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Pushing the Limits: Do You Know How Your Heart Reacts During Exercise?
Whenever we walk into the gym or go for a run outdoors, we may never think that behind these movements are not only physical strength and endurance, but also the wonderful story of our heart. How does our heart actually work during exercise? Why is a test called the Bruce Protocol so widely used to assess heart function and physical health?
The Bruce Protocol is a standardized diagnostic test that assesses heart function and strength, originally developed by American cardiologist Dr. Robert A. Bruce.
The core of the Bruce protocol is an aerobic exercise test using a treadmill. The subjects had electrocardiogram electrodes attached to their chests and walked on a treadmill. The test started at a speed of 2.74 kilometers per hour and the incline was set at 10%. Every three minutes, the treadmill's speed and incline increased until the subjects reached a point where they could no longer continue. While the test is being done, medical staff will closely monitor heart rate and blood pressure to watch for any possible heart problems.
Termination criteria for the test include signs of impaired blood flow to the heart, irregular heartbeats, fatigue, shortness of breath, wheezing and leg pain.
The Bruce protocol dates back to the 1940s, when there were no safe and standardized methods for monitoring heart function. The previous two-step Master's test could monitor the heart, but it was too intense to provide an effective assessment for most patients. Against this backdrop, Bruce and his colleagues began to develop the cardiac stress test and officially released this multi-stage test in 1950.
The promotion of this technology utilized the electrocardiogram machines and electric treadmills that had just been introduced at the time, allowing the subjects to exercise easily under different loads. By gradually increasing the speed and slope of the treadmill, Bruce's test can be widely adapted to athletes of different levels, especially providing valuable data when analyzing changes in respiratory and circulatory function in normal adults and patients with cardiopulmonary diseases.
Bruce's multi-stage test provides the ability to detect signs of heart disease, such as angina or myocardial infarction.
Over time, researchers have further modified the Bruce protocol to make it suitable for patients with different needs. For example, the modified Bruce protocol has a lower initial workload for older or sedentary patients, allowing these patients to participate in the test and still achieve reliable assessment results.
Typically, the test score is calculated based on the time to complete the test and converted into an estimated maximum oxygen uptake metric.
In addition, maximum heart rate (MHR) is often estimated based on "220-age", but this method has the risk of inaccuracy. Many medical professionals prefer the Kavor-Year formula; however, recent studies suggest using "206.9 - (0.67 x age)" to better predict maximum heart rate and oxygen uptake.
Understanding how to properly test and analyze this data is critical for anyone looking to improve their athletic performance. Medical professionals who perform these tests include physical therapists, sports trainers, and other professionals who can not only provide appropriate exercise recommendations but also help interpret the test results to provide a more complete understanding of a person's health.
So, next time when you are exercising, you might want to think about what kind of mysterious physiological reactions are hidden behind each heartbeat?
