics, 2012. By Elizabeth Quinn, MS Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. 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